ISSN 1028�334X, Doklady Earth Sciences, 2012, Vol. 443, Part 1, pp. 371–376. © Pleiades Publishing, Ltd., 2012.Original Russian Text © A.V. Maslov, V.P. Shevchenko, Yu.L. Ronkin, O.P. Lepikhina, A.N. Novigatskii, A.S. Filippov, N.V. Shevchenko, 2012, published in Doklady AkademiiNauk, 2012, Vol. 443, No. 2, pp. 214–220.

371

The peculiarities of the formation of modern bot�tom sediments of the White Sea and rivers flowing in it(Severnaya Dvina, Onega, Kem’, and others) haverecently attracted a great deal of attention fromresearchers. This interest was essentially stimulated byspecial multidisciplinary studies within the project“The White Sea System” [1, 2]. As a result of investi�gations performed in 2009–2011, we established thatthe systematics of Th, Cr, Hf, Co, and rare�earth ele�ments in modern bottom sediments of the White Seaand lower reaches of the Severnaya Dvina River is con�sistent with the model of mixing of clastics from twogeochemically contrasting areas of feeding: the north�western predominantly composed of crystalline rocksof the Archean and Early Proterozoic and the south�eastern, the structure of which includes sedimentaryformations of the Upper Vendian, Cambrian, Carbon�iferous, Permian, and Mesozoic. This is most clearlyreflected in the change in the model Nd age and εNd.

The composition and geochemical peculiarities ofdeposits of the White Sea, as well as large and smallrivers flowing into it, are controlled by several feedingprovinces. The largest of them are the Kola–Kareliageoblock (western and northwestern parts of thecatchment area), on the one hand, and the significantpart of the northwestern periphery of the Mezenskayasyneclise of the Russian Plate (southeastern White Seaarea, and areas located to the south and southeast fromit) (Fig. 1) [3, 4]. Approximately 85% of the first ofmentioned provinces is represented by tonolite–trondhjemite gneisses, granites, migmatites, and granu�lites, tholeiitic and ferrometabasalts, metadacites, met�athyolites, conglomerates, and gabbro�anorthosites

and alkaline granites of Archean age. Lower Protero�zoic rocks (various terrigenous and carbonate depos�its, metapyroxenites, granophyres, and gabbroids)compose ~10% of the Kola–Karelia geoblock area,whereas the portion of Riphean sedimentary and mag�matic complexes does not exceed 5% [5, 6]. Thecatchment area of the Severnaya Dvina and Onega riv�ers, as well as their tributaries, is composed of tuffo�gene–terrigenous formations of the Late Vendian(Valdaiskaya Series), Paleozoic (Carboniferous andPermian), and Mesozoic [4].

The Upper Vendian deposits are outcropped in thecliffs of the White Sea, along the rivers cutting deepvalleys on the Belomorsko–Kuloiskoe Plateau, as wellas on the coast of the Dvinskii and Onezhskii bays.Their systematics to a variable degree is comparablewith the systematics of magmatic rocks predominantlyof acidic composition: (La/Yb)PAAS varies from 0.6to 1.4, (Gd/Yb)PAAS ranges within 0.8–1.9, and the Euanomaly is positive 1.2 ± 0.4 (being normalized onaverage post�Archean shale, PAAS [7]). The modelNd age (TDM) of argillites of the Lyamitskaya Suiteis ~1.53 Ga. The TDM value in argillites of the overly�ing Verkhovskaya and Erginskaya Suites is 1.73–1.71 Ga.Clay rocks of the Zimnegorskaya Suite have a modelNd age of 1.57–1.53 Ga; the age of Cambrian argillitesof the Padunskaya Suite is 1.66–1.64 Ga [8]. Data onthe REE�systematics and TDM values for youngerdeposits of the southeastern feeding area are absent;because of this, all further comparisons will be basedon the data given above.

We studied a collection of 70 samples collected indifferent years during expeditions in the basin of theSevernaya Dvina River and its tributaries and voyagesof the R/V Professor Shtokman and analyzed at theInstitute of Geology and Geochemistry, Ural Branch,Russian Academy of Sciences, using a high�resolutionsector mass�spectrometer ELEMENT2 for investiga�tion of the minor element systematic of modern bot�tom sediments of the White Sea and its southeasternfeeding province [9]. TDM values were also determined

Systematics of Th, Cr, Hf, Co, and Rare�Earth Elements in Modern Bottom Sediments of the White Sea and Lower Reaches

of the Severnaya Dvina RiverCorresponding Member of the RAS A. V. Maslova, V. P. Shevchenkob, Yu. L. Ronkina,

O. P. Lepikhinaa, A. N. Novigatskiib, A. S. Filippovb, and N. V. Shevchenkoc

Received October 21, 2011

DOI: 10.1134/S1028334X12030166

a Zavaritskii Institute of Geology and Geochemistry, Ural Branch, Russian Academy of Sciences, Yekaterinburg, Russiab Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russiac Moscow State University, Moscow, Russiae�mail: maslov@igg.uran.ru

GEOCHEMISTRY

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for ten of them representing the lower reaches of theSevernaya Dvina and Pinega rivers, the marginal filterof the Severnaya Dvina River, littoral deposits of theTerskii coast of the Kola Peninsula, and a deep part ofDvina Bay at the boundary with the White Sea basin.The sample preparation was performed by the meth�odology described in [10]. According to the granulom�etric composition, most of the studied samples relateto aleuropelites.

REE systematics. The average total REE concen�tration in the studied samples varies from 26–37 ppm(areas from the Severnaya Dvina River upstream anddownstream of the Pinega River mouth and lowerreaches of the Pinega River) to 66–96 (SevernayaDvina delta and Dvina Bay) and ~130 ppm (theboundary between Dvina Bay and basin and Terskiicoast). This is slightly lower than the value given forthe Severnaya Dvina River suspension [11], but thetotal character of REE distribution in these samples ofbottom sediments and the Severnaya Dvina River sus�pension does not differ.

PAAS�normalized spectra of the REE distributionin bottom sediments of the Pinega River, the samplesof which were collected from the Pinega Village to itsmouth, are quite flat, poorly bulging in the area ofMREEs (Fig. 2a) being characterized by the following

main peculiarities: (La/Yb)PAAS = 0.56 ± 0.09,(La/Sm)PAAS = 0.75 ± 0.06. Depletion of HREEs isabsent in them ((Gd/Yb)PAAS = 0.95 ± 0.13), and theEu anomaly (by PAAS) varies from 1.08 to 1.52. To adefinite degree, these spectra are similar to the REEspectra of clay schists and argillites from covers ofancient platforms (Russian, Northern American, Chi�nese, and others [12]), but have a more clearlyreflected positive Eu anomaly.

Bottom sediments of the Severnaya Dvina Riverupstream and downstream from the Pinega Rivermouth are distinguished by lower, as well as higher, valuesof (La/Yb)PAAS, (Eu/Eu*)PAAS, and other parameters(Fig. 2b, Table 1), which most likely provides evidencefor the absence of effective mixing of sediments insome cases resulting from the relatively low speed offlow and/or influence of tributaries. At the same time,the REE systematics of bottom sediments in the Sev�ernaya Dvina River delta statistically almost does notdiffer from the systematics of bottom sediments of thePinega River (Fig. 2b), although the total REE con�centrations in the latter case are slightly lower. Exceptfor the slightly lower average value (Eu/Eu*)PAAS, thisis typical for modern bottom sediments of Dvina Bayas well.

m�24

WHITESEA

m�64m�6

m�5

m�20м�53

m�14m�36 mm�4

mm�8

Mezen’ R.

Onega

Arkhangelsk

1

2

3

4

5

6

7

8m�24

Severnaya Dvina R.

Fig. 1. Scheme of the geological structure of the White Sea catchment area (the catchment area boundary is shown after [3]) andlocation of the samples for which the Sm–Nd systematics was studied. (1) Archean and Proterozoic; (2) Vendian; (3) Carbonif�erous; (4) Permian; (5) Triassic; (6) Jurassic; (7) catchment area boundary; (8) sample and its number.

DOKLADY EARTH SCIENCES Vol. 443 Part 1 2012

SYSTEMATICS OF Th, Cr, Hf, Co, AND RARE�EARTH ELEMENTS 373

The general peculiarity of bottom sediments of allareas described above is the quite clearly reflected pos�itive Eu anomaly in relation to PAAS, the value ofwhich ranges from 1.1–1.2 to 1.3, and in the samplecollected in the Severnaya Dvina River 2 km down�stream from the Pinega River mouth, it reaches ~1.6.Such a high average value (Eu/Eu*)PAAS (~1.68) is typ�ical of the samples collected in the littoral zone nearthe Terskii coast of the White Sea. The maximal valueof this parameter there is ~2.3 (Fig. 2c, Sample m�25).

The points of the compositions of most studiedsamples on the diagram GdN/YbN–Eu/Eu*1 are local�ized in the area of post�Archean cratonic sediments(Fig. 3a). At the same time, some points are character�ized by quite low negative Eu/Eu* values or theabsence of an Eu anomaly plot near the average com�position of Archean argillite [7]; they include somesamples collected in the lower reaches of the PinegaRiver, in the Severnaya Dvina River 2 km downstreamfrom the Pinega River mouth, and in the SevernayaDvina delta. Two of four samples collected in the littoralzone of the Terskii coast (Samples m�24 and m�25) arecharacterized by significantly higher values of the pos�itive Eu anomaly than the average in Archean argillite.

Systematics of Th, Cr, Hf, and Co. Practically noneof the studied samples plots in the field of values typi�cal for the products of washing of primitive Archeansubstrates [13] on the Co/Hf–Ce/Cr diagram (Fig. 3b),although some samples have Ce/Cr ratios comparablewith these values.

Almost all points of the available set on theEu/Eu*–Cr/Th diagram (Fig. 3c) are characterizedby Cr/Th values intermediate between those typical ofthe average Archean argillite and PAAS. Analysis ofthe field formed on this diagram by the samples col�lected in the lower reaches of the Pinega River, in theSevernaya Dvina delta, in Dvinskii Bay, and at theboundary of the latter with the basin (Fig. 3d) demon�strates significant overlapping and, thus, their similar�ity resulting from the role of the Severnaya DvinaRiver as the main supplier of terrigenous material forthe White Sea. Because of the high Eu/Eu* values intwo samples, the compositional field of modern lit�toral sediments of the Terskii coast has a quite differentorientation in comparison with the fields of the forma�tions considered above. However, we may assume thatin this case both Archean and post�Archean compo�nents occur in the mentioned area as well, which doesnot contradict the general geological setting.

The position of the points of the studied formationson the Hf–La/Th diagram (Fig. 3e), as well as theirREE systematic, provides evidence for the leading roleof the products of washing of the mature continentalcrust in the formation of their geochemical pattern.

Sm–Nd systematics. The TDM values in Samp�les mm�4 and mm�8 collected upstream from the vil�

1 The REE concentrations in the samples are chondrite�normal�ized here [7].

lage of Pinega and in the area of the village of Orletsy,respectively, vary from 1.60 to 1.34 Ga (Table 2),which is slightly or remarkably lower than those infine�granular terrigenous rocks of the ValdaiskayaSeries [8]. This most likely provides evidence forwashing within the southeastern feeding province of“juvenile” magmatic complexes in the post�Vendian,especially for Sample mm�8. The TDM parameter insediments of the marginal filter of the Severnaya DvinaRiver ranges from ~1.60 to 1.86 Ga.

Bottom sediments collected at the boundarybetween Dvinskii Bay and the Basin (Samples m�5 andm�6) are characterized by a slightly older model Nd

10

1

0.1LuYbTmErHoDyTbGdEuSmNdPrCeLa

10

1

0.1

10

1

0.1

River suspensionof the Severnaya Dvina River

Clay rocks of coversof ancient platforms

mm�1

mm�8

(а)

(b)

(c)

m�23

m�26

m�24

m�25

Fig. 2. PAAS�normalized spectra of REE distribution inmodern bottom sediments of the White Sea and the easternpart of its catchment area. (a) Gray background: samplescollected in the lower reaches of thePinega River from thevillage of Pinega to its flow into the Severnaya Dvina River;Sample mm�8, the Severnaya Dvina River, 20 kmupstream the Pinega River flow into it; Sample mm�1, theSevernaya Dvina River, 2 km downstream from the PinegaRiver flow into it. (b) Gray background: samples collectedin the Severnaya Dvina delta; a solid line indicates thesamples collected in Dvinskii Bay; a dashed line indicatesthe samples collected at the boundary between DvinskiiBay and the Basin. (c) Samples collected on the Terskiicoast of the Kola Peninsula in the Varzuga River mouth.

374

DOKLADY EARTH SCIENCES Vol. 443 Part 1 2012

MASLOV et al.

age (TDM ~2.0 Ga). Finally, some of the studied sam�ples of littoral deposits collected on the Terskii coast ofthe Kola Peninsula are characterized by two featuresclearly distinguishing them from both sediments of the

marginal filter of the Severnaya Dvina River anddeposits of the Basin. First, they have a clearly reflectedpositive Eu anomaly (for example, Sample m�24,(Eu/Eu*)PAAS = 2.1, Eu/Eu* = 1.38). Second, they

Table 1. Concentration (ppm) of minor elements and values of some of their indicator ratios in modern bottom sedimentsof the White Sea and the basin of the lower reaches of the Severnaya Dvina River and its tributaries

Elementsand ratios I II III IV V VI VII

Cr 194.89 16.94

Co 4.38 2.81

La 6.77 5.13

Ce 13.81 10.71

Hf 2.54 0.78

Th 1.16 3.00

Cr/Th 168.01 5.65

La/Th 5.83 1.71

Ce/Cr 0.07 0.63

Co/Hf 1.73 3.61

Eu/Eu* 0.75 1.07

GdN/YbN 0.81 2.01

(La/Yb)PAAS 0.33 1.02

(La/Sm)PAAS 0.77 0.77

(Gd/Yb)PAAS 0.6 1.48

(Eu/Eu*)PAAS 1.14 1.63

n 1 6 1 34 15 5 4

Note: The average value and standard deviation are given above the line; the minimal and maximal values are given below the line. n is thenumber of analyzed samples. Places of sampling: (I) Severnaya Dvina River, 20 km upstream from the place of the Pinega River enteringinto it; (II) the Pinega River, from the village of Pinega to the mouth; (III) Severnaya Dvina River, 2 km downstream from the PinegaRiver entering into it; (IV) the Severnaya Dvina delta; (V) Dvinskii Bay; (VI) boundary between Dvinskii Bay and the Basin; (VII) Ter�skii coast (Kola Peninsula) in the area of the Varzuga River.

21.22 33.83±

8.51–99.59�������������������������� 36.01 50.79±

6.17–251.30�������������������������� 78.94 60.57±

37.77–303.39��������������������������� 78.30 33.56±

45.88–120.95��������������������������� 28.89 96.46±

11.73–223.41���������������������������

2.74 0.46±

2.33–3.75���������������������� 3.99 5.39±

1.34–18.94����������������������� 6.96 4.38±

3.73–17.48���������������������� 12.17 8.47±

5.43–25.61������������������������ 3.67 11.45±

1.54–26.53������������������������

5.69 1.77±

4.01–8.67��������������������� 8.80 8.68±

4.02–33.12���������������������� 16.21 7.66±

9.63–32.18������������������������ 20.73 13.43±

9.50–42.22�������������������������� 8.42 31.58±

4.33–71.29������������������������

13.03 3.50±

8.31–19.67������������������������ 18.00 17.40±

8.03–69.19�������������������������� 33.76 16.05±

20.11–65.74�������������������������� 47.79 23.66±

25.12–78.67�������������������������� 20.88 68.18±

11.07–155.99���������������������������

1.42 1.07±

0.92–3.53��������������������� 1.96 1.79±

0.77–8.69��������������������� 3.97 1.28±

1.82–7.03��������������������� 3.20 0.54±

2.68–3.81���������������������� 3.85 10.46±

2.23–24.25������������������������

1.47 0.58±

0.78–2.29��������������������� 1.87 2.68±

0.71–9.19��������������������� 3.86 2.54±

1.95–9.85���������������������� 5.61 4.48±

2.29–12.73���������������������� 2.92 4.60±

1.61–11.01����������������������

12.24 14.66±

3.91–43.51�������������������������� 18.20 24.80±

6.91–112.63�������������������������� 17.34 17.81±

10.21–79.45�������������������������� 11.48 4.46±

8.81–20.05������������������������ 10.48 7.03±

6.18–20.30������������������������

3.54 1.19±

2.23–5.38��������������������� 4.11 0.93±

2.66–6.03��������������������� 3.89 0.70±

2.85–5.10���������������������� 3.43 0.43±

3.04–4.15���������������������� 3.10 1.92±

2.31–6.48���������������������

0.35 0.48±

0.14–1.59���������������������� 0.33 0.24±

0.09–1.30���������������������� 0.36 0.16±

0.09–0.65��������������������� 0.63 0.06±

0.55–0.70��������������������� 0.65 0.19±

0.47–0.94���������������������

1.58 0.75±

0.87–2.79��������������������� 1.71 1.15±

0.47–5.04��������������������� 1.59 1.08±

0.54–4.34��������������������� 4.01 2.16±

1.97–7.76��������������������� 1.08 0.55±

0.69–2.01���������������������

0.87 0.11±

0.71–1.00��������������������� 0.84 0.13±

0.67–1.06��������������������� 0.76 0.10±

0.66–1.05��������������������� 0.76 0.13±

0.67–0.99��������������������� 0.99 0.40±

0.68–1.51���������������������

1.34 0.28±

1.13–1.90��������������������� 1.39 0.22±

1.02–1.79��������������������� 1.42 0.27±

1.08–1.87��������������������� 1.84 0.31±

1.53–2.31��������������������� 1.26 0.20±

1.10–1.53���������������������

0.56 0.09±

0.42–0.65��������������������� 0.75 0.15±

0.4–1.06��������������������� 0.77 0.16±

0.55–1.04��������������������� 1.06 0.42±

0.42–1.76��������������������� 0.60 0.06±

0.53–0.68���������������������

0.75 0.06±

0.69–0.84���������������������� 0.84 0.09±

0.67–1.03���������������������� 0.85 0.09±

0.68–1.01���������������������� 0.87 0.18±

0.18–1.17��������������������� 0.77 0.09±

0.70–0.90���������������������

0.95 0.13±

0.83–1.14��������������������� 1.04 0.16±

0.75–1.32��������������������� 1.08 0.20±

0.80–1.37��������������������� 1.38 0.23±

0.23–1.69��������������������� 0.94 0.15±

0.81–0.13���������������������

1.33 0.17±

1.08–1.52��������������������� 1.31 0.19±

1.02–1.61��������������������� 1.17 0.15±

1.01–1.60��������������������� 1.18 0.20±

0.20–1.52��������������������� 1.68 0.62±

1.03–2.31���������������������

DOKLADY EARTH SCIENCES Vol. 443 Part 1 2012

SYSTEMATICS OF Th, Cr, Hf, Co, AND RARE�EARTH ELEMENTS 375

are characterized by the highest model Nd age(~2.8 Ga) among all analyzed samples, which is closeto the median TDM value for magmatic andsupracrustal formations of the main structural ele�ments of the Baltic Shield (~2.9 Ga) [8].

The εNd(0) value in bottom sediments of the Sever�naya Dvina River upstream from the Pinega Rivermouth is –8.5; in sediments of the Pinega River lower

reaches, the Severnaya Dvina River delta, and Dvin�skii Bay, it ranges from –11.7 to 14.6, which is quiteconsistent with the data presented in [12] for clayrocks of the Russian Plate ( = –13.4). Littoral

formations on the Terskii coast are characterized by asignificantly lower εNd(0) value (–25.6), whereas bot�tom sediments at the boundary between Dvinskii Bayand the Basin have values (–16.9 and –18.0, Table 2)

εNDaverage

14

0 15Hf

La/Th

5

PAAS

10

1.6

0 3GdN/YbN

Eu/Eu*

1.2

0.8

0.4

21

ArArg

PAAS

0.4 1.6

Cr/Th1000

100

10

1.20.8

7

4

ArArg

PAAS

100

10

1.2 1.60.8

Eu/Eu*

2

0 10Co/Hf

Ce/Cr

1

84

PAAS

62

12

10

8

6

4

2

ArArg

1234567

(а) (b)

(d)

(c)

(e)

Post�Archeancratonicsediments Field of the

values typical ofArchean compositions

Tholeiitesof oceanic islands

Andesiticisland�arc source

Trend ofmixing of felsiticand basic material

Maturecontinental crust (felsiticsource)

2

5

Fig. 3. Distribution of figurative points of the composition of modern bottom sediments of the White Sea and the eastern part ofits catchment area on various geochemical diagrams (a–e). (1) The Severnaya Dvina River, 20 km downstream from the PinegaRiver entrance; (2) the Pinega River, from the village of Pinega to the entrance into the Severnaya Dvina River; (3) the SevernayaDvina River, 2 km downstream from the Pinega River entrance; (4) the Severnaya Dvina River delta; (5) Dvinskii Bay; (6) bound�ary between Dvinskii Bay and the Basin; (7) Terskii coast (Kola Peninsula) in the Varzuga River mouth area. PAAS is the averagepost�Archean Australian clay schist; ArArg is the average Archean argillite, after [7]; the field of values typical of Archean com�positions is given after [13]; the compositional field on the diagram (e) is given after [14, 15].

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DOKLADY EARTH SCIENCES Vol. 443 Part 1 2012

MASLOV et al.

intermediate between those of sediments of the Terskiicoast and the marginal filter of the Severnaya DvinaRiver. Similarly to the data on the model Nd age, thismay be interpreted as a reflection of mixing of fine alu�minosilicate materials transported to the White Seafrom the Kola Peninsula and the Mezenskaya syneclise.

As a whole, the character of distribution of figura�tive points of the compositions of modern bottom sed�iments of the White Sea and the basin of the lowerreaches of the Severnaya Dvina River on theGdN/YbN–Eu/Eu* and Eu/Eu*–Cr/Th diagrams, aswell as the values of some other indicator ratios ofminor elements typical for them, provides grounds toconsider that the systematics of Th, Cr, Hf, Co, andREEs in modern bottom sediments of the White Seaand the basin of the lower reaches of the SevernayaDvina and its tributaries is consistent with a quite sim�ple model of mixing of clastics from two geochemicallycontrasting feeding areas: western and northwesternmainly composed of Archean and Early Proterozoiccrystalline complexes and eastern and southeasternalmost exclusively composed of Phanerozoic sedimen�tary formations. The model Nd age of the studied fine�granular terrigenous formations and the εNd(0) param�eter are the most sensitive indicators of this.

ACKNOWLEDGMENTS

The authors are grateful to AcademicianA.P. Lisitzin and V.B. Korobov for valuable com�ments, D.V. Eroshenko, V.A. Zhamoida, S.M. Isa�chenko, N.K. Fedorova, and the crews of the R/VProfessor Shtokman, Iceberg�2, and Akvanavt�2 forhelp in sample collection.

This study is partially supported by the RussianFoundation for Basic Research (project nos. 06�05�64223 and 09�05�00279), by the Foundation of thePresident of the Russian Federation for Support ofLeading Scientific Schools (grant NSh�3714.2010.5),and by the Presidium of the Russian Academy of Sci�ences (project no. 21 “Systematic Investigations of theSeas of European Russia”).

REFERENCES

1. A. P. Lisitzin, V. P. Shevchenko, I. A. Nemirovskaya,et al., in Physical, Geological, and Biological Investiga�tions of Oceans and Seas (Nauchnyi Mir, Moscow,2010), pp. 559–597 [in Russian].

2. The System of the White Sea. Natural Environment of theWhite Sea Catchment Area, Vol. 1, Ed. by A. P. Lisitzin,I. A. Nemirovskaya, and V. P. Shevchenko (NauchnyiMir, Moscow, 2010) [in Russian].

3. A. P. Lisitzin, in The System of the White Sea. NaturalEnvironment of the White Sea Catchment Area, Vol. 1(Nauchnyi Mir, Moscow, 2010), pp. 353–445 [in Rus�sian].

4. M. G. Gubaidullin, in The System of the White Sea.Natural Environment of the White Sea Catchment Area,Vol. 1 (Nauchnyi Mir, Moscow, 2010), pp. 40–57 [inRussian].

5. Precambrian Geology of the USSR, Ed. by D. V. Rund�kvist and F. P. Mitrofanov (Nauka, Leningrad, 1988) [inRussian].

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Table 2. Model Nd age of modern bottom sediments of the White Sea and the Severnaya Dvina and Pinega rivers

Sample Place of sampling Sm, ppm Nd, ppm 147Sm/144Nd ± 2σ 143Nd/144Nd ± 2σ εNd(0) TDM, Ma

mm�8 I, st. 28 (SD�2004) 1.07 5.46 0.1180 ± 6 0.512198 ± 4 –8.5 1337

mm�4 II, st. P�1 (SD�2006) 3.77 19.3 0.1185 ± 6 0.512038 ± 3 –11.7 1596

m�53 V, 0�2 PSh�4925 4.03 20.7 0.1177 ± 6 0.511974 ± 6 –12.9 1682

m�20 V, 0�2 PSh�4684 3.22 16.2 0.1199 ± 6 0.511890 ± 3 –14.6 1859

m�36 IV, st. 64, (SD–2005, May) 5.02 25.5 0.1191 ± 6 0.511959 ± 4 –13.2 1731

m�14 IV, st. 41 (SD–2006, May) 0.86 4.19 0.1238 ± 6 0.511976 ± 4 –12.9 1794

m�24 VII, t. 22 (2008, July) 1.16 5.82 0.1208 ± 6 0.511325 ± 15 –25.6 2822

m�6 VI, 0�5 PSh�4698 6.53 33.9 0.1165 ± 6 0.511770 ± 4 –16.9 1981

m�5 VI, 0�3 PSh�4697 7.01 37.1 0.1143 ± 6 0.511714 ± 4 –18.0 2024

Note: See Table 1 for places of sampling (I–VII). Correction ±2σ corresponds to the last significant digits.