Post on 10-Jun-2020
“COLLINGWOOD” STRATA IN SOUTH-CENTRAL
ONTARIO – A PETROPHYSICAL
CHEMOSTRATIGRAPHIC APPROACH TO COMPARISON
AND CORRELATION USING GEOPHYSICAL BOREHOLE
LOGS.
by
Christopher C. Rancourt
A thesis submitted in conformity with the requirements for the degree of Master of Science
Department of Geology University of Toronto
© Copyright by Christopher C. Rancourt, 2009
ii
“COLLINGWOOD” STRATA IN SOUTH-CENTRAL ONTARIO – A PETROPHYSICAL
CHEMOSTRATIGRAPHIC APPROACH TO COMPARISON AND CORRELATION USING
GEOPHYSICAL BOREHOLE LOGS.
Christopher C. Rancourt
Department of Geology, University of Toronto, 2009
ABSTRACT
A petrophysical chemostratigraphic comparison and correlation of “Collingwood” strata across
central Ontario was conducted using geophysical borehole log data and core produced by the
Ontario Oil Shale Assessment Project (OSAP). Outcrop sections were also measured, sampled
and described. The resultant geophysical correlation was compared to sections in the Michigan
Peninsula. Microfacies analyses and a biostratigraphic review were also conducted. The dark
organic rich rocks collectively referred to as the “Collingwood Member, Lindsay Formation”, in
Ontario were deposited during the progressive drowning of a mid to late Ordovician carbonate
ramp. Due to variability in ramp palaeotopography, condensation intensity (sedimentation
stress) varied across the region during drowning. This variability resulted in regional differences
in Collingwood section thickness and facies. Less condensed carbonate rich “Collingwood”
sections are associated with palaeotopographic highs such as the Algonquin Arch in Ontario and
grade upwards and outwards (off-arch) from predominantly deep-shelf carbonates (microfacies
type SMF 9, FZ 2 – open sea shelf –deep undatherm below wave base) to more condensed
deeper water shale rich strata (microfacies type SMF 3, FZ1- basin fondotherm below oxygen
level) – that contain abundant graptolites and Triarthrus trilobites.
iii
ACKNOWLEDGEMENTS
Special thanks and my deepest gratitude go to Andrew Miall for supervising this work and to
Nick Elyes, Ulrich Wortman and Jörg Bollmann for serving as my committee on such short
notice. I dedicate this work to my wife Kasia, daughters Megan and Emily, my Father the late
Andre L. Rancourt and mother Merle J. Rancourt. Special thanks also go to John B. Lawson for
being a friend and mentor in life.
iv
TABLE OF CONTENTS ABSTRACT .......................................................................................................................................... ii
ACKNOWLEDGEMENTS .................................................................................................................. iii
TABLE OF CONTENTS ..................................................................................................................... iv
1.0 INTRODUCTION ................................................................................................................. 1
2.0 STRATIGRAPHIC REVIEW ................................................................................................ 3
3.0 GEOLOGICAL SETTING .................................................................................................... 5
4.0 LOCALTIES AND DATA COLLECTION .......................................................................... 6
5.0 REGIONAL SUBSURFACE STRATIGRAPHY ................................................................. 6
6.0 MICROFACIES ANALYSIS ................................................................................................ 8
6.1 Lower Mbr. (Lindsay Fm.) Nodular Limestones. SMF 9, Facies Zone 2 .............................. 8
6.2 Collingwood Mbr. (Lindsay Fm.) Marlstone SMF 3, Facies Zone 1 ................................... 10
6.3 Collingwood Mbr. (Lindsay Fm.) Pale Grey and Buff -coloured Carbonate interbeds SMF
9, Facies Zone 2 ................................................................................................................... 12
6.4 Blue Mountain Fm. Shale/calcareous shale .......................................................................... 12
6.5 Microfacies Analysis Results ............................................................................................... 12
7.0 BIOSTRATIGRAHY AND PALAEOBIOLOGY .............................................................. 13
7.1 Trilobites .............................................................................................................................. 13
7.2 Graptolites ............................................................................................................................ 13
7.3 Conodonts ............................................................................................................................. 14
7.4 Chitinozoa ............................................................................................................................ 14
7.5 Biostratigraphy and Palaeobiology Results .......................................................................... 14
8.0 GEOPHYSICAL BOREHOLE LOG CORRELATION ..................................................... 16
8.1 Method .................................................................................................................................. 16
8.2 Geophysical Borehole Log Identified Unit (Petrophysical Chemostratigraphic approach) . 16
8.3 Condensation ........................................................................................................................ 19
8.4 “Collingwood” Strata in Central Ontario and the Michigan Basin ...................................... 23
8.5 Datum, Stratal Condensation and Boundary Contacts ......................................................... 24
9.0 DISCUSSION AND CONCLUSIONS................................................................................ 26
10.0 REFERENCES ..................................................................................................................... 30
FIGURES………………………………………………………………………………..(1 through 24)
APPENDIX A …………………………………………………………………………...(Plates 1 & 2)
1
1.0 INTRODUCTION
Between 1980 and 1983 the economic potential of Ontario's "oil shales" was investigated
by the Ontario Geological Survey. The study was known as the “Ontario Oil Shale Assessment
Project” OSAP (See Johnson et al., 1983, 1985). In South-central Ontario the Collingwood
Member of the Lindsay Formation, at that time the Craigleith Member of Liberty's (1969)
Whitby Formation were among some of the “oil shales” assessed (see Collingwood distribution
map Figure 1 and historic stratigraphic nomenclature Figure 2). Because these strata were
known from only a scant few geographically isolated outcrops (Figure 3), none of which exposed
complete sections, OSAP’s borehole program promised to provide much needed stratigraphic
data (Russell and Telford, 1983).
Since the publication of OSAP data by Johnson et al., (1983-1985), biostratigraphic,
petrographic, petrochemical, and stratigraphic analyses (including a stratigraphic revision) have
been conducted and published by various authors (See Russell and Telford (1983); Churcher et
al. (1986); Churcher et al. (1991); Hiatt (1985); Hiatt and Nordeng (1985); Wilson and Sengupta
(1985); Snowdon (1984); Macauley et al. (1990); Johnson et al. (1991); Lehman et al. (1995).
Yet despite the new OSAP data, analyses, and stratigraphic revision, our understanding of these
organic-rich strata does not appear to have advanced significantly, as the wide range in post-
OSAP palaeoenvironmental interpretations bear witness. These include normal marine shallow-
shelf, deep-shelf, stratified marine, stranded basin and restricted lagoon interpretations.
The areal distribution of Collingwood strata was estimated by Churcher et al. (1991)
(Figure 1). Pleistocene glacial scouring removed the Collingwood Mbr. north and east of St.
Joseph's Island, Manitoulin Island, Craigleith, and Bowmanville, exposing older parts of the
carbonate shelf and Precambrian Shield (Churcher et al., 1991). Collingwood Mbr. strata were
reported to thin basinward toward the Michigan and Appalachian basins (Churcher et al., 1991;
Johnson et al., 1983; Hiatt, 1985; Hiatt and Nordeng, 1985). According to Russell and Telford
(1983) total organic carbon content (TOC) also decreases basinward. A thin phosphatic bed was
reported to replace Collingwood Mbr. strata basinward (Michigan Basin) of its pinchout
(Churcher et al., 1991). According to Churcher et al. (1991), Collingwood strata have been
identified as outliers in only a few holes in Southwestern Ontario (see Figure 4).
2
The lithologic content of the Collingwood Mbr. and its stratigraphic boundary contacts
were defined in the stratigraphic revision proposed by Russell and Telford, (1983). Russell and
Telford (1983) based their stratigraphic revision and conception of the “Collingwood Mbr.” on
(a) mappable geophysical borehole log signatures and (b) similarities in correlative lithologies
across the region. However, preliminary investigation of these strata and geophysical borehole
logs indicated to the author regional differences in facies, section thickness, and contact
boundary conditions that suggest the lithostratigraphic formation model adopted by Russell and
Telford (1983) is problematic.
Regional differences in facies, section thickness, and contact boundary conditions would
explain much of the variability not only in environmental interpretations but also in pre-OSAP
geologic reports on lithologic content and boundary contacts. “With great understatement” was
the comment Russell and Telford (1983) used to acknowledge Winder’s (1961) declaration that
geologic reports showed inconsistencies.
Geophysical borehole log profiles ( gamma and resistivity) of Collingwood Mbr. strata
have been described as “characteristic” in the Michigan Peninsula by Hiatt and Nordeng (1985);
Wilson and Sengupta (1985), and in Ontario by Russell and Telford (1983); Churcher et al.,
(1991). The purpose of this study was to determine if a petrophysical chemostratigraphic
approach (using geophysical borehole logs) to compare and correlated Collingwood strata in
South-central Ontario would provide a better understanding of these strata. In addition to the
petrophysical chemostratigraphic comparison and correlation a microfacies analysis and review
of the biostratigraphic data was also conducted. The petrophysical chemostratigraphic
comparison and correlation of Collingwood strata in central Ontario was also compared to
reportedly correlative strata in the Michigan Peninsula.
3
2.0 STRATIGRAPHIC REVIEW
A comprehensive review of pre-1983 stratigraphic nomenclature and age attribution for
strata equivalent to the Collingwood was conducted by Liberty (1955; 1969). Another
researcher, Winder (1961), produced a lexicon of Palaeozoic names in Southwestern Ontario, in
which the various stratigraphic nomenclature uses were discussed. Figure 2 summarizes and
compares the historic and current stratigraphic nomenclature use in South-central Ontario. In
addition Figure 2 presents the current stratigraphic nomenclature for Southwestern Ontario and
Eastern Ontario.
In 1983, Russell and Telford used OSAP data to propose a stratigraphic reassignment of
Liberty’s (1969) Craigleith Mbr. of the Whitby Fm. (see Figure 2). The Craigleith Mbr. was re-
named the Collingwood Mbr. and re-assigned to the Lindsay Fm. The name “Collingwood”
(first used by P.E. Raymond in 1912) has historically been in use variably as an age and/or
lithologic assignment. Historic descriptions of lithologic content and contact definitions will in
part be discussed in later sections of this study.
At present Collingwood strata are interpreted to be early Upper Ordovician in age
(biostratigraphic age: Maysvillian). In South-central Ontario Collingwood strata are included as
the upper most strata of the combined Simcoe and Basal Groups (equivalent to the Trenton-
Black River Group of Southwestern Ontario and the Michigan Peninsula). In Ontario the upper
Collingwood contact boundary represents the upper boundary of Depositional Sequence 2.
According to Johnston et al. (1991), Depositional Sequence 2 is comprised of primarily craton
derived clastic rocks succeeded by shallow water carbonates and is roughly equivalent to the
Sauk-Tippecanoe sequence of Sloss (1963, 1988)(Johnston et al., 1991) Figure 2. Note however,
that this “sequence boundary” was largely based on the break between predominately carbonate
vs. clastic deposition and does not represent an erosional unconformity in the sense of Mitchum
et al. (1977) (Melchin et al., 1994).
Collingwood strata are reported to be equivalent to the Boas River Fm. (Hudson Bay and
Moose River basins) and the Eastview Mbr. of the Lindsay Fm. (Eastern Ontario) (see Johnston
et al. (1991). However, it was beyond the scope of this study to review those strata. The Boas
River Fm. and the Eastview Mbr. (Lindsay Fm) are separated from Collingwood strata in South-
central Ontario by large distances over which equivalent strata have been removed during
4
Pleistocene glaciation. Therefore, a petrophysical chemostratigraphic comparison of these strata
would require much speculation. To date the relatedness of these strata is based on similar
lithologic and biostratigraphic data.
5
3.0 GEOLOGICAL SETTING
During the Middle Ordovician, closure of the Iapetus Ocean resulted in a series of
collision events at the eastern margin of Laurentia (North America). The subduction of Iapetus
crust and collision with an island arc (Rowley and Kidd, 1981; Cisne et al., 1982; Hay and Cisne,
1988) and or microcontinent/s (Delano et al., 1990) produced the Taconic orogen. Lithospheric
downwarping associated with cratonward loading of thrust blocks (taconic allochthon) produced
a peripheral foreland basin (the Western Taconic Foreland) (Rowley and Kidd, 1981; Quinlin
and Beaumont, 1984; Lash 1988; Bradley and Kidd, 1991). The eastern portion of a shallow
marine carbonate platform now drowned and faulted formed the floor of the basin. Movement
along high-angled faults with strike parallel to the basin axis (north-northeast-south-southwest)
produced grabens and half grabens on the deeper eastern portion of the basin (Cisne et al., 1982;
Bradley and Kidd, 1991). Siliciclastic deposition in the basin migrated with time to the
northwest encroaching on the Trenton carbonate platform/ramp (Rowley and Kidd, 1981;
Bradley and Kusky, 1986; Lehman et al., 1995). The upper Collingwood Mbr. boundary (base
of Blue Mountain Fm.) is thought to represent the first arrival in Ontario of the migrating
siliciclastics (see Johnson et al., 1991).
Today the Michigan and Appalachian basins separated by the Central and Western St.
Lawrence platforms dominate the subsurface (see Figure 5). The Algonquin Arch runs centrally
through the Western St. Lawrence platform producing the only significant topographic relief on
the platform. Similarly the Frontenac Arch (Johnson et al., 1991) interrupts the Western and
Central St. Lawrence platforms. The Laurentian Arch continues northeastward from the
Algonquin Arch.
At the northernmost outcrop (Manitoulin Island), Figure 3, a localized Precambrian
metaquartzite mound is unconformably overlain by Lower Mbr. and Collingwood Mbr. strata
(Johnson and Jia-yu, 1989) (Goldman and Bergstrom, 1997). The development of a short-lived
metaquartzite boulder beach in that area is interpreted to indicate a rapid transgression across the
Precambrian metaquartzite mound (Johnson and Jia-yu, 1989. The Collingwood Mbr. has not
been recognized south of Lake Ontario (Lehman et al., 1995)
6
4.0 LOCALTIES AND DATA COLLECTION
Collingwood Mbr. strata, as defined by Russell and Telford (1983), outcrop in 3 laterally
isolated areas in South-central Ontario (Fig. 3). At each of the three outcrop localities the lower
boundary can reportedly be observed. The upper boundary has not been recognized in outcrop.
Therefore, to examine the Collingwood Mbr. and both boundaries at any given geographic point
requires subsurface data (geophysical borehole-logs and/or core). In this study, 3 outcrop and 15
borehole localities (represented by geophysical borehole logs - 7 with core) were examined.
Outcrop and OSAP borehole locations are shown in Figure 6.
5.0 REGIONAL SUBSURFACE STRATIGRAPHY
A stratigraphic cross section through the preserved palaeozoic units in South-central
Ontario is presented in Figure 7. The cross section runs from northwest to southeast along the
Niagara escarpment and shows the generalized progression of lithologic units upwards from the
Precambrian discontinuity. The units have been grouped into Johnston et al.’s (1991)
depositional sequences 1 through 6 (see discussion of depositional sequences in section 3). The
cross section was based on the subsurface correlation work conducted by Armstrong and Carter
(2006) and generalized lithologic descriptions of formation units in Johnston et al. (1991). Table
1 (after Johnston et al., 1991) below, compares the relevant six depositional sequences to the
North American Sequences of Sloss (1963, 1988) (Johnston et al., 1991) and provides the epoch,
period and generalized depositional mode.
7
Table 1
Period, Epoch and Sequence Comparison
Period Epoch Depositional Sequence North American Sequence
Silurian
Late Upper 6 - carbonate and evaporitic deposits. Some orogen derived clastic sediments
Tippecanoe
Middle 5 - extensive carbonate deposition with some shale
Early 4 - orogen derived fluvial to shallow marine clastics
and marine carbonates Lower
Ordovician
Late 3 - orogen derived clastic rocks
2 - initial craton derived clastics then dominated by shallow marine carbonates Middle
Early 1 - predominantly craton derived clastic sediments Sauk
Cambrian Upper
After Johnston et. al. (1991)
8
6.0 MICROFACIES ANALYSIS
The Collingwood Mbr. was reported by Russell and Telford, (1983) to consist of
interbeded limestone and marlstone. The mineral content was reported to be calcite (up to or
greater than 50%), quartz (35%), clays (15% illite and iron chlorite), pyrite, phosphate, and
locally dolomite (Russell and Telford, 1983; Snowdon, 1984; Macauley et al., 1991; Churcher et
al., 1991). Although the lithology and mineralogy of the Collingwood Mbr. has been
investigated and generalized little has been discussed with respect to stratigraphic and lateral
variation of these components. Therefore samples from core and outcrops were collected from
the nodular limestone of the Lower Mbr., marlstones and carbonate interbeds of the Collingwood
Mbr., and shales of the Blue Mountain Fm. A thin phosphatic bed observed at the upper
Collingwood Mbr. boundary, Clarksburg locality, was also sampled.
Thin sections made from core and outcrop samples collected from the nodular limestones
of the Lower Lindsay Mbr., marlstones and carbonates of the Collingwood Mbr., and shales of
the Blue Mountain Fm. were prepared and examined under reflected and transmitted plain and
cross-polarized light using a petrographic microscope. The sections were described by
comparison to the carbonate microfacies of Wilson (1975) and Flugel (1982). A representative
image for each microfacies type appears beside the description. In addition acid resistant
microfossils and minerals were obtained through acid digestion of carbonate samples (2 kg each)
collected from outcrop localities. The microfossils were used as palaeoenvironmental indicators
(note: microfossils collected during this study have been lost).
6.1 Lower Mbr. (Lindsay Fm.) Nodular Limestones. SMF 9, Facies Zone 2
Samples of nodules represent highly bioturbated
argillaceous, organic biomicrite/wakestones with
burrows. The sample shown here was imaged under
transmitted light.
Circular cross-sections of burrows indicate early burial lithification with compression of
burrow cross-sections increasing (up to 100%) toward the darker envelopes surrounding the
nodules. The micritic fabric may be described as microsparite. Pockets of sparry calcite
2mm
9
replacement are common in areas of coarser bioclastic concentration (see Appendix A, Plate 1,
slides 3 &4).
Sparry dolomite replaces much of the calcite at the Manitoulin Island localities (see
Appendix A, Plate 1, slides 1&2). At the Manitoulin Island outcrop locality, the upper contact is
marked by a brecciated quartzite and fining upward (subangular to rounded) Quartzite cobbles,
pebbles, sand and silt. The quartzite clasts appeared in association with a local Precambrian
metaquartzite outlier. Sparse disseminated quartz silt was observed at other localities. At the
Manitoulin Island outcrop locality the Lower Mbr. did not exhibit the nodular bedding. Lack of
nodular bedding at this locality may be due to deposition within a zone of higher energy
associated with the "short-lived boulder beach" interpretation of Johnson and Jia Yu, (1989).
The lack of nodular bedding at the Manitoulin Island locality negated the use of Russell and
Telford’s (1983) described criteria for locating the upper boundary (i.e. – last nodular interbed).
In general these Lower Member samples were comparable with microfacies SMF 9 of
Wilson (1975), in Flugel (1982). While type SMF 9 is associated with either Facies Zone 7 (FZ
7 - Shelf Lagoons with open circulation) or Facies Zone 2 (FZ 2 - Open sea shelf - Deep
undatherm below wave base) Flugel (1982), the nodular bedding and marl associations indicate
they belong to the later Facies Zone (FZ 2).
Recurrent textural inversion from 1 to 8cm thick grainstone interbeds (Facies SMF 10 of
Wilson (1975); Facies Zone 2 of Flugel (1978), is a common feature of these facies and
continues to be a feature in the Collingwood beds described below. These grainstone units were
noted by Tufnell (1986) and Moffat et al. (1998). Tufnell (1986) described these units as
laterally extensive graded storm beds and noted that within drab carbonate facies these units
were often obliterated due to bioturbation. Moffat and Brett (1998) interpreted these units as
autochthonous condensed sections formed during short-term fluctuations in relative sea-level.
Handford and Louks (1993) state that down-dip transport of carbonate turbidites can be initiated
by storms or changes in relative sea-level. According to the carbonate platform facies models of
Read (1985, 1995); Handford and Louks (1993) and Loucks and Sarg (1993), argillaceous
nodular limestone facies represent deep-shelf facies common to drowning carbonate platforms.
Residues produced by acid digestion of outcrop samples contained hexactinellid sponge
spicules, phosphate nodules and conodonts. Preliminary analysis of conodont elements indicated
that Amorphognathus superbus(?) was representative of these facies. At locality 2, abundant
10
large rounded conodont fragments suggested energy sorting and support the higher energy zone
interpretation of Johnston and Jia Yu, (1989) for that locality.
A deep, phosphate rich, cool-water environment is indicated by the presence of
Amorphognathus (Sweet, 1988). However, Sweet (1988) argued that upwelling of cool
phosphate-rich waters may have brought Amorphognathus into shallower water.
6.2 Collingwood Mbr. (Lindsay Fm.) Marlstone SMF 3, Facies Zone 1
Samples represent fine grained (often
fossiliferous) dark organic-rich mudstones, ranging
from calcareous shale to argillaceous micrite. The
sample shown here was imaged under transmitted light.
Alternating dark and light grey laminations are common. Bioturbation is rare to absent
with marked reduction in macrofauna diversity noted. Fine disseminated pyrite with pyrite
replacement of fossils common. Dolomite replaces most of the Calcite at the Manitoulin Island
localities (Appendix A, Plate 1, slide 1&5). At the Manitoulin Island localities a quartz- sand
and silt component, associated with a local Precambrian metaquartzite outlier is restricted to the
base of this unit and rapidly fines upward (Appendix A, Plates 1, slides 1&5). Sparse
disseminated quartz silt was occasionally observed elsewhere – often as a component of
grainstone interbeds. Thin to fine carbonate grainstone units (SMF 10) (textural inversion) fine
upward and are absent in the upper-most Collingwood Mbr. They also appear to be much
reduced in number, thickness, and grain size at localities southeast and northwest of the
Algonquin Arch region.
These samples are comparable with SMF 3 of Wilson (1975) and are associated with
Facies Zone 1 of Flugel (1982) (Basin fondotherm below oxygenation level). Within the Facies
Zone scale of Flugel (1982), (FZ 1) represents an incremental increase in palaeodepth relative to
FZ 2.
Residues produced by acid digestion of outcrop samples (2kg) produced some conodonts
including Amorphognathus superbus? but not hexactinellid spicules or phosphatic pellets. It is
2mm
11
unknown whether or not this was due to environmental exclusion or a shift in preservation
potential.
In the Clarksburg locality core (Clarksburg site is located
within the Collingwood cluster, Figure 6) a phosphatic bed
presumably the “phosphatic” bed described by Churcher et al.
(1991) as erosional remnants of the Collingwood strata was
observed. The sample shown here was imaged under re
transmitted light.
The sample represents an intrasparite/ironstone
(Appendix A, Plate 1, slide 1 through 6) that contains lithoclasts, worn bioclasts, peloids,
ooids(?), and clasts of phosphatic micrite. The carbonate matrix appeared to be dolomitic.
Geopetal filling of shell fragments can be observed.
This unit was comparable to SMF 14 of Wilson (1975)(slow accumulation of coarse
material in a zone of winnowing) and is associated with Facies Zone 6 (FZ 6 - Winnowed
platform edge sands) Flugel (1982). Although autochthonous components are typical of SMF 14
(Wilson, 1975), in this case the dramatic environmental and textural inversion from the deep-
water laminated marlstone facies, SMF 3, (below), indicates a down-dip transport of this material
(allochthonous carbonate turbidite).
According to Churcher et al. (1991), this phosphatic unit was reported to be found where
Rouge River Mbr. and Collingwood Mbr. strata were absent and was interpreted to represent
erosional remnants of these members. However, a review of the geophysical log for the
Clarksburg locality indicated that the locality contains one of the thicker Collingwood sections.
The Clarksburg log will be presented and discussed further in later sections of this report.
12
6.3 Collingwood Mbr. (Lindsay Fm.) Pale Grey and Buff -coloured Carbonate interbeds SMF 9, Facies Zone 2
Samples represent biomicrite/wackestones. The
sample shown here was imaged under transmitted light.
Pockets of sparry calcite replacement are
common in areas of coarser bioclastic concentration. Sparse disseminated quartz silt. Fine
pyrite crystals occasionally cluster around fossils. Grainstone interbeds (1 to 8cm
packstone/coquina interbeds), representing SMF 10 of Wilson (1975), Facies Zone 2 of Flugel
(1982), occur, as textural inversion.
The absence of well developed and or total lack of nodular bedding distinguishes these
facies from the Nodular Limestone of the Lower Mbr. of the Lindsay Fm. These carbonate
interbeds were not observed in core from localities north and south of the Algonquin Arch
region.
Residues produced by acid digestion of outcrop samples (2kg) contained hexactinellid
sponge spicules, phosphate nodules and conodonts. Preliminary analysis of conodont elements
indicates that Amorphognathus superbus(?) is representative of these facies.
6.4 Blue Mountain Fm. Shale/calcareous shale
Samples are best described as calcareous
claystones (often dolomitic) with sparse to rare
disseminated pyrite, bioclasts and silt. The sample
shown here was imaged under reflected light.
The dolomitic component of the shales make Russell and Telford’s (1983) criteria for
locating the upper Collingwood boundary (i.e. the “last calcareous shales” problematic.
6.5 Microfacies Analysis Results
The observed progression of carbonate microfacies types from SMF 9, FZ 2 (Lower
Mbr.) to SMF 3, FZ 1(Collingwood Mbr.) indicated deepening upward conditions. At some
localities upward deepening appeared to be intermittently interrupted as evidenced by brief
2mm
2mm
13
periods of re-established carbonate deposition (SMF 9, FZ 2). In South-central Ontario these
localities were invariably associated with the centroid (represented by the Collingwood cluster
and Corbetton locality) of the study area from the Lower Mbr. through the Collingwood Mbr.
There was a distinct upward reduction in carbonate content, though dynamic, accompanied by an
increase in clay until the carbonate dominated system was ultimately replaced by a clastic clay
dominated system (Blue Mountain Fm.).
7.0 BIOSTRATIGRAHY AND PALAEOBIOLOGY
The data for the biostratigraphic component of this study consists of published ranges for
trilobites, graptolites, conodonts, and chitinazoa (Figure 8). Data obtained from OSAP core and
outcrop localities, published by others, was restored to stratigraphic position and will be
presented and discussed in a latter section of this report. The use of current nomenclature for
generic and specific names was adopted here but reference is made to synonymous names
appearing in the original literature.
7.1 Trilobites
The high abundance of Triarthrus trilobite remains in the shaley interval equivalent to the
Collingwood Mbr through Blue Mountain Fm. inspired Parks (1928) to construct a
biostratigraphic scheme based on the trilobite genus Triarthrus. Utilizing data collected by
Tuffnell (1986) from OSAP core - restored in Figure 1A - Tuffnell (1986); Tuffnell and
Ludvigsen (1984); Ludvigsen and Tuffnell (1984), re-evaluated Park's (1928) trilobite
biostratigraphy. These authors concluded that ranges of Triarthrus species overlapped and
cautioned against the use of Triarthrus as a conventional biostratigraphic tool. However, because
certain species appeared more representative of specific lithostratigraphic intervals, Tuffnell and
Ludvigsen (1984); Ludvigsen and Tuffnell (1984), proposed a battleship type Triarthrus
biostratigraphy (Figure 8). According to Tuffnell and Ludvigsen (1984); Ludvigsen and Tuffnell
(1984), a higher abundance of Triarthrus etoni was associated with Collingwood Mbr. strata
while higher abundances of T. canadensis, T. rougensis and T. spinosus were associated with
Blue Mountain strata (Figure 8).
7.2 Graptolites
According to Riva (1974), strata equivalent to the Collingwood Mbr. were assigned to
the Climicograptus pygmaeus syn. Geniculograptus pygmaeus zone while strata equivalent to the
14
Blue Mountain Fm. were assigned to the Amplexograptus manitoulinensis zone (Riva, 1974).
The Upper Geniculograptus pygmaeus zone was later designated as lower Maysvillian in age
while the A. manitoulinensis zone was designated as upper Maysvillian in age (Bergstrom and
Mitchell, 1986) (Goldman and Bergstrom, 1997) (Figure 8).
7.3 Conodonts
Conodont zonation is reported to be coarse during Maysvillian times and is represented
by a single conodont zone (Amorphagnathus superbus zone) (Goldman and Bergstrom, 1997)
(Figure 8). Conodont specimens recovered during this study appeared consistent with the
Amorphognathus superbus conodont zone.
7.4 Chitinozoa
Chitinozoan data (Figure 8) support a lower Maysvillian age for Collingwood Mbr. strata
but do not offer further time-stratigraphic resolution (Melchin et al., 1994).
The lower sub-unit of the Lower Mbr. (Lindsay Fm.) contains chitinozoan assemblage
ChA-6 dominated by species of Herchochitina with species of Angochitina and Belochitina also
representative (Melchin et al., 1994). The upper Lower Mbr. (Lindsay Fm.) contains chitinozoan
assemblage ChA-8 marked by high species diversity with no individual species dominant
(Melchin et al., 1994). Chitinozoan assemblage ChA-8 is also representative of the Collingwood
Mbr. (Lindsay Fm.). Upward-increasing chitinozoan diversity (from ChA-6 to ChA-8) (Figure
8) in the Lindsay Fm. is interpreted to indicate deepening-upward conditions (Melchin et al.,
1994). Based on the persistence of high planktic chitinozoan diversity across the lower
Collingwood Mbr. Boundary, environmental change, indicated by marked reduction in (a)
bioturbation, (b) infaunal and benthic macrofaunas and (c) increased organic preservation
relative to the Lower Mbr., is interpreted to be restricted to bottom waters (Russell and Telford,
1983; Melchin et al., 1994).
7.5 Biostratigraphy and Palaeobiology Results
The biostratigraphic and palaeobiology data appear to support three conclusions:
• Upward deepening conditions from the Lower Mbr. through the Collingwood Mbr.
• Gradational change from the Lower Mbr. through to the Blue Mountain Fm.
15
• The Lower Mbr. and Collingwood Mbr. strata appear to be Lower Maysvillian in age
with the Blue Mountain Fm. strata assigned as upper Maysvillian in age.
16
8.0 GEOPHYSICAL BOREHOLE LOG CORRELATION
8.1 Method
Churcher et al. (1991) produced a “schematic” gamma log signature depicting the
Collingwood as a linear transition from argillaceous limestone (Lower Member of the Lindsay
Formation) to shale (Blue Mountain Fm.) (Figure 9). According to Churcher et al. (1991), if the
transition zone was absent then the Collingwood was absent. For comparison, Churcher et al.
(1991) presented two examples of each type of “actual” gamma-logs (figure 10). The sample
localities illustrated were from Southwestern Ontario where Collingwood strata, according to
Churcher et al. (1991), exist in a few areas as outliers – presumably the Collingwood was eroded
away from the rest of Southwestern Ontario (see location of outliers in Figure 4). In the
Collingwood distribution/isopach maps presented in Churcher et al. (1991), localities with
Collingwood strata present were identified with the pre-fix WC (“With Collingwood”) while
holes without Collingwood were denoted with the pre-fix NC (“No Collingwood”). A
significant technical problem with their comparison reproduced in figure 10 is that the gamma
log scale (API units) for the NC holes should read 0 to 200 API and not 0 to 100 API. In
addition transposition of signals higher than 100 API units in the WC logs was not conducted for
the comparison. When scaled for comparison the geophysical log signatures for the WC holes
no longer appeared significantly different from the NC hole logs (Figure 11).
WC-36 (with Collingwood) was compared to NC-36 (no Collingwood) (Figure 12). The
two holes are approximately 25 kilometres apart. Re-scaled and normalized NC-36 showed a
very similar “transition zone” and the Collingwood unit (gamma log/petrophysical
chemostratigraphic unit) appeared to be equally present in NC-36 -then why do we not recognize
Collingwood strata in NC-36? – or in general Collingwood strata in Southwestern Ontario?
8.2 Geophysical Borehole Log Identified Unit (Petrophysical Chemostratigraphic approach)
The gamma log line is used to review down-hole changes in stratal clay content. Natural
gamma radiation detected by the tool emanates from radioisotopes of potassium, thorium, and
uranium associated with clay (shale) and organic deposits. The more clay and/or organic
enriched the strata are the higher the gamma log signals are until levels reach the theoretical
“shale line” - indicating shale strata. The resistivity log line is a measure of electrical resistance
to current flow. Accumulation of organic material (hydrocarbons) results in high electrical
17
resistance and thus is an important tool for hydrocarbon exploration. The neutron log line is
produced by irradiating the strata and measuring induced radioactivity. The amount of induced
radiation is proportional to the density of the strata. Therefore the neutron log line is used to
examine differences in stratal density.
Geophysical borehole logs (gamma, neutron, and resistivity) from OSAP holes were
traced, scanned and scaled/normalized for comparison. The upper Trenton boundary (upper
Collingwood Mbr. boundary) was used as the datum. For initial review purposes the
Collingwood boundaries/contacts identified in the OSAP logs by Johnston et al. (1983-1985)
were used. During review of the geophysical and written logs it was noticed that discrepancies
in logged depth existed for many of the Collingwood cluster holes. In those cases where
discrepancies existed between written and geophysical logs the upper and lower Collingwood
boundaries were estimated based on the authors interpretation of the geophysical logs (core was
not available to qualify the estimates).
In South-central Ontario, OSAP data was obtained from three geographically isolated
regions. Within each region a cluster of shallow boreholes exists. These clusters were located in
Toronto, Collingwood, and on Manitoulin Island (Figure 13). There were three deep OSAP
boreholes advanced to tie-in the three clusters (Figure 14). Two of the deep boreholes were
located between the Toronto and Collingwood clusters (the Corbetton and Nobelton holes) and
the other hole was located between the Collingwood and Manitoulin Island clusters (the Wiarton
hole).
Figure 15 shows the Collingwood as it appears in the geophysical record from the three
OSAP clusters in South-central Ontario. A review of Collingwood petrophysical
chemostratigraphy in the Collingwood cluster, Figure 15, revealed that the strata were consistent
and mappable over the entire Collingwood region. Note that Collingwood strata were not fully
penetrated at CLGD4b, CLGD6a, and CLGD7a. The same cannot be said for the Toronto and
Manitoulin Island clusters in Figure 15, where signatures showed differences between localities
within each cluster and between clusters. In the Toronto cluster , Collingwood signatures
indicated that strata thin from left to right (from northeast to southwest). In the Manitoulin
Island cluster the two signatures were similar but did not share the “carbon copy” appearance
that the Collingwood cluster signatures exhibited. Overall the signatures were different between
clusters and the transition interval (Collingwood) showed significant variation in length.
18
Collingwood section thickness ranged from approximately 11.5 to 1.5 metres. The signatures
presented in Figure 15 also revealed that the transition from carbonate dominated to shale
dominated deposition was dynamic.
In order to better evaluate the relatedness of these clusters, geophysical borehole log
signatures for OSAP “tie-in” localities were examined and compared to the cluster signatures.
First, tie-in locality logs were compared to the Collingwood cluster signatures (Figure 16).
Comparison of the Collingwood cluster with the Corbetton Tie-in log (approximately 40
kilometres away) showed little change in stratal composition and revealed that Collingwood
strata were readily mappable between these localities. Collingwood section thickness changed
from approximately 9.58 to 11.5 metres. Comparison between the Collingwood cluster and the
Wiarton Tie-in locality (approximately 30 kilometers away) showed that signatures/strata,
though mappable, were more condensed (reduced in thickness) from Collingwood (9.58 metres)
to Wiarton (6.2 metres). Note the contacts were transposed from the positions indicated in the
Johnston et al. (1983-85) log for Wiarton. The transposition is indicated in Figure 16.
A comparison between the three clusters and tie-in localities is presented in Figure 17.
While Figure 17 provides the reader with a good comparison of overall Collingwood strata
characteristics from north to south in central Ontario, the OSAP tie-in localities are not sufficient
to map changes north and south of the tie-in localities to the Manitoulin Island and Toronto
cluster localities.
The tie-in localities provided the data necessary to map with confidence Collingwood
strata over an approximately 100km distance within the centroid of the study area. However, an
environmental gradient exited somewhere between the Tie-in localities and the Toronto and
Manitoulin Island clusters. An investigation was conducted to determine if logs from sources
other than the OSAP, existed to serve as additional tie-in localities. The unpublished OSAP log
for the Nobelton hole was obtained from the Ministry of Northern Development and Mines.
Other localities that could be used as Tie-in logs were not found. Review of the Nobleton log
indicated that Johnston et al. (1983-1985) placed the lower contact boundary at a
stratigraphically lower position in this well. The boundary was moved to a position that was
more consistent with other localities. This decision will be supported further in latter sections of
this report. The OSAP Nobelton hole was located between the Corbetton hole and the Toronto
cluster (see Figures 14 and 18). Examination of Collingwood strata in the Nobelton log showed
19
that condensation of strata there was comparable in degree to the Toronto cluster and that the
signature did not appear to be serviceable as a tie-in log. In order to proceed with the study a
different approach was needed.
Because the carbonate microfacies and palaeobiology indicated that the nodular
limestone facies of the Lower Mbr. were, like Collingwood strata, consistent with a drowning
carbonate ramp scenario the author decided to determine if these strata too were mappable in the
subsurface and whether or not they could be used to better understand the stratigraphic
relationship between the clusters. However, only three OSAP logs (represented by the tie-in
localities) fully penetrated the Lower Mbr. Therefore, borehole logs from other sources were
obtained and examined.
Comparison of Lower Mbr. strata in the centroid of the study area showed that mappable
geophysical units could be constructed (Figure 19). Comparison of these geophysical borehole
log units to the Toronto and Manitoulin Island clusters (Figure 20) showed that like Collingwood
strata Lower Mbr. strata too exhibited regional differences in relative stratal condensation.
Moreover, like Collingwood strata Lower Mbr. strata become more condensed (thin) north and
south of the Collingwood cluster. The use of geophysical units below the Collingwood provided
stratigraphic control from which to review, in context, regional changes in Collingwood strata in
South-central Ontario. While the correlation of strata from the tie-ins to the Manitoulin Island
and Toronto clusters is here presented as tentative it is clear that Collingwood and Lower Mbr.
strata are more condensed north and south of the centroid (Wiarton, Collingwood cluster, and
Corbetton) of the study area. In some cases the added control required that the lower
Collingwood boundary be moved. The resultant differences are indicated in Figure 20. The
implication of these boundary changes will be discussed in subsequent sections. The next
section is dedicated to an explanation and discussion on condensation and a comparison between
the geophysical signatures and correlative facies observed in core.
8.3 Condensation
The statement that strata are “condensed” implies deposition occurred during a period of
diminished sedimentation rates. Potential causes of diminished sedimentation rates might
include sediment starvation during relative sea-level rise, depth related carbonate stress,
sediment bypass (hard grounds or omission surfaces). While there are many references to
“condensed sections” in the literature including descriptions of how to recognize them and
20
comments about their utility in stratigraphic correlation it is not often stated that condensation is
a relative term. The term is relative because a sediment interval at any given locality may be
more or less condensed compared to the same time correlative interval at other localities within
the region. For example, during drowning of a carbonate dominated system, the effects of depth
related carbonate stress would occur later in shallower areas and earlier in deeper areas. While
both areas will eventually be stressed the shallower area will be less condensed overall. The
converse is true in a clastic dominated deposition system.
In clastic dominated systems chemical/biochemical deposition and preservation are not
important factors therefore, when sediment supply to the basin is interrupted, for example during
sea level rise, a single (hypo) deposition mode (slow rate of sediment supply and accumulation)
produces a thin ”starved” sediment deposit across the basin. Sediment by-pass of topographic
highs may intensify starvation. Therefore in regions of variable palaeotopographic relief we
should expect to observe a range of condensation intensity with gradations in between expressed
in the facies and ultimately time correlative section thickness. In carbonate dominated systems
strata will be thickest over topographic highs and thin toward topographic lows such as basins.
In clastic dominated systems strata may be thickest in topographic lows and thin toward
topographic highs (see schematic drawing in Figure 21). Recognition of these two different
condensation responses to relative sea level rise is important and will be revisited.
Note in Figure 22a, that the “transition intervals” (Collingwood strata) observed in the
gamma logs for the Corbetton and Toronto cluster locality SIS3 are quite different. In the
Corbetton gamma log the transition does not start from the base of the Collingwood like it does
in the SIS 3 log. The less condensed Corbetton section which contains recurrent interbeded
carbonates does not transition until carbonate sedimentation all but ceases in the uppermost
portion of the section. This is in contrast to the Toronto cluster locality SIS 3. In the SIS 3
gamma log the transition begins at the base of the Collingwood and continues upward throughout
the Collingwood. If Collingwood section thickness at SIS 3 were reduced in thickness compared
to the Corbetton section due to post depositional erosion as proposed by others then the SIS 3 log
would appear more carbonate rich and lack a ”transition” (Figure 22b).
To demonstrate how regional differences in stratal condensation indicated in the
geophysical record are exhibited in the lithofacies a comparison of OSAP core with
corresponding gamma logs was conducted. Some of the core recovered during the OSAP project
21
was available for study through the Ontario Ministry of Northern Development and Mines
(MNDM). The core was re-measured, sampled, and described. A comparison of the available
core sections with their corresponding gamma log signatures is presented in Figure 23.
One significant observation to be made in Figure 23 is that the thickest Collingwood
strata which are located in the centroid of the study area (represented by the Collingwood cluster
and Corbetton hole) contained interbeded light coloured carbonates while Collingwood strata in
the Toronto and Manitoulin Island clusters did not. Much of the core in the Manitoulin Island
locality was missing, however, in the Toronto localities Collingwood strata were very dark,
graptolitic, and finely laminated throughout indicating they are more condensed compared to the
Collingwood cluster and Corbetton localities. In addition the grainstone interbeds observed in
the Collingwood cluster and Corbetton cores were in the Toronto cluster localities significantly
reduced in thickness and grain size indicating their position as more distal to the source
compared to the centroid of the study region. Clearly the Collingwood sections in Toronto could
not have been reduced to their observed thickness simply by having eroded the tops of thicker
Collingwood cluster like sections – a conclusion already supported by the chemostratigraphic
petrophysical signatures presented in Figures 22a and 22b. This study proposes that variability
in Collingwood section thickness observed in this study resulted from variability in stratal
condensation.
In South-central Ontario the Algonquin Arch (a palaeotopographic high) underlies the
centroid of the study area (refer back to see Figure 5). The presence of less condensed strata
overlying a palaeotopographic high (a topographic high known to pre-date deposition of
Collingwood strata) is consistent with the drowning carbonate ramp scenario supported by the
microfacies and palaeobiology and will be discussed further in later sections.
During review of Collingwood strata in OSAP core it was often difficult to distinguish
grossly between dark coloured carbonates and “marlstones”. This fact resulted in the appearance
(see Figure 23) of carbonate interbeds appearing to dissolve into marlstone from north to south in
the Collingwood cluster through to the Corbetton core. Note however, in the same figure that in
corresponding gamma logs the carbonate rich intervals are indicated to be consistent and
mappable. A look at the outcrop section in the Collingwood area shows that due to weathering it
was more readily subdivided making it appear different from the Collingwood cluster core.
Clearly the gamma log line provides a more accurate measure of lithic changes compared to
22
gross examination. That said gross examination of the strata and comparison with the gamma
logs revealed that Collingwood strata exhibit significant regional differences in light vs. dark
colouring (the reader is notified that the fill pattern used in Figure 23 does not show the reader
the range in dark colouring – from dark grey to black and even brown-black).
The Clarksburg core, which shared the same “carbon copy” gamma log signature with the
other Collingwood cluster sites, was the lightest in colour overall and appeared to contain the
fewest number of “marlstone” interbeds (Figure 23). This was noteworthy because the light
coloured appearance of these strata made them look less Collingwood-like. Furthermore, at the
top of this Collingwood section was a “thin phosphatic bed” like that reported by others to
replace the Collingwood at localities where it was interpreted to be removed due to erosion.
Another OSAP hole (CLGD No. 17, geophysical log unpublished and unavailable)
located just west of the Clarksburg hole was described by Johnston et al. (1983), to contain only
2 metres of Collingwood strata. This seems anomalous since the same authors reported
approximately 10 metres of Collingwood strata throughout the rest of the Collingwood cluster.
CLDG No. 17, like the Clarksburg hole may have contained light coloured facies much of which
were not recognized as “Collingwood”. The association of lighter coloured lithology and the
phosphatic bed (interpreted here as a down dip transport deposit from shallower water) in the
Clarksburg hole suggests that shallower water with relatively higher oxygen content must have
existed locally.
In Figure 20, compared to Collingwood cluster holes, the Collingwood base appears to be
placed (by OSAP workers) in a stratigraphically older position in the Nobelton hole. Evidently
increased condensation experienced in the Nobleton area resulted in formation of Collingwood-
like strata at an earlier period in time (also refer to Figure 23). Similarly gross examination of
the lighter coloured lithologies in the Clarksburg and CLGD No. 17 localities might result in a
decision to place the Collingwood base at a stratigraphically younger position. In summary,
regional differences in stratal condensation have led to miss-identification of the lower
Collingwood boundary. That said the lighter coloured facies variant though related to
condensation was not necessarily accompanied by differences in Collingwood section thickness
(see Figure 23). Differences in light vs. dark colouring observed in the carbonate interbeds are
interpreted to be due to variation in organic preservation potential. It would appear that organic
preservation potential like condensation increased off-Arch.
23
The characteristic and mappable petrophysical chemostratigraphic signatures presented in
this study are interpreted by the author to be formed in the following manner. Concomitant with
carbonate sedimentation on the ramp is entrainment of trace amounts of terrigenous clay
minerals from suspension. While carbonate sedimentation rates fluctuate over time and across
the region the clay content at any given time in suspension would remain somewhat uniform
regionally. Thus due to dynamic fluctuations in sedimentation through time the entrained clay
minerals at a given point in time produce a signal that is regionally encoded. Together these clay
mineral encoded points in time begin to stack and produce unique mappable signatures across the
region.
8.4 “Collingwood” Strata in Central Ontario and the Michigan Basin
In order to better understand the relatedness between Collingwood strata in Ontario and
the Michigan Peninsula their respective stratigraphic positions in the geophysical record were
reviewed in context to the entire carbonate ramp sequence from the “Collingwood” down to the
Shadow Lake Fm. In South-central Ontario these combined strata are referred to as the Simcoe
Group while in Southwestern Ontario and in the Michigan Peninsula they are referred to as the
Trenton and Black River Group. A comparison between representative Trenton and Black River
Group sections in the Michigan Peninsula with the Corbetton hole in South-central Ontario is
presented in Figure 24a & b.
The Michigan Peninsula correlation was conducted by others using the “TG-1 and TG-2
doublets” (highly mappable bentonites) used by subsurface workers to locate boundaries in the
subsurface (Wilson and Sengupta, 1985; Wilson et al., 2001). Figure 24a & 4b illustrate 3
important facts:
1) there is significant regional variation in combined section thickness. (Note: this
comparison does not present the full range of regional differences in section
thickness. Sections in the southern portion of the basin in Ontario and the US are
much thicker still).
2) while overall Trenton -Black River Group sections in the Michigan Peninsula
correlation thin northward in a shallowing direction – Collingwood strata become
significantly thicker in that direction.
3) Collingwood strata are mappable into the Michigan Peninsula but the base of the
Collingwood in the Michigan Peninsula correlation appeared to be placed
24
stratigraphically lower/older than in Ontario (again like the Nobelton hole in
Ontario, the increased degree of condensation exhibited in these Michigan
Peninsula localities compared to the Corbetton locality appeared to result in
earlier deposition of Collingwood-like strata there).
In the Michigan Peninsula correlation and in the South-central Ontario study area
Collingwood strata appear to become less condensed in a shallowing direction, north toward the
basin rim in the Michigan Basin and over the Algonquin Arch in South-central Ontario.
8.5 Datum, Stratal Condensation and Boundary Contacts
The “Upper Collingwood boundary” is reportedly equivalent to Johnson et al.’s (1991),
“upper boundary for depositional sequence 2”, and was used as the datum in this study.
According to Johnson et al. (1991), the datum is supposed to represent the boundary between
two modes of deposition (from carbonate dominated to clastic dominated) (see Johnson et al.
(1991). However, due to regional differences in stratal condensation and palaeotopography the
datum, like the lower Collingwood boundary, may not represent a strict time-stratigraphic feature
– a result that should be expected. To explain this fully we need to return to the discussion on
differences in carbonate vs. clastic deposition response to sea level rise. During initial deposition
of “Collingwood” strata under upward deepening conditions, rate of carbonate deposition was
the limiting factor in Collingwood section condensation. However, during clastic dominated
deposition the limiting factor in section condensation would be sediment supply (proximity of
the locality to the prograding clastic wedge and potential by-pass of topographic highs.
In South-central Ontario the datum was placed at the upper Collingwood Mbr. boundary
identified in the OSAP geophysical logs. Placement of the datum in the centroid of the study and
to a lesser degree in the Toronto cluster appeared intuitive; however, placement of the datum in
the Manitoulin Island cluster appeared to be more arbitrary. In the Manitoulin Island sections,
upper Collingwood like conditions appeared to re-establish above the datum. The reader can
observe this by reviewing the Upper Collingwood boundary in Figure 17. To understand better
these uppermost Collingwood strata more extensive borehole coverage linking tie-in localities
with the Toronto and Manitoulin Island clusters would be necessary.
The conventional explanation for the more concentrated upper Collingwood boundary in
the Collingwood area is that the bituminous Rouge River Mbr. shales of the Blue Mountain Fm.
25
identified in the Toronto area were subsequently eroded from the Collingwood area sites (see
Churcher et al., 1991). An alternative explanation but similar in result would be that sediment
by-pass of the Arch may have produced a much condensed interval/surface there while
accumulation of organic clays was experienced in deeper localities (less condensed) north and
south of the Algonquin Arch. In either event the biostratigraphic zonation boundaries and
palaeobiology data presented in Figures 8 and 25 do not offer evidence for a natural boundary
(upper Collingwood boundary). The upper “Collingwood” boundary appeared to be transitional
with no significant loss of time indicated.
The phosphatic unit observed at the upper Collingwood boundary in the Clarksburg
locality and apparently found at other localities in Southwestern Ontario and the Michigan Basin,
suggests that shallower water conditions existed in proximity to those localities. In the Michigan
Basin, Wilson and Sengupta (1985), report that sections consistently reflect facies that grade
from crinoidal shoal facies in the south along the north flank of the Findley Arch (southwestward
extension of the Algonquin Arch) to deeper water dark organic wakestone facies in the north.
With the Taconic foreland basin to the south of the shoal shelf-like environment along the
Findley Arch these authors concluded that a restricted lagoon environment existed north of the
Findley Arch and that Collingwood strata were deposited in the lagoon during a period of
maximum restriction (during sea level drop) – a similar conclusion was drawn in Ontario by
Churcher et al. (1991). However, in Central Ontario maximum observed Collingwood unit
thickness occurs in the region over the Algonquin Arch and since it is well established that the
Algonquin Arch pre-dates the Collingwood, a “restricted lagoonal environment” was unlikely.
Moreover, as previously discussed above, microfacies analyses of the “nodular limestones” and
“marlstones” over the Algonquin Arch region in South-central Ontario indicated a deep open
shelf and deeper environments rather than a lagoonal one. That said the observation of less
condensed Collingwood strata in the Algonquin Arch region in Central Ontario was consistent
with the findings of Wilson and Sengupta (1985) and Hiatt and Nordeng (1985), that the Findley
Arch (southwestward extension of the Algonquin Arch) was the site of shallower higher energy
water relative to regions north and south of the arch.
26
9.0 DISCUSSION AND CONCLUSIONS
CONCLUSIONS
The OSAP drilling program/sampling strategy, designed primarily to assess the economic
potential of Ontario’s oil shales, resulted in some regions being under- represented (where
Collingwood strata were located deep within the subsurface) while other regions (where
Collingwood strata were located at or near surface) were well represented by clusters of shallow
boreholes. Presumably with “economic potential” being the main consideration, Collingwood
strata located deep within the subsurface would not be readily exploitable and thus not as
important to the OSAP mandate. Only 3 deep boreholes exist from which to tie-in and
investigate Collingwood strata between outcrop localities – some tens of kilometers apart. While
this sampling strategy was considered adequate for the gross lithostratigraphic survey conducted
by Johnson et al. (1983-1985), and Russell and Telford (1983), the sampling bias presents a
challenge to those who wish to study in more detail development of strata across the region. To
this limitation was added the fact that where Collingwood strata were well represented by drill
holes the drill holes did not penetrate much if at all beyond the Collingwood.
These limitations were in part overcome by the use of data from strata located below the
Collingwood and by incorporating geophysical data from sources other than the OSAP. To
qualify further the conclusions made using the geophysical correlation of Collingwood strata a
microfacies analysis was conducted using core and outcrop samples. In addition a
palaeobiologic and a palaeostratigraphic review were also conducted. The Lower Mbr. strata of
the Lindsay Fm. like Collingwood strata appeared to be deposited during upward drowning of
the ramp. Both “Collingwood” and “Lower Mbr.” strata appeared to be highly correlatable
across the region in South-central Ontario.
The gross lithostratigraphic correlation and lithostratigraphic formation re-assignment
advanced by Russell and Telford (1983) did not appear to resolve questions regarding
palaeoenvironmental context and timing. The failure to recognize in the “Collingwood” both
regional and temporal changes in facies as related to changes in environment has led to historic
confusion about Collingwood boundaries and composition and frustrated attempts to reconstruct
palaeoenvironmental conditions. Historically, palaeoenvironmental interpretations tended to be
isostatic environmental settings such as “normal shallow marine shelf”, “deepest shelf”, stranded
27
basin” or “lagoonal” and neither of these static environments would explain the wide variety of
facies collectively referred to in South-central Ontario as the “Collingwood”.
A study of the geophysical borehole log records, core, palaeobiologic and
biostratigraphic data were used to examine Collingwood strata in South-central Ontario. The
following is a brief summary of results:
• Carbonate Microfacies types: in Ontario, carbonate microfacies types grade
upwards and off arch from SMF 9 (FZ2) to SMF 3 (FZ1). This facies progression
represents a shift from open sea shelf –deep undatherm below wave base to basin
fondotherm below oxygenation level – consistent with deepening upward
conditions.
• Palaeobiologic and Biostratigraphic data: a shift from Chitinozoan assemblage
ChA-6 to ChA-8 in the upper Lower Member, Lindsay Formation and extension
into the Collingwood Mbr. indicated upward deepening conditions. The
dominance of the Triarthrus trilobites (a slope biofacies) and deep cool water
conodonts Amorphognathus are consistent with a deeper water interpretation.
• Geophysical: An upward and off-arch increase in strata condensation was
observed in the petrophysical chemostratigraphic data. The data was consistent
with the carbonate microfacies observed in core and outcrop samples.
Comparison of a South-central Ontario section with a Collingwood correlation in
the Michigan Basin showed that upward deepening conditions caused a
significant regional shift in overall stratal geometry from basinward thickening
carbonate sequences to strata that thicken in a shallowing direction – toward the
Algonquin arch and the Michigan basin rim. Together the data presented in this
study support an upward drowning ramp scenario.
DISCUSSION
Without a stratigraphic reference point from which to compare Collingwood strata
to extrabasinal formations such as the Boas River Fm. it is not possible to
determine whether or not they represented part of an extensive time correlative
event or if they represent separate events staggered in time. Even comparison of
28
Collingwood strata in South-central Ontario with localities in Ottawa, Ontario,
would be problematic. Not only are these Ottawa sections isolated by hundreds of
kilometers from sections to the west but thermal maturation experienced in the
Ottawa region had significantly altered the electrical resistance of the unit and
therefore the “Characteristic” resistivity borehole log profile. That being said
Ottawa localities exhibited both bio- and litho-facies development most
comparable to Collingwood cluster localities suggesting they shared a similar
palaeoenvironmental history. Raymond (1912) first coined the “Collingwood
Formation” based on similarities between these two localities.
In Ontario, the Collingwood has been reported to share the same geochemical
characteristics as reservoir hydrocarbons in Southwestern Ontario Snowdon,
(1984); Obermaeyer et al. (1999). However no satisfactory explanation existed to
account for the migration of hydrocarbons from South-central Ontario to
Southwestern Ontario. Currently Trenton strata in Southwestern Ontario (where
Collingwood strata were reported absent) are now thought to be self- sourcing
(see Obermaeyer et al. 1999). Based on the conclusion here that the Collingwood
was deposited under a widespread drowning ramp scenario combined with a
preliminary look at the petrophysical chemostratigraphic data in a few localities
located in Southwestern Ontario it is likely that the “self sourcing strata” are time
correlative with the Collingwood. In part the time correlative facies in
Southwestern Ontario may be a lighter coloured facies variant. According to the
drowning carbonate ramp model hydrocarbon accumulation is expected to occur
in palaeotopographic highs which are often dolomitic much like the reservoirs in
Southwestern Ontario.
Beyond the academic interest in Collingwood strata there may be an economic
reason to advance further the work initiated by this study. A recent study by
Carter et al. (2005) states that since 1984, 39 new Trenton-Blackriver oil and gas
pools have been discovered with oil production up from 60,000 barrels/year to
over 1,000,000 barrels/year. Carter et al. (2005) estimated that 83% of the natural
gas and 40% of the oil resources are still undiscovered. A detailed borehole-log
and facies study of Southwestern Ontario should prove invaluable both from the
standpoint of hydrocarbon exploration and to further our recognition of the extent
29
and scope of facies produced during this drowning event. Because this region of
the basin contains hydrocarbons many boreholes were advanced from which data
is available for future investigation.
Since initiation of this study two significant geophysical subsurface studies have
been conducted (one in the Michigan Basin by Wilson et al. (2001), and one in
central and Southwestern Ontario by Armstrong and Carter (2006)). It appears in
both cases that the researchers constructed the correlations using a
lithostratigraphic approach for control rather than using the petrophysical
chemostratigraphic data and core to examine facies progressions. For example, if
the Collingwood was not recognized in the core then regardless of the
petrophysical chemostratigraphic data/signature the Collingwood would be
dismissed from the correlation at that point.
30
10.0 REFERENCES
Armstrong, D.K., Carter, T.R., 2006, An Updated Guide to the Subsurface Paleozoic
Stratigraphy of Southern Ontario, Open File Report 6191.
Bergstrom, S.M., Mitchell, C.E., 1986. The graptolite correlation of the north American Upper
Ordovician Standard. Lethaia, 19, p. 247-266
Bradley, D. C., and Kidd, W.S. F., 1991, Flexural extension of the upper continental crusts in
collisional foredeeps: Geological Society of America Bulletin, c. 103, p. 1416-1438.
Bradley, D. C., and Kusky, T. M., 1986, Geologic evidence for rate of plate convergence during
the Taconic arc-continent collision: Jour. Geology, b. 94, p. 667-681
Carter, T. R., McFarland, S., Trevail, R. A., Gorman, J. Walsh, P., 2005, Trenton-Black River
Hydrothermal Dolomite Resevoirs in Ontario: Geology, Reserves and Potential Resources.
AAPG Annual Meeting, June 19-22, 2005, Calgary, Alberta,(Abstract).
Churcher, P.L., 1986. Middle Ordovician (Trenton) disconformity in Michigan and lllinois
Basins: subaerial or submarine origin? American Association of Petroleum Geologists,
Bulletin, 70(8):1064 (abstract).
Churcher, P.L., Johnson, M.D., Telford, P.G., & Barker, J.F., 1991. Stratigraphy and oil shale
resource potential of the Upper Ordovician Collingwood Member, Lindsay Formation,
Southwestern Ontario. Ontario Geological Survey, Open File Report 5817, 98p.
Cisne, J. L., Karig, D.E., Pabe, D.D., and Hay, B.J., 1982, Topography and tectonics of the
Taconic outer trench slope as revealed through gradient analysis of fossil assemblages:
Lethaia, v. 15, P. 229-246
Coniglio, M., Melchin, M.J., and Brookfield, M.E., 1990. Stratigraphy, sedimentology and
biostratigraphy of Ordovician rocks of the Peterborough-Lake Simcoe area of southern
31
Ontario; A.A.P.G., 1990 Eastern Section Meeting, hosted by Ontario Petroleum Institute,
Field Trip Guidebook no. 3, 82p.
Delano, J. W., Shirnick, C., Bock, B., Kidd, S. F., Heizler, T., Putnam, G. W., Delong, S. E., and
Ohr, M., 1990, Petrology and geochemistry of Ordovician K-bentonites in New York State:
Constraints on the nature of a volcanic arc: Journal of Geology, v. 98, p. 157-170.
Flugel, E., 1982. Microfacies analysis of limestones. Berlin-Heidelberg-New York: Springer
Goldman, D., & Bergstrom, S.M., 1997. Late Ordovician graptolites from the North American
midcontinent. Palaeontology, 40(4): 965-1010.
Handford, C.R., Louks, R.G., 1993. Carbonate depositional sequences and systems tracts;
responses of carbonate platforms to relative sealevel rise. AAPG Memoir 57, p3-41.
Hay, H. B., and Cisne, J.L., 1988. Deposition in the oxygen-deficient Taconic foreland basin,
Late Ordovician, in Keith, B. D., ed., The Trenton Group (Upper Ordovician Series) of
Eastern North America: American Association of Petroleum Geologists, Studies in Geology,
v. 29, p. 113-134.
Haq, B.U., Hardenbol, J. and Vail, P.R., 1987, Chronology of fluctuating sea levels since the
Triassic. Science,235,p.1156-1166.
Hiatt, C.R., 1985. A petrographic, geochemical and well log analysis of the Utica Shale-Trenton
Limestone transition in the northern Michigan Basin; unpublished M.Sc. thesis, Michigan
Technical University, Michigan, 152p.
Hiatt, C.R. & Nordeng, S., 1985. A petrographic and well log analysis of five wells in the
Trenton-Utica transition in the northern Michigan Basin, in Michigan Basin Geological
Society, Special Paper No.4, 1985
Johnson, M.D., Russell, D.J., & Telford, P.G., 1983. Oil shale assessment project, Volume 1
Shallow drilling results 1981/82. Ontario Geological Survey Open File Report 5458, 36p.
32
Johnson, M.D., Russell, D.J., & Telford, P.G., 1983. Oil shale assessment project, Volume 2
Drillholes for regional correlation 1981/82. Ontario Geological Survey Open File Report
5459, 20p.
Johnson, M.D., Russell, D.J., & Telford, P.G., 1985. Oil shale assessment project, Volume 2
Drillholes for regional correlation 1983/84. Ontario Geological Survey Open File Report
5565, 20p.
Johnson, M.E., Jia-Yu, R., 1989. Middle to Late Ordovician rocky bottoms and rocky shore from
the Manitoulin Island area, Ontario, in Canadian Journal of Earth Sciences, v.26,Number4,
p.642-653.
Johnson, M.D., Armstrong, D.K., Sanford, B.V., Telford, P.G., & Rutka, M.A., 1991. Paleozoic
and Mesozoic geology of Ontario. Ontario Geological Survey, Special Volume 4, Pt. 2, 907-
1008.
Lash, G. G., 1988a, Middle and Late Ordovician shelf activation and foredeep evolution, central
Appalachian orogen, in Keith, B. D., ed., The Trenton Group (Upper Ordovician Series) of
eastern North America: American Association of Petroleum Geologists, Studies in Geology,
v. 29, p. 37-54.
Lehmann, D.L., Brett, C.E., Cole, R., & Baird, G., 1995. Distal sedimentation in a peripheral
foreland basin: Ordovician black shales and associated flysch of the western Taconic foreland,
New York State and Ontario. GSA Bulletin 107(6): 708-724.
33
Liberty, B.A., 1969. Paleozoic geology of the Lake Simcoe area, Ontario; Geological Survey of
Canada, Memoir 355,201p.
Loucks, R. G. & Sarg, J. F. (EDITED BY) Carbonate Sequence Stratigraphy : Recent
Developments and Applications, Tulsa, Oklahoma, U.S.A., American Association of
Petroleum Geologists, 1993. 545p.p. (ISBN: 0-89181-336-5)
Ludvigsen, R., Tuffnell, P., 1984, The last Olenacean trilobite: Triarthrus in the Whitby
Formation (Upper Ordovician) of Southern Ontario, New York State Bulletin 481.p.183-212.
Macauley, G., Fowler, M.G., Goodarzi, F., Snowdon, L.R., & Stasiuk, L.D., 1990. Ordovician
oil shale - Source rock sediments in the central and eastern Canada mainland and eastern
Arctic areas, and their significance for frontier exploration. Geological Survey of Canada,
Paper 90-14, 51p.
Melchin, M. J., Brookfield, M. E., Armstrong, D. K., and Coniglio, M., 1994. Stratigraphy,
Sedimentology and Biostratigraphy of the Ordovician Rocks of the Lake Simcoe Area, South-
Central Ontario, in Geological Association of Canada/Mineralogical Association of Canada
Joint Annual Meeting, 1994, Waterloo, Ontario, Canada: Field Trip A4: Guidebook 13-15
May 1994.
Mitchum, R.M., Vail, P.R., and Thompson,S., 1977. Seismic stratigraphy and global changes of
sea level; Part2: The depositional sequence as a basic unit for stratigraphic analysis, in
Payton,C.E.(ed.):Seismic Stratigraphy –applications to hydrocarbon exploration: AAPG
Memoir 26, p.53-62.
Moffat, H.A., Brett, C.E., Soldani, D., 1998, Comparative taphnofacies within Ordovician and
Jurassic meter-scale cycles; implications for depositional processes. Geological Society of
America, 1998 Annual Meeting. Geological Society of America 30 (7) p.383.
Parks, W. A., 1928. Faunas and stratigraphy of the Ordovician black shales and related rocks in
Southern Ontario. Transactions of the Royal Society of Canada, 3rd series, section IV,22,p.39-
92.
34
Raymond, P.E., 1912, Invertebrate. Notes on field work in the Ottawa Valley. In summary report
1911. Geological Survey of Canada, p.351-357.
Quinlan, G. M., and Beaumont, C., 1984, Appalachian thrusting, lithospheric flexure, and the
Paleozoic stratigraphy of the eastern interior of North America: Canadian Journal of Earth
Sciences, v. 21, p. 973-996.
Read, J. Fred., 1985. Carbonate platform facies models, AAPG Bulletin, 69(1),p.1-21.
Read, J.F., 1995, Overview of carbonate platform sequences, cycle stratigraphy and reservoirs in
greenhouse and icehouse worlds: in Read, J.F., Kerans, C., Weber, L.J., Sarg, J.F., and Wright
F.W., Milankovitch sea level changes, cycles and reservoirs on carbonate platforms in
greenhouse and icehouse worlds, SEPM Short Course Notes No. 35, p. 1-102.
Riva, J., 1974. A revision of some Ordovician Graptolites of eastern North America.
Palaeontology. Volume 17.
Russell, D.J., & Telford, P.G., 1983. Revisions to the stratigraphy of the Upper Ordovician
Collingwood beds of Ontario - a potential oil shale. Can. J. Earth Sci., 20: 1780-1790.
Rowley, D.B., and Kidd, W.S.F., 1981, Stratigraphic relationships and detrital composition of
the Medial Ordovician flysh of western New England: Implication for the tectonic evolution
of the Taconic orogeny: Journal of Geology, v. 89, p.199-218.
Snowdon, L.R., 1984. A comparison of Rock-Eval pyrolysis and solvent extraction results from
the Collingwood and Kettle Point oil shales, Ontario; Bulletin of the Canadian Society of
Petroleum Geology, 32(3): 327-334.
Sweet, W.C., 1988. The conodonta; morphology, taxonomy, paleoecology, and evolutionary
history of long extinct animal phylums, Oxford monographs of geology and geophysics, 10
p.212.
35
Tuffnell, P. 1986. Triarthrus biostratigraphy of the Whitby Formation (Upper Ordovician) of
Southern Ontario. Masters Thesis, University of Toronto.
Tuffnell, P., Ludvigsen, R., 1984. The trilobite Triarthrus in the Whitby Formation (Upper
Ordovician) of Southern Ontario and a biostratigraphic framework, in Ontario, Geological
Survey, Open File Report 5516.
Wilson, J.L., 1975. Carbonate facies in geologic history. 471pp.30Pls., 183Figs., Berlin-
Heidelberg-New York: Springer.
Wilson, J.L. & Sengupta, A., 1985. The Trenton Formation in the Michigan Basin and environs:
pertinent questions about its stratigraphy and diagenesis, in Michigan Basin Geological
Society, Special Paper No.4, 1985.
Wilson, J.L., Budai, J.M., Sengupta, A., (2001) Trenton-Blackriver Formations of Michigan
Basin. Masera Corporation, Tulsa, Oklahoma, summarized in Search and Discovery Article
#10020 (2001).
Winder, C.G., 1961, Lexicon of Paleozoic names in Southwestern Ontario. University of Toronto
Press, Toronto, Ont.,121p.
0
W
Inferred Isopac map of Collingwood according to Churcher et.al. (1991)
Canadian Shield (Precambrian)
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
Figure 1
0m
2.5m
5m
5m 2.5m 0m
10m
7.5m
Collingwood distribution and Isopach Map, Collingwood Member, Lindsay Formation
0m
G.M. Kay1960 (1943, 1948)
Richmondian
Maysvillian
EdenianCn
cin
at
in
ian
Gloucesterian
Collingwoodian
Tre
no
nia
nt
it
in
Pc
on
a
Cobourgian
Shermanian
Kirkfieldian
Rocklandian
Ne
on
tian
alm
Chaumontianian
Lowvillian
Pamelian
lc
eB
akr
ivria
n
B. A. Liberty1964 and present
report
Silurian
Queenston
Georgian Bay
Whitby
Nt
so
ta
wa
ag
aG
rou
p
U
M
L
L
U
Precambrian
Shadow Lake
Gull River
Bobcaygeon
Verulam
Lindsay
ie
p
Sm
coG
rou
BasalGp
L
U
U
L
M
U
L
M
B. A. LibertyLitho-and Biostratigraphy
Interpretation
BasalGp
ie
p
Sm
coG
rou
Nt
so
ta
wa
ag
aG
rou
p
Queens-ton
Silurian
Richmondian
Maysvillian
Edenian(after
Sinclair 1964)
ae
dB
rne
vl
Wild
er
sn
es
oa
Bl
ria
nT
ren
on
ian
t
Cobourgian
Shermanian
Nealtonian
(=Rocklandian;see text underBobcaygeon)
Chaumontian
Lowvillian
Pamelian
Silurian
Upper
Ordovician
?
Middle
Ordovician
Cambrian
Precambrian
G
F
E
D
C
B
A
2
11
2
1
2
1
3
21
3
4
Biostratigraphy Lithostratigraphy BiostratigraphyLitho-
Time
Si
ce
Gr
pm
oo
u
Verulam Fm.
Lindsay Fm.
Bobcaygeon Fm.
Gull River Fm.
Shadow Lake Fm.
(Collingwood Mbr.)
(Lower Mbr.)
after Johnston et. al., (1991)
South CentralOntario
Litho-
ro
Te
nt
nia
n
Shermanian
Kirkfieldian
Rocklandian
Edenian
Maysvillian
Blackriverian
Stage
Se
qu
ee
n
c2
eq
ue
S
en
c3
Sie
se
r
rd
o
Up
pe
Or
vici
an
Mi
dle
Ord
ovi
cia
n
d
Maysvillian
Richmondian
Blue Mountain Fm.
Georgian Bay Fm.
Queenston Fm.
(Craigleith Mbr.)
after B.A.Liberty (1969)
cS
equ
en
e
B.V. Sanford1960
Silurian
Queenston
Meaford-Dundas
Precambrian
Shadow Lake
Gull River
Kirkfield
Sherman Fall
Cobourg
rG
Te
nto
n
rou
p
BasalGp
Blue Mountain
Collingwood
Coboconk
B.A. Liberty1953, 1955
Silurian
Queenston
Dundas-Meaford
Rouge River
iW
htb
yG
rou
p
Precambrian
Shadow Lake
Gull River
Kirkfield
Verulam
Cobourg
ie
p
Sm
coG
rou
BasalGp
Blue Mountain
Craigleith
ota
wN
ta
-sa
gG
pa
Coboconk
L
U
lc
p
Ba
k R
ive
rG
rou
(South-Central Ontario)
(South-Central Ontario)
HISTORIC CURRENT
J.F. Caley and B.A.- Liberty 1950-1952
B.A. Liberty 1952-1953
Queenston
MeafordDundas ‘Fm’
‘Fm’
Gloucester strata
pr
Up
er
Od
ovi
cia
n
Precambrian
Basal beds
Lowville beds
Rockland-Hull beds
Sherman Fall beds
Cobourg beds
ro
Go
Te
nt
n
ru
p
Not recognized
Collingwood Srata
Leray Coboconk
Bla
ck R
ive
r G
rou
p
Pamelia ? beds
Hall beds
Rockland beds
Transition beds
G.M. Kay1937
Gloucester
Chaumont
Sherman Fall
Cobourg
Tre
nto
n G
ou
pr
Collingwood
Rockland = Coboconk
lc
p
Ba
k R
ive
rG
rou
Hillier
Hallowell
Hull
Not recognized
W.A. Parks 1928
Lower Gloucester
Trenton
Upper Cobourg
Upper Collingwood
Lower Collingwood
Lower Cobourg
Trenton (restricted)
Upper Cobourg
Collingwood
Lower Cobourg
Hull Rockland
ren
on
Go
up
Tt
r
Praspora beds
Upper
Collingwood
Lower
Hull Rockland
Picton
Gloucester
Praspora
Fusipira and Hormotoma
Ogygites canadensis
Rafinesquina deltoidea
Crinoid Triplecia extans
Climacogratus typicalis
Goniaceras anceps
Tetradium cellulosum
Onchometopus simplex
Fauna variable
Trenton
Upper Picton
Collingwood
Lower Picton
Hull
Rockland
Utica
Leray
Lowville
Upper Pamelia
Lower Pamelia
reo
nl
eo
Gr
Tn
t i
mst
ne
o
up
Bl
ckR
iv G
rp
a
er
ou
P.E. Raymond
1914 1914 1916 1921
Climacogratus typicalis beds
Ogygites canadensis beds
Hormotoma and Fusispira beds
Rafinesquina deltoidea beds
Praspora beds
Crinoid beds
Damanella beds
Gonioceras anceps Transition beds
‘Calcarenite ‘ beds (Liberty)
Columnaria beds
Tetradium cellulosum beds
Onchometoptus beds
Basal beds
Beatricea beds
‘pre O: simplex beds’ (Liberty)
icG
roU
ta
u
p
aM
pp
ing
Ro
ck-
un
it n
um
be
rs
Silurian
Upper
Ordovician
?
Middle
Ordovician
Precambrian
Time
A2
13
4
O
B1
B2
B3
C1 A
B
C2
D
E AE B
F1
2
G1
G2
oS
imc
e G
roup
Verulam Fm.
Lindsay Fm.
Bobcaygeon Fm.
Gull River Fm.
Shadow Lake Fm.
(Collingwood Mbr.)
(Lower Mbr.)
after Johnston et. al., (1991)
South-CentralOntario
Litho-
reo
Tnt
nia
n
Shermanian
Kirkfieldian
Rocklandian
Edenian
Maysvillian
Blackriverian
Stage
Se
quen
e 2
ce
Sq
uence
3
Sie
s
er
eO
ri
Upp
r d
ov
cian
M
iddle
do
ian
Or
vic
Maysvillian
Richmondian
Blue Mountain Fm.
Georgian Bay Fm.
Queenston Fm.
Tre
nto
n G
rou
p
Sherman Fall Fm.
Cobourg Fm.
Coboconk Fm.
Gull River Fm.
Shadow Lake Fm.
Blue Mountain Fm.
Georgian Bay Fm.
Queenston Fm.
Kirkfield Fm.B
lck
Re
r G
rou
a
ivp
South WesternOntario
Litho-
eS
eq
ue
nc
( Ontario)
CURRENT
ta
oup
Otaw
Gr
Shadow Lake Fm.
Gull River Fm.
Bobcaygeon Fm.
Verulam Fm.
Lindsay Fm.
Eastview Mbr.)
Rockcliffe Fm.
Boas River Fm.
?
Litho- Litho-
Eastern Ontario
Hudson BayMoose River
Basins
Queenston Fm.
Carlsbad Fm.
Billings Fm.
Red Head Rapids Fm.
Churchill River Gp.
Figure 2
Historic and Current Collingwood Nomenclature for Central Ontario
W
Canadian Shield (Precambrian)
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
Figure 3Location of Collingwood outcrops in South-central Ontario
Collingwood outcrop
BowmanvilleCraigleith
Sheguiandah
0
W
Inferred Isopac map of Collingwood according to Churcher et.al. (1991)
Canadian Shield (Precambrian)
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
Figure 4
0m
2.5m
5m
5m 2.5m 0m
0m
0m
0m0m
0m
0m
0m
10m
7.5m
Isopac Map showing outliers, Collingwood Member, Lindsay Formation
0W C
W
Michigan Basin
Appalachian Basin
Western (W), Central (C) St. Lawrence Platform
Arch Appalachian structural front
Contour on Precambrian basement in metres (Datum: sea level)
Erosional limit of Collingwood Mbr.
Canadian Shield (Precambrian) Utica Trough
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
Frase
rdale Frontenac
rA ch
et
Laur n ian
chAr
Alg
onq
inu
Arhc
rh
Find
lay
Ac
N
-5 00
-1000
-2000
4-000
-6000
8-000
-100
00-1
2000
0
1000-
-4000
-3000
-2000
-1000
-5000
0
-5 00
Figure 5Structural setting
NOTTAWASAGA BAY
COLLING- WOOD
MEAFORD
OWEN SOUND
HANOVER
o44 30'
o80 30'
0 10 km
N
OTOR NTO
LAKE ONTARIO
AURORA
MARKHAM
AJAX
OSHAWA
o79 30' 30'
o44
o44
N
0 10 km
30'o82
o45 30'
o46
0 10 km
N
LITTLE CURRENT
MANITOULIN ISLAND
LAKEURON
H
GA
BA
GEO
RI
N
Y
Manitoulin Island Cluster
Collingwood Cluster
Toronto Cluster
City/Township Limits
International boundary
Railway tracks
SIS4
SIS1
SIS2
SIS3
Bowmanville
CLGD16
ClarksburgCLGD2
CLGD1Craigleith
CLGD4CLGS6a
CLGD7a
SIS5
Sheguiandah
SIS6
** Outcrop
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
NobletonCorbetton
Wiarton
Figure 6
Borehole Outcrop
Nobleton
Corbetton
OSAP Borehole and outcrop location map.
Toronto Cluster
Collingwood Cluster
Manitoulin Island Cluster
300
250
200
150
100
50.0
0.00
-50.0
-150.0
-200.0
-250.0
-300.0
-350.0
-400.0
-100.0
-450.0
-500.0
-550.0
450
400
Precambrian
Cambrian
Shadow Lake
Gull RiverGull River
Coboconk
Bobcageon/Kirkfield
Verulam/Sherman Fall
Lindsay/Cobourg
Collingwood
Blue Mountain and Georgian Bay
Queenston
Manitoulin
Cabot Head
Fossil Hill
Amabel
Guelph
A1-Carb.
Grimsby
Irondequoit
Reynales
RochesterRochester
Gasport
Dyer Bay
St. Edmond
Wingfield
Niagara Escarpment
Niagara Escarpment
Algonquin Ach
r
Elevation(metres above or below sea level)
A
B
Canadian Shield (Precambrian)
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
Figure 7Cross section through palaeozoic units (southcentral Ontario) withdepositional sequences indicated by (S#). Based on subsurface correlation work conducted by Armstrong and Carter (2006) and generalized lithologic descriptions of formations in Johnston et. al. (1991).
B
A
S1
S2
S3
S4
S5
S2
S6
S5
S4
Manitoulin IslandOGS-83-5 6V
Howland
Based on:Imperial Oil 528
St. Edmund
OGS-82-4Wiarton
Moray Enterprises Inc.Moray No. 1
Egermont-4-VI.#
Buxton Oil & Gas Ltd..Buxton Bozian No. 1
Arthur 8-25-V
OGS 83-1Halton
Nassagaweya-9-VII
Imperial Oil Ltd.Imperial Oil
Saltfleet-12-IV
Lowrie Holdings Inc.Imperial
Grantham-3-III
RANGES OF GRAPTOLITE SPECIES RANGES OF CONODONT SPECIESTRILOBITEBIOSTRAT
CHITINOZOANDIVERSITY
20 30 40
#OF CHITINOZOAN SPECIES PER ASSEMBLAGE
GraptolitebiozonesN
.A.
Sta
ge
s
N.A
.Se
ries
CIN
CIN
NATI
AN
RIC
HM
ON
DIA
NM
AYS
VIL
LIA
NED
EN
IAN
Am
ple
xog
rap
tus
ma
nito
ulin
ensi
s
Ge
nic
ulo
gra
ptu
sp
ygm
ae
us
C. (D.)Spiniferus
Dic
ello
gra
ptu
sc
om
pla
na
tus
Conodontbiozones
Am
orp
ho
gna
thus
sub
erb
us
Am
orp
ho
gna
thus
ord
ovi
vic
us
From Goldman and Bergstrom (1997)From Ludvigsenand Tufnell (1984)
From Melchin et al. (1994)
SEQ
UEN
CE 3
SEQ
UEN
CE 2
Johnson et al.(1991)
Sequence Stratin Ontario
Re
cto
gra
ptu
sa
mp
lexi
ca
ulis
Ort
ho
gra
ptu
sq
ua
drim
uc
rona
tus
Ort
ho
gra
ptu
s sp
ing
eru
sG
enic
ulo
gra
ptu
s ty
pic
alis
typ
ica
lis
Ge
nic
ulo
gra
ptu
s p
ygm
ae
us
Clim
ico
gra
ptu
stu
bulif
ero
us
‘Gly
pto
gra
ptu
s’ lo
rra
ine
nsi
s
Oth
og
rap
tus
euc
ha
ris
Ge
nic
ulo
gra
ptu
s ty
pic
alis
ma
gnifi
cus
Am
ple
xog
rap
tus
ma
nito
ulin
ensi
sC
limic
og
rap
tus
putil
is
Arn
he
imo
gra
ptu
s a
na
ca
nth
us
Re
cto
gra
ptu
s p
eo
sta
Clim
ico
gra
ptu
s ne
vad
ensi
s
Dic
ello
gra
ptu
s g
ravi
s
Dic
ello
gra
ptu
s c
om
pla
na
tus
Dic
ello
gra
ptu
s o
rna
tus
Clim
ico
gra
ptu
s ha
sta
tus
Ap
he
log
na
thus
po
litus
Am
orp
ho
gna
thus
sup
erb
us
Icrio
de
lla s
up
erb
a
Rho
de
sog
na
thus
ela
ga
ns
Pe
rio
do
n g
rand
isR
hip
ido
gna
thus
sym
etr
icus
Co
lum
bo
din
a o
cc
ide
nta
lis
Co
lum
bo
din
a p
enna
Pro
top
and
ero
dus
insc
ulp
tus
Pse
ud
ob
elo
din
a in
clin
ata
Ple
cto
din
a flo
rid
a
Am
orp
ho
gna
thus
ord
ovi
vic
us
Pse
ud
ob
elo
din
a v
ulg
aris
vulg
aris
Olu
lod
us
ulric
hi
Tria
rthru
s b
ec
kii
Tria
rthru
s e
ato
ni
Tria
rthru
s c
ana
de
nsi
s
Tria
rthru
s ro
ug
ensi
s
Tria
rthru
s sp
ino
sus
Figure 8Comparison of biostratigraphic ranges.
Figure 9Schematic illustration showing how to determine if Collingwood strata are present in the subsurface (Figure 9 from Churcher et al. (1991)).
Actual gamma log examples comparing two holes where collingwood are indicated (WC-35 and WC-36) and two holes where Collingwood strata are not indicated (NC-42 and NC-44) (from Curcher et al. (1991), Figures 10 and 11). Note that the API scales are not comparable. WC-35 and WC-36 log responses above 100 API have not been transposed.
Figure 10
WC-35 and WC-36 from Figure 9 have been re-scaled (approximate) to provide a more meaningful comparison with NC-44 and NC-42. Note that in WC-35 and WC-36, when scaled, the transition from carbonate to shale no longer appears distinctively gradual as was proposed by the authors.
Figure 11
N. DORCH.
NC-36DEREHAM
WC-36
Gamma Neutron
}Collingwood unit identified by Churcher et al. (1991)
Borehole- no Collingwood (NC)
Borehole With Collingwood (WC)
Gamma Neutron
Figure 12
Note that the petrophysical chemostratigraphic units are very similar yet Collingwood strata were not identified in NC-36. Both NC-36 and WC-36 localities are located in Southwestern Ontario approximately 25km apart.
0
100
Scale ft.
NOTTAWASAGA BAY
COLLING- WOOD
MEAFORD
OWEN SOUND
HANOVER
o44 30'
o80 30'
0 10 km
N
TOONTO
R LAKE ONTARIO
AURORA
MARKHAM
AJAX
OSHAWA
o79 30' 30'
o44
o44
N
0 10 km
30'o82
o45 30'
o46
0 10 km
N
LITTLE CURRENT
MANITOULIN ISLAND
LAKEURON
H
GA
BA
GEO
RI
N
Y
Manitoulin Island Cluster
Collingwood Cluster
Toronto Cluster
City/Township Limits
International boundary
Railway tracks
SIS4
SIS1
SIS2
SIS3
Bowmanville
CLGD16
ClarksburgCLGD2
CLGD1Craigleith
CLGD4CLGS6a
CLGD7a
SIS5
Sheguiandah
SIS6
** Outcrop
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
Toronto Cluster
Collingwood Cluster
Manitoulin Island Cluster
Figure 13
Borehole Outcrop
Location map for boreholecluster and outcrop localities
NOTTAWASAGA BAY
COLLING- WOOD
MEAFORD
OWEN SOUND
HANOVER
o44 30'
o80 30'
0 10 km
N
OTOR NTO
LAKE ONTARIO
AURORA
MARKHAM
AJAX
OSHAWA
o79 30' 30'
o44
o44
N
0 10 km
30'o82
o45 30'
o46
0 10 km
N
LITTLE CURRENT
MANITOULIN ISLAND
LAKEURON
H
GA
BA
GEO
RI
N
Y
Manitoulin Island ClusterCollingwood Cluster
Toronto Cluster
City/Township Limits
International boundary
Railway tracks
SIS4
SIS1
SIS2
SIS3
Bowmanville
CLGD16
ClarksburgCLGD2
CLGD1Craigleith
CLGD4CLGS6a
CLGD7a
SIS5
Sheguiandah
SIS6
** Outcrop
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
Nobleton
Corbetton
Wiarton
Figure 14
Borehole Outcrop
Nobleton
Corbetton
Location Map for tie-in boreholes, borehole clusters and outcrops
G R N
G R N
CLGD2 CLGD4b
G GG
GR RR
RN NN
NG R N
G R N
CLGD16 CLGD1 CLGD6a CLGD7a
G GG
GR RR
RN NN
N
Datum (U)
G R N
G R N
SIS5
SIS6
Datum (U)
SIS1
SIS2
SIS3SIS4
GG
G
G
RR
R
R
NN
N
N
Datum (U)
Comparison of Collingwood strata represented in OSAP geophysical logs from the 3 clusters (Manitoulin Island, Collingwood, and Toronto) in Central Ontario. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines. Each locality is numbered for reference to Locality Map Figure 6.
Manitoulin Island Cluster
Toronto Cluster
Collingwood Cluster
(L)
(L)
(L)
Figure15
G R N
G R N
CLGD2
G GR RN NG R N
G R N
CLGD16 CLGD1 CLGD4b
G GR RN N
Datum (U)
Comparison between representative Collingwood cluster signatures and signatures from OSAP tie-in localities (Wiarton and Corbetton). The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines. The two grey lines on the Wiarton log show the position of the contacts in the Johnston et al. (1983-1985) log.
Collingwood Cluster
(L)
FIGURE 16
G R N
G R N
Tie-inWiarton
Tie-inCorbetton
G R NG R N
Datum(U)
Comparison between OSAP tie-in localities and the Manitoulin Island, Collingwood, and Toronto clusters. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines.
(L)
FIGURE 17
G R N
G R N
G R N
G R N
GG
G
G
RR
R
R
NN
N
N
Manitoulin Island Cluster Toronto ClusterTie-inCorbetton
Tie-inWiarton
Collingwood ClusterRepresentative
SIS5
SIS6
CLGD16SIS3
SIS2
SIS1SIS4
G R NG R N
Datum (U)
Comparison between OSAP tie-in localities (including the Nobleton locality) and the Manitoulin Island, Collingwood and Toronto clusters. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines. In the Nobleton log the two gray lines mark the position of the Collingwood boundary contacts indicated in the Johnston et al. (1983-1985) log.
(L)
FIGURE 18
G R N
G R N
G R N
G R N
SIS6SIS4SIS1
SIS2
GG
G
G
RR
R
R
NN
N
N
Manitoulin Island Cluster Toronto ClusterTie-inCorbettonWiarton
Collingwood ClusterRepresentative
G PR
Tie-inNobleton
SIS5 CLGD16 SIS3
Datum (U)
Comparison between deep OSAPborehole Tie-in localities and signatures from two localities outside of the known Collingwood range. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines.
(L)
FIGURE 19
Tie-inCorbetton
G PR
Elma Maryborough
G
G
N
NG R N
Tie-inWiarton
G R N
Tie-inNobleton
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
Wiarton
Maryborough
ElmaNobleton
Corbetton
Shadow Lake Fm.
Shadow Lake Fm.
Datum (U)
Comparison between signatures of representative Collingwood, Toronto, and Manitoulin Island clusters, OSAP tie-in localities, and two additional borehole logs (Elma and Mayrborough). The Elma and Maryborough localities are located outside of the recognized range of Collingwood strata. The log lines are gamma(G), resistivity (R) and Neutron (N). The upper (U) and lower (L) ”Collingwood” boundaries were used as tie-in lines.
Collingwood ClusterRepresentative
(L)
FIGURE 20
G R N
G R N
G R N SIS2
SIS3
G
G
R
R
N
N
Manitoulin Island ClusterRepresentative
Toronto ClusterRepresentatives
Tie-inCorbetton
Tie-inWiarton
G PR
Elma
G
G
N
N
SIS5
G R NG R N
CLGD16
Tie-inNobletonMaryborough
LEGEND
Carbonate
Cross section through topographic high
Cross section through topographic high
Terriginous clay
Figure 21
Comparison of condensation response between (A) carbonate vs (B) clastic dominated systems over a topographic high.
(A)
(B)
Tie-inCorbetton
G
G
R
R
N
N
SIS3
{Collingwood {Collingwood
Figure 22a
Variability in Collingwood strata thickness and apparent rate in transition from carbonate to shale chemistry observed in two south-central Ontario borehole logs.
Tie-inCorbetton
G R N
Hypothetical Toronto ClusterLocality.
{Collingwood
Figure 22b
Variability in Collingwood strata thickness if caused by post depositional erosion ( the upper portion of the Corbetton section was removed to create the hypothetical Toronto Cluster locality). Note that the transition would be lost and the gama log indicates that the Collingwood is much more carbonate like which is in contrast to the shale/clay rich composition indicated in the actual Toronto Cluster logs such as SIS3 in Figure 21a above.
G R
N
{Collingwood
-S 5-S 4
77.18m-
425.83m-
414.34m-
120.12m-
118.66m-
37.16m —
30.97m-
62.10m-
52.52m-67.65m-
22.38m-
15.93m-
3
233.93m-
221.01m-
-S 20-S 21
-S16 -S 17
-S 18-S 19
-S 11-S 10
-S 9-S 8
-S 3
-S 2
-S 6-S 1-S 7
-S 26-S 27
-S 28-S 29
-S 30-S 31
DatumP
-S 22-S 23-S 24-S 25
G GG G GGG
Figure 23Comparison between geophysical data and facies. The lower contacts indicated in the Johnston et al. (1983-1985) logs are shown as light grey lines.
SIS5 Corbetton Nobleton SIS3 SIS4Clarksburg CLGD1
U
L
DARK ORGANIC DOLOSTONE AND MARL (UNDIFERENTIATED)
DARK ORGANIC LIMESTONE AND MARL (UNDIFERENTIATED)
Nodular Limestone
Limestone
Sand
=SiltstoneST
=Breccia
Covered interval
=Unconformity
Missing core
P = Phosphate bed
Nodular Dolostone
0.93m-
0.00m-
Craigleith
0m-
3.92m-
Bowmanville
0.00m-
0.30m-
Sheguiandah
-S 40-S 41-S 42
-S 43
-S 44
-S 45
-S 46
-S 36-S 35-S 38-S 37
-S 34
Outcrop Localities
G Gamma Log
Legend
4500
4500
3500
0
100
200
0 200
GAMMA RAY
API UNITS
0 100
GAMMA RAY
API UNITS
100 200
0 150
GAMMA RAY
API UNITS
150 300
DATUM
TRENTON
BLACKRIVER
Pan American Petroleum Co.
D.E. Draysey No 1
Sec. 29, T 35 N. R. 2 E.
Ground Level Elevation 795 5’
Northern Michigan Exploration Co.
State-Waverly No 1-24
Sec. 24, T 35 N. R. 1 W.
Ground Level Elevation 788.9’
Atlantic Inland Oil Corp.
E.G. White & T.R. Burns No1
Sec. 35, T 37 N. R. 4 W.
Ground Level Elevation 704.0’
TG-1
BR-1
Tie-inCorbetton
-A- -B-
-C-
L
S
G
B
B
LOGS FROM MICHIGAN PENINSULA REGION
NOTE: Published pics (base of formations) for well logs are included for comparison as follows:
Bl = Bluemountain Fm.S = Sherman Falls Fm.L = Lindsay Fm.C = Coboconk Fm.Bo = Bobcageon Fm.Gu = Gull River Fm.S = Shadow Lake Fm.
G R
RG
Datum
4500
4500
3500
0
100
200
0 200
GAMMA RAY
API UNITS
0 100
GAMMA RAY
API UNITS
100 200
0 150
GAMMA RAY
API UNITS
150 300
DATUM
TRENTON
BLACKRIVER
Pan American Petroleum Co.
D.E. Draysey No 1
Sec. 29, T 35 N. R. 2 E.
Ground Level Elevation 795 5’
Northern Michigan Exploration Co.
State-Waverly No 1-24
Sec. 24, T 35 N. R. 1 W.
Ground Level Elevation 788.9’
Atlantic Inland Oil Corp.
E.G. White & T.R. Burns No1
Sec. 35, T 37 N. R. 4 W.
Ground Level Elevation 704.0’
TG-1
BR-1
Tie-inCorbetton
-A- -B-
-C-
L
S
G
B
B
LOGS FROM MICHIGAN PENINSULA REGION
G
G
Datum
Figure 24a
Figure 24b
76 W80 W84 W88 W92 W
40 N
44 N
48 N
44 N
48 N
40 N
76 W80 W84 W88 W92 W
0 100 200 km
N
Corbetton
A
B
C
Appendix A, Plate 1
Quartz clast
(1) Gradational contact between Lower Mbr. and Collingwood Mbr. showing angular quartz clasts in organic rich dolomite matrix. Transmitted light (Manitoulin Island Outcrop) .
(2) Sparry dolostone, Lower Mbr.. Transmitted light (Manitoulin Island , SIS 5).
(3) Secondary sparry calcite infilling of brachiopod. Note pressure solution features in
(4) Secondary sparry calcite replacement. Carbonate interbed. Transmitted light (Ottawa
2 mm
calcite on right hand side of slide. Transmitted light (Ottawa Outcrop).
outcrop).
romb
(5) Collingwood Mbr. Transmitted light (Manitoulin Island outcrop). Note dolomite rombs. Quartz is now rare to absent.
(6) Dolomitic Bluemountain Fm.. Transmitted light (Manitoulin Island, SIS 5).
BLithoclast
Appendix A, Plate 2
B
C
ContactAA(1) Phosphatic intrasparite/ironstone. Upper Collingwood Mbr. contact. Transmitted light (Clarksburg) Note lithoclast. Also see details A,B,C.
(2) Upper Collingwood contact detail showing soft sediment inversion – not erosional. Transmitted light (Clarksburg).
A
Iron sulphide
B B2 mm
(3) Detail showing iron sulfide replacement of bioclasts. Reflected light (Clarksburg).
(4) Detail showing iron sulfide replacement of bioclasts. Transmitted light (Clarksburg).
C C
Concentric rings
C C
(5) Detail of cluster (pelloids?) Note concentric rings in central body. Transmitted light (Clarksburg).
(6) Detail of cluster (pelloids?). Reflected light (Clarksburg).