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99GEODIVERSITAS • 2002 • 24 (1) © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. www.mnhn.fr/publication/

Silurian and Devonian strata on the SevernayaZemlya and Sedov archipelagos (Russia)

Peep MÄNNIKInstitute of Geology, Tallinn Technical University,

Estonia Ave 7, 10143 Tallinn (Estonia) [email protected]

Vladimir V. MENNERInstitute of Geology and Exploitation of Combustible Fuels (IGIRGI),

Fersman Str. 50, 117312 Moscow (Russia) [email protected]

[email protected]

Rostislav G. MATUKHINSiberian Research Institute of Geology,

Geophysics and Mineral Resources (SNIIGiMS),Krasnyj Ave 67, 630104 Novosibirsk (Russia)

[email protected]

Visvaldis KURŠSInstitute of Geology, University of Latvia,

Raina Ave 19, LV-1050 Rīga (Latvia) [email protected]

Männik P., Menner V. V., Matukhin R. G. & Kuršs V. 2002. — Silurian and Devonian strataon the Severnaya Zemlya and Sedov archipelagos (Russia). Geodiversitas 24 (1) : 99-122.

ABSTRACT Silurian and Devonian strata are widely distributed on the islands of theSevernaya Zemlya and Sedov archipelagos. The Silurian is represented byfossiliferous shallow-water carbonates underlain by variegated sandstonesand siltstones of Ordovician age. The Devonian consists mainly of variousred sandstones, siltstones and argillites, with carbonates only in some inter-vals. The best sections available for study are located in the river valleys, andin the cliffs along the coastline of islands. Type sections of most of the strati-graphical units identified are located on the Matusevich River, OctoberRevolution Island. As the Quaternary cover is poorly developed onSevernaya Zemlya, the Palaeozoic strata can be easily traced also outside thesections.

KEY WORDSSilurian,

Devonian, Sedov Archipelago,

Severnaya Zemlya Archipelago, Russia,

lithostratigraphy, biostratigraphy.

406

INTRODUCTION

The Severnaya Zemlya and Sedov archipelagoslie north of the Tajmyr Peninsula, between theKara and Laptev seas. The Severnaya ZemlyaArchipelago, with a total area of about 37 000km2, consists of four large islands (OctoberRevolution, Bol’shevik, Komsomolets andPioneer) and up to 70 smaller ones. Six islands– Srednij, Golomyannyj, Domashnij, Figurnyj,Vostochnyj and Samojlovich – form the SedovArchipelago. About half of the SevernayaZemlya Archipelago’s territory is covered bycontinental glaciers (Fig. 1). Due to a very poorvegetation, the rocks are well exposed.Numerous continuous sections of highly fossil-iferous Lower and Middle Palaeozoic strata putthe archipelagos among the key areas for geo-logical studies in the Circum-Arctic region. Thebeginning in 1996 of the IGCP Project 406(Circum-Arctic Lower and Middle PalaeozoicVertebrate Palaeontology and Biostratigraphy)reactivated the studies connected withSevernaya Zemlya. The aim of the present paper is to give a generalidea about the sections, lithologies and stratigra-phy of the Silurian and Devonian strata onSevernaya Zemlya.

Männik P. et al.

100 GEODIVERSITAS • 2002 • 24 (1)

PREVIOUS STUDIES

The Severnaya Zemlya Archipelago was discov-ered in 1913. The first evidence of the existenceof Palaeozoic strata on the Severnaya Zemlya,but also in the Sedov Archipelago, came fromcollections made by G. A. Ushakov and N. N.Urvantsev during the expedition in 1930-1932.In samples from Severnaya Zemlya, B. B.Chernyshev identified Silurian tabulates, similarto those known from Tajmyr and NovayaZemlya. In 1948-1954, a group of geologistsfrom the Scientific Research Institute ofGeology of Arctic (NIIGA, St.-Petersburg), ledby B. Kh. Egiazarov, studied the archipelagosand compiled a geological map on a scale of1:1 000 000. A rich collection of fossils was stud-ied by A. P. Bystrov, Z. G. Balashov, V. A.Vostokova, R. S. Eltysheva, M. S. Zhizhina,B. N. Nalivkin, O. I. Nikiforova, V. N.Ryabinin, Ya. D. Zekkel’ and S. V. Cherkesova.The general stratigraphy of the Palaeozoic stratawas published in a number of papers and mono-graphs (Egiazarov 1957, 1959, 1970, 1973).Modern understanding of the Lower andMiddle Palaeozoic strata on Severnaya Zemlyais based mainly on the data of detailed geologi-cal mapping by V. A. Markovskij, A. A.

RÉSUMÉLes niveaux stratigraphiques silurien et dévonien des archipels de SevernayaZemlya et de Sedov (Russie).Sur les îles de Severnaya Zemlya et de Sedov, les niveaux du Silurien et duDévonien sont bien représentés. Le Silurien est représenté par des carbonatesfossilifères de dépôts peu profonds, recouverts par des grès et des silts d’âgeordivicien. Les niveaux dévoniens sont représentés par des grès rouges, dessilts et des argilites, qui alternent parfois avec des niveaux carbonatés.Comme souvent, les meilleures coupes sont localisées dans les vallées et surles falaises le long des côtes. Les coupes-types des unités stratigraphiquessont principalement localisées dans la vallée de la rivière Matusevich sur l’îlede la Révolution d’Octobre. Sur l’archipel de Severnaya Zemlya, la couver-ture quaternaire est si réduite que les niveaux paléozoiques peuvent être faci-lement retrouvés en dehors des coupes-types.

MOTS CLÉSSilurien,

Dévonien, archipel de Sedov,

archipel de Severnaya Zemlya, Russie,

lithostratigraphie, biostratigraphie.

Silurian and Devonian strata on Severnaya Zemlya

101GEODIVERSITAS • 2002 • 24 (1)

SchmidtIsland

Glacier ofAcademy of Sciences Komsomolets

Island

OctoberRevolution

Island

RusanovGlacierPioneer

Island

Golomyannyj I.

Domashnij I.

SedovArchipelago

SrednijIsland

Figurnyj I.

Pionerka R.

VkhodnojPeninsula

Vostochnyj I.

Bedov R.

Bol'shaya R.

Pod. R.

Obryv. R.

Al'banovGlac. Krasn.

Bay

C

A

BMal'yutka

Glacier

KarpinskiGlacier

VstrechnayaHill

VatutinPeninsula

Glacierof

University

VavilovGlacier

Samojlovich(Dlinnyj)Island

KARA

SEA

KARA SEA

LAPTEV SEA

10 0 10 20 30 40 km

1 2 3 4Bol'shevik

Island

102°

FIG. 1. — Distribution of Palaeozoic strata on Severnaya Zemlya, showing location of studied sections and spot samples (geologymodified from Egiazarov 1959). Areas A, B and C show the location of detailed maps in Figs 2; 6; 9. Areas of Silurian outcrops stud-ied on Pioneer Island (according to Klubov et al. 1980) are indicated as follows: I, samples 2A-4G; III, samples 4D-6A, 8G; V, sample12. Samples 7A-7B, 8D-8G, 9E, 9Zh and 10A-10B come from areas I or II (precise location not known). Bedov. R., Bedovaya River;Obryv. R., Obryvistaya River; Gr. R., Gremyashchaya River; Krasn. Bay, Krasnaya Bay; Pod. R., Pod’’emnaya River. 1, Cambrianand older rocks; 2, Ordovocian; 3, Silurian; 4, Devonian to Quaternary strata.

Makar’ev, Yu. G. Rogozov, B. N. Batuev, A. F.Khapilin and others in 1973-1979. A properstratigraphical framework for the mapping wasprovided by special sedimentological and bios-tratigraphical studies. During field-work in1974, 1976, 1978 and 1979, many sections indifferent parts of the archipelagos weredescribed in detail and fossils collected. Yu. G.Samojlovich, D. K. Patrunov and A. A. Egorova(St.-Petersburg, Russia), V. Karatajūtē-Talimaaand J. Valiukevičius (Lithuania), E. Mark-Kurikand P. Männik (Estonia), V. Kuršs (Latvia),R. G. Matukhin (Novosibirsk, Russia), V. Vl.Menner (Moscow, Russia), and B. A. Klubovand E. I. Kachanov (Magadan, Russia) partici-pated in the expeditions. The collections werestudied and described by A. Abushik (ostra-codes), O. Afanassieva (vertebrates), A. Blieck(vertebrates), S. Cherkesova (brachiopods), D.Drygant (conodonts), I. Evdokimova (ostra-codes), V. Karatajūtē-Talimaa (vertebrates),E. Levitski (trilobites), E. Lukševičs (verte-brates), Z. Maximova (trilobites), E. Mark-Kurik (vertebrates), T. Modzalevskaya(brachiopods), P. Männik (conodonts), T. Märss(vertebrates), L. Nekhorosheva (bryozoans),H. Nestor (stromatoporoids), M. Shurygina(rugose corals), M. Smirnova (tabulate corals),N. Sobolev (conodonts), G. Stukalina (crinoids),V. Sytova (rugose corals), G. Vaitiekūnienē

(miospores), and J. Valiukevičius (vertebrates).A special meeting devoted to the stratigraphy ofSevernaya Zemlya was held in Vilnius,Lithuania, in 1980, and several papers were pub-lished later (e.g., Kurik et al. 1982; Matukhin etal. 1982; Markovskij & Smirnova 1982). Also in1980, during a meeting in Novosibirsk, an offi-cial stratigraphic scheme of the Silurian andDevonian systems of Severnaya Zemlya was rat-ified (Gurari & Krasilov 1982).

GENERAL GEOLOGY AND STRATIGRAPHY

The sequence of sedimentary rocks onSevernaya Zemlya ranges from the Upper

Proterozoic on Bol’shevik Island (Kaban’kov etal. 1982) to the Upper Palaeozoic (small oucropsof Carboniferous and Permian rocks onBol’shevik, October Revolution andKomsomolets islands; Dibner 1982) (Fig. 1).Large areas on northern Komsomolets Islandare covered with Cenozoic sediments. The old-est Palaeozoic strata (Cambrian) are exposed inthe eastern part of October Revolution Island. The Cambrian-Devonian sediments in the mid-dle and eastern parts of October RevolutionIsland are folded, with the Silurian andDevonian outcrops situated on the limbs of anorth-west south-east trending anticline. Thisstructure extends to the southwesternmostKomsomolets Island. The core of the anticline isformed of Ordovician rocks. On westernOctober Revolution Island and on PioneerIsland, the Palaeozoic strata are less deformed.

SILURIAN

The best Silurian sections available for study arelocated in the river valleys, perpendicular to theoutcrop belts in the central part of OctoberRevolution Island, and in the cliffs along thecoastline of the Sedov Archipelago islands. Over40 years ago, Egiazarov (1959) noted that themost complete sequence of Ordovician, Silurianand Devonian strata is exposed on theMatusevich River (Figs 1; 2). Later, this sectionhas been studied in detail by many geologists,and the type sections of most of the Silurian for-mations are located there (see below). Almostcomplete, but not studied in detail, Siluriansequences are known from the southwesternpart of Komsomolets Island (Fig. 1), and fromsome areas on western and northern PioneerIsland. In general, the Silurian strata onSevernaya Zemlya are represented by fossilifer-ous shallow-water carbonates, underlain by var-iegated sandstones and siltstones of Ordovicianage, and overlain by mainly red terrigenous sed-iments of Devonian age. All Silurian formationswere erected and described during field-work in1978 by a team (included V. Karatajūtē-Talimaa,V. Kuršs, V. Markovskij, R. Matukhin, V.Menner, Yu. Samojlovich and J. Valiukevičius)

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102 GEODIVERSITAS • 2002 • 24 (1)

led by V. Menner. The Ust’-SpokojnayaFormation was originally described as IzluchinaFormation, and was renamed later (see below).

Llandovery and WenlockVodopad Formation. The Vodopad Formationis the lowermost Silurian unit on SevernayaZemlya (Fig. 3). It is named after the waterfall(in Russian, “vodopad”) on the MatusevichRiver, October Revolution Island, where thetype section of the formation is located (out-crops 14 and 13a; outcrop 13, beds 87-141;Figs 2; 4; 5) (Menner et al. 1979). The lowerboundary of the Vodopad Formation corre-sponds to the level where variegated mainly ter-rigenous rocks of the Strojnaya Formation(Upper Ordovician) are replaced by dark greylimestones and dolostones.The formation has highly variable lithologies,formed in open-shelf conditions during the first

major early Silurian transgression in theSevernaya Zemlya region. It is dominated bygrey to dark grey fine- to coarse-grained biode-trital and dolomitic limestones. Tabulate andrugose corals, stromatoporoids, brachiopods,ostracodes and echinoderms are abundant, par-ticularly in the upper part of the formation. Thelowermost and uppermost strata are rich in pen-tamerid brachiopods. At some levels pentameridcoquinas occur. In the lower pentamerid inter-val, Borealis Boucot, Johnson & Rubel, 1971 hasbeen identified (T. Modzalevskaya pers.comm.). An interval of thin-bedded argillaceouslimestones, rich in stromatolites but almostlacking other fossils, divides the VodopadFormation into two parts, the upper one con-taining large colonies of tabulate corals andsiliceous nodules.On October Revolution Island the thickness ofthe Vodopad Formation varies within 240-280 m



Mal'yutkaGlacier

18

18a

17

19

7

6 5 431 2

12

11

1314

1013a

N

1 0 1 2 3 4 km

Mat

usev

ich

Rive

r

FIG. 2. — Localities on the Matusevich River (= A on Fig. 1). For legend refer to Fig. 1. Numbers along river correspond to outcrops asshown on logs in Figs 4 and 12.

in the Ushakov and Matusevich River sections,but reaches up to 360 m in the Krasnaya Bayregion. On the Sedov Archipelago islands, onlythe uppermost part of the formation is exposed.The Vodopad Formation can be recognized alsoon the southwestern Komsomolets Island.

The assemblages of stromatoporoids (includingClathrodictyon boreale Riabinin, 1951, C. vario-lare (Rosen, 1867), Ecclimadictyon microvesicu-losum Riabinin, 1951; H. Nestor pers. comm.),rugose corals (Shurygina & Sytova 1999), tabu-late corals (Markovskij & Smirnova 1982),ostracodes (Abushik 1999, in press) and bra-chiopods (Modzalevskaya 1999, in press) indi-cate a Llandovery age for the VodopadFormation. The assemblages of conodonts andcrinoids occurring in this formation allow us tocorrelate it with the upper Rhuddanian andlower Aeronian (Männik 1997, 2002; Stukalina1999) (Fig. 3).Golomyannyj Formation. This formation isnamed after Golomyannyj Island in the SedovArchipelago (Menner et al. 1979) (Fig. 1).However, the type section of the formation islocated on the Matusevich River, OctoberRevolution Island (outcrop 13, beds 34-86; Figs2; 5). The lower boundary of the formation istaken just above the uppermost bed with pen-tamerid brachiopods. Sedimentological and palaeontological data sug-gest that the strata of the Golomyannyj Forma-tion were formed in the conditions of a majormarine regression. The formation is built up ofthin-bedded argillaceous limestones withinterbeds of sandstone, stromatolitic limestone,and dolostone at some levels. Mud-cracks arecommon in many intervals. Ostracodes, gas-

Männik P. et al.

104 GEODIVERSITAS • 2002 • 24 (1)

SERIES STAGE FORMATION

Upper

Middle

Lower

Přidoli

Ludlow

Wenlock

Llando-very

Famennian

Frasnian

Givetian

Eifelian

Emsian

Pragian

Lochkovian

Ludfordian/Gorstian

Homerian/Sheinwoodian

Telychian

Aeronian

Rhuddanian

Mal'yutka

Vavilov

Matusevich

Gremyashchaya

Vatutin

Vstrechnaya

Al'banov

Rusanov

Spokojnaya

Pod''emnaya

SevernayaZemlya

KrasnayaBukhta

Ust'-Spokojnaya

Samojlovich

Srednij

Golomyannyj

Vodopad

SIL

UR

IAN

DE

VO

NIA

NS

YS

TEM

?

FIG. 3. — The sequence of Silurian and Devonian formations ofSevernaya Zemlya and its probable correlation with the interna-tional subdivisions of the Silurian and Devonian Periods.

FIG. 4. — Limestones in the lower part of the VodopadFormation. Matusevich River, outcrops 13a and 13. Photo byP. Männik.



Matusevich River Spokojnaya RiverKrasnaya Bay

D1D1

1 2 3 4 5 6

7 8 9 10 11 12

13 14 15 16 17 18

19 20 21 22 23 24

O3

Vod

opad

Fm

. G

olom

yann

yj F

m.

Sre

dni

j Fm

.

Sam

ojlo

vich

Fm

. U

st'-

Sp

okoj

naya

Fm

.

Ust

'-S

pok

ojna

ya F

m.

Kra

snay

a B

ukht

a Fm

.

2223

1

1

50

24

1

24

1

8

9

12

1

51

1

2122

86

1

16

27

293334

8687

122123

124

141Outcrop 14

Outc

rop

13Ou

tcro

p 13

aOu

tcro

p 12

Outc

rop

11

Outc

rop

2Ou

tcro

p 11

Outc

rop

47Ou

tcro

p 45

Outc

rop

46

FIG. 5. — Silurian section on the Matusevich River, and in the Spokojnaya River-Krasnaya Bay region (for location of outcrops seeFigs 1; 2; 9). To the right of the lithological log are shown the numbers of the beds described, and the extent of the outcrops studied.The interval above bed 24 in outcrop 45 was not logged in detail. 1, limestone; 2, argillaceous limestone; 3, dolomitized limestone;4, limestone with pentamerids; 5, limestone with tabulate corals; 6, limestone with stromatoporoids; 7, limestone with stromatolites;8, coral-stromatoporoid biostromes and bioherms; 9, oolithic limestone; 10, oncolitic limestone; 11, carbonate conglomerates;12, silicified limestone; 13, sandstone; 14, conglomeratic sandstone; 15, fine cross-bedding in sandstone; 16, coarse cross-beddingin sandstone; 17, marlstone; 18, dolomitized marlstone; 19, siltstone; 20, argillite; 21, gypsum. Colour of rock for Fig. 12: 22, grey;23, red; 24, variegated.

tropods, small brachiopods and fragments ofechinoderms are abundant in the argillaceouslimestones, whereas rugose corals, tabulatecorals and stromatoporoids are very rare. Thebest sections of the Golomyannyj Formation,up to 100-120 m thick, are located on theMatusevich and Ushakov rivers (Figs 2; 5; 6). Inthe sections of the Sedov Archipelago the thick-ness of the formation does not exceed 60-70 m.Poor faunas from the Golomyannyj Formation,including among others the tabulate coralsPalaeofavosites schmidti Sokolov, 1951,Mesofavosites fleximurinus Sokolov, 1951 andFavosites gothlandicus Lamarck, 1816, ostra-codes Hogmochilina orientalis Abushik, 1975and Tollitia navicula Abushik in press, bra-

chiopods Dubaria tenera Nikiforova &T. Modzalevskaya, 1968 and conodontsPranognathus tenuis (Aldridge, 1972) andIcriodella aff. inconstans Aldridge, 1972, indicatean Aeronian age (Nikiforova & Modzalevskaya1968; Markovskij & Smirnova 1982; Johnson etal. 1997; Männik 1997, 2002; Abushik 1999, inpress; Modzalevskaya 1999, in press) (Fig. 3).In the paper by Markovskij & Smirnova (1982)the Vodopad and Golomyannyj formations aredealt with as the lower and upper subformationsof the Snezhinka Formation.Srednij Formation. The Srednij Formation isnamed after Srednij Island in the SedovArchipelago (Menner et al. 1979) (Fig. 1). Thelower boundary of this formation corresponds

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106 GEODIVERSITAS • 2002 • 24 (1)

N31

31a 32 46

Ushakov River

VavilovGlacier 53 52

51 50

Strojna

ya R

iver

1 0 1 2 3 4 km

FIG. 6. — Localities on the Ushakov and Strojnaya rivers. For legend refer to Fig. 1. Numbers correspond to outcrop numbers.

to the contact between the uppermost bed ofsandstone in the Golomyannyj Formation andthe overlying fossiliferous limestones. Alike tothe Vodopad Formation, the Srednij Formationalso formed during an extensive transgression.However, the sedimentological and palaeonto-logical data suggest that the sea was shallower,and the environmental conditions more variablethan in early Llandovery. In its type section onthe Matusevich River (outcrop 13, beds 1-33;outcrop 12; and beds 22-23 of outcrop 11;Figs 2; 5), the Srednij Formation consists ofcyclic intercalations of horizontal-bedded, some-times silicified, tabulate-stromatoporoid lime-stones with tabulate-stromatoporoid (less withalgal) biostromes and bioherms, and thick layersof brownish-grey limestones containing ostra-codes, gastropods, echinoderms, cephalopodsand rare tabulate corals. The coral-stromato-poroid biostromes and bioherms (Fig. 7) occurmore frequently in the middle and upper partsof the formation. Interbeds of greenish-greythin-bedded dolomitic limestones are poor infauna, dominated mainly by ostracodes. In theseintervals, stromatolitic limestones and mud-crack structures may occur. The thickness of the Srednij Formation onOctober Revolution Island varies from 290 to350 m in the sections on the Matusevich andUshakov rivers, and reaches up to 500 m in theKrasnaya Bay region. In the latter region thelithology of the formation changes consider-ably: its lower part (200 m) is represented bydark grey biodetrital limestones, the middle part(150 m) consists of intercalated grey limestonesand black marlstones with rare fauna, and theupper part (100-150 m) is characterized bycoral-stromatoporoid biostromes and biohermsin biodetrital limestones. The Srednij Formation can be recognized alsoon southwestern Komsomolets Island and,probably, on Pioneer Island. In the SedovArchipelago its thickness evidently does notexceed 130 m, although the rocks are very simi-lar lithologically to those in the type locality onthe Matusevich River. According to Yu. G.Samojlovich, on Samojlovich Island the Srednij

Formation is about 300 m thick. Here, three dis-tinct intervals with coral-stromatoporoidbiostromes and bioherms are recognized, andthe upper strata of the formation are consider-ably more argillaceous than the lower ones. Although the associations of stromatoporoids,tabulate corals, and rugose corals allow precisecorrelation with coeval strata in Siberia, in theTiman-Urals region, and Novaya Zemlya, cor-relation of the Srednij Formation with the inter-national Silurian standard has for a long timebeen unclear, because different groups of fossilshave given inconsistent ages. The assemblages ofstromatoporoids (including Vikingia tenuis(Nestor, 1966), Ecclimadictyon robustumNestor, 1966, Simplexodictyon validum (Nestor,1966, etc.) and tabulate corals, indicate aWenlock age for the Srednij Formation(Markovskij & Smirnova 1982; H. Nestor pers.comm.). However, the ostracodes Hogmo-chilina maackii (Schmidt, 1873), Noviportia aff.silurica (Sarv, 1962) and some new taxa(Abushik in press), the brachiopod Meristinanorilica (Nikiforova, 1961), and conodontsApsidognathus sp. and some others, correlatethese strata with the Telychian (Männik 1997,2002; Abushik 1999, in press; Modzalevskaya1999, in press). It is this solution which is adopt-ed here (Fig. 3).Samojlovich Formation. The SamojlovichFormation (with its type section on the



FIG. 7. — Reef in the upper part of the Srednij Formation. SrednijIsland, outcrop 1(79). Photo by P. Männik.

Matusevich River: outcrop 11, beds 1-21, andoutcrop 2, beds 51-86; Figs 2; 5) is named afterSamojlovich (Dlinnyj) Island in the SedovArchipelago (Menner et al. 1979) (Fig. 1). Theboundary with the underlying SrednijFormation is placed at the top of the uppermost,2-3 m thick bed of limestone with abundantstromatoporoids. The Samojlovich Formationshows rhythmic intercalation of highly variablelimestones (grey stromatolitic, oolitic andoncolitic limestones; greenish-grey thin-beddedargillaceous limestones with numerous gas-tropods, brachiopods, ostracodes and trilobites),with almost unfossiliferous dolomitic lime-stones and argillaceous dolostones. In thedolomitic rocks mud-cracks are quite common.Characteristically, the Samojlovich Formationalmost totally lacks beds with tabulates andstromatoporoids, but contains abundant stro-matolitic structures (including stromatolitic bio-stromes; Fig. 8). With the stromatolitic strata areconnected numerous lens-like interbeds of car-bonate conglomerates. In most of theseinterbeds the pebbles are inclined. Tabulate, andalso rugose corals, have only been recordedfrom some beds in the upper SamojlovichFormation. In the uppermost strata of the for-mation the number and taxonomic variation offossils decrease rapidly, and the content ofsandy material increases. Sedimentological fea-

tures in the Samojlovich Formation indicate thatthese strata were formed in shallow-waterrimmed-shelf environments, under conditionsof continuous shallowing of the basin.In the sections on the Ushakov and Matusevichrivers the formation thickness is 240-280 m,increasing to 400 m in the Krasnaya Bay region,as does also the content of clay in the rocks. Theformation has been recorded also on southwest-ern Komsomolets Island (150-180 m thick), inseveral regions on Pioneer Island, and in theSedov Archipelago (Srednij and Samojlovichislands; Fig. 1).The age of the Samojlovich Formation is stillunder discussion. Traditionally, based on theassemblages of stromatoporoids, tabulate corals,ostracodes and brachiopods, the lowerSamojlovich Formation has been considered oflate Wenlock age, and the upper part of Ludlowage (Abushik 1982; Smirnova 1982; Markovskij& Smirnova 1982; Matukhin et al. 1982; Kuriket al. 1982). However, the occurrence of anApsidognathus-fauna in the lower SamojlovichFormation suggests a Telychian age for thesestrata, whereas the conodonts Ozarkodinaconfluens bucerus (Viira, 1983) and Kockelellacf. ortus (Walliser, 1964), and the vertebrateLoganellia grossi Fredholm, 1990 indicate mid-dle to late Wenlock age for the upper part of theformation (Männik 1997, 2002; Märss &Karatajūtē-Talimaa in press) (Fig. 3).Ust’-Spokojnaya Formation. This stratigraphicunit was originally described as the IzluchinaFormation (Menner et al. 1979), but was laterrenamed the Ust’-Spokojnaya Formation(Menner et al. 1982). The new name is derivedfrom the Spokojnaya River, as the mostcomplete sections of this formation occur closeto the river mouth (Fig. 9). However, the typesection of the Ust’-Spokojnaya Formation islocated on the Matusevich River (outcrop 2,beds 1-50; Figs 2; 5). The lower boundary ofthis formation corresponds to the base of thelowermost distinctive sandstone bed. On theMatusevich and Ushakov rivers the upper partof the formation has been eroded beforeDevonian sedimentation started, and its upper

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108 GEODIVERSITAS • 2002 • 24 (1)

FIG. 8. — Stromatolites in the middle part of the SamojlovichFormation. The length of the hammers handle is about 80 cm.Ushakov River, outcrop 32. Photo by P. Männik.

boundary corresponds to the erosional surfaceat the base of the Severnaya Zemlya Formationof early Devonian age (Figs 5; 10). The upperpart of the formation is available for study onlyin the Krasnaya Bay region, near the mouth ofthe Spokojnaya River (section 47, beds 9-12;Figs 5; 9). Here, the upper boundary of the Ust’-Spokojnaya Formation corresponds to the tran-sition from variegated marlstones withostracodes to the red sandstones and argillites ofthe overlying Krasnaya Bukhta Formation.The Ust’-Spokojnaya Formation consists main-ly of brownish-red, violet-grey and greenish-grey marlstones with thin lens-like interbeds ofargillaceous limestone containing ostracodes,bivalves, gastropods, and vertebrate remains(Fig. 11). Interbeds of grey, greenish-grey anddark grey fine-grained and oolitic limestonescontaining bivalves, ostracodes, cephalopods,stromatolites and oncolites, characterize thelowermost part of the formation. Stromatopo-roids, rugose and tabulate corals, and echino-

derms have not been found. The lowermost partof the formation contains interbeds of sand-stone, and thin beds of dolostone are common.The lithology of the Ust’-Spokojnaya Formationindicates the continuous shallowing of the sedi-mentary basin, and an increasing input of red ter-rigeneous material from neighbouring land areas.The thickness of the Ust’-SpokojnayaFormation is highly variable: from 60-100 m inthe central part of October Revolution Island(where the upper strata of the formation aremissing) to 270-340 m in the Kasnaya Bayregion. Strata on Komsomolets Island, probablycorresponding to this formation are 180 m thick.The Ust’-Spokojnaya Formation can be recog-nized also on Pioneer Island, and probably alsoin the eastern part of the Sedov Archipelago(Figurnyj and Vostochnyj islands; Fig. 1).The Ust’-Spokojnaya Formation is of Ludlowage based on the occurrence of the vertebratesTremataspis obruchevi Afanassieva & Karatajūtē-Talimaa, 1998, Paralogania martinssoni (Gross,



5048

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1967), Phlebolepis elegans Pander, 1856, andAndreolepis sp., and also on the ostracodesEukloedenella posterioalta Abushik, 1980,Herrmannina nana Abushik, 1960, H. hebesAbushik, 1980, Tollitina minuta (Abushik,

1980) (Märss et al. 1995; Abushik & Evdo-kimova 1999; Abushik 1999, in press; Karatajūtē-Talimaa & Märss in press) (Fig. 3).Krasnaya Bukhta Formation. The KrasnayaBukhta Formation is named after Krasnaya Bay(in Russian “bukhta”), October RevolutionIsland (Menner et al. 1982) (Fig. 1). Its typesection lies close to the northern coast of thisbay, about 0.5 km east from the mouth of theSpokojnaya River (outcrop 47, beds 1-8; out-crop 45; and beds 1-24 of outcrop 46; Figs 5; 9). The Krasnaya Bukhta Formation represents theyoungest part of the Silurian sequence onSevernaya Zemlya. It contains brownish-redsiltstones, argillites, marlstones and sandstoneswith rare interbeds of greenish-grey marlstonesand argillaceous limestones. In the carbonateinterbeds ostracodes, bivalves, vertebrates andcharophytes (algae) have been found. At thelower boundary of the Krasnaya BukhtaFormation variegated marlstones, characteristicof the underlying Ust’-Spokojnaya Formation,are replaced by red sandstones (Fig. 5). The sed-iments of the Krasnaya Bukhta Formation wereevidently deposited in shallow-water restrictedmarine environments during a continuingregression of sea. Most common in the poorfauna of this formation are micro- and macro-remains of vertebrates, but some beds also con-tain ostracodes and charophytes occur.The total thickness of the Krasnaya BukhtaFormation in the region just north fromKrasnaya Bay is about 350-400 m. To the westthe thickness of the formation decreases rapidlydue to the pre-Devonian denudation of upperSilurian strata. It does not exceed 100-150 m inthe outcrops to the west of the SpokojnayaRiver. Further to the north from Krasnaya Bay,in the Bedovaya River region, the thickness ofthe formation increases to 600-700 m. Beside thenortheastern part of October Revolution Island,the Krasnaya Bukhta Formation can probablybe recognized only on southwestern Komso-molets Island, and on Pioneer Island.Thelodonts Paralogania cf. borealis (Karatajūtē-Talimaa, 1978), Loganellia cuneata (Gross,1947), Gonioporus alatus (Gross, 1947) and the

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110 GEODIVERSITAS • 2002 • 24 (1)

FIG. 10. — The Silurian-Devonian boundary between argilla-ceous limestones below and conglomeratic sandstones above.The hammer lies on the upper surface of the Silurian strata.Matusevich River, contact between sections 2 (below) and 1(above). Photo by P. Männik.

FIG. 11. — Dolomitic marlstones and argillaceous dolostones ofthe Ust’-Spokojnaya Formation. Matusevich River, outcrop 2.Photo by P. Männik.

osteostracan Hemicyclaspis sp. correlate theKrasnaya Bukhta Formation with the Přidoli(Märss & Karatajūtē-Talimaa in press) (Fig. 3).Acanthodians, represented by the Poracantho-des punctatus Zone assemblage (Valiukevičius1999, in press), and ostracodes are also indica-tive of a Přidoli age (Abushik & Evdokimova1999; Abushik 1999, in press).

DEVONIAN

On October Revolution Island, but particularlyon Komsomolets and Pioneer islands, theDevonian strata are more widely distributedthan the Silurian sediments. In the SedovArchipelago, the Devonian is known only fromFigurnyj and Vostochnyj islands (Fig. 1). Elevenformations, most of them recognized all overthe archipelago, are identified in the almostcomplete Devonian sequence on SevernayaZemlya, and all standard Devonian stages arerepresented by deposits (Fig. 3). Most of theformations were originally defined anddescribed in the continuous Devonian sectionon the Matusevich River, October RevolutionIsland (Menner et al. 1979). However, later itappeared that in several sections on Pioneer andKomsomolets islands some intervals of theDevonian sequence are more completely repre-sented than along the Matusevich River.

Lower DevonianSevernaya Zemlya Formation. The SevernayaZemlya Formation was originally described in1978 (Menner et al. 1979). Its lower boundarycorresponds to the base of coarse-grained con-glomeratic sandstones unconformably overlyingthe rocks of the Krasnaya Bukhta or Ust’-Spokojnaya formations (Fig. 10). The type sec-tion of the Severnaya Zemlya Formation islocated on the Matusevich River (outcrop 1,beds 21-28; Figs 2; 12). The Severnaya Zemlya Formation can be subdi-vided into lower and upper parts. On OctoberRevolution Island, in the sections on theMatusevich, Ushakov and Spokojnaya rivers(Figs 2; 6; 9; 12), the basal strata of the lowerSevernaya Zemlya Formation are represented

by greenish-grey coarse-grained sandstoneswhich contain numerous lenses or interbeds ofconglomerates with pebbles of different Silurianrocks. Higher in the sequence, these sedimentsare replaced by variegated siltstones andargillites. The upper part of the Severnaya ZemlyaFormation consists of dark grey slate-like lime-stones, marlstones and argillites with numerousflat nodules holding well-preserved (often com-plete) fish remains, eurypterids, ostracodes andalgae (Fig. 13). The thickness of the lower partof the formation varies between 17 and 70 m,and of the upper part between 20 and 30 m. Thetotal thickness of the Severnaya ZemlyaFormation on October Revolution Island is 30-100 m, and on Komsomolets Island it is also upto 100 m thick. The formation has also beenidentified on Pioneer Island but its thicknessthere is not known.The association of heterostracans, representedby the genera Anglaspis Jaekel, 1926, CorvaspisWoodward, 1934, Ctenaspis Kiaer, 1930,Lepidaspis Dineley & Loeffler, 1976, PhialaspisWills, 1935, Protopteraspis Leriche, 1924,Tesseraspis Wills, 1935 and Unarkaspis? Elliott,1983, indicates a Lockhovian age for theSevernaya Zemlya Formation (Karatajūtē-Talimaa & Blieck 1999) (Fig. 3). The Lockho-vian age is also evidenced by acanthodians,represented here by the assemblage of thePoracanthodes menneri Subzone (lower part ofthe Nostolepis minima Zone; Valiukevičius inpress), and the ostracode Herrmannina convexaAbushik, 1980 (Abushik & Evdokimova 1999;Evdokimova & Abushik in press).At the end of the Silurian, sedimentation termi-nated in several areas on Severnaya Zemlya andthe uppermost Silurian strata were denudated.The early Lochkovian time was characterizedby a new transgression in this region but eventhe uppermost strata of the Severnaya ZemlyaFormation formed still in extremely shallow-water conditions, in an environment closest tolagoonal.Pod’’emnaya Formation. The Pod’’emnayaFormation is named after the Pod’’emnaya



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112 GEODIVERSITAS • 2002 • 24 (1)

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FIG. 12. — Devonian section on the Matusevich River (for location of outcrops see Figs 1 and 2; for legend refer to Fig. 5). To the rightof the lithological log are shown the rock colour, the numbers of the beds described, and the extent of the outcrops studied. Theinterval above bed 6 in outcrop 18a was not described in detail. Abbreviation: S, top of Silurian strata (Ust’-Spokojnaya Formation).

River (western October Revolution Island),where a section yielding the richest assemblagesof vertebrates was described (Menner et al.1979). The type section is located on theMatusevich River (outcrop 1, beds 1-20; out-crops 3 and 4; outcrop 5, beds 1-14; Figs 2; 12).The lower boundary of the Pod’’emnayaFormation corresponds to the upper surface ofthe dark grey carbonate argillites of the under-lying Severnaya Zemlya Formation, and itsupper boundary to the base of the variegatedsandstones of the overlying SpokojnayaFormation.On October Revolution Island the Pod’’emnayaFormation was differentiated into two parts.The lower part comprises grey siltstones andquartz-feldspar sandstones with interbeds ofargillites, and contains plant fossils and rare ver-tebrates. The upper part consists of a rhythmicintercalation of reddish-brown and greenish-grey sandstones, siltstones, and argillites withinterbeds of variegated argillaceous dolostonesyielding concretions of celestite. Flat nodules ofgypsum are common. Ostracodes and fishremains occur in abundance in dolostones.The lower part of the Pod’’emnaya Fomation is50-90 m thick, and the upper part is 80-190 mthick. The total thickness of the formation onOctober Revolution Island varies from 160 m(Pod’’emnaya River) to 280 m (SpokojnayaRiver). The Pod’’emnaya Formation is also wellexposed on Komsomolets and Pioneer islands.The age of the Pod’’emnaya Formation, basedon the associations of ostracodes (Leperditia cf.marinae Abushik, 1980, Herrmannina aff.orbiculata Abushik, 1980, Hogmochilinaisochilinoides (Jones, 1883) and H. teres Solle,1935), and heterostracans (identical to those inthe Severnaya Zemlya Formation; see above), isLochkovian (Abushik & Evdokimova 1997,1999; Evdokimova & Abushik in press;Karatajūtē-Talimaa & Blieck 1999). The acan-thodians, represented by the Diplacanthuspoltingi Subzone (upper part of the Nostolepisminima Zone) fauna, correlate the Pod’’emnayaFormation with the upper Lochkovian(Valiukevičius in press) (Fig. 3).

Spokojnaya Formation. The SpokojnayaFormation is named after the Spokojnaya River,at the middle course of which one of the mostcomplete sections of this formation is located(Menner et al. 1979) (Fig. 14). The type sectionof this formation is located on the MatusevichRiver (outcrop 5, beds 15-38; Figs 2; 12). Itslower boundary corresponds to the base of var-iegated sandstones and siltstones, and its upperboundary to the base of grey dolostones orlimestones of the overlying Rusanov Formation.The lower part of the Spokojnaya Formation (1-151 m thick) is represented by red and variegat-ed quartz-feldspar sandstones, siltstones andargillites. In some sections also intervals of var-iegated marlstones occur. Fossils in the lower



FIG. 13. — Severnaya Zemlya Formation. In the centre of the fig-ure (cliff), argillaceous limestones and argillites of the upper partof the formation are exposed. Spokojnaya River, outcrop 41(?).Photo by V. Menner.

FIG. 14. — Spokojnaya Formation. Spokojnaya River, outcrop43. Photo by V. Menner.

Spokojnaya Formation are mainly representedby vertebrates.Higher in the sequence, variegated terrigenoussediments are gradually replaced by grey argilla-ceous carbonate rocks indicative of the develop-ing Early Devonian transgression in theSevernaya Zemlya region. The upper part of theformation (50-145 m thick) consists of grey, andsome greenish-grey, dolomitic marlstones withinterbeds of grey argillaceous dolostones andsiltstones. In the sections where the formation isthicker, numerous interbeds of gypsum occur inthe dolomitic marlstones. Fossils in the upperSpokojnaya Formation are represented by rareostracodes, bivalves, stromatolites and verte-brates. On October Revolution Island the thickness ofthe formation varies widely, from 25 m on thePod’’emnaya River up to 300 m on theSpokojnaya River. In the Matusevich andUshakov rivers’ sections it is about 80-90 mthick, and on Komsomolets and Pioneer islandsup to 100 m thick. The comparison of the vertebrate assemblagesfrom the Spokojnaya Formation with those fromSpitsbergen and other regions has revealed thatthis formation, most probably, corresponds tothe boundary beds of the Lochkovian andPragian stages (Afanassieva & Karatajūtē-

Talimaa 1999; Karatajūtē-Talimaa & Blieck 1999;Mark-Kurik 1999). However, considering theages of the underlying Pod’’emnaya Formation(see above), and the overlying Rusanov Forma-tion (see below), the Spokojnaya Formation iscorrelated with the Pragian (Fig. 3). Rusanov Formation. The Rusanov Formationwas originally described by Egiazarov (1959) onPioneer Island, in the valley of the PionerkaRiver. The name was given in the honour ofV. A. Rusanov, an Arctic explorer. Later, in1972-1979, during the geological mapping ofSevernaya Zemlya and special stratigraphicalstudies, a new type section for this formationwas selected and described on the MatusevichRiver, about 3 km upstream from the waterfalls(Menner et al. 1979; outcrop 5, beds 39-45;Figs 2; 12; 15). Here, the lower boundary of theRusanov Formation corresponds to the base ofgrey limestones or dolostones containing a richassemblage of marine invertebrates. The Rusanov Formation is known fromOctober Revolution, Komsomolets and Pioneerislands in Severnaya Zemlya, and from FigurnyjIsland in the Sedov Archipelago. In all knownsequences a carbonaceous lower member and agypsum-rich upper member are distinguished inthis formation. A rich association of fossils inthe lower member allows detailed correlation of

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114 GEODIVERSITAS • 2002 • 24 (1)

FIG. 15. — Rusanov and Al’banov formations, and the lower-most part of the Vstrechnaya Formation. Boundaries betweenformations are indicated by lines. Abbreviations: D1rs, RusanovFormation; D1al, Al’banov Formation; D2vs, VstrechnayaFormation. Matusevich River, outcrop 5. Photo by V. Menner.

FIG. 16. — The contact between the argillites of the VatutinFormation (D2vt) and coarse-grained sandstones of theGremyashchij Formation (D2gr). Matusevich River, outcrop 7.Photo by P. Männik.

these strata with the sequences on Tajmyr andNovaya Zemlya, but also with the internationalDevonian standard.The lower member of the Rusanov Formationon October Revolution Island (17-50 m thick) isrepresented by grey dolomitized limestones(Fig. 15). In the middle of this interval a numberof interbeds rich in stromatoporoids, tabulateand rugose corals, brachiopods, bivalves, ostra-codes, trilobites, echinoderms and vertebratesoccur. In some beds stromatoporoids formsmall bioherms. Dolomitization of these lime-stones is probably connected with a stratigraph-ical gap between the lower and upper parts ofthe Rusanov Formation. The upper member ofthe Rusanov Formation (20-50 m thick) consistsof grey gypsum interbedded with dolostones. In southwestern Komsomolets Island, and onPioneer Island, the limestones of the lowerRusanov Formation are less dolomitized thanon October Revolution Island. Here, an intervalrich in stromatoporoids, tabulate and rugosecorals, brachiopods, echinoderms, trilobites andconodonts occurs in the lower part of these stra-ta. Higher in the sequence is an interval of lime-stones and dolostones, not known in thesections of the Rusanov Formation on OctoberRevolution Island. In this interval stromato-poroids and corals are missing, but brachiopods,trilobites and vertebrates are common. Thethickness of the lower member of the RusanovFormation in this region is 85-110 m, and theupper member is 50-135 m thick. The lower strata of the Rusanov Formation wereformed during the maximum transgression of theEarly Devonian in the Severnaya Zemlya basin.This is the only interval in the Devonian se-quence on Severnaya Zemlya containing rich andvariable invertebrate faunas. The late Rusanovtime was characterized by a rapid regressionwhich resulted in deposition of evaporites. According to Valiukevičius (1999), the upperpart of the lower member of the RusanovFormation corresponds to the lower part of his“Beds with Watsonacanthus costatus”. Based onthe co-occurrence in these strata of acanthodi-ans and conodonts (Pandorinellina exiqua exi-

qua (Philip, 1966), P. expansa Uyeno & Mason,1975, etc.), the “Beds with W. costatus” correlatewith the dehiscens-inversus conodont zones(lower-middle Emsian; Valiukevičius in press).The Emsian age of the upper part of the lowermember is also supported by the containedostracodes (Abushik & Evdokimova 1997;Evdokimova & Abushik in press). However, theoccurrence of the ostracode Eomoelleritia kon-diaini Abushik, 1972 in the lower part of thismember indicates a Pragian age. The upperPragian-Emsian age of the Rusanov Formationis evidenced also by other marine invertebrates(Khapilin 1982; Kurik et al. 1982; Menner et al.1982) (Fig. 3).Al’banov Formation. The Al’banov Formationwas originally described by Egiazarov (1959) inthe sections on the Pionerka and Burnaya rivers,Pioneer Island. The formation was named inhonour of V. I. Al’banov, an Arctic explorer. In1979 a new type section for the Al’banovFormation was described on the MatusevichRiver, October Revolution Island (Menner et al.1979; outcrop 5, beds 46-84; Figs 2; 12; 15). Thedistribution of the Al’banov Formation coin-cides with that of the Rusanov Formation. Thelower boundary of the Al’banov Formation ismarked by the disappearance of gypsum, whichis characteristic of the upper member of theRusanov Formation.In the section on the Matusevich River, twomembers (respectively 48 m and 34 m in thick-ness) were recognized in the Al’banov Forma-tion. The basal beds of the lower Al’banovFormation consist of grey dolomitic marlstonesand dolostones followed by an intercalation ofgrey dolostones, limestones and greenish-greyargillaceous limestones containing fish remains,large ostracodes, eurypterids and bivalves. Theupper member of the Al’banov Formation isrepresented by an intercalation of light variegat-ed siltstones, sandstones and argillites rich inaggregates of siderite, and containing interbedsof oolitic goethite ore and breccia. In severalsections a big stratigraphical gap has been iden-tified between the lower and upper members ofthe Al’banov Formation.



In the Pod’’emnaya River region the upper car-bonate interval of the lower part of the lowermember of the Al’banov Formation is mostlymissing. Here the total thickness of the forma-tion is only c. 36 m. On Komsomolets andPioneer islands the lithology of the lower mem-ber of the Al’banov Formation is similar to thaton the Matusevich River, and its upper part isrepresented by grey and red argillites. These aremissing from the October Revolution Islandsequence, either due to a stratigraphical gap orto facies changes.The strata of the Al’banov Formation wereformed during alternating short-term transgres-sions and regressions in a generally shallowingbasin, which was evidently still connected withthe marine basins in northern Europe and Siberia.Egiazarov (1957) considered the Al’banovFormation to be of Givetian age. However, laterpalaeontological studies have revealed a consid-erably older age, with acanthodians characteris-tic of the “Beds with Watsonacanthus costatus”indicating an Emsian age (Valiukevičius 1999)(Fig. 3). The Emsian age is supported by theoccurrence of a rich and diverse assemblage ofplacoderms, several representatives of which(Wijdeaspis Obruchev, 1964, early heterostiids,buchanosteids, etc.) have a global distribution(Mark-Kurik 1991, 1998). The fauna of ostra-codes in this formation, almost identical to thatin the upper part of the lower member of theRusanov Formation, is also Emsian in age (seeabove; Evdokimova & Abushik in press).

Middle DevonianThree formations – Vstrechnaya, Vatutin andGremyashchaya – have been established in theMiddle Devonian sequence in the central andwestern parts of the Severnaya ZemlyaArchipelago (Fig. 3). Type sections of all theseformations are located on the Matusevich River.Quite probably the basal strata of the overlyingMatusevich Formation are also of MiddleDevonian age (see below). The sediment sequence in the Vstrechnaya andVatutin formations indicates a gradual deepen-ing of the sea in the Severnaya Zemlya region

after an extensive regression in late Emsian (theupper Al’banov Formation; see above). Thestrata of the upper Gremyashchaya Formationwere deposited in conditions of a new regres-sion. On the geological map of SevernayaZemlya, compiled by V. Markovskij, the stratacorresponding to the Vstrechnaya, Vatutin andGremyashchaya formations are indicated as asingle unit – the Geographers Formation withits type section on Komsomolets Island (Gurari& Krasilov 1982).Vstrechnaya Formation. The formation isnamed after hill Vstrechnaya in the western partof October Revolution Island (Fig. 1) (Menneret al. 1979). The type section of the formation islocated on the Matusevich River (outcrop 5,beds 85-152; Figs 2; 12). The lower boundary ofthe Vstrechnaya Formation corresponds to thebase of the coarse-grained sandstones contain-ing Middle Devonian vertebrates. In the sectionson the Matusevich, Ushakov and Pod’’emnayarivers, and close to the northern coast ofOctober Revolution Island, the VstrechnayaFormation consists of rhythmically intercalatingbrownish-red terrigenous sediments. The basalparts of the cycles are composed of coarse-grained cross-bedded sandstones with lenses orlens-like interbeds of conglomerates, haematiticpebbles and bone-breccias. Higher in the cyclesthe grain size in sandstones decreases, and theirupper parts are represented by siltstones andargillites. Commonly, the bases of the cyclesexhibit erosional surfaces. Ostracodes, inarticu-late brachiopods and plant remains are found inthe siltstones and argillites. In the western partof the Severnaya Zemlya Archipelago, onKomsomolets and Pioneer islands, red sand-stones of the lower Vstrechnaya Formation arereplaced by light-grey and yellowish-grey ones.The thickness of the Vstrechnaya Formation onOctober Revolution Island varies between 70and 160 m, except in the north, in theObryvistaya River region, where its thicknessmay reach some 400 m.The association of Psammosteidae in theVstrechnaya Formation is typical of the MiddleDevonian (Karatajūtē-Talimaa pers. comm.).

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116 GEODIVERSITAS • 2002 • 24 (1)

The assemblages of placoderms indicate anEifelian to Givetian age (Mark-Kurik 1998, pers.comm.). Acanthodians of the Diplacanthussolidus Assemblage from the upper part of theformation also indicate an Eifelian-Givetian age(Valiukevičius 1999, in press) (Fig. 3).Vatutin Formation. This formation is namedafter the Vatutin Peninsula on western OctoberRevolution Island, where it is well exposed(Fig. 1) (Menner et al. 1979). The best sectionsof the Vatutin Formation are located on theMatusevich and Pod’’emnaya rivers, and closeto Vstrechnaya hill. The type section of the for-mation is located on the Matusevich River (out-crop 5, bed 153; outcrop 6, and outcrop 7, beds1-37; Figs 2; 12; 16). The lower boundary of theVatutin Formation corresponds to the uppersurface of the sandstones of the underlyingVstrechnaya Formation, and its upper boundaryto the base of the basal sandstones of the overly-ing Gremyashchaya Formation.The 100-130 m thick Vatutin Formation con-sists mainly of rhythmically intercalating red-dish-brown siltstones and argillites with rarethin interbeds of greenish-grey dolomitic marl-stones. Sandstones are missing. The basal part ofthe formation includes beds of grey argillitescontaining nodules of gypsum, shells of LingulaBruguière, 1797, and ostracodes. Plant remainsare also quite common.The age of the Vatutin Formation is problemat-ic, but rare psammosteid heterostracans(Psammolepis Agassiz, 1844, Tartuosteus?Obruchev, 1961, Psammosteus Agassiz, 1844)suggest Givetian age (Mark-Kurik pers. comm.)(Fig. 3).Gremyashchaya Formation. The Gremyash-chaya Formation is named after the Gremyash-chaya River, a tributary of the Pod’’emnayaRiver in the western part of October RevolutionIsland (Fig. 1) (Menner et al. 1979). Its type sec-tion is located on the Matusevich River (outcrop7, beds 38-58; Figs 2; 12). The GremyashchayaFormation consists of yellowish and violetcoarse- to fine-grained quartz sandstones withrare interbeds of conglomerates, red siltstones,argillites and marlstones. Thin interbeds of

oolitic or nodular limestones occur at some lev-els. In the coarse-grained sandstones large frag-ments of fossil plants occur, and ostracodes andstromatolites are common in the argillites andmarlstones. The formation is characterized byabundant and well-preserved vertebrateremains. The lower boundary of theGremyashchaya Formation is marked by theappearance of coarse-grained sandstones abovethe fine-grained sediments of the VatutinFormation (Fig. 16).The thickness of the Gremyashchaya Formationon October Revolution Island varies from 15 mon the Pod’’emnaya River, 70 m on theMatusevich River, to up to 150 m on theObryvistaya River. The association of vertebrates indicates a corre-lation of the Gremyashchaya Formation withthe middle Givetian Abava Regional Substage inthe Baltic sequence (Mark-Kurik 1998).

Upper DevonianMatusevich, Vavilov and Mal’yutka formationscorrespond to the Upper Devonian onSevernaya Zemlya (Fig. 3). However, it is quitepossible that the basal strata of the MatusevichFormation are still of Middle Devonian in age(see below). Type sections of all these forma-tions are located on the Matusevich River. TheMatusevich and Vavilov formations have beenrecognized on October Revolution andKomsomolets island, the Mal’yutka Formationonly in the central part of the OctoberRevolution Island.Lithological changes in the MatusevichFormation reflect the cyclic development of theFrasnian transgression, the sediments of theVavilov Formation formed in time when the sealevel reached its highest position in lateFrasnian, and those of the Mal’yutka Formationalready in conditions of the Famennian regres-sion. Matusevich Formation. The formation waserected by Egiazarov (1957) and named after theMatusevich River, October Revolution Island.Later, the boundaries of the formation havebeen revised (Menner et al. 1979). The type



section of the Matusevich Formation is locatedon the Matusevich River (outcrop 7, beds 59-102; outcrops 19, 17, and beds 1-5 of outcrop 18;Figs 2; 12). Its lower boundary corresponds tothe base of a very distinctive bed of coarse-grained conglomeratic sandstones.The strata of the Matusevich Formation areexposed on October Revolution andKomsomolets islands. The formation shows arhythmic intercalation of variegated and redquartz sandstones, siltstones and argillitesformed in a gradually deepening basin. Thelower parts of the cycles are represented by red-dish-brown cross-bedded coarse-grained sand-stones replaced upwards by interbeddingfine-grained sandstones, siltstones and argillites.Particularly characteristic of the MatusevichFormation, but also of the overlying strata, arereddish-brown thin-bedded fine-grained sand-stones and siltstones. Interbeds of greenish-greysediments are rare in this interval. The strata ofthe Matusevich Formation are rich in plant fos-sils and vertebrates.In the type section on the Matusevich River fiveunits have been described in the sequence of theMatusevich Formation, viz., from bottom totop:1) grey coarse-grained sandstones, 35 m;2) intercalation of red sandstones (dominating),siltstones and argillites, 240 m;3) red argillites and siltstones with rare interbedsof sandstones, 150 m;4) red sandstones, 90 m;5) intercalation of sandstones, siltstones andargillites (dominating), 65 m.In the neighbouring regions (Ushakov,Pod’’emnaya, Bol’shaya rivers) only some inter-vals of this sequence are represented. OnKomsomolets Island, the Matusevich Formationis well exposed in many regions, and may reach470 m in thickness. The heterostracan Psammosteus cf. maeandrinusAgassiz, 1844, and placoderms Asterolepis cf.maxima Agassiz, 1844, Bothriolepis cf.obrutschevi Gross, 1942, B. cf. trautscholdiJaekel, 1927 and B. cf. maxima Gross, 1933,indicate a Frasnian age for this formation

(Lukševičs 1997, 1999) (Fig. 3). However, in thetype section on the Matusevich River the typicalFrasnian fauna appears only in bed 2 (seeabove), so it is possible that the lowermost partof the formation is of late Givetian age(Lukševičs 1999). Bothriolepis cf. obrutschevifrom the lower part of the formation correlatesthese strata with the upper Givetian or lowerFrasnian Amata Formation of the Baltic (Mark-Kurik 1998).Vavilov Formation. The Vavilov Formation,first identified by Egiazarov (1957), was namedafter the Vavilov Glacier (southwestern OctoberRevolution Island). Its type section is located onthe Matusevich River and on its tributaries (out-crop 18, beds 6-33, and outcrop 18a, lower part;Figs 2; 12). The lower boundary of the Vavilov Formationcorresponds to the base of the lowermost bed oflimestones. Characteristic of this formation isthe dominance of fine-grained sediments –mainly red to variegated siltstones and argilliteswith interbeds of fine-grained sandstone. Rareinterbeds of grey limestones with abundantplant remains are up to 2.7 m thick. The lime-stones are rich in vertebrate remains, and thin-walled ostracodes are common. The VavilovFormation was formed during the maximum ofthe Late Devonian transgression. The thickness of the Vavilov Formation reachesup to 200-300 m on October Revolution Island,and varies between 150 and 290 m on Komso-molets Island.A poor vertebrate fauna in the Vavilov Forma-tion does not allow its precise age-dating.However, considering the ages of the underly-ing Matusevich Formation (see above), and theoverlying Mal’yutka Formation (see below), theVavilov Formation is correlated with theFrasnian (Fig. 3; see also Lukševičs 1999).Mal’yutka Formation. The Mal’yutkaFormation is named after a tiny glacier justnorth of the Vavilov Glacier, on the upperreaches of the Matusevich River (Fig. 1)(Menner et al. 1979). This is the only regionwhere the strata of the Mal’yutka Formation areknown to be exposed. The type section of this

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118 GEODIVERSITAS • 2002 • 24 (1)

formation is located on the Matusevich River(outcrop 18a, upper part; Figs 2; 12). The lower boundary of the Mal’yutka Formationcorresponds to the upper surface of the last lime-stone bed in the underlying Vavilov Formation.In comparison with the underlying VavilovFormation, the amount of sandstone increasesconsiderably and limestones are missing in theMal’yutka Formation. The formation consists ofan intercalation of red and variegated sandstoneswith interbeds of conglomerates, siltstones andargillites. At some levels flat nodules of pink gyp-sum are common. Vertebrate and plant remainsare the only fossils. The sediments of theMal’yutka Formation were formed in graduallyshallowing basin. On the Matusevich River,where the Upper Devonian sequence is mostcomplete in the region, the Mal’yutka Formationis at least 300 m thick. A new subspecies of the placoderm Bothriolepisleptocheira Traquair, 1893, occurring in theupper part of the Mal’yutka Formation, suggestsFamennian age for these strata (Lukševičs 1999)(Fig. 3). The age of the lower part of this forma-tion is not known but is assumed to be Frasnian.

CONCLUSIONS

The development of the Silurian and Devoniansedimentation in the Severnaya Zemlya regionwas affected by both, global eustatic events andregional tectonics in northern Europe, Urals,and Central Siberia. Rhuddanian-early Aeronian normal marine car-bonates (Vodopad Formation) formed duringthe major early Llandovery transgression.Assemblages of stromatoporoids, corals,crinoids, and ostracodes from the VodopadFormation indicate not only to the open-shelfenvironment of sedimentation but also to thegood connections of the sea in the SevernayaZemlya region with the Siberian and Timan-Urals but also Baltic basins. In late Aeronian (Golomyannyj Formation), inconditions of a global regression, common ele-ments with Baltic faunas became rare or disap-

peared. During the major late Llandovery(Telychian) transgression (Srednij Formation), inshallow-shelf environments biostromes and bio-herms flourished in the Severnaya Zemlya region.Starting from the end of Llandovery, the generaltendency of the development of sedimentationin Severnaya Zemlya and Sedov archipelagoswas regressive, with transgressive oscillations insome periods. Carbonates were replaced by var-iegated and red terrigenous sediments inLudlow to Přidoli time (Ust’-Spokojnaya andKrasnaya Bukhta formations). In the lateSamojlovich time, Severnaya Zemlya evidentlybecame semi-isolated also from the Siberianbasin (common taxa are found only amongostracodes and vertebrates), and starting fromthe Ust’-Spokojnaya Formation some faunalsimilarities are noticed only between theSevernaya Zemlya and Svalbard sequences(Markovskij & Smirnova 1982). At the end ofthe Silurian, sedimentation terminated in severalareas in the Severnaya Zemlya basin and theuppermost Silurian strata were lost to erosion.In some regions both the entire Přidoli and theupper Ludlow are missing.Unlike the Silurian, Devonian strata are domi-nated by variegated terrigenous rocks. Threemain periods, related to the global eustaticcyclicity, can be recognized in the Devoniansedimentation on Severnaya Zemlya: 1) after a considerable gap, and denudation of thelate Silurian sediments, the sedimentation startedagain in Lochkovian. During the initial stage ofthe Early Devonian transgression mainly terrige-neous sediments accumulated (Severnaya Zemlya,Pod’’emnaya and Spokojnaya formations);2) the transgression reached its maximum in thelate Pragian-early Emsian (Rusanov and earlyAl’banov) time (the lower Rusanov Formationis the only interval in the Devonian sequence onSevernaya Zemlya containing rich and variableopen marine invertebrate faunas). Based on ver-tebrates, in early Lochkovian the SevernayaZemlya region had some connections only withthe northern Europe. In late Lochkovian, thedeveloping transgression re-opened migrationalways, and in late Pragian-early Emsian faunas



became similar in Severnaya Zemlya, Tajmyr,Central Siberia, Timan-Urals region, NovayaZemlya, and Svalbard; 3) the main part of the Devonian sequence,starting from the upper Al’banov Formation, ismainly represented by variegated or red terrige-neous sediments formed in an extremely shal-low-water epicontinental basin with abnormalsalinity. Rare thin interbeds of carbonate rocksare found only at some levels. The vertebrateassociations in these strata possess some similar-ity to those from Baltic.

AcknowledgementsThe authors are grateful to A. Abushik,I. Evdokimova, V. Karatajūtē-Talimaa,E. Lukševičs, E. Mark-Kurik, T. Modzalevskaya,T. Märss, H. Nestor and J. Valiukevičius forvaluable comments on biostratigraphy. A. Noormade linguistic improvements to the manuscriptand O. Hints assisted in scanning the figures.The manuscript was much improved followingthe comments of referees A. Blieck and G. C.Young. The study by P. Männik was supportedby grant No. 3749 of the Estonian ScienceFoundation and by governmental research grantNo. 0330360s98.

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Submitted on 13 April 1999;accepted on 30 October 2001.

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