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doi: 10.1130/GES00872.1 published online 11 October 2013;Geosphere

and Ross H. WilliamsMiriam E. Katz, James V. Browning, Kenneth G. Miller, Donald H. Monteverde, Gregory S. Mountain foraminifera: Insights on New Jersey shelf architecture, IODP Expedition 313Paleobathymetry and sequence stratigraphic interpretations from benthic

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Paleobathymetry and sequence stratigraphic interpretations from benthic foraminifera: Insights on New Jersey

shelf architecture, IODP Expedition 313

Miriam E. Katz1, James V. Browning2, Kenneth G. Miller2, Donald H. Monteverde2,3, Gregory S. Mountain2, and Ross H. Williams1,*1Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180, USA2Department of Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey 08854, USA3New Jersey Geological Survey, PO Box 427, Trenton New Jersey 07640, USA

ABSTRACT

Integrated Ocean Drilling Program (IODP) Expedition 313 drilled three holes (Sites M27, M28, and M29; 34–36 m present water depth) across a series of prograding clinothems from the inner continental shelf of the New Jersey (USA) margin, a region that is sensitive to sea-level change. We exam-ined 702 late Eocene to Miocene samples for benthic foraminiferal assemblages and planktonic foraminiferal abundances. We integrate our results with lithofacies to recon-struct paleobathymetry. Biofacies at all three sites indicate a long-term shallowing-upward trend as clinothems built seaward and sedi-ment fi lled accommodation space. Patterns in biofacies and lithofacies indicate shal-lowing- and deepening-upward successions within individual sequences, providing the basis to recognize systems tracts, and there-fore sequence stratigraphic relationships in early to early-middle Miocene sequences (ca. 23–13 Ma). The clinothem bottomsets and the lower portions of the foresets, which con-tain the thickest parts of clinothems, yield the deepest water biofacies. Shallower bio facies characterize the sequences in the upper por-tions of the clinothem foresets and on the topsets. Topsets are characterized by trans-gressive (TST) and highstand systems tracts (HST). Foresets contain lowstand systems tracts (LST), TSTs, and HSTs. Flooding sur-faces mark parasequence boundaries within LSTs, TSTs, and HSTs. Superimposed on the

long-term trends, short-term variations in paleowater depth are likely linked to global sea-level changes indicated by global oxygen isotopic variations.

INTRODUCTION

The New Jersey (USA) margin (Figs. 1 and 2) is an ideal setting for evaluating sequence strati-graphic principles and assumptions because it provides: (1) a thick accumulation of seismi-cally imaged Oligocene to Holocene sediments (Poag, 1977; Schlee, 1981; Greenlee et al., 1988, 1992; Monteverde et al., 2008) that were depos-ited during a time of glacioeustatic oscillations (see Miller and Mountain, 1994; Austin et al., 1998); (2) a stable passive margin setting in a late stage of thermal cooling; (3) a mid-latitude location with excellent chronostratigraphic con-trol; and (4) a substantial body of existing data ranging from seismic lines to wells to outcrops (see Mountain et al., 2010, for background on the transect). The New Jersey sea-level transect was designed to unravel the complex relation-ships between eustatic change and passive con-tinental margin sedimentation. Studies from Ocean Drilling Program (ODP) Legs 150 (con-tinental slope; Mountain et al., 1994) and 174A (outer continental shelf and slope; Austin et al., 1997) provided dates for the major sequence boundaries on the outermost shelf and upper slope. Onshore coastal plain studies from ODP Legs 150X and 174AX provided substantial detail of Late Cretaceous to Miocene sequences and facies (e.g., Miller et al., 2003). Integrated Ocean Drilling Program (IODP) Expedition 313 drilled a critical nearshore segment of the transect from the region that is most sensitive to sea-level change, the inner to middle conti-nental shelf (Mountain et al., 2010). The goals

of Expedition 313 focused on several aspects of sea-level change, including amplitude, sedimen-tary response, and related sequence stratigraphy.

Variations in global sea level (eustasy), tec-tonism, and sediment supply control the dis-tribution of sediments, stratal geometries, and stacking patterns within depositional sequences on continental margins, especially on passive margins (Vail et al., 1977, 1991; Haq et al., 1987; Weimer and Posamentier, 1993; Christie-Blick and Driscoll, 1995). Mitchum et al. (1977, p. 53) defi ned a depositional sequence as a “stratigraphic unit composed of a relatively con-formable succession of genetically related strata and bounded at its top and base by unconformi-ties or their correlative conformities.” The disci-pline of sequence stratigraphy was pioneered by Exxon Production Research Company (Exxon; Vail et al., 1977; Haq et al., 1987; Posamentier et al., 1988), which used it to extract eustatic records from passive margin sequences and to predict the facies distributions that control fl uid resources. Exxon focused on eustasy as the pri-mary genetic control, although this has been controversial (e.g., Christie-Blick et al., 1990; Miall, 1991) largely because distinguishing it from the many other processes that imprint con-tinental margin records requires a wide range of data. Several studies have supported the chro-nology of the Exxon eustatic variations (e.g., Miller et al., 1996; Eberli et al., 1997), but the amplitude and shape of the Exxon curve have been shown to be incorrect (Christie-Blick et al., 1990; Miall, 1991; Miller et al., 1998, 2005). Despite this, Exxon documented that depositional sequences can be used objectively to partition the stratigraphic record. Exxon also provided several generations of depositional models for within-sequence facies variations, such as the systems tracts of Posamentier et al.

For permission to copy, contact [email protected]© 2013 Geological Society of America

1

Geosphere; December 2013; v. 9; no. 6; p. 1–26; doi:10.1130/GES00872.1; 18 fi gures; 3 supplemental tables.Received 11 October 2012 ♦ Revision received 20 July 2013 ♦ Accepted 4 September 2013 ♦ Published online 11 October 2013

Results of IODP Exp313: The History and Impact of Sea-level Change Offshore New Jersey themed issue

*Present address: Department of Earth, Atmos-pheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA.

Katz et al.

2 Geosphere, December 2013

(1988). These depositional models have wide applicability (e.g., Winn et al., 1995; Abreu and Haddad, 1998; West et al., 1998), although many aspects of the models remain controver-sial or untested.

Many studies have applied the concept of systems tracts to sequence interpretations (e.g., Abbott and Carter, 1994; Kolla et al., 2000). However, few studies of offshore marine sec-tions have continuously cored and logged sequences that display a classic clinothem geometry on a siliciclastic passive margin. Clino thems are packages of sediment gener-ated by strata that prograde seaward into deeper water, and are bounded by surfaces (in this case sequence boundaries) with distinct sigmoidal (clinoform) shape. Clinothems have distinct

topsets, foresets, and bottomsets (Fig. 2). Expe-dition 313 was designed to sample sequences in all three settings.

Paleobathymetric trends of shallowing and deepening can be used to identify systems tracts (Fig. 2, inset). Identifying the vertical succession of benthic foraminiferal biofacies and interpreting those changes with regard to paleobathymetric changes (e.g., Natland, 1933; Bandy, 1960) is a critical component of recog-nizing systems tracts. Planktonic foraminiferal abundance changes provide an additional proxy for water depth variations (e.g., Grimsdale and van Morkhoven, 1955); higher abundances typi-cally indicate deeper waters, although this index can be infl uenced by other effects (e.g., produc-tivity and dissolution).

Lithofacies variations can also provide a basis for interpreting paleoenvironmental changes; for example, clays and silts tend to dominate low-energy environments, whereas sands tend to characterize higher energy environments. However, lithofacies are rarely environmentally unique, and thus paleoenvironmental interpreta-tions based on lithofacies alone can be incorrect. Nonetheless, Expedition 313 used an effective wave-dominated shoreline model for depths <30 m that recognized upper shoreface (0–5 m), lower shoreface (5–10 m), shoreface-offshore transition (10 to 20–30 m), and offshore (>20–30 m) environments, with excellent paleodepth resolution (±5 m) (summarized in Mountain et al., 2010). Lithofacies are usually insuffi -cient for estimating paleodepths deeper than

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Paleobathymetry and sequence stratigraphy: Benthic foraminifera from IODP Expedition 313

Geosphere, December 2013 3

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Katz et al.


shoreface-offshore transition facies (>30 m). The reliability of paleoenvironmental interpretations can be greatly improved by integrating biofacies and lithofacies analyses (Fig. 3), viewed within the seismic stratigraphic framework.

In this paper, we use IODP Expedition 313 drilling results (Mountain et al., 2010) from late Eocene to Miocene sequences to link microfau-nal and sedimentologic data with prograding clinoform geometries on the inner continental shelf of the New Jersey passive margin. Spe-cifi cally, we document the benthic foraminiferal assemblages and planktonic foraminiferal abun-dances at Sites M27, M28, and M29 (Figs. 1 and 2). We integrate the foraminiferal data with chronostratigraphy (Browning et al., 2013), lithofacies, seismic stratigraphy, and downhole logs (Miller et al., 2013a; Inwood et al., 2013) to produce paleobathymetric reconstructions within a seismic stratigraphic framework. We integrate these studies to interpret systems tracts and sequence stratigraphy.

METHODS

Biofacies

Samples were soaked overnight in a sodium metaphosphate solution made with deionized water (5.5 g/L) and then washed with tap water through a 63 μm sieve and oven-dried at ~50 °C overnight. We analyzed a total of 702 samples from the 3 Expedition 313 sites; 271 samples yielded benthic foraminifera, 427 samples were barren, and 4 samples contained planktonic (but no benthic) foraminifera. Sample resolution is typically 1–3 m (1–3 samples/3 m core). Higher

resolution samples (~4–10 cm intervals) were analyzed around some sequence boundaries and lithology changes.

Foraminifera were picked from the >150 μm fraction because previous studies used for com-parisons (e.g., Olsson et al., 1987; Miller et al., 1997) were based on data sets that used the >150 μm fraction. The 63–150 μm fraction was not quantitatively picked for this study, although it was observed that foraminifera typically were rare or absent in the 63–150 μm fraction, which may indicate dissolution or winnowing. Using a sample splitter, samples were split to a size that targeted ~100 specimens per aliquot. Samples with as few as 20 specimens were included in the multivariate analyses (see following). Some very large samples (>20 g) yielded sparse benthic foraminifera (i.e., with too few speci-mens to be included in multivariate analyses) and very low diversity (or even monospecifi c) assemblages lacking depth-diagnostic taxa (e.g., dominated by large Lenticulina spp.). In these cases, a split was picked, and then the rest of the sample was scanned to confi rm the low diversity or monospecifi c nature of the sample, because picking that entire sample would not meaning-fully alter the result, but was time consuming.

We performed Q-mode varimax factor analy-ses on the relative abundance (percentage) data using Systat Software (www.systat.com) SYSTAT version 5.2.1. The Q-mode varimax factor program utilizes a cosine-theta matrix, standardizing each sample to unit length. Sam-ples load onto a sample-defi ned vector in these Q-mode analyses. We chose this method over other methods because it yielded useful results in studies that we use for comparison (e.g.,

Miller et al., 1997; Pekar et al., 1997), and our results are consistent with these studies. Each of the 3 sites was analyzed separately, and all sam-ples with at least 20 specimens were included in the factor analysis, which is lower than the 50 specimen cutoff used in Miller et al. (1997). The 20 specimens per sample cutoff is extremely low, even for high-dominance low-diversity assemblages typical of shelf assemblages (e.g., Murray, 1991; Miller et al., 1997). We note that only 21 samples have 20–49 specimens (8 at Site M27, 4 at Site M28, and 9 at Site M29). Of these 21 samples, only 2 yield factor analysis and abundance results that are inconsistent with surrounding samples. One of these samples con-tains 100% Lenticulina spp. and is not used in the paleobathymetric interpretation. The other sample indicates a paleodepth change at Site M27 that is consistent with a well-constrained paleobathymetric change at Site M29 in the same sequence (see Discussion), and therefore is used in the paleobathymetric reconstruction.

Taxonomic concepts were drawn from mul-tiple references (Cushman and Cahill, 1933; Gibson, 1983; Schnitker, 1970; Boersma, 1984; Snyder et al., 1988; Parker, 1948; Poag, 1988; van Morkhoven et al., 1986; see these for taxo-nomic details and illustrations of species identi-fi ed in this study). In addition, Expedition 313 specimens were compared with samples from our previous studies (Miller et al., 1997; Katz et al., 2003a) and with type specimens archived at the National Museum of Natural History (Smithsonian Institution, Washington, D.C.). To supplement the detailed information provided in the preceding citations, we offer notes for iden-tifying certain species.

Shoreface-offshoretransition (10 to 20–30 m)

Dominated by amalgamatedHCS vf-f sand withshells and gravel

Offshore (20–30 to 100 m)Sand and silt laminaeand bioturbated mud

Integrated Biofacies - Lithofacies Paleodepth Model

Lowershoreface

Uppershoreface

Inner neritic (0-30 m) Middle neritic (30-100 m) Outer neritic (100–200 m)

Maximum wave base

Offshore (>100 m)Bioturbated mud

~10 m0 m ~25 m ~75-80 m~50 m ~100 m

Mean fairweather wave base

Mean storm wave base

0–10 mElphidium spp.

10–25 mHanzawaia hughesi

25–50 m Pseudononion pizarrensis

50–80 mBulimina gracilis& Bolivina paula

75–100 m Uvigerina spp. &Bolivina floridana

>100 m high diversity, low dominance assemblages (e.g., Cibicidoides pachydermaCibicidoides primulusHanzwaia mantaensisOridorsalis umbonatus)

Shoreface (0–10 m)Large-scale high-angle

stratified sand and small-scale wave-ripple

cross-stratification

Figure 3. Integrated biofacies and lithofacies paleodepth model. Major benthic foraminiferal species from this study are added to the bio facies model of Miller et al. (1997) and lithofacies model of Mountain et al. (2010). HCS—hummocky cross-stratifi cation; vf—very fi ne; f—fi ne.



The holotype of Bulimina gracilis is elon-gated with an overall twist in the test. B. elon-gata is essentially the same as B. gracilis but without the twist, and with a small curvature. Paratypes of B. gracilis vary in the degree of elongation and of twist; in fact, some com-pletely lack a twist. The holotype of B. elongata is missing, so a direct comparison to B. gracilis could not be made. Some specimens from Expe-dition 313 samples display the two end-member morphologies of B. gracilis and B. elongata, but most range from elongated to short, and vary in degree of twist and curvature, with no clear dividing line between the two species morphol-ogies. They tend to co-occur, and do not appear to indicate different environments; therefore, we combine them under the name B. gracilis.

Buliminella curta is distinct from B. gracilis . The chamber length to width ratio is consis-tently higher in B. curta, resulting in vertically elongated chambers compared to the cham-bers of B. gracilis; this distinction places the two species in different genera. The sutures between chambers are slightly more depressed in B. gracilis, giving the chambers a somewhat puffi er look than in B. curta. B. curta tests are distinctively twisted, without the variability seen in Bulimina gracilis/elongata. The combi-nation of the test twist, longer chambers, and the smoother, fl atter transition between chambers gives B. curta a morphology that is distinct from Bulimina gracilis/elongata.

Several species of Uvigerina are abundant in many of the Expedition 313 samples. Holotypes and paratypes of species named in studies of the eastern U.S. continental margin were examined at the Smithsonian, including U. subperegrina, U. calvertensis, U. juncea, and U. modeloen-sis. U. subperegrina is entirely costate , with relatively large costae. Compared to U. subpere-grina, U. calvertensis and U. juncea have fi ner costae, more elongate tests, and fi nal chambers that are sometimes fi nely hispid with or without fi ne costae, or even nearly smooth. U. modelo-ensis is nearly entirely smooth, with very faint striae sometimes visible. Some specimens display the end-member morphologies of the various Uvigerina species in Expedition 313 samples , but many show intermediate morphol-ogies that are not readily distinguishable, with no clear dividing line among the different spe-cies. Therefore, we combined them for the fac-tor analyses and abundance plots.

Paleobathymetry

Benthic foraminifera are the only seafl oor-dwelling microfossils that occur consistently in Expedition 313 marine facies, providing the best means to reconstruct paleobathym-

etry. Different benthic foraminiferal species typically colonize certain water depth ranges, with key depth-indicator species providing an invaluable tool for reconstructing paleobathym-etry (e.g., Olsson et al., 1987; Browning et al., 1997; Miller et al., 1997; Pekar et al., 1997; Katz et al. 2003a). Therefore, the paleodepth history of a site can be determined by docu-menting benthic foraminiferal changes through time. In addition, higher planktonic forami-niferal abundances typically indicate deeper waters (Grimsdale and van Morkhoven, 1955). Patterns in foraminiferal data indicate shallow-ing- and deepening-upward successions within a sequence. In addition, lithologic trends are important in reconstructing paleodepth his-tory. The Expedition 313 sedimentologists produced visual core descriptions and differen-tiated clay, silt, and various sand fractions visu-ally and using smear slides (Mountain et al., 2010). In Miller et al. (2013a), quantitative and qualitative lithology data were added; weight percent mud (<63 μm), fi ne to very fi ne sand (63–250 μm), and medium sand and coarser sediment (>250 μm) were measured, and semiquantitative estimates made of the abun-dances of glauconite, shells, and mica in the sand fraction. Water depth trends determined from forami nifera (e.g., deepening-upward transgressive and shallowing-upward regres-sive successions) combined with water depth trends inferred from sedimentology (grain-size changes and facies analysis) can be used to infer systems tracts and hence sequence strati-graphic relationships (see inset, Fig. 2).

At the Expedition 313 sites, paleobathy-metric ranges were based primarily on benthic foraminiferal biofacies determined from fac-tor analysis, with the highest loading factor taking precedence; a broader depth range was assigned when the two highest factors yielded approximately the same loadings. Within this framework, paleodepths were fi ne-tuned using abundances of key depth-indicator taxa, supple-mented by planktonic foraminiferal relative abundances. We note that species abundances in samples with few specimens were not used to fi ne-tune factor analysis results. In general, the low-diversity and high-dominance benthic foraminiferal assemblages in the Expedition 313 boreholes are marked by biofacies that are dominated by 1–3 species or genera; this is typi-cal of shallow-water shelf environments (e.g., Murray, 1991; Miller et al., 1997).

A paleobathymetric calibration for ben-thic foraminiferal biofacies was established in Miller et al. (1997), using the paleoslope model of Olsson et al. (1987) for Miocene sequences drilled on the New Jersey coastal plain. The paleoslope model method has been

used successfully for New Jersey coastal plain sequences of different ages (e.g., Browning et al., 1997; Pekar et al., 1997), and is based on Walther’s Law (lateral biofacies variations are also expressed as vertical variations). This method uses a paleoslope of 1:1000, calcu-lated using two-dimensional (2-D) backstrip-ping (Steckler et al., 1999), and equivalent to the modern slope in New Jersey. Boreholes are projected along strike to place them on a common dip line, vertical offsets among the boreholes are determined, and biofacies differ-ences are documented for the same age samples at the different boreholes. This allows coeval biofacies to be linked within sequences. Litho-facies models place additional constraints on shallower biofacies. For example, inner neritic (<30 m) environments recognized using bio-facies can be further subdivided into foreshore (<5 m), upper shoreface (~5–10 m), and lower shoreface to shoreface–offshore transition (10 to 20–30 m) environments (Mountain et al., 2010). We compare our results to distance from shoreline estimates that are based on the abundances of marine versus terrestrial palyno-morphs (McCarthy et al., 2013). In addition to variations in sea surface productivity, terres-trial and marine palynomorph abundances are related mechanisms that transport pollen and embryophyte spores offshore, including wind, rivers, ocean currents, and downslope trans-port, most of which are related to distance from shoreline.

Bathymetric zones are defi ned as inner neritic (0–30 m), middle neritic (30–100 m), and outer neritic (100–200 m) (van Morkhoven et al., 1986). In Miller et al. (1997), these zones were subdivided on the New Jersey margin when they interpreted Elphidium-dominated bio-facies as upper inner neritic (<10 m), Hanza-waia hughesi–dominated biofacies as mid-inner neritic (10–25 m), Pseudononion pizarrensis–dominated biofacies as lower inner neritic to upper middle neritic (25–50 m), B. gracilis–dominated biofacies as middle middle neritic (50–80 m), and Uvigerina-dominated biofacies as outer middle neritic (>75 m). The absence of Elphidium in our samples may indicate a differ-ent paleoenvironmental setting than in the Miller et al. (1997) study, or dissolution in the shallow-est water environments (<10 m) at the Expedi-tion 313 sites. Alternatively, Elphidium may be present in interbeds of mud in shoreface sedi-ments that were not sampled.

We build on the paleobathymetric calibra-tions for benthic foraminiferal biofacies estab-lished using the paleoslope method for New Jersey coastal plain Miocene sequences (Miller et al., 1997) as follows (Fig. 3). Lenticulina spp. (and/or the related Astacolus dubius) is common

Katz et al.


in many samples and was delineated by factor analysis at all three Expedition 313 sites. Len-ticulina spp. is found from the inner shelf to the deep sea through the Cenozoic (e.g., Culver and Buzas, 1980; Katz et al., 2003b; Miller and Katz, 1987; Speijer et al., 1996; Tjalsma and Lohmann, 1983), and therefore is not a useful depth indicator. Four isolated samples yielding several planktonic foraminifera, but no benthic foraminifera, must have been deposited in a marine setting, and were assigned a paleodepth of at least 0–10 m, but were not used in the paleobathymetric interpretation (1 sample at Site M27, 1 sample at Site M28, and 2 samples at Site M29) (Supplemental Table 11).

Based on factor analyses, we identify several additional depth-diagnostic species that can be used in paleobathymetric reconstructions. Bolivina paula is associated with B. gracilis, indicating 50–80 m paleodepths in this region (see following discussion of Site M29). Simi-larly, B. fl oridana is associated with Uvigerina spp., and therefore is also is indicative of 75–100 m paleodepths in this region (see follow-ing discussion of Site M28).

For deeper biofacies not recovered by Miller et al. (1997), we use key taxa (e.g., Cibicidoides pachyderma, Cibicidoides primulus, H. man-taensis, Oridorsalis umbonatus) often found in high-diversity, low-dominance assemblages that indicate outer neritic paleodepths (100–200 m; e.g., Katz et al., 2003a; Parker, 1948; Poag, 1981; van Morkhoven et al., 1986). Because changes from the Uvigerina spp. biofacies to the deeper biofacies occur gradually within sequences, we infer that the maximum water depths are in the shallower part of the outer neritic zone (~120 m).

Paleobathymetric reconstructions in paleo-shelf settings (such as drilled by Expedition 313) can be hampered by samples dominated by coarse sediment that are devoid of foraminifera. These barren sediments may be in situ mid-shelf sands, in situ extremely shallow-water deposits, or transported shallow-water and/or terrigenous sediments. Alternatively, all foraminifera may have been dissolved out of the barren intervals, typically in prodelta shoreface, river-infl uenced offshore, and bottom-of-slope coarse-grained sediments (see following). Because we cannot distinguish among these possibilities, barren intervals of ~10 m or greater are left blank in the paleobathymetric reconstruction fi gures, and no paleodepth estimate is made for isolated bar-ren samples or thin barren intervals. The sample

coverage in these barren intervals is indicated in the fi gures and in Supplemental Table 1 (see footnote 1), Supplemental Table 22, and Supple-mental Table 33.

Age Control and Sequence Boundaries

Ages, sequence boundaries, and intrasequence surfaces used in this paper build on the work in Mountain et al. (2010). All ages provided in this study are from the chronostratigraphy in Browning et al. (2013), wherein latest Eocene to middle Miocene sequences at Sites M27, M28, and M29 were dated using integrated biostra-tigraphy (primarily calcareous nannoplankton, diatoms, and dinocysts) and strontium isotopic stratigraphy. In general, the age resolution is ±0.5 m.y., and is as good as ±0.25 m.y. in many sequences.

All identifi cations of sequence boundaries and intrasequence surfaces are from Miller et al. (2013a), based on an integrated study of core surfaces, lithostratigraphy and process sedi-mentology (grain size, mineralogy, facies, and paleoenvironments), facies successions, stack-ing patterns, benthic foraminiferal water depths, downhole logs, core gamma logs, and chrono-stratigraphic ages. The sequence boundaries and surfaces are identifi ed based on integration of seismic profi les, core surfaces, lithostratigra-phy (grain size, mineralogy, facies, and paleo-environments), facies and biofacies successions, downhole and core gamma logs, and chrono-stratigraphic ages.

Paleobathymetric Reconstructions and Sequence Stratigraphy

We use benthic and planktonic foraminif-eral evidence, integrated with lithologic and seismic evidence, to delineate shallowing- and deepening-upward successions as our primary means of recognizing systems tracts. Each sys-tems tract is marked at its base and its top by a key surface that is defi ned by its stratal (seismic, log, and core) character. By placing these sur-faces with a seismic resolution of 5 m, we can then interpret facies changes within sequences and more accurately locate these important stratal boundaries. Sequences are separated by sequence boundaries. Sequence boundaries are

recognized on seismic lines by classic criteria of onlap, toplap, downlap, and erosional truncation (Mitchum et al., 1977). Sequence boundaries are recognized in cores by the criteria outlined in Miller et al. (2013a). The transgressive sys-tems tract (TST) is recognized by a deepening-upward facies succession that is bounded by a transgressive surface (TS) below and a maxi-mum fl ooding surface (MFS) above (Posamen-tier et al., 1988). MFSs are often identifi ed as downlap surfaces on seismic profi les and omis-sion surfaces in cores; however, the placement of a MFS is often ambiguous, using seismic or lithofacies criteria. Benthic foraminifera and abundances of planktonic foraminifera often provide the strongest evidence for the greatest water depths associated with MFSs landward of the rollover, although often these are zones rather than distinct surfaces (Loutit et al., 1988). Changes from deepening-upward (retrograda-tional) to shallowing-upward (progradational) successions are used to identify MFSs (Fig. 2, inset; Posamentier and Vail, 1988; Neal and Abreu, 2011; Miller et al., 2013b). MFSs normally mark the deepest water depths in a sequence and are associated with peaks in per-cent planktonic foraminifera, heavy bioturba-tion, and, in some cases, authigenic deposits (in situ glauconite and phosphorites; Loutit et al., 1988). Seaward of this, deep-water benthic foraminifera occur on the bottomsets, but often display no clear trends and identifi cation of the MFS is not possible.

The highstand systems tract (HST) overlies the MFS and shallows upward to the overlying sequence boundary (Posamentier et al., 1988). In our interpretations, for example, an intra-sequence succession of shallowing-upward foraminifera overlain by deepening-upward foraminifera indicates lowstand systems tract (LST) deposits transitioning to, or overlain by, TST deposits. Sedimentological criteria typi-cally support water depth inferences derived from foraminifera; for example, LSTs tend to coarsen upsection, TSTs tend to fi ne upsection, and HSTs tend to coarsen upsection (Fig. 2, inset). This integrated approach has been used in previous studies of the New Jersey margin transect from the coastal plain to the conti-nental slope (e.g., Olsson et al., 1987; Miller et al., 1997; Pekar et al., 1997; Browning et al., 1997; Katz et al., 2003a). An important additional step is to integrate stratal architec-ture with the biofacies and lithofacies of the Expedition 313 sections, a task attempted for sequences m5.8, m5.4, and m5.2 in Miller et al. (2013b); sequences m5.8 and m5.2 appear to be single million-year-scale sequences, whereas sequence m5.4 is a composite of three higher frequency sequences.

2Supplemental Table 2. Site M28 foraminiferal data. If you are viewing the PDF of this paper or read-ing it offl ine, please visit http://dx.doi.org/10.1130/GES00872.S2 or the full-text article on www.gsapubs.org to view Supplemental Table 2.





The LST can be recognized as a regressive deposit between a sequence boundary and an overlying TS (Posamentier et al., 1988) typically preserved on a foreset (Fig. 2, inset; Miller et al., 2013b), but LSTs are more diffi cult to recognize in shelf boreholes using paleontological criteria alone (Katz et al., 2003a). LST sediments often consist of reworked coarse sediments contain-ing transported shallow-water foraminifera. It can be diffi cult to differentiate shallow-water in situ foraminifera from shallow-water trans-ported foraminifera. Although usually depos-ited in deeper water, LST deposits can resemble shoreface sands. We rely on the presence of deeper water indicators or abundant reworked (damaged) specimens to differentiate shallow- from deep-water sands. In general, LSTs should shallow upward due to progradation or show relatively constant water depths during aggrada-tion (Posamentier et al., 1988).

We use integrated benthic and planktonic foraminiferal biofacies, lithofacies, and seismic evidence as the primary basis for reconstruct-ing paleobathymetry and recognizing systems

tracts, providing constraints on the prograding clinothems sampled at each site. This is done to the fullest extent that we are able to do with-out conducting: (1) 1-D backstripping, a tech-nique used to account for compaction, loading, and thermal subsidence (Kominz et al., 2008); and (2) 2-D backstripping, a technique that also accounts for fl exural rigidity between locations and provides an estimate of paleotopography (Steckler et al., 1999).

RESULTS

Site by Site Biofacies

Site M27We examined 206 samples from Site M27

(Figs. 4–6; Supplemental Table 1 [see footnote 1]). Q-mode analysis was based on 75 taxa and 72 samples, with 83.34% of the variance explained by 5 factors (Fig. 4). Factor 1 accounts for 18.28% of the total variance and is charac-terized by B. gracilis, indicating paleodepths of ~50–80 m. Factor 2 (19.26% of the total vari-

ance) is characterized by Lenticulina spp. Factor 3 (20.52% of the total variance) is characterized by P. pizarrensis (25–50 m), Hanzawaia sp. 1, and H. hughesi (10–25 m). Factor 4 (10.43% of the total variance) is characterized by C. primu-lus and Gyroidinoides spp. (>100 m). Factor 5 accounts for 14.85% of the total variance, and is characterized by Uvigerina spp. (U. calver-tensis, U. juncea, U. modeloensis, and U. sub-peregrina) and Gyroidinoides spp. (75–100 m).

Factor analysis indicates that there is an overall paleobathymetric shallowing upsection (Fig. 6), from 100 to 120 m (~630–620 m composite depth, mcd), to 75–100 m (~600–500 mcd), to 50–80 m (~470–420 mcd), to 25–50 m with spo-radic deeper facies (~335–200 mcd). Within this long-term trend, there are depth variations within the sequences that are discussed in the following sections.


(Figs. 7–9; Supplemental Table 2 [see foot-note 2]). Many samples below ~400 mcd were

200

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450

500

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600

0 0.2 0.4 0.6 0.8 1

Factor 1 (18.28%)Bulimina gracilis 8.381

Factor 2 (19.26%)Lenticulina spp. 8.338

0 0.2 0.4 0.6 0.8 1

Factor 3 (20.52%)Pseudononion pizarrensis 7.92 Hanzawaia sp. 1 2.36Hanzawaia hughesi 1.608

0 0.2 0.4 0.6 0.8 1

Factor 4 (10.43%)Cibicidoides primulus 7.402Gyroidinoides spp. 3.464

0 0.2 0.4 0.6 0.8 1

Factor 5 (14.85%)Uvigerina spp. 7.849Gyroidinoides spp. 2.069

Site M27

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m5.47

m5.7

m5.8

m5.3

m4.5

m5.2m5

m5.33

O3O1

O6

m6

Figure 4. Integrated Ocean Drilling Program Expedition 313 Site M27 factors within the sequence stratigraphic framework (mcd—meters composite depth). Samples examined for benthic foraminifera are indicated in the samples column. Species that characterize each factor are shown with the factor scores, along with the variance explained by each factor. The cumulative percentage plot shows lithology (Miller et al., 2013a). Brown—mud; light yellow—fi ne quartz sand; dark yellow—medium-coarse quartz sand; green—glauconite sand; blue—car-bonate (shells and foraminifera).

Katz et al.


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Site M27

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m5.33

m5.2m5

m4.5

m5.3

Lenticulina spp. Hanzawaia hughesi Hanzawaia sp. 1 Pseudononion pizarrensis Bulimina gracilis

m4.1

m5.34/m5.4

m5.45

m5.47

m5.7

m5.8

m5.33

m5.2m5

m4.5

m5.3

m6

Uvigerina spp.0 20 40 60

Cibicidoides primulus0 5 10 15

Cibicidoides pachyderma planktonic foraminifera0 20 40 60 80 1000 20 40 60

Gyroidinoides spp.0 5 10 15 20 25

m6

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0 50 100


0 50 100

Figure 5. Integrated Ocean Drilling Program Expedition 313 Site M27 relative abundances (percentages) of dominant species delineated by factor analysis, along with percentage of planktonic foraminifera, shown within the sequence stratigraphic framework (mcd—meters composite depth). Samples examined for benthic foraminifera are indicated in the samples column. The cumulative percentage plot shows lithology (Miller et al., 2013a). Brown—mud; light yellow—fi ne quartz sand; dark yellow—medium-coarse quartz sand; green—glauconite sand; blue—carbonate (shells and foraminifera).



barren ; below ~500 mcd, nearly all samples were barren. Q-mode analysis was based on 45 taxa and 34 samples, with 96.53% of the vari-ance explained by 5 factors (Fig. 7–9). Factor 1 accounts for 35.51% of the total variance, and is characterized by H. hughesi (10–25 m). Factor 2 (30.60% of the total variance) is characterized by Lenticulina spp. Factor 3 (10.18% of the total variance) is characterized by Uvigerina spp.

(U. calvertensis, U. juncea, U. modeloensis, and U. subperegrina) and B. fl oridana (75–100 m). Factor 4 accounts for 12.50% of the total vari-ance, and is characterized by A. dubius and Len-ticulina spp. Factor 5 accounts for 7.58% of the total variance, and is characterized by P. pizar-rensis (25–50 m) and B. gracilis (50–80 m).

Factor analysis indicates that there is an overall paleobathymetric shallowing upsec-

tion (Fig. 9), from 75 to 100 m (~500–475 mcd), to 50–60 m (~430 mcd), to 0–25 m (~390–270 mcd).


(Figs. 10–12; Supplemental Table 3 [see foot-note 3]). Q-mode analysis was based on 60 taxa and 121 samples, with 89.91% of the

Site M27

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m5.3


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LST

TST

TSTHSTTSTHST

TSTHST

TST

LSTTST

TST

HST

HST

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500

550

600

?

?

?

sam

ples

sy

stem

str

acts

O3O1

O6

Figure 6. Integrated Ocean Drilling Program Expedition 313 Site M27 paleodepths are estimated from benthic foraminifera and shown within the sequence stratigraphic framework (mcd—meters composite depth). Shaded swath is best estimate; black envelope indicates possible paleodepth range. Systems tracts interpretations are shown. TST—transgressive systems tract; LST—lowstand systems tract; HST—highstand systems tract. The cumulative percentage plot shows lithology (Miller et al., 2013a). Brown—mud; light yellow—fi ne quartz sand; dark yellow—medium-coarse quartz sand; green—glauconite sand; blue—carbonate (shells and foraminifera).

Katz et al.


m4.5

m5 m5.2

m5.3

m5.35

m5.34

m5.4

m5.32

m5.33

m5.37

250

300

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Depth in core (mcd)

Fac

tor

1 (3

5.51

%)

Han

zaw

aia

hugh

esi 6

.082

Fac

tor

2 (3

0.60

%)

Lent

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(7.5

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Pse

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Fac

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.837

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Site

M28

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81

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81

litho

logy

(c

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505010

00

300

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samples

Fig

ure

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Site M28

0 20 40 60 80

Lenticulina spp.

0 10 20 30 40 50 60

Hanzawaia hughesi

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Astacolus dubius

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planktonic foraminifera

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Site M28

0 5 10 15 20 25

Bulimina gracilis

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Pseudononion pizarrensis

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Uvigerina spp.

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Bolivina floridana

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m5.8

m5.7

m5.6

m5.45

m5.35m5.37

m5.34

m5.32m5.33

m5.4

Figure 8. Integrated Ocean Drilling Program Expedition 313 Site M28 relative abundances (percentages) of dominant species delineated by factor analysis, along with percentage of planktonic foraminifera, shown within the sequence strati-graphic framework (mcd—meters composite depth). Samples examined for benthic foraminifera are indicated in the sam-ples column. The cumulative percentage plot shows lithology (Miller et al., 2013a). Brown—mud; light yellow—fi ne quartz sand; dark yellow—medium-coarse quartz sand; green—glauconite sand; blue—carbonate (shells and foraminifera).

Katz et al.


variance explained by 5 factors (Fig. 10). Fac-tor 1 accounts for 35.68% of the total vari-ance and is characterized by Uvigerina spp. (U. calvertensis, U. juncea, U. modeloensis, and U. subperegrina; 75–100 m). Factor 2 (20.45% of the total variance) is characterized by Lenticulina spp. Factor 3 (11.53% of the total variance) is characterized by B. gracilis (50–80 m), B. paula, and Hanzawaia sp. 1. Factor 4 (9.57% of the total variance) is char-acterized by H. hughesi (10–25 m). Factor 5

(12.68% of the total variance) is characterized by P. pizarrensis (25–50 m).

Factor analysis indicates that there is an overall paleobathymetric shallowing upsection, with short-term variations superimposed on the long-term trend (Fig. 12). From ~750–490 mcd, paleodepths are ~75–100 m, and some-times as deep as 120 m or as shallow as 25 m. From ~330 to 490 mcd, paleodepths are cen-tered around 50–80 m, with variations from 10 to 100 m.

Within-Sequence Trends

Eocene SequenceAt Site M27, the only sample (630.17

mcd) examined from a fi ne-grained Eocene sequence (625.83 mcd to base of hole, 631.15 mcd) deposited in offshore environments (Mountain et al., 2010) is characterized by a diverse, deeper shelf benthic foraminiferal assemblage (e.g., Alabamina midwayensis, C. pachyderma, Trifarina wilcoxensis, Siphonina

Site M28

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e (m

cd)

sam

ples

syst

ems

trac

ts

LSTTST

HST

HST

LST

HST

?

HST

TST

HST

HST

m5.37

m4.5m5

m5.2

m5.3

m5.47

m5.8

m5.7

m5.6

m5.45

m5.35

m5.34

m5.32

m5.33

m5.4

250

300

350

400

450

500

550

600

650

LST

TST?

TST

Figure 9. Integrated Ocean Drilling Pro-gram Expedition 313 Site M28 paleodepths are estimated from benthic foraminifera and shown within the sequence stratigraphic framework (mcd—meters composite depth). Shaded swath is best estimate; black enve-lope indicates possible paleodepth range. Systems tracts interpretations are shown. TST—transgressive systems tract; LST—lowstand systems tract; HST—highstand systems tract. The cumulative percentage plot shows lithology (Miller et al., 2013a). Brown—mud; light yellow—fi ne quartz sand; dark yellow—medium-coarse quartz sand; green—glauconite sand; blue—car-bonate (shells and foraminifera).



claibornensis ) and abundant planktonic forami nifera (47.9%), indicating ~100–120 m paleodepth (Figs. 4–6).

Sequence O1Sequence O1 was found only at Site M27

(625.83–617 mcd, ca. 32.3–32.2 Ma), where it consists of glauconitic clay. The sample (618.02 mcd) examined from this sequence is characterized by a diverse, deeper shelf benthic forami niferal assemblage (e.g., A. midwayensis, C. pachyderma, Hoeglundina elegans, S. clai-bornensis, Sphaeroidina bulloides), indicating ~100–120 m paleodepth (Figs. 4–6).

Sequence O3Sequence O3 was found only at Site M27

(617–538.68 mcd, 29.3–28.2 Ma), where it was deposited on a bottomset (Fig. 2). The lithology consists of a basal glauconitic-quartzose sandy clay, a glauconite clay, and glauconitic quartz-ose clay–clayey glauconitic quartz sand (Miller et al., 2013a). We examined 23 samples in this sequence. Benthic foraminiferal assemblages

indicate variability within outer middle neritic depths (75–100 m) throughout this section (Figs. 4–6). Planktonic foraminiferal abundances are ~0%–2%; this is lower than expected for this water depth (Grimsdale and van Morkhoven, 1955), but there is no evidence of dissolution of the planktonic foraminifera in these samples. The dominance of the Uvigerina spp.–Gyroidi-noides spp. biofacies (factor 5), together with the lack of B. gracilis, indicates paleodepths of 80–100 m from ~601.35 to 593.41 mcd (Figs. 4–6). Above this, an increase in taxa such as C. pachyderma, Gyroidi noides spp., and Melonis pompilioides indicates a slight deepening to 90–100 m (592.07–589.10 mcd). A slight deep-ening to ~100 m is indicated by a shift to the C. primulus–Gyroidinoides spp. biofacies (fac-tor 4), and higher abundances of C. pachyderma in many samples (570.73–549.04 mcd). A shift back to the factor 5 Uvigerina spp.–Gyroidi-noides spp. biofacies indicates 75–100 m paleodepth at the top of this sequence (543.30–540.21 mcd). The Lenticulina spp. biofacies (factor 2) occurs intermittently throughout the

sequence. These paleodepth variations may indicate fl ooding surfaces associated with para-sequence boundaries (Figs. 4–6).

Sequence O6Uppermost Oligocene sequence O6 is found

only at Site M27 (538.68 to 509 or 515 mcd; 23.5–23.0 Ma), where it is dominated by clayey, slightly glauconitic fi ne quartz sand. The entire sequence (11 samples examined) is characterized by the Uvigerina spp.–Gyroidi-noides spp. biofacies (factor 5), indicating 75–100 m paleodepth from ~538.56 to 513.31 mcd (Figs. 4–6). Elevated abundances of B. gracilis and higher loadings on factor 1 at 531.09 mcd indicate a shallowing to the upper end of the depth range for this sample, to ~75–80 m paleodepth.

Sequence m6Sequence m6 was fully recovered only at Site

M27 (509/515–494.87 mcd, 20.9–20.7 Ma), where it consists of clayey glauconite-quartz sands deposited in a bottomset. Two samples

Site M29

0 0.2 0.4 0.6 0.8 1

Factor 1 (35.68%)Uvigerina spp. 7.541

0 0.2 0.4 0.6 0.8 1

Factor 2 (20.45%)Lenticulina spp. 7.571

0 0.2 0.4 0.6 0.8 1

Factor 3 (11.53%)Bulimina gracilis 7.089Bolivina paula 2.106Hanzawaia sp. 1 1.224

0 0.2 0.4 0.6 0.8

Factor 4 (9.57%)Hanzawaia hughesi 7.110

0 0.2 0.4 0.6 0.8 1

Factor 5 (12.68%)Pseudononion pizarrensis 7.451

300

400

500

600

700m5.6

m5.8

m4.2

m4.4

m4.3

m4.5

m5

m5.2

m5.4m5.3

m5.45m5.47

m5.7

m5.45 alt

m4.1

m5.47 alt

Dep

th in

cor

e (m

cd)

300

400

500

600

700


0 50 100

sam

ples

Figure 10. Integrated Ocean Drilling Program Expedition 313 Site M29 factors within the sequence stratigraphic framework (mcd—meters composite depth). Samples examined for benthic foraminifera are indicated in the samples column. Species that characterize each factor are shown with the factor scores, along with the variance explained by each factor. The cumulative percentage plot shows lithology (Miller et al., 2013a). Brown—mud; light yellow—fi ne quartz sand; dark yellow—medium-coarse quartz sand; green—glauconite sand; blue—car-bonate (shells and foraminifera).

Katz et al.


0 20 40 60 80

Lenticulina spp.

0 10 20 30 40 50

Hanzawaia hughesi

0 10 20 30 40

Hanzawaia sp. 1

0 20 40 60 80

Pseudononion pizarrensis

0 20 40 60 80 100

Bulimina gracilis

Dep

th in

cor

e (m

cd)

300

400

500

600

700


0 50 100sa

mpl

es

Dep

th in

cor

e (m

cd)

300

400

500

600

700


0 50 100

sam

ples

300

400

500

600

700m5.6

m5.8

m4.2

m4.4

m4.3

m4.5

m5

m5.2

m5.4m5.3

m5.45m5.47

m5.7

m5.45 alt

m4.1

m5.47 alt

0 20 40 60 80 100planktonic foraminifera

0 20 40 60 80Uvigerina spp.

0 10 20 30 40 50 60Bolivina paula

0 10 20 30 40Cibicidoides pachyderma

0 5 10 15 20 25Bulimina mexicana

300

400

500

600

700m5.6

m5.8

m4.2

m4.4

m4.3

m4.5

m5

m5.2

m5.4m5.3

m5.45m5.47

m5.7

m4.1

m5.47 altm5.45 alt

Site M29

Site M29

Figure 11. Integrated Ocean Drilling Program Expedition 313 Site M29, relative abundances (percentages) of dominant species delineated by factor analysis, along with percentage of planktonic foraminifera, shown within the sequence stratigraphic framework (mcd—meters composite depth). Samples examined for benthic foraminifera are indicated in the samples column. The cumulative percentage plot shows lithology (Miller et al., 2013a). Brown—mud; light yellow—fi ne quartz sand; dark yellow—medium-coarse quartz sand; green—glauconite sand; blue—carbonate (shells and foraminifera).



yielded depth-diagnostic benthic foraminifera; most samples (5) were either barren or did not yield depth-diagnostic foraminifera. The lower-most sample (508.87 mcd) is characterized by the Uvigerina spp.–Gyroidinoides spp. fauna (factor 5), indicating ~75–100 m paleodepth (Figs. 4–6). A shallowing within the middle neritic zone from ~75–100 m water depth at the base of the sequence to 50–80 m paleodepth in the middle of the sequence (500.60 mcd) is indi-cated by an increase in B. gracilis.

At Site M28, the 3 samples examined in the partially recovered m6 sequence (below 662.98 mcd) yielded too few foraminifera to make a fi rm paleodepth estimate, although sparse benthic foraminifera at 664.22 mcd may indi-cate 50–80 m paleodepth, based on B. gracilis abundance.

Sequence m5.8The foreset of sequence m5.8 was cored at

Site M27 (494.87–361.28 mcd; 20.1–19.2 Ma) near where the sequence reaches its maximum thickness and appears stratigraphically most complete. We examined 61 samples for bio-facies. Benthic foraminifera are absent from all 24 samples in the lower part of the sequence (494.77–469.895 mcd; Figs. 4–6 and 13). Two coarsening-upward successions in the lower part of the sequence (494.87–485; 485–477.52 mcd) were deposited on a bottomset and are interpreted as an LST (Miller et al., 2013b). The TS is placed at the change from regressive to transgressive sedimentary facies at 477.52 mcd, marking the top of the LST.

The LST is overlain by a fi ned-grained succession to ~415 mcd, deposited in a river-

infl uenced offshore environment (Mountain et al., 2010) (Figs. 6 and 13). A fi ning-upward succession from 477.52 to 460 mcd indicates a deepening above the TS. A deeper water section (50–80 m paleodepth; 467.01–421.31 mcd) at Site M27 is indicated by the B. gracilis biofacies (factor 1). Within this section, varia-tions in water depth are interpreted based on changing abundances of secondary taxa, with higher abundances of P. pizarrensis (factor 3) indicating shallowing to ~50–60 m, and higher abundances of Uvigerina spp. indicating deeper water (~75–80 m; Figs. 4–6 and 13). High load-ings on both factor 1 (B. gracilis) and factor 5 (Uvigerina spp. and Gyroidinoides spp.), along with high planktonic foraminiferal abundances, indicate 75–80 m paleodepth in two sam-ples (463.865, 460.96 mcd). The paleodepth

Site M29D

epth

in c

ore

(mcd

)

300

400

500

600

700

0 20 40 60 80 100 120

300

400

500

600

700

LST

TST

TST

?

?

?

LST

TST

HST

HST

HST

LST

Paleodepth (m)

sam

ples

sy

stem

str

acts

lithology (cumulative percent)0 50 100

m4.2

m4.4

m4.3

m4.5

m5

m5.2

m5.4m5.3

m5.45m5.47

m5.47 altm5.6

m5.8

m5.7

m4.1

m5.45 alt

Figure 12. Integrated Ocean Drilling Program Expedition 313 Site M29 paleodepths are estimated from benthic foraminifera and shown within the sequence stratigraphic framework (mcd—meters composite depth). Shaded swath is best estimate; black envelope indicates possible paleodepth range. Systems tracts interpretations are shown. TST—transgressive systems tract; LST—lowstand systems tract; HST—highstand systems tract. The cumulative percentage plot shows lithology (Miller et al., 2013a). Brown—mud; light yellow—fi ne quartz sand; dark yellow—medium-coarse quartz sand; green—glauconite sand; blue—carbonate (shells and foraminifera).

Katz et al.


Ben

thic

Fora

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8010

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Pal

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6080

Ben

thic

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208R

209R

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211R

212R

213R

214R

215R

216R

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0 m

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0 m

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Environment

BenthicBiofacies

IntegratedWaterdepth

Cum

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Lith

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Reflector

Depth (mcd)

Age (Ma)

m5.

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m5.

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753.

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7575 75

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20.0

20.2

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0

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M28

147R

148R

149R

150R

151R

152R

153R

154R

155R

156R

157R

158R

159R

160R

161R

162R

163R

164R

165R

166R

167R

168R

169R

170R

171R

670

660

650

640

630

620

610

600

gg

gg

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wd g

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50-8

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50-8

0 m

50-6

0 m

50-8

0 m

50-8

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50-8

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50-8

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50-6

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50-6

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50-8

0 m

75-8

0 m

75-8

0 m

75-8

0 m

50-8

0 m

TapronEnvironment

BenthicBiofacies


5 10 30 75 75 6075 35 50

HS

T

LST

TS

TSystemsTract

Reflector

Depth (mcd)

Age (Ma)

171R

172R

173R

174R

175R

XX

XX

XX

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XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

XX

X

XX

XX

XX

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XX

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127R

128R

129R

130R

131R

132R

133R

134R

135R

136R

137R

138R

139R

140R

141R

142R

143R

144R

145R

146R

147R

148R

149R

150R

151R

152R

153R

154R

155R

156R

157R

158R

159R

160R

161R

162R

163R

164R

165R

166R

167R

168R

169R

170R

XX

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370

380

390

400

410

420

430

440

450

460

470

480

490

5010

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Cum

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Lith

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csm

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—ro

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), a

nd c

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(gr

ay—

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p). C

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b):

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ifer

a];

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—m

ica)

, lit

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ain

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; s—

silt

; vf

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ne

sand

; m

—m

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and;

vc—

very

coa

rse

sand

; g—

grav

el a

nd/o

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(SF

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ST—

high

stan

d sy

stem

s tr

act.



fl uctuations in this section are also evident in palynomorph distance from shoreline estimates (McCarthy et al., 2013), and may indicate fl ooding surfaces associated with parasequence boundaries.

Peak planktonic abundances at 457.78 mcd suggest that this may be the MFS. Another peak in the B. gracilis and Uvigerina spp.–Gyroidinoides spp. biofacies (factors 1 and 5) at ~448.42 mcd may be an FS, although ben-thic foraminiferal abundances are low in this sample. Uniform, very slightly sandy, silty clay from 460 to 440 mcd does not contain a single discrete surface that can be identifi ed as the MFS. Lithologic criteria suggest that the MFS occurs at 451.36 mcd or 448 mcd where mica, laminations, and percent sand reach a minimum (Fig. 13). A major downlap surface appears to tie to 442 mcd at Site M27 and is the best seismic candidate for an MFS. The slight differences in placement based on seismic, lithologic, and benthic foraminiferal criteria illustrate that picking an unequivocal MFS is complicated. Therefore, we conclude that instead of a distinct MFS, there is a zone of maximum fl ooding from 460 to 440 mcd (see Loutit et al., 1988).

Offshore silts continue to characterize the sediments up to ~435 mcd. Above this, fi ne sands deposited in shoreface-offshore transi-tion environments are overlain by medium- to coarse-grained sands deposited in shoreface environments. The transition to the sand-domi-nated lithofacies that begins at ~435 mcd sug-gests that the section above this is part of the HST. Samples in most of the HST are barren (above 420 mcd; Figs. 4–6).

At Site M28, there were no benthic forami-nifera in 37 samples examined from sequence m5.8 (662.98–611.60 mcd; 20–19.5 Ma; Figs. 7–9 and 13).

In sequence m5.8 at Site M29 (753.80/746–728.56 mcd; 20.2–20 Ma), 14 samples were examined for biofacies. The lowermost sam-ples are dominated by the Uvigerina spp. biofacies (factor 1) that indicates paleodepths of 75–100 m, or by the B. gracilis–B. paula–Hanzawaia sp. 1 biofacies (factor 2) that indi-cates paleodepths of 50–80 m (Figs. 10–13). This is overlain by barren samples. A single sample near the top of sequence m5.8 is char-acterized by the factor 2 biofacies, indicating 50–80 m paleodepths.

Paleodepths indicated by the biofacies in sequence m5.8 are 50–80 m in a foreset at Site M27, with 50–60 m or 75–80 m indicated in some samples (Figs. 6 and 13). Situated in a prodelta bottomset at Site M29, biofacies indi-cate overall deeper paleodepths, ranging from 50–80 m to 75–100 m (Figs. 12 and 13).

Sequence m5.7At Site M27, seismic profi les show the thin

(5.75 m) sequence m5.7 (361.28–355.53 mcd) as a remnant immediately landward of the rollover (Fig. 2). No foraminifera were found in the two samples examined in this sequence, consistent with the interpretation of shallow-water (shore-face) deposits (Mountain et al., 2010) (Figs. 4–6 and 14). The sequence coarsens upsection, likely refl ecting an HST. At Site M28, sequence m5.7 (611.6–567.5 mcd; 18.8–18.6 Ma) coars-ens upsection to uniform medium sands (~595 mcd) devoid of foraminifera (32 samples exam-ined), deposited on a bottomset (Figs. 4–6 and 14). Sequence m5.7 at Site M29 (728.56 to 710 or 707.56 mcd; ca. 18.8–18.6 Ma) is a basal glauconitic quartz sand that fi nes upward to a fi ne to coarse sand, and then to an offshore clay, all deposited on a bottomset. We examined 11 samples in this sequence. The lowermost 3 sam-ples are barren (728.46–726.16 mcd). Above this, the Uvigerina spp. biofacies (factor 1) indi-cates paleodepths of 75–100 m in this sequence (721.08–712.31 mcd). A dramatic increase in the abundance of C. pachyderma at 714.94 mcd indicates a deeper paleodepth (90–110 m; Figs. 10–12 and 14).

Sequence m5.6Sequence m5.6 is absent from Site M27. At

Site M28, sequence m5.6 (567.5–545.5 mcd) is a bottomset sand devoid of foraminifera (13 samples examined). At Site M29, sequence m5.6 (710 or 707.56 to 695.65 or 687.87 mcd; 18.3–18.1 Ma; 11–17 samples examined) is barren in the lower section (710–700.08 mcd; Figs. 10–12). Benthic foraminiferal biofacies from 698.58 to 686.54 mcd (which encom-passes the uncertain zone of the sequence m6-m5.47 transition) indicate that the entire section was deposited in relatively deep water (75–120 m), likely with fl uctuations within this paleodepth range (Figs. 10–12). Two samples (698.58, 697.07 mcd) within sequence m5.6 have high loadings on the factor 1 biofacies (Uvigerina spp.), indicating paleodepths of 75–100 m. However, deeper paleodepths are indicated by high abundances of C. pachy-derma (~20%) in both samples, coupled with the disappearance of shallower water taxa (B. gracilis) especially in the upper sample; therefore, we place 698.58 mcd at 90–110 m paleodepth, and 697.10 mcd at 100–120 m paleodepth (Figs. 10–12). Similarly, the Uvigerina spp. biofacies (factor 1), low abun-dances of B. gracilis, and moderate to high abundances of C. pachyderma (~6%–42%) in all samples from 695.60 to 686.54 mcd indi-cate paleodepths ranging from 80 to 100 m to 100–120 m within this section.

Sequence m5.47At Site M27, sequence m5.47 (355.53–

336.06 mcd) consists of glauconitic sands that are interpreted as channel-fi ll deposits and that cannot be dated (Mountain et al., 2010). It is devoid of foraminifera (5 samples examined). At Site M28, this sequence (545.5–533.59 mcd) consists of glauconite-quartz sands deposited on a bottomset that is devoid of foraminifera (10 samples examined).

At Site M29, both the upper and lower boundaries that mark sequence m5.47 are uncertain (695.65 or 687.87 to 681 or 673.81 mcd; 18.0–17.9 Ma; 6–13 samples examined). Samples from 683.46, 684.81, and 685.75 mcd are barren. The top of sequence m5.47 may be at 681 or 673.81 mcd. Two samples within this interval yield benthic foraminifera (680.32 and 677.29 mcd). For 680.32 mcd, the Uvigerina spp. bio facies (factor 1) and ~21% C. pachy-derma indicate a paleodepth of ~90–110 m, with a downslope transport component indi-cated by ~23% H. hughesi. Similarly, the sam-ple at 677.29 mcd is characterized by factor 4 (Hanzawaia biofacies with ~46% H. hughesi) and contains common B. gracilis (~14%) and Uvigerina spp. (~6%), indicating 25–80 m paleodepth with possible downslope transport; based on the species abundances and ~59% planktonic foraminifera, we narrow this esti-mate to 50–80 m paleodepth with downslope transport (Figs. 10–12).

Sequence m5.45At Site M27, sequence m5.45 (336.06–295.01

mcd; 18.0–17.7 Ma; 28 samples examined) shows two distinct coarsening-upward para-sequences (336–323 and 323–309 mcd) within an otherwise fi ne-grained unit (Miller et al., 2013a). The lowermost two samples (335.85 and 332.79 mcd) are barren (Figs. 4–6), and may be either LST or transported sediments within a TST (as interpreted in Miller et al., 2013a). The factor 3 biofacies (P. pizarrensis, Hanza-waia sp. 1, and H. hughesi) indicates paleo-water depths of ~25–50 m for 329.81 mcd and 318.81–311.46 mcd; based on moderate abun-dances of B. gracilis and Uvigerina spp., and abundant planktonic foraminifera (~7%–43%), we narrow this paleodepth estimate to 40–50 m for most of the section, possibly shallowing to 25–50 m toward the top. We tentatively place the MFS at the highest peak in planktonic foramin-ifera (~43%) and a secondary mud peak (329.81 mcd). A sample at the upper sequence boundary (295.01 mcd) has an estimated paleodepth of ~25 m paleodepth (Figs. 4–6 and 15). The shal-lowing indicated by the biofacies, overlain by barren samples, is consistent with the upper part of the sequence interpreted as an HST.

Katz et al.


At Sites M28 and M29, samples from sequence m5.45, deposited as bottomsets, were devoid of foraminifera (13 samples examined at Site M28; 10 samples examined at Site M29).

Sequence m5.4Analysis of seismic profi les, core data, and

log stacking patterns of the section between sequence m5.4 and m5.3 refl ectors led to the conclusion (Miller et al., 2013b) that sequence m5.4 is actually a composite of three higher order (100 to 400 k.y. scale) sequences called m5.4–1 (the sequence that directly overlies surface m5.4), m5.34, and m5.33. All three sequences are found at Site M28, which was drilled through the foreset. At Site M27, sequences m5.34 and m5.33 are found at the topset, but sequence m5.4–1 apparently is eroded. At Site M29, drilled on a bottom-set, the seismic resolution did not permit the higher order sequences to be defined and the section there is referred to as m5.4 (Miller et al., 2013b).

At Site M27, sequence m5.34 (295.01–271.23 mcd; 17.0–16.9 Ma; 19 samples examined) was deposited on a topset (Figs. 2 and 16). A sample (295.01 mcd) at the base of sequence m5.34 contains ~29% H. hughesi, ~17% P. pizarrensis, and ~51% Lenticulina spp., indicating ~25 m paleodepth. Samples at 294.71 and 294.12 mcd are characterized by the P. pizarrensis biofacies (factor 3), indicating ~25–50 m water depth; we narrow this depth estimate to 40–50 m, based on ~14%–15% Uvigerina spp. in these two samples, and place it within the TST (Figs. 4–6 and 16). Barren samples extend from 293.18 up to 268.84 mcd, consistent with HST deposition (Miller et al., 2013b).

The m5.33 sequence at Site M27 (271.23–256.19 mcd; 16.9–16.8 Ma; 13 samples exam-ined) was deposited on a topset. Barren sam-ples are interspersed with occasional samples (265.74, 264.56, 261.09 mcd) that yield the P. pizarrensis biofacies (factor 3), indicating ~25–50 m paleodepth (Figs. 4–6 and 16). One of these samples (264.56 mcd) also has ~14% Uvigerina spp., indicating a paleodepth at the deep end of this range (35–50 m). Facies trends above m5.33 are unclear, but the ~35–50 m paleodepth at 264.56 mcd is consistent with a major downlap surface (263 mcd) identifi ed in Miller et al. (2013b) as the MFS. The overlying HST (9 samples examined) is mostly devoid of foraminifera, with the exception of 261.09 mcd, which is characterized by the P. pizarrensis biofacies (factor 3), indicating ~25–50 m (Figs. 6 and 16).

Site M28 cored composite sequence m5.4 (512.33–361 mcd; 17.7–16.6 Ma; 80 samples examined) on the foreset where the sequence

6080

100

120

Ben

thic

Fora

min

ifera

lP

aleo

dept

h (m

)

barr

en

barr

en

Ben

thic

Fora

min

ifera

lP

aleo

dept

h (m

)B

enth

icFo

ram

inife

ral

Pal

eode

pth

(m)

OF

F

90-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

50-1

00 m

90-1

10 m

Environment

BenthicBiofacies


Cum

ulat

ive

Lith

olog

y (%

)

50

5010

00

Cum

ulat

ive

Lith

olog

y (%

)

Reflector

Depth (mcd)

Age (Ma)

m5.

6

m5.

7

567.

5

611.

6

?

18.6

18.8

19.5

Lith

olog

yC

ore

reco

very

Reflector

Depth (mcd)

Age (Ma)

m5.

6

m5.

7

707.

56/7

10

728.

56

75 75 75 75

18.3

18.6

18.8

20.0

100

0

131R

132R

133R

134R

135R

136R

137R

138R

139R

140R

141R

142R

143R

144R

145R

146R

147R

148R

149R

150R

151R

610

600

590

580

570

560

gg

gg

ggg

gg

gg

g

xxxxxxx

gg

g

gg

gg

gg

gg

xxxxxxx

gg

gg

gg

wd

wd

Depth (mcd)

gw

d15

2R

153R

154R

620

Lith

olog

yC

ore

reco

very

xxxxxxxxxxxxxxx

xxxxxxxxxxxxxxx

gg

gg

xxxxxxxxxxxxxxx

xxxxxxxxxxxxxxx

XX

X

Xgx

Depth (mcd)70

0

71

0

72

0

73

0

74

0

198R

199R

200R

201R

202R

203R

204R

205R

206R

207R

208R

209R

210R

211R

M27

Seq

uenc

e m

5.7

Ero

ded

clin

ofor

mB

otto

mse

tB

otto

mse

t

M28

M29

Toe slope apron OFF

10-2

5 m

?

Environment

BenthicBiofacies


75 25

123R

124R

125R

126R

127R

128

R

129R

130R

XX

XX

XX

XX

XX

XX

XX

XX

XX

gg

gg

gg

Depth (mcd)

350

360

370

5010

00

Cum

ulat

ive

Lith

olog

y (%

)

Environment

BenthicBiofacies


SF

SF

5 510

Cor

ere

cove

ryLi

thol

ogy

HS

TSystemsTract

Reflector

Depth (mcd)

Age (Ma)

m5.

47

m5.

736

1.28

355.

53m

5.6

cuto

ff? ?

19.2?

csm

gvf

vcSa

nd

csm

gvf

vcSa

nd

cs

mg

vfvc

San

d

Fig

ure

14.

Sequ

ence

m5.

7 co

mpa

riso

ns a

mon

g In

tegr

ated

Oce

an D

rilli

ng P

rogr

am E

xped

itio

n 31

3 Si

tes

M27

, M

28,

and

M29

sho

win

g de

taile

d pa

leob

athy

met

ry a

nd s

yste

ms

trac

ts b

ased

on

fora

min

ifer

al a

nd l

itho

logi

c in

terp

reta

tion

s (s

ee F

ig.

13 c

apti

on f

or d

etai

ls a

nd

abbr

evia

tion

s).



is thickest (Figs. 2, 7–9, and 16). Higher order sequences m5.4–1 (512.33 mcd), m5.34 (479 mcd), and m5.33 (405 mcd) were identifi ed in Miller et al. (2013b) based on seismic, core, and stacking patterns. Within sequence m5.4–1 (512.33–479 mcd), barren samples characterize the LST, with sparse benthic foraminifera mark-ing the TS at ~501 mcd at the beginning of a fi ning-upward section (Figs. 7–9 and 16).

An intrasequence refl ection (m5.35, 494 mcd) at Site M28 corresponds to the contact between a thin sand bed over a clayey silt, which coincides with a transition to forami-niferal assemblages (factor 3, Uvigerina spp. and B. fl oridana ; factor 5, P. pizarrensis and B. gracilis ; factor 1, H. hughesi; factor 2, Lenticu lina spp.) that indicate ~50–100 m paleodepth (493.77–485.335 mcd). We inter-pret this contact as the MFS, with the HST above. Variability of species abundances and factor-defi ned biofacies within this interval (493.77–485.335 mcd) indicate paleodepth fl uc-tuations, with higher abundances of Uvigerina spp. (493.77, 485.335 mcd) indicating 75–100 m, and higher abundances of H. hughesi and P. pizarrensis (492.26, 489.20, 486.17 mcd) indicating 50–75 m paleodepth (Figs. 7–9 and 16). Abundant planktonic forami nifera (to 76%) support the deep-water setting indicated by the biofacies in this section. These samples are in the lower portion of a coarsening-upward, regressive package from m5.35 (494 mcd) to m5.34 (479 mcd), associated with shoreface-offshore transition and offshore deposits. The middle portion yields barren samples (484.37–482.5 mcd). The upper portion (481.4–477.07 mcd) is characterized by the factor 3 biofacies (Uvigerina spp. and B. fl oridana) that indicates ~75–100 paleodepth; an upsection decrease in Uvigerina spp. and increases in H. hughesi and P. pizarrensis indicates somewhat shallower depths in the upper samples (50–75 paleodepth), consistent with the upsection lithologic coarsen-ing (Figs. 7–9 and 16) and interpretation of the section from 494 to 479 as an HST.

Refl ector m5.34 (479 mcd) is interpreted as a sequence boundary. Coarsening (479–475 mcd) and fi ning (475–449 mcd) upward suc-cessions are interpreted as an LST and a TST, respectively, but are devoid of foraminifera. A coarsening-upward, regressive HST package (449–415 mcd) is associated with a shift from offshore to shoreface-offshore transition depos-its. Samples in this section are barren up through 395.12 mcd, with 2 exceptions. The P. pizar-rensis–B. gracilis biofacies (factor 5) indicates 25–80 m paleodepth, which we refi ne based on abundances of shallow versus deep secondary taxa, at 430.99 mcd (50–60 m paleodepth) and 417.13 mcd (25–50 m paleodepth; Figs. 7–9 and

Ben

thic

Fora

min

ifera

Pal

eode

pth

(m)

2040

3010

50

HS

T

LST

TS

T

HS

T

40-5

0 m

25-5

0 m

25 m

40-5

0 m

40-5

0 m

40-5

0 m

25 m

Ben

thic

Fora

min

ifera

Pal

eode

pth

(m)

4060

8010

012

0

SystemsTract

181R

182R

183R

184R

185R

186R

187R

188R

189R

190R

191R

192R

68

0

67

0

66

0

XXXX

Xg

XX

XX

XX

XX

XX

XX

XX

X

wdg

g

XX

XX

XX

XX

XX

XXXX

Xg

XXXX

Xwd

Lith

olog

yC

ore

reco

very

Depth (mcd)

Toe

ToeEnvironment

BenthicBiofacies


75-1

00 m

75-1

00 m

50-8

0 m

90-1

00 m

Cum

ulat

ive

Lith

olog

y (%

)

50

Reflector

Depth (mcd)

Age (Ma)

m5.

45

m5.

45

m5.

466

2.37

673.

71

681

75 75 85 75 90

17.7

17.7

17.8

17.9

100

0

5010

00

Cum

ulat

ive

Lith

olog

y (%

)

Channelfill

Toe slopeapron

Toe slopeapronEnvironment

Paleodepth

Integrated 755010

7R

108R

109R

110R

111R

112R

113R

114R

115R

116R

117R

118R

119R

120R

121R

530

520

510

500

wd

wd g

gg

wdg

g

XX

XX

XX

XXXX

XX

Depth (mcd)

Reflector

Depth (mcd)

Age (Ma)

m5.

4

m5.

45

512.

33

533.

59

17.7

17.9

18.0

Lith

olog

yC

ore

reco

very

M27

M28

M29

??

102R

103R

104R

105R

106R

107R

108R

109R

110R

111R

112R

113R

114R

115R

116R

117R

118R

119R

Depth (mcd)

300

310

320

330

340

Cor

ere

cove

ry

5010

00

Cum

ulat

ive

Lith

olog

y (%

)

Environment

BenthicBiofacies


OF

F

Lag

OF

F

5025 50 35 3550 50 25 4040

HS

T

LST

Systems

(M)F

S

(M)F

S/

TS

FS

Tract

SystemsTract

gg

**

*

gg

gg

gg

Lith

olog

y

Reflector

Depth (mcd)

Age (Ma)

m5.

4533

6.06

295.

0117

.0

17.7

18.0 ?

Seq

uenc

e 5.

45

Top

set

Bot

tom

set

Bot

tom

set

Ben

thic

Fora

min

ifera

Pal

eode

pth

(m)

barr

en

csm

gvf

vcSa

nd

m5.

34/

m5.

4m

erge

dcs

mg

vfvc

Sand

cs

mg

vfvc

San

d

Fig

ure

15.

Sequ

ence

m5.

45 c

ompa

riso

ns a

mon

g In

tegr

ated

Oce

an D

rilli

ng P

rogr

am E

xped

itio

n 31

3 Si

tes

M27

, M

28,

and

M29

sho

win

g de

taile

d pa

leob

athy

met

ry a

nd s

yste

ms

trac

ts (

FS—

fl ood

ing

surf

ace)

bas

ed o

n fo

ram

inif

eral

and

lith

olog

ic in

terp

reta

tion

s (s

ee F

ig. 1

3 ca

p-ti

on f

or d

etai

ls a

nd a

bbre

viat

ions

).

Katz et al.


16). This supports the shallowing-upward inter-pretation derived from lithofacies.

Refl ector m5.33 (405 mcd) tentatively is interpreted as a sequence boundary, whereas refl ector m5.32 (391 mcd) is a major down-lap surface that is an MFS overlain by an HST (m5.32-m5.3; 391–361 mcd). Samples from 391.2 to 361 mcd contain the H. hughesi bio-facies (factor 1), indicating 10–25 m paleodepth. Samples straddling refl ector m5.32 (389 mcd) contain common Uvigerina spp. and planktonic foraminifera (Fig. 8), consistent with this being an MFS and regressive HST above.

At Site M29, sequence m5.4 (662.37–643.19 mcd; 17.7–17.6 Ma; 8 samples examined) con-sists primarily of silt with fl oating granules and coarse quartz sand deposited on a bottomset and dated at this site with no discernible gap at its base. The entire sequence is characterized by outer middle neritic (75–100 m) foraminiferal assemblages, characterized by the Uvigerina spp. biofacies (factor 1; Figs. 10–12 and 16). No obvious water depth trends are discernible.

Sequence m5.3The placement of the basal sequence bound-

ary of m5.3 is equivocal at Site M27, either at 256.19 or 249.76 mcd (Miller et al. 2013a); we follow the level favored in Miller et al. (2013a), with m5.3 at 256.19 mcd based on the litho-facies. Sequence m5.3 (256.19–236.15 mcd; 15.8–15.6 Ma; 13 samples examined) was drilled on a topset consisting of either one or two fi ning-upward successions (depending on placement of the sequence boundary). The lowest sample examined in this sequence (255.06 mcd), within the fi rst fi ning-upward succession, has high abundances of P. pizarrensis, H. hughesi, and Hanzawaia sp. 1, indicating ~25 m paleodepth (Figs. 5, 6, and 17). An upsection increase in abundance of Uvigerina spp. indicates ~75 m paleodepth in 2 samples (250.46 and 245.88 mcd), consistent with ~39% planktonic foramin-ifera; an intervening sample dominated by Len-ticulina spp. (~73%) may contain transported shallow-water specimens. We interpret this as a TST with an MFS near the top of the sequence (Figs. 6 and 17).

At Site M28, sequence m5.3 (361–323.23 mcd; 16.3–15.7 Ma; 12 samples examined) was recovered immediately landward of the foreset (Fig. 2). This sequence consists of a thick pile of coarse slightly glauconitic quartz sand deposited in shoreface environments and capped by a channel (Fig. 17). Foraminiferal assemblages are dominated by Lenticulina spp. and A. dubius (Factors 2 and 4), which are not useful depth indicators (Fig. 7). Based on abun-dance of H. hughesi, we interpret paleodepths of 10–25 m for 358.37–346.26 mcd and a single

Ben

thic

Fora

min

ifera

lP

aleo

dept

h (m

)60

8010

0

Ben

thic

Fora

min

ifera

lP

aleo

dept

h (m

)60

200

4080

100

2040

6080

100

Ben

thic

Fora

min

ifera

lP

aleo

dept

h (m

)

100

0

175R

176R

177R

178R

179R

180R

181R

182R

183R

184R

66

0

65

0

64

0xx

xxxx

xxx

XX

XX

XX

XX

XX

wd g

XX

XX

XX

XX

XX

XX

XX

X

wd

gg

xxxxxxxxxxxxxxx

gg

g

xxxx

xxxx

x

Lith

olog

y

Bas

ed o

n ag

es

Base

d on

age

s

Cor

ere

cove

ry

Toe

Toe

Environment

BenthicBiofacies


70-8

0 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

Cum

ulat

ive

Lith

olog

y (%

)

50

Reflector

Depth (mcd)

Age (Ma)

m5.

4

m5.

364

3.19

662.

37

70 75 75 75

16.0

17.6

17.7

17.7

490

480

470

460

450

440

430

420

410

400

390

380

370

360

56R

57R

58R

59R

60R

61R

62R

63R

64R

65R

66R

67R

68R

69R

70R

71R

72R

73R

74R

76R

77R

78R

79R

80R

81R

82R

83R

84R

85R

86R

87R

88R

89R

90R

91R

92R

93R

94R

95R

96R

97R

98R

99R

100R

101R

102R

103R

104R

105R

g

g

gg

g g

g

gg

g

g

g xxxx

xxx

gwd

? ? ? C.D.

C.D.

wd wd

wd

wd

wd

wd

x

wd

wd

wd wd

wd wd

wd

Depth (mcd)

500

106R

wd

wd

107R

108R

109R

110R

111R

112R

520

510

wd

wd

wd gLith

olog

yC

ore

reco

very

25-5

0 m

50-6

0 m

50-7

5 m

50-7

5 m

75-1

00 m

75-1

00 m

50-7

5 m

SF River-influencedSOT SOT

River-influencedOFF

OFF

10-2

5 m

10-2

5 m

10-2

5 m

10-2

5 m

10-2

5 m

10-2

5 m

15 10 1025 25 30 50 50 50 75 50 507550

-100

m

BenthicBiofacies


Systemstracts

Environment

Cum

ulat

ive

Lith

olog

y (%

)50

100

0

m5.

4

m5.

34

m5.

33

m5.

336

1

405

449

479

512.

33

16.6

17.7

17.6

17.4

16.7

17.6

17.9

16.3

16.9

/

16.9

/16

.7

Reflector

Depth (mcd)

Age (Ma)

m5.

32

Seq

uenc

e m

5.4

For

eset

Top

set

Bot

tom

set

M27

M28

M29

HS

T

HS

T

HS

T

LST

TS

T

TS

T

LST

LST

TS

m5.

3549

4

501

MF

S

MF

STS

MF

S

87R

88R

89R

90R

91R

92R

93R

94R

95R

96R

97R

98R

99R

100R

Depth (mcd)

270

250

260

280

290

101R

102R

103R

104R

gg

**

*

300

Cor

ere

cove

ryLi

thol

ogy

75 m

75 m

25-5

0 m

25-5

0 m

25-5

0 m

SO

T

OT

OF

FEnvironment

BenthicBiofacies

IntegratedWaterdepthSystems

35 75 30 403045 15 50

HS

T

HS

T

TS

T

TS

T

S

5010

00

Cum

ulat

ive

Lith

olog

y (%

)

m5.

3

m5.

3

249.

76

256.

19

295.

01

15.8

16.5

17.0

17.7

15.8

16.8

16.9

16.9

Reflector

Depth (mcd)

Age (Ma)

m5.

3327

1.23

m5.

34/

m5.

4m

erge

d

MF

S ?TS

MF

S

35-5

0 m

OF

F

25 m

475

tracts

40-5

0 m

391

393

10-2

5 m

10-2

5 m

75-1

00 m

25 m

SF

River-influenced Toe slopeapron

River-influencedSF

TS

40

Depth (mcd)

16.7

csm

gvf

vcSa

nd

csm

gvf

vcSa

nd

cs

mg

vfvc

San

d

Fig

ure

16.

Sequ

ence

m5.

4 co

mpa

riso

ns a

mon

g In

tegr

ated

Oce

an D

rilli

ng P

rogr

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n 31

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tes

M27

, M

28,

and

M29

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win

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ry a

nd s

yste

ms

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ased

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sample at 324.42 mcd (Figs. 7–9 and 17). Two samples (345.81 and 336.07 mcd) with few foraminifera, dominated by Lenticulina spp., may indicate dissolution, winnowing, and/or downslope transport. The shallow-water bio-facies and barren samples are consistent with deposition in shallow water for this sequence.

At Site M29, sequence m5.3 (643.19–602.25 mcd; 16.0–15.8 Ma) was deposited on a bottom-set with two coarsening-upward successions separated by a silt unit. Despite the abundant coarse sands in this sequence, benthic forami-nif era indicate relatively deep water throughout, based on 19 samples examined. We note com-mon specimens of transported Lenticulina spp. and H. hughesi along with deep-water taxa. We interpret this as an excellent example of trans-ported shallow-water material mixed with in situ deep-water biofacies on a bottomset. The lowermost sample examined in this sequence (642.29 mcd) contains abundant B. gracilis (34%) and Uvigerina spp. (20%), indicating 75–80 m paleodepth (Figs. 10–11 and 17). Above this, samples through 633.13 mcd are barren. From 631.61 to 602.62 mcd, assem-blages indicate water depth variations ranging from ~75 to 120 m. Samples with abundant Uvigerina spp. indicate deposition in the shal-lower depth of this range, whereas samples with more abundant C. pachyderma are interpreted to be deeper, 100–120 m paleodepth (631.61, 616.36, 610.26 mcd).

Portions of the TST and HST were preserved in the topset of sequence m5.3 at Site M27, with sparse foraminifera indicating paleodepths ranging from 25 to 75 m (Fig. 17). At Site M28, the shallower (0–25 m) HST sediments are preserved. Paleodepths in the bottomset at Site M29 vary from 75–100 m to 100–120 m, consistent with the deeper bottomset environ-ment expected for the seismic geometry (Figs. 2 and 17).

Sequence m5.2At Site M27, 3 samples were examined from

sequence m5.2 (236.15–225.45 mcd; 15.0–14.8 Ma; Figs. 4–6), which was deposited on a topset (Fig. 2). The lower 2 samples were barren (233.14 and 232.19 mcd). A sample near the top of the sequence (227.27 mcd) yielded an assem-blage dominated by Lenticulina spp. (58%); a paleodepth estimate of 75 m is inferred from 21% Uvigerina spp., together with very few shallow-water indicators (Figs. 4–6). We interpret the Lenticulina spp. as transported. We interpret the upsection facies change from a basal quartz sand to a medial clay yielding deeper water forami nif-era (~75 m paleodepth) to an upper quartz sand as refl ecting a thin TST, MFS, and thin truncated HST (Figs. 6 and 18).

Sequence m5.2 at Site M28 (323.23–276.81 mcd; 15.1–14.8 Ma; 21 samples examined) was drilled immediately landward of the fore-set. Barren samples (321.38–313.41, 306.16–298.92, 297.07, 276.75 mcd) interspersed with shallow-water assemblages (10–25 m) char-acterize sequence m5.2 (Figs. 7–9 and 18). Samples with 100% Lenticulina spp. (312.06–307.71, 297.88 mcd) may indicate dissolution, winnowing, and/or downslope transport. Sam-ples characterized by the H. hughesi biofacies (factor 1) indicate 10–25 m paleodepth (290.83, 287.40, 281.62, 278.64 mcd) at the top of the sequence. We use a qualitative assessment of the fi ne fraction (63–150 μm) to tentatively estimate paleodepths in several samples. (1) At 319.46 mcd, P. pizarrensis, Uvigerina spp., H. hughesi, and Lenticulina spp. possibly indicate ~50 m paleodepth, and (2) at 313.72 mcd, H. hughesi, Lenticulina spp., and planktonic foraminifera possibly indicate 10–25 m paleodepth. We place the MFS at a distinct burrowed surface at 320.55 mcd near a sample with the deepest biofacies at 319.72 mcd. The coarsening-upward sediments above ~310 mcd indicate shallowing upsection from offshore to shoreface-offshore transition to channel fi ll, indicating HST sediments. The barren samples interspersed with shallow-water assemblages (10–25 m) support this inter-pretation.

Site M29 sampled sequence m5.2 (602.25–502.01 mcd; 15.6–14.6 Ma; 50 samples exam-ined) on a foreset just seaward of its maximum thickness, with the facies consisting primarily of fi ne sandy silt. The Uvigerina spp. biofacies (factor 1) characterizes much of this sequence (594.94–517.47 mcd) and indicates 75–100 m paleodepth; sporadic barren samples or sam-ples with shallow-water species likely indicate downslope transport (Figs. 10–12 and 17). Two barren samples in the lowest part of the sequence occur in a coarsening-upward pack-age (602–593 mcd) that is tentatively inter-preted as the LST. The MFS is placed at peaks in planktonic foraminifera and mud at ~582 mcd. The section above this coarsens upward in general, and is interpreted as an HST with four parasequences bounded by FSs. A decrease in Uvigerina spp. abundances coupled with an increase in the factor 3 biofacies (B. gracilis, B. paula, and Hanzawaia sp. 1) in the upper part of the sequence (512.83–501.73 mcd) indicates somewhat shallower paleodepths within the middle neritic zone (50–80 m).

The biofacies in the topset of sequence m5.2 at Site M27 indicate 75–80 paleodepth in the TST and lower HST (Fig. 18). If the TST inter-pretation is correct and the recovered sections are coeval, then the shallower paleodepths (25–50 m) at Site M28 are unexpectedly shallow.

Pal

eode

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(m)

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2040

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84R

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86R

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88R

89R

90R

91R

75 m

25 m

75 m

25-5

0 m

25-5

0 m

35 75 35 75 30 4510

230

240

250

260

Cor

ere

cove

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thol

ogy

10-2

5 m

10-2

5 m

10-2

5 m

10-2

5 m

10-2

5 m

10-2

5 m

10-2

5 m

10-2

5 m

BenthicBiofacies

Lith

olog

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Environment

BenthicBiofacies

SystemsTract

Toeset

OFF

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Cum

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Lith

olog

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5010

00

15.8

15.6

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Reflector

Depth (mcd)

Age (Ma)

SF

Cha

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Rol

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E

0

Depth (mcd)

5010

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m5.

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361

15.7

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Reflector

Depth (mcd)

Age (Ma)

Seq

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5.3

M27

M28

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Depth (mcd)

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Depth (mcd)

Age (Ma)

m5.

3

m5.

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15

249.

76

256.

19

15.0

15.6

15.8

16.8

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Ben

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)

75-1

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75-1

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100-

120

m

100-

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m

75-8

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100

m

85IntegratedWaterdepth

75 75 100

100

75 95 100

70 75

160R

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176R

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650

640

630

620

610

gg

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g

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gg

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gg

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Depth (mcd)

15 15

53R

54R

55R

56R

57R

58R

g

g

g

360

350

340

330

320

38R

39R

40R

41R

49R

50R

51R

52R

gg

g g

g

gg

g

g

Lith

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m5.

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M27

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Katz et al.


This may be explained by the fact that the off-shore (>30 m paleodepth) clay and silty clays of cores 36 and 37 at Site M28 lack forami nifera >150 μm due to preservation. The foreset of sequence m5.2 at Site M29 is dominated by biofacies that indicate 75–100 m, with some variation.

Sequence m5At Site M27, sequence m5 (225.45–218.39

mcd; 13.7–13.6 Ma) is thin, truncated, and fi nes upsection, deepening from shoreface to offshore, and is interpreted as a TST. Benthic foraminiferal assemblages are characterized by P. pizarrensis, indicating that paleodepths were ~25–50 m in the 4 samples examined (Figs. 4–6).

At Site M28, sequence m5 (276.81–254.13 mcd; 13.7–13.5 Ma) was deposited on a top-set and coarsens upsection. This is interpreted as an HST, with the MFS/TS merged with the sequence boundary (Miller et al., 2013a). Forami nifera were examined only near the base of the sequence (3 samples), and indicate ~10–25 m paleodepth based on high abundances of H. hughesi (Figs. 7–9).

Sequence m5 at Site M29 (502.01–478.61 mcd; 13.7–13.6 Ma; 12 samples examined) consists of two coarsening-upward successions deposited on the lower foreset to bottomset. The lowermost sample examined (501.73 mcd) is dominated by the shallow-water indicator H. hughesi (indicating 10–25 m), but the pres-ence of deeper water taxa (B. gracilis ~9.5%, C. pachyderma 7%) in the same sample indicate deposition at a greater paleodepth (~50–60 m) with downslope transport (Figs. 10–12). The factor 1 biofacies (Uvigerina spp.) characterizes most of sequence m5, with both the shallower water H. hughesi and the deeper water C. pachy-derma occurring in relatively high abundances in several of these samples, indicating ~75–100 m paleodepth. There are barren samples scattered through this sequence. There is little indication of variation in paleodepth, so systems tracts interpretations were not made.

Sequence m4.5Sequence m4.5 at Site M27 (218.39–209

mcd; 13.5–13.2 Ma; 7 samples examined) was deposited on a topset and fi nes upsection to ~217 mcd in a TST and coarsens above in an HST. It is characterized by the factor 3 bio-facies (P. pizarrensis, Hanzawaia sp. 1, and H. hughesi), indicating paleowater depths of 10–50 m (Figs. 4–6). Based on higher abun-dances of Hanzawaia sp. 1 and H. hughesi, 213.86 and 212.66 mcd are interpreted as ~25 m paleodepth; the absence of these two species, and the abundant P. pizarrensis (46%) indicate

4060

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Pal

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(m)

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5010

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Cum

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Lith

olog

y (%

)

330

320

310

300

290

280

21R

22R

23R

24R

25R

26R

27R

28R

29R

30R

31R

32R

33R

34R

35R

36R

37R

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Depth (mcd)

Cor

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cove

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Reflector

Depth (mcd)

Age (Ma)

13.7

14.8

15.1

15.7

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m5.

232

3.23

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276.

81

Seq

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5.2

M27

M28

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10-2

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25 10 25 50 30 25 1530

HS

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FS

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25-5

0 m

10-5

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OF

F

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T

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FEnvironment

BenthicBiofacies


35 30 20 3510

HS

T

TS

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76X

77X

78X

79R

80R

81R

82R

83R

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Depth (mcd)

220

230

240

Cor

ere

cove

ryLi

thol

ogy

5010

00

Cum

ulat

ive

Lith

olog

y (%

)

m5Reflector

Depth (mcd)

Age (Ma)

m5.

2

225.

45

236.

15

13.7

14.8

15.0

15.6

Cum

ulat

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Lith

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y (%

)

5010

00

Lith

olog

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very

151R

152R

153R

154R

155R

156R

157R

158R

159R

160R

161R

162R

600

590

580

126R

127R

128R

129R

130R

131R

132R

133R

134R

135R

136R

137R

138R

139R

140R

141R

142R

143R

144R

145R

146R

147R

148R

149R

150R

570

560

550

540

530

520

510

500

g gg g

gg

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Depth (mbsf)

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50-6

0 m

(50-

80 m

)50

-60

m (5

0-80

m)

50-8

0 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

75-1

00 m

??25

-50

m

90-1

00 m

OFF

75-1

00 m

(10-

25?

m)

Environment

BenthicBiofacies


SystemsTract

75 50 80 90 75 75 75 75

HS

T

TS

T

LST

602.

25m

5.2

m5

502.

0114

.613

.7

15.8

15.6

Reflector

Depth (mcd)

Age (Ma)

TS

MF

S

FS

FS

FS

SO

T

75-1

00 m

75 m

75-1

00 m

FS

MF

S

SF

75

er-influencedSOT

75-1

00 m

593

581

csm

gvf

vcSa

nd

cs

mg

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d

csm

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nd

Fig

ure

18. S

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m5.

2 am

ong

Inte

grat

ed O

cean

Dri

lling

Pro

gram

Exp

edit

ion

313

Site

s M

27, M

28, a

nd M

29 s

how

ing

deta

iled

pale

o-ba

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etry

and

sys

tem

s tr

acts

bas

ed o

n fo

ram

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and

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ns).



25–50 m at 210.665 mcd. There are also barren samples in this sequence.

At Site M29, sequence m4.5 (478.61–408.65 mcd; 13.6–13.3 Ma; 42 samples examined) was deposited at very high sedimentation rates (>200 m/m.y.) on a truncated foreset (Fig. 2). It consists of a lower coarsening-upward regres-sive LST succession to 470 mcd. This section yields 2 barren samples near the base (477.08 and 475.58 mcd), overlain by the shallow-water H. hughesi biofacies (factor 4; 10–25 m paleodepth; 474.38 mcd; Figs. 10–12). Sam-ples at 473.01 and 470.99 mcd are slightly deeper, characterized by both the H. hughesi and P. pizarrensis biofacies (factors 4 and 5), likely indicating ~25 m paleodepth (within the 10–50 m range indicated by the combination of the two biofacies). We place a TS at 470 mcd at the top of the regressive succession, based on lithology and foraminifera, with a paleodepth estimate of 50–75 m for 469.91 mcd based on high abundances of P. pizarrensis (21%) and Uvigerina spp. (21%), along with 11% B. gracilis (Figs. 10–12). The Lenticulina spp. biofacies (factor 2) that characterizes several samples (473.01 and 466.86 mcd) may indicate downslope transport. Foraminifera are sparse in the three overlying samples (468.36, 466.86, 463.86 mcd), and no paleodepth determination was made (Figs. 10–12). Above this (460.79, 459.21, and 457.71 mcd), high loadings on the factor 5 biofacies (P. pizarrensis) and factor 3 biofacies (B. gracilis, B. paula, and Hanza-waia sp. 1) indicate paleodepths near the tran-sition between the two biofacies. We assign a paleodepth of 40–50 m to 460.79 mcd based on the absence of Uvigerina spp. from this sample. The presence of Uvigerina spp. (~6%–9%) indi-cates slightly deeper paleodepths at 459.21 and 457.71 mcd (40–60 m).

The deepest paleodepths (75–100 m) in sequence m4.5 at Site M29 are recorded in 4 samples from 455.57 to 451.65 mcd, as indi-cated by high loadings on the factor 1 bio facies (Uvigerina spp.; Figs. 10–12). The MFS is placed at 448 mcd. Together, the TS and MFS bracket a fi ning-upward TST (470–448 mcd) with the deepest water biofacies of the sequence.

Much of the thick silty HST at Site M29 yields few or no benthic foraminifera below 413.50 mcd; nonetheless, paleobathymetric esti-mates can be determined for some of the sam-ples. Overlying the MFS (448 mcd), a sample at 447.32 mcd is dominated by Lenticulina spp. (63.5%); based on 6%–14% each of P. pizar-rensis, B. gracilis, B. fl oridana, and Uvigerina spp., we estimate 25–75 m paleodepth for this sample (Figs. 10–12). Similarly, a sample with Lenticulina spp. (86%) and P. pizarrensis (14%) is estimated as 10–50 m paleodepth. Samples

from 442.56 to 433.29 mcd were barren or yielded too few specimens to provide a paleo-bathymetric estimate.

Benthic foraminifera indicate that most of the remainder of the HST in sequence m4.5 was deposited in the middle-middle neritic zone, with varying abundances of B. gracilis and B. paula indicating 50–80 m paleodepth (Figs. 10–12). This section includes sporadic barren samples, and a section of barren samples from 419.60 to 415.07 mcd. In contrast, abundant for-aminifera from 413.50 to 410.80 mcd support a 50–80 m paleodepth in the HST, suggesting an FS at ~430 mcd.

Sequence m4.4Sequence m4.4 at Site M29 (409.27–377.15

mcd; 13.3–13.2 Ma; 23 samples examined) sampled a highly truncated foreset that consists of silt and silty clay capped by a few sand beds, deposited at very high sedimentation rates (>300 m/m.y.). A shallowing to 25–50 m paleodepth in the lowermost portion of the sequence (408.90 mcd) is indicated by the P. pizarrensis bio-facies (factor 5; Figs. 10–12); this is consistent with the interpretation that these sediments were deposited at the shallowest depths of the offshore zone (Mountain et al., 2010). Similar to the upper portion (HST) of the underlying m4.5 sequence, much of sequence m4.4 is char-acterized by the factor 3 biofacies (B. gracilis, B. paula, and Hanzawaia sp. 1), indicating 50–80 m paleodepth (Figs. 10–12). Two closely spaced samples in the lower part of the sequence (404.35 and 404.32 mcd) may indicate slightly shallower paleodepths (25–80 m), as indicated high abundances of P. pizarrensis (67%–69%), in addition to B. gracilis (8%–17%); however, this paleodepth estimate is not well constrained because the samples yielded sparse foraminifera (10–17 specimens). This sequence includes spo-radic barren samples.

Sequence m4.3Sequence m4.3 (377.15–364.86 mcd; 13.2–

13.1 Ma; 8 samples examined) at Site M29 is highly truncated. The B. gracilis biofacies (fac-tor 3) indicates that the lower portion of this sequence was deposited at 50–80 m paleodepth (376.76–372.36 mcd; Figs. 10–12). The remain-ing samples in this sequence yield rare benthic (B. gracilis or Lenticulina spp., 1–3 speci-mens) and/or rare planktonic (1–5 specimens) foraminifera, providing insuffi cient basis for a paleobathymetric estimate.

Sequence m4.2-4.1At Site M29, sequence m4.2 (364.86–342.81

mcd; 13.1–13.0 Ma; 16 samples examined) is heavily eroded, and consists of two coars-

ening-upward successions that appear to be parasequences within the LST. The lower para-sequence (9 samples from 364.70 to 350.99 mcd, excluding 2 barren samples) is character-ized by the P. pizarrensis biofacies (factor 5), indicating 25–50 m paleodepth; the lowermost sample (364.70 mcd) may be slightly shallower, as indicated by H. hughesi and P. pizarrensis, indicating 10–50 m paleodepth (Figs. 10–12). The higher abundance of Uvigerina spp. (9%) at 353.71 mcd may indicate deposition toward the lower end of this depth range (50 m). Samples in the upper parasequence are barren (344.12–349.62 mcd).

The m4.1 surface (343.81 mcd; 13.0 Ma) is most likely a merged sequence boundary–TS (36 samples were examined above m4.1). Ben-thic foraminiferal assemblages support this interpretation, with the Uvigerina spp. bio facies (factor 1) indicating paleodepths of 75–100 m above refl ector m4.1 (338.81–335.76 mcd; Figs. 10–12). This section is interpreted as a thin TST, with the MFS at ~340–335 mcd. Two samples that overlie the TST yield foraminifera that indicate shallower depths, consistent with this section being the base of a regressive HST (Figs. 10–12). At 334.23 mcd, the paleodepth is estimated at 40–60 m, refl ecting the abundances of P. pizarrensis (25%) and Uvigerina spp. (17.5%). At 332.71 mcd, an increase in P. pizar-rensis (65%) indicates a shallower paleodepth (25–50 m). The remainder of the HST yields only barren samples. Estimates of distance from shoreline based on palynomorphs are consistent with the detailed paleobathymetric variations in m4.4–m4.1 (McCarthy et al., 2013).

Sequences m4.4, m4.3, m4.2, and m4.1 merge landward of Site M29, and the m4.1-4.4 concatenated sequence boundary occurs at 209 mcd at Site M27. Nearly all the samples examined for foraminifera above this sequence boundary were barren (8 samples from 208.99 to 195.62 mcd). A single sample (204.13 mcd) yields an assemblage (11.4% P. pizarrensis, 14.3% B. gracilis, 54.3% Buliminella curta) that indicates 25–80 m paleodepth; we tenta-tively narrow this estimate to 50–80 m, based on the abundance of Buliminella (Figs. 4–6).

DISCUSSION

Our Expedition 313 samples yield pre-dominantly in situ biofacies, although there are several excellent examples of mixing of downslope-transported specimens within deep-water (75–120 m) deposits. Examples include sequence m5.4–1 at Site M28, and sequences m5.47, m5.3, m5.2, and m5 at Site M29. Downslope transport is most prevalent at Site M29, which primarily sampled bottomsets older

Katz et al.


than sequence m5 (older than 14.6 Ma) and truncated foresets younger than sequence m5 (younger than 13.7 Ma). At Site M29, Sr isotope analyses also indicate extensive reworking and downslope transport in sediments younger than ca. 15 Ma; however, sediments older than 15 Ma show less pervasive reworking, according to Sr isotope analyses (Browning et al., 2013).

The deepest water in situ biofacies at the Expedition 313 sites occur in bottomsets of the clinothems and the lower portions of the fore-sets. At Site M27, the Eocene–earliest Oligo-cene bottomsets (>617 mcd) yield the deepest water biofacies (100–120 m; Figs. 2 and 6). The overlying bottomset sequences are slightly shallower, but are still relatively deep (75–100 m for 617–509 mcd; 50–80 m for 500.06 mcd). Sequence m5.8 was sampled on the foreset in the thickest part of the clinothem at Site M27 (beneath the m5.7 rollover; Fig. 2), with a zone of maximum fl ooding (467.01–421.31 mcd) characterized by biofacies indicating 50–80 m paleodepth. The deepest water biofacies at Site M28 occurs within the thick foreset of sequence m5.4 (Figs. 2 and 9) and on bottomsets. At Site M29, the deepest water biofacies also occur in the bottomsets and/or foresets, in and below the lower portion of sequence m4.5 (Figs. 2 and 12). Above these paleodepth maxima, the long-term paleobathymetric reconstructions show an overall shallowing-upward trend as sediment accumulation resulted in reduced accommoda-tion space.

Short-term paleodepth fl uctuations punctu-ate the long-term shallowing-upward succes-sions at the Expedition 313 sites. On the topset of Site M27, a rapid deepening that occurs in sequence m5.3 continues into sequence m5.2, with biofacies that indicate unexpectedly deep paleodepths of ~75–80 m (Uvigerina spp.), con-sistent with estimates of distance from shoreline based on palynomorphs (McCarthy et al., 2013). Biofacies at Site M29 also record a deepening in sequence m5.3 (from 75–100 m to 100–120 m). At Site M28, biofacies indicate a deepening in the lower part of sequence m5.2 (from 10–25 m to 25–50 m). Sequences m5.3 and m5.2 were deposited during the Middle Miocene Climatic Optimum, when global sea level was likely rela-tively high (see Browning et al., 2013, for com-parison of Expedition 313 sequences with the global oxygen isotope curve), suggesting that this deepening had a global cause.

Shallower biofacies characterize prograda-tion that occurred above sequence m5.2 as the clinothems built up and accommodation space decreased (Figs. 2, 6, 9, 12, and 18). Site M29 sampled the post-m5.2 sequences on truncated foresets (Fig. 2), where biofacies indicate a decrease in overall paleodepth to 50–80 m in the

upper parts of sequences m4.5 and m4.4, with further shallowing to 25–50 m in sequences m4.3 and m4.2. The exception to this shoaling-upward trend is sequence m4.1 at Sites M27 and M29, which yield biofacies that indicate water depths of 50–80 m and 75–100 m, respec-tively; this is ~50 deeper than the underlying sequences, and suggests that a regional fl ooding event occurred at this time. The event was brief, with biofacies indicating a return to shallower depths in sequence m4.1 (25–50 m at M29; bar-ren samples at M27). The sequence m4.1 bound-ary correlates with the Miocene isotope event Mi4 δ18O increase (Browning et al., 2013), an ~40 m glacioeustatic lowering based on Mg/Ca and δ18O (Westerhold et al., 2005). Sea level rose rapidly (0.1–0.2 m.y.) following Mi4, but only by ~25 m (Westerhold et al., 2005). There-fore, the regional fl ooding event must be due to either regional subsidence (unlikely, because the event was so rapid) or a decrease in sedimenta-tion rate. Seismic profi les show that extensive bypassing occurred at Sites M27–M29 above sequence m4.1 (Karakaya, 2012), suggesting that the increased water depths were due to sedi-ment starvation.

Similar brief paleodepth changes are indi-cated by shallow biofacies punctuating sections otherwise characterized by deeper biofacies. Some of the shallow excursions correspond well with the oxygen isotopic compilation that indicates relatively low global sea level (see Browning et al., 2013). These include samples at or near sequence boundaries, which in most cases correspond to global sea-level lowering, including Site M29 sequence boundaries m5.7, m5.6, m5.45, m4.5, m4.4, and m4.2 (Fig. 12). In the thick m5.2 sequence, two brief shallowings appear to correspond to δ18O increases ca. 15.1 and 15.3 Ma.

CONCLUSIONS

Biofacies at all three Expedition 313 sites indicate a long-term shallowing-upward trend as clinothems built seaward and accommoda-tion fi lled up from the latest Eocene to middle Miocene (Figs. 6, 9, and 12). The bottom-sets of the clinothems and the lower portions of the foresets (thick parts of clinothems, under the rollover) yield the deepest water biofacies. The upper portions of the foresets and the top-sets are characterized by shallower biofacies, as the accommodation decreased as sediment accumulated (Figs. 13–18).

Superimposed on this, short-term variations in paleowater depth, indicated by integrated bio-facies and lithofacies, are likely linked to global sea-level changes indicated by the global oxy-gen isotope curve. A regional signal is apparent

during Mi4, when extensive bypassing and sedi-ment starvation above sequence m4.1 (Kara-kaya, 2012) resulted in increased water depths.

We used our paleobathymetric reconstruc-tions in a sequence stratigraphic framework to evaluate systems tracts within several early to early-middle Miocene (ca. 23–13 Ma) pro-grading clinothems sampled at the Expedition 313 sites. Sites M27 and M28 are dominated by TST and HST deposits, with limited LST sedi-ments. Foresets contain all three systems tracts, but tend to be dominated by TST and HST deposition at all three sites. Flooding surfaces associated with parasequence boundaries occur in all systems tracts. Topsets are characterized by TSTs and HSTs.

ACKNOWLEDGMENTS

We thank the drillers and scientists of Integrated Ocean Drilling Program (IODP) Expedition 313 for their enthusiastic collaboration, the Bremen IODP Core Repository for hosting our studies, and B. King, K. Monahan, and H. Smith for laboratory work. Fund-ing was supplied by the U.S. Science Support Pro-gram Consortium for Ocean Leadership and samples were provided by the IODP and the International Con-tinental Scientifi c Drilling Program (ICDP). We thank Jean-Noel Proust, Robert Speijer, and an anonymous reviewer for comments that helped to improve this manuscript.

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