Biostratigraphy and palaeobiology of Early Neoproterozoic strata of the Kola Peninsula, Northwest Russia

JOAKIM SAMUELSSON

Samuelsson, J.: Biostratigraphy and palaeobiology of Early Neoproterozoic strata of the Kola Peninsula, Northwest Russia. Norsk Geologisk Tidsskrift, Vol. 77, pp. 165-192. Oslo 1997. ISSN 0029-196X.

Shales and siltstones from the Early Neoproterozoic K.ildinskaya, Volokovaya and Einovskaya Groups and the Skarbeevskaya Fonnation (Kildin Island, Sredni and Rybachi Peninsulas) and the Chapoma Fonnation (Tiersky Coast) on the Kola Peninsula, Northwest Russia yielded assemblages of moderately well-preserved organic-walled acid-resistant microfossils (acritarchs, and prob­ able cyanobacterial sheaths). The assemblages consist of cosmopolitan taxa recovered from various Early Neoproterozoic (Late and Terminal Riphean) settings in Scandinavia, Russia, Yakutia, North America and elsewhere. Among the recovered taxa, Lopho­ sphaeridium laufeldii Vida) 1976 comb. nov., Satka colonialica Jankauskas, Simia annulare (Timofeev) Mikhailovna, Tasmanites rifejicus Jankauskas, Valeria lophostriata Jankauskas and Vandalosphaeridium ?varangeri Vida! are regarded as the biostratigraphi­ cally most significant. One taxon, Trachysphaeridium laufeldi Vida) is transferred to Lophosphaeridium laufeldii (Vida!) Samuelsson comb. nov. The units examined herein are all considered to be Late Riphean in age and are correlated with other units of similar age in northem and southem Scandinavia, Svalbard, East Greenland and the southem Urals.

Joakim Samuelsson, Uppsala University, Institute of Earth Sciences, Micropalaeontology, Norbyviigen 22, S-752 36 Uppsala, Sweden.

Introduction Neoproterozoic strata worldwide (e.g. Vidal 1976a; Vidal During the Neoproterozoic, the Baltica palaeocontinent 1981a; Knoll 1982a, 1982b; Vidal & Siedlecka 1983; underwent major sedimentological, tectonic and palaeo­ Knoll 1984; Vidal 1985; Knoll et al. 1989; Jankauskas et geographical changes (Kumpulainen & Nystuen 1985; al. 1989; Vidal & Nystuen 1990a, 1990b; Moczydlowska Vidal & Moczydlowska 1995). In the Late Riphean, 1991; Knoll et al. 1991; Knoll 1992). In addition to sedimentological changes occurred that comprised the biostratigraphy, acritarchs have also been widely used transition from predominantly non-marine into shallow­ for palaeoenvironmental analyses (e.g. Ivanovskaya & marine sedimentation regimes in a number of basins, Timofeev 1971; Golubic & Hofmann 1976; Knoll et al. including passive margin sequences (e.g. the western 1981, 1991; Mansuy & Vidal 1983; Green et al. 1987, Baltoscandian basins within the Caledonides; Kumpu­ 1988; Palacios Medrano 1989; Moczydlowska & Vidal lainen & Nystuen (1985)) and intracratonic settings (e.g. 1992; Butterfield & Chandler 1992). the Visingso Group; Vidal (1982)). Associated with these Better understanding of the Neoproterozoic evolu­ sedimentological changes is the initiation of the break-up tion of Baltica can be achieved through detailed strati­ of a large supercontinent ('Rodinia') in pre-Varangerian graphic correlation of all preserved successions on the time (Storey 1993). Significant pre-Varangerian events Baltic Shield. The reviews by Kumpulainen & Nystuen include the episodic emp1acement of do1eritic dyke (1985), Føyn (1985), Hambrey (1988) and Vida1 & swarms (Kumpulainen & Nystuen 1985; Vidal & Moczydlowska (1995) dealt with Neoproterozoic (Late Moczydlowska 1995). Palaeomagnetic data show that Riphean and Vendian) successions in the northern and together with Laurentia, Ba1tica was situated at low to western part of Baltica. With the exception of Hambrey equatorial latitudes during most of the Riphean, but it (1988), the important Late Riphean deposits of drifted southward during Vendian times (Gurnis & the Kola Peninsula have not been included in these

Torsvik 1994). In Early Vendian ( = Varangerian) time, reviews. glacier ice covered wide areas of Baltica. In Late In this paper I report on the occurrence of organic­ Varangerian time, the melting of the ice sheet resulted in walled microfossils (acritarchs and probable cyanobacte­ deposition of glacial material, preserved as tillites in, e.g., rial sheaths) from two areas in the northeastern margin central East Greenland, Svalbard, the Varanger Penin­ of the Baltic Shield, namely Kil din Island, the Sredni and sula in Norway, the proximity of the Caledonides and Rybachi Peninsulas in the Murmansk Coast of the the Urals (Kumpulainen & Nystuen 1985; Føyn 1985; northern Kola Peninsula, and the Chapoma River, lo­ Hambrey 1988; Vidal & Moczydlowska 1995). cated on the Tiersky Coast in the southern coast of the Acritarchs, cysts of algal protists, have been success­ Kola Peninsula (Fig. 1). The purpose of this work is to fully used for establishing stratigraphy and correlation of complement previously presented data on the biostrati- NORSK GEOLOGISK TIDSSKRIFT 166 J. Samuelsson 77 (1997) A \ D

KOLA PENINSULA l '( RUSSIA Chapoma River \ ORWAY� l ,_ ,... r -FINLAND '\ ,_....

N�

50 km

c

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++++++++++++++++ ++++++++++++++++++ ++++++t!++++++++++++ ·+++++. ++++++++++ 4+•• +�+++++++ �- ...... +

o 2 4 6 8 10 km NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 167 graphy and palaeobiology of these successions that oc­ Sea Region in Norway with the successions in Sredni­ cupy a key position in relation to the East European Rybachi and Kildin. They suggested that the Kildin­ Platform and the Varanger Peninsula. Further investiga­ skaya Group could be time-equivalent with the tions on stable isotope geochemistry are also in progress Kongsfjord and Båsnæring Formations of the Barents (Samuelsson et al. in prep.). Sea Group. In a review paper on the Late Proterozoic Stratigraphy of the Barents Shelf, Hambrey (1988) in­ cluded a discussion on the geology, age and correlation Research history of the Early Neoproterozoic settings in the Kola Penin­ sula. Lyubtsov et al. (1989) presented a synthesis on the The geology and stratigraphy of Neoproterozoic succes­ lithostratigraphy and micropalaeontology of the succes­ sions on the Sredni-Rybachi Peninsula, on the Kildin sions on the Murmansk and Tiersky Coast of the Kola Island and of the Chapoma River were dealt with in Peninsula. A guide to Neoproterozoic sections on the numerous Russian and some Finnish papers (see Murmansk coast and Tiersky Coast was published by the Siedlecka 1975 and references therein). Timofeev (1969) Kola Science Centre, Russia (Lyubtsov et al. 1991a, reported a poor, but typically Upper Riphean microfossil 1991b). Vidal et al. (1993) discussed the biostratigraphic assemblage from the Kildinskaya Group on Sredni and time-stratigraphic implications of a Chuaria/Tawuia Peninsula. He also reported a taxonomically more di­ assemblage and accompanying acritarchs from the verse assemblage from the Volokovaya Group on Sredni. Neoproterozoic of Yakutia and forwarded suggestions Negrutsa (1971) outlined the geo1ogy of the Sredni upon age relationships with the Kildinskaya Group. Peninsula and subdivided the Kildinskaya and Voloko­ Various aspects of the Neoproterozoic of the northeast­ vaya Groups into several formations. Siedlecka (1975) ern part of Baltica in Norway and Russia were dealt with published a review article (based largely on Russian recently in a number of papers in NGU Special Publica­ data) on the Neoproterozoic geology of the northeastern tion 7 (Roberts & Nordgulen, eds. 1995). Drinkwater et margin of the Fennoscandian Shield including Northern al. (1996) evaluated the Late Proterozoic stratigraphy in Norway (Varanger Peninsula), the Sredni-Rybachi northern Norway and northern Russia and presented a Peninsulas, the Aynov and Kildin Islands, Kanin Penin­ palaeogeographical reconstruction of these units. sula and the Timan Ridge. Konopleva (1977) discussed the age of the rocks on Rybachi and interpreted them as Middle Riphean. Ragozina & Stepkin (1979) examined the biostratigraphy of rocks on Sredni and Kildin. On Geological setting mainly biochronological evidence, Vidal & Siedlecka (1983) discussed the possible age relationships of the The Baltic Shield comprises northwestern Russia, Fin­ largely Upper Riphean Barents Sea Group in the Barents land, parts of northern and southern Norway and almost

RYBACHI PENINSULA SREDNI PENINSULA KILDIN ISLAND

Bargoutnaya Group \blokovaya Group Kildinskaya Group

• Tsypnavolokskaya Formation 9 Pumanskaya Formation [JJ] Slantzevoozerskaya Formation [TI Zubovskaya Formation f'� 'd Kuyakanskaya Formation (22l Pridorozhnaya Formation � Maiskaya Formation Kildinskaya Group m Pestzovozerskaya Formation Einovskaya Group ffi Karuyarvinskaya Formation � Chernorechenskaya Formation D Perevalnaya Formation Jfll Zemlepakhtinskaya Formation � Bezymyannaya Formation E::::::J Lonskaya Formation f----1 Poropelonskaya Formation

� Motovskaya Formation § Palvinskaya Formation ITITJ Korovinskaya Formation

f.,...... 1 lernovskaya Formation

O Skarbeevskaya Formation !IHII Kutovaya Formation � Archaean Basement

Fig. I. Maps showing outcrop areas and sampling localities. A: Map of northern Fennoscandia showing position of map B. B: Map showing the inferred relationship between the Varanger Peninsula, Norway, and the Sredni-Rybachi Peninsula, Russia. C: Geological map of the Sredni-Rybachi Peninsula and Kildin Island. Arrows and numbers within frames refer to sampled fossiliferous localities. D: Map of the Kola Peninsula showing position of the Sredni-Rybachi Peninsula and the Chapoma River. Figures JA-C modified from Siedlecka et al. (1995a) and Siedlecka (1995) with permission. 168 J. Samuelsson NORSK GEOLOGISK TIDSSKRIFT 77 (1997) all of Sweden with the exception of the Caledonides, stones. Both forrnations were previously referred to as southwestern Scania and the southern part of the Baltic the Pjarjajarvinskaya Forrnation (Negrutsa 1971), and Sea. In the area of the western part of the East European were interpreted as deposited in a fiuvial to marine Platforrn, the Baltic Shield is overlain by Cambrian and high-energy environment in the lower part, whereas the successively younger Phanerozoic strata. Sedimentary upper part was probably deposited in a prograding delta Neoproterozoic rocks of the Kola Peninsula and of the (Siedlecka et al. 1995a). The succeeding Palvinskaya Varanger Peninsula in Norway rest disconforrnably on Forrnation consists of sandstones and mudstones in its folded and strongly metamorphosed older Proterozoic lower part and oncolithic carbonate, dolostone and shale and Archean rocks (Fig. l C). The Neoproterozoic suc­ at the top, tentatively interpreted as representing coastal cessions are predominantly terrigenous and contain an beach and aeolian dune sediments (Siedlecka et al. abundance of sedimentary structures. The geology of the 1995a). The Poropelonskaya Forrnation rests with an Sredni Peninsula, the Kildin Island and the Rybachi erosional contact on the Palvinskaya Forrnation and Peninsula was described by Siedlecka et al. (1995a, contains a variety of lithologies, including sandstones, 1995b). Below, a short review of the geology of these conglomerates and muddy and sandy shales. The overly­ areas and the Chapoma Forrnation on the Tiersky Coast ing Zemlepakhtinskaya Forrnation has a somewhat simi­ is given. For completeness, even those units not sampled lar composition and, together with the Poropelonskaya in the present examination are included in the review. Forrnation, was thought to represent a progradational The Rybachi-Sredni Peninsula is dissected by a north­ prodelta-delta front (Siedlecka et al. 1995a). The overly­ west-southeast trending fault. The fault has a westward ing Karuyarvinskaya Forrnation comprises fine-grained extension on Varanger Peninsula in Northern Norway terrigenous sediments and carbonates, mainly dolomites. (Fig. lB). This structural junction between Sredni and Siedlecka et al. (1995a) interpreted this forrnation as Rybachi was interpreted as a reverse fault, where rocks being deposited in a delta plain or a coast of interdis­ underlying Rybachi have been uplifted and thrust against tributary bays and lagoons associated with the delta. Sredni (Wegmann 1928, 1929; Lupander 1934; Polkanov The lower part of the Volokovaya Group, the 1934, 1936; Keller & Sokolov 1960 and Keller et al. Kuyakanskaya Forrnation, consists of a coarse-grained, 1963). In contrast, Negrutsa (1971) and Lyubtsov et al. poorly sorted polymict conglomerate, overlain by thick­ (1989) proposed that there is a stratigraphic relationship bedded quartzitic sandstones, regarded as a succession between the Kildinskaya Group and the sedimentary deposited under fiuvial, coastal marine and, again fiuvial succession in Rybachi and they regarded the Rybachi environments (Siedlecka et al. 1995a). The overlying deposits as younger. This interpretation further implies Pumanskaya Forrnation is composed of dark muddy that the Rybachi succession has an age comparable to shale with sandy interbeds, displaying a certain cyclicity, the Volokovaya Group on Sredni (Lyubtsov et al. 1978). interpreted as bay deposits accumulated as a result of the However, re-examination of the key area in the field did delta front and beach progradation (Siedlecka et al. not reveal any sedimentary contact and therefore strati­ 1995a). graphic relationship has to be based on other criteria (Siedlecka 1995).

Geology of the Kildin Island The 1ower part of the Kildinskaya Group on Kildin Geology of the Sredni Peninsula consists of alternating terrigenous and carbonate units, The Kildinskaya Group on Sredni comprises entirely whereas the upper Kildinskaya Group is entirely terrige­ terrigenous deposits referred, in ascending order, to the nous. The succession was interpreted as deposited under Kutovaya, Iernovskaya, Palvinskaya, Poropelonskaya, transgressive-regressive events (Lyubtsov et al. 1989; Fig. Zemlepakhtinskaya and Karuyarvinskaya Forrnations 2). (Siedlecka et al. 1995a; Fig. 2). Approximately 140 m sandstone, siltstones and clay­ The Kildinskaya Group is unconforrnably overlain in stone comparable to the lernovskaya Forrnation on the northwestern part of Sredni by the Volokovaya Sredni Peninsula has been found in drill cores from Group. This approximately 450 m thick succession is Kildin Island (Lyubtsov et al. 199la). The upper Ier­ composed of terrigenous rocks. It is not clear if the novskaya Forrnation crops out only on the southern erosional contact between the Kildinskaya and Voloko­ coast of the island (Fig. IC), where it consists of dark­ vaya Groups is an angular unconforrnity, but it is grey muddy shales. The overlying Korovinskaya Forrna­ undoubtedly the most conspicuous erosional break tion consists of muddy sandstones and interbeds of within the entire sequence on Sredni (Siedlecka et al. stromatolitic carbonates. The entire stromatolitic assem­ 1995a). blage on Kildin Island, exclusively represented by bio­ The lowerrnost unit of the Kildinskaya Group on herrns, was considered as analogous to the Karatavian

Sredni, the Kutovaya Forrnation, is composed of cross­ ( = Upper Riphean R3) type section in the Urals (Raaben bedded feldspathic sandstones and the overlying Ier­ et al. 1995). The Korovinskaya Forrnation is con­ novskaya Forrnation mostly of glauconitic quartz sand- forrnably overlain by the Bezymyannaya Forrnation, NORSK GEOLOGISK TIDSSKR!Ff 77 (1997) Early Neoproterozoic strata, Kola Peninsula 169 composed of siltstones and muddy sandstone with in­ However, no detailed argument for the proposed correla­ terbeds of glauconitic sandstone and oncolithic dolostone tion was accommodated by Lyubtsov et al. (1989). (Lyubtsov et al. 1991a). The succeeding Chernorechen­ skaya Formation consists of red-coloured, argillaceous Geology of the Rybachi Peninsula rocks, siltstones and limestones. The overlying succession of approximately 180 m thick subgreywackes, muddy The bulk of the Rybachi Peninsula is underlain by a sandstones and claystones referred to the Pestzovozer­ Proterozoic succession attaining an approximate thick­ skaya Formation is exposed to the north of the extension ness of 4000 m, and has been subdivided into the area of the previous formations (Fig. l C). The overlying Einovskaya and Bargoutnaya Groups (Fig. 1). The se­ Pridorozhnaya and Slantsevoozerskaya Formations, 600 quence represents a basinal turbidite system overlain by and 250 m thick respectively, are largely composed of upper slope deposits (Siedlecka 1995; Siedlecka et al. fine- to medium-grained sandstones. l995b). It shows a higher level of lithification and is In summary, the Kildinskaya Group is tentatively more intensely folded than the successions on Sredni interpreted as a shallow-marine deposit in the lower 300 Peninsula and Kildin Island (Siedlecka 1975; Roberts m, and as representing parts of prograding deltaic sys­ 1995). The base of the Einovskaya Group (Fig. 2), the tems in the overlying section (Siedlecka et al. 1995a). Motovskaya Formation, is mainly composed of coarse­ The Korovinskaya, Bezymyannaya and Chernorechen­ grained deposits including conglomerates and breccias skaya Formations on Kildin Island are thought to corre­ (Siedlecka et al. 1995b). The Motovskaya conglomerate spond to the Palvinskaya Formation on Sredni, whereas has been altematively interpreted as glacial (W egmann the Pestzovozerskaya, Pridorozhnaya and Slantsevozer­ 1928), or as a debris ftow (Siedlecka et al. 1995b). The skaya Formations on Kildin Island are correlated with overlying Lonskaya and Perevalnaya Formations are the Poropelonskaya and Zemlepakhtinskaya Formations approximately 2700-m-thick sandstone units that were on Sredni (Lyubtsov 1975; Lyubtsov et al. 1989; Fig. 2). interpreted as proximal turbidites (Siedlecka et al. 1995b ).

lmst dolomites and limestones IJ) Æ > 1/) a. 1/) Cl Q) o conglomerate .::J c: ....o Formations -"' o (.) .r= (.!) sandstone :E1- �

«< siltstone > Tsypnavolokskaya 260 �lmst:::: «< -r::: mudstone and sandstone . ::J Zubovskaya 500 o CUIUQG sandstone and siltstone e' Skarbeevskaya «< Malskaya 250 Fm ID ;:;r;;;_;;;;;;. unconformity «< Perevalnaya 2000 .:;-;;;; ;�--

> � 1/) Æ � c. 1/) Cl IJ) :l (/) QQQQQ� Q) o > Lonskaya 700 c: 2 Formations -"' o o (!) (.) .r= r::: :E � iii Motovskaya 350 1- ;ra;;·-;;;·- tectonic "' contact Slantsevozerskaya 250 Pumanskaya 300 \ �> � o \ -"' o Pridorozhnaya 600 \ Kuyakanskaya 150 a. g lill ".11 11 � :::J \ \ "-o Pestsovozerskaya 180 Karuyarvinskaya 250 �imst:::: V'-���"'

The overlying Bargoutnaya Group is subdivided into

- the Maiskaya, Zubovskaya and Tsypnavolokskaya For­ c::[ Si; El siltstone mations. The Maiskaya Formation consists of sandstones, �

Geo/ogy of the Chapoma River area A few dispersed Proterozoic rock units, the Turin, Tiersk Riphean (R3) and Vendian. However, a somewhat and Chapoma Formations, occur along the southern different stratigraphic subdivision is also in use (e.g. coast of the Kola Peninsula (Fig. ID). On palaeontologi­ Chumakov & Semikhatov 1981) which includes an addi­ cal evidence, the Turin and Tiersk Formations are consid­ tional unit, Riphean R4 or Kudashian, between the ered to be Middle Riphean or older (Lyubtsov et al. 1989). Upper Riphean (R3) and Vendian. The Kudashian The youngest unit, the Chapoma Formation, is exposed (Riphean R4) is defined on the basis of a change in the along the steep margins of a gra ben on the shores of River Riphean R3 assemblage of stromatolites and oncolites. Chapoma, on the southeastern coast of the Kola Penin­ Micropalaeontologically, the Kudashian is rec�gnized by sula (Tiersky Coast; Fig ID). The formation, approxi­ decrease in diversity of the microbiota followed by an mately 250 m in thickness (Fig. 3), consists of red quartz increased abundance of tubular microfossils, such as sandstone, siltstone, mudstone and laminated sandy car­ Eomycetopsis psilata (Jankauskas 1982). The type section bonate rocks at the base. The basal mudstones display of the Kudashian R4 strata, the Kudash Group, is mudcracks, whereas the carbonates have synaeresis cracks situated within the southern Urals and consists of ter­ and, additionally, comprise stratiform stromatolites at rigenous, carbonate and sandy-shaly deposits (Chu­ some levels. Some carbonate-cemented sandstones with makov & Semikhatov 1981). In the European part of loadcasts and cross-laminated ripples occur at the lower Russia and in eastern Europe, the Kudashian is closely levels of the formation. The top of the formation consists related to the Upper Riphean R3 (Chumakov & of alternating grey sandstone, siltstone and dark-grey to Semikhatov 1981). The lower boundary of the Vendian is black shale with halite pseudomorphs (Lyubtsov et al. usually placed where the Laplandian ( = Varangerian) 1989; pers. obs.). These observations suggest that the glacial horizon first occurs (e.g. Keller et al. 1977). Chapoma Formation is a shallow-water sequence. Sometimes, the base of the Vendian has been defined lower in the sequence, i.e. at the lower boundary of the Kudashian R4 (e.g. Chumakov & Semikhatov 1981; Semikhatov 1991), and this has created some confusion. Chronostratigraphic subdivision This paper follows Vidal & Siedlecka (1983), who consid­ The four-fold subdivision of the Neoproterozoic of Rus­ ered beds formerly regarded as Early Vendian in age as sia includes the Lower {Rl), Middle (R2) and Upper possibly equivalent with Riphean R4 (Kudashian) strata. NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 171

As mentioned above, a sedimentological change from Chapoma Formation is 0.62, (n = 7; Samuelsson, unpub­ predominantly non-marine fluvial and deltaic into shal­ lished data). The average TOC and H/C levels indicate low marine deposits is recorded in numerous successions that the microfossils have undergone a modest thermal in Baltica during Latest Riphean times (e.g. Røe 1975; alteration, and this is further supported by the thermal Siedlecka 1985; Kumpulainen & Nystuen 1985). Often, alteration index (TAl) of kerogens from each sample (see the change is also observed in the record of microfossil 'Appendix' for details). assemblages (Vidal 1976a, 1981; Vidal & Siedlecka 1983). The state of preservation of the microfossils from the This event might mark the transition from Upper Murmansk and Tiersky Coasts is highly variable. As all Riphean R3 to Terminal Riphean R4 age in the Baltica investigated rocks have undergone thermal alteration, no palaeocontinent (G. Vidal, pers. comm. 1996). definitely light-coloured organic matter is found in any of the examined samples. Nevertheless, some samples con­ tain exceptionally well-preserved acritarchs and filamen­ tous sheaths coloured light to dark-brown, with a TAl Material and methods ranging from 2+ to 3+ (Pearson 1984). Some samples Forty-six out of 67 investigated samples of fine-grained contain kerogenous matter that is significantly more siliciclastics and carbonates proved to yield microfossils. altered, with maximum TAI values. Acritarchs in these Following the name of the formation, the numbers thermally altered samples are relatively few and the within parentheses refer to the fossiliferous samples samples contain quantitatively more structureless sapro­ within each formation. The microfossils are obtained pellic matter than fossil-rich samples. Additional samples from the lernovskaya (4), Chernorechenskaya (2), Pest­ yield microfossils of variegated coloration that indicate zovozerskaya (l), Poropelonskaya (11) and Karuyarvin­ variable levels of preservation. Presumably, this could be skaya (2) Formations of the Kildinskaya Group on due to varying levels of structural deformation and/or Kildin Island and Sredni; the Pumanskaya (5) Formation thermal alterati on, or alternatively redeposition of micro­ of the Volokovaya Group on Sredni; the Motovskaya (l) fossils with a different thermal and preservational his­ and Perevalnaya (l) Formations of the Einovskaya tory. lrradiation from natura! decay of radiogenic iso­ Group on Rybachi; and the Skarbeevskaya (4) Forma­ tapes has also been invoked to explain similar character­ tion on Rybachi. Twenty out of 67 investigated samples istics in other sedimentary settings (e.g. Moczydlowska & are from the Chapoma Formation on the Tiersky Coast, Vidal 1992). of which 15 samples proved to be fossiliferous. Owing to The taxonomic diversity measured as the total number the generally discontinuous nature of the outcrops, nei­ of taxa in acid-resistant residues is low. The taxonomically ther of the investigated units was sampled in strictly richest samples yielded only 12 form-taxa (Fig. 4). This continuous sections. generally corresponds well to most previously reported The microfossils were extracted from the rock samples Upper Riphean microfossil assemblages, although some using the standard palynological technique (Vidal 1988). Late Riphean assemblages show a more diverse taxonomy Strew slides were made using EPOTEK 301 as a perma­ due to the accounting of microfossils preserved in chert nent mounting medium. (e.g. the Svanbergfjellet Formation of the Akademiker­ Besides acid macerate, petrographic thin sections were breen Group in Svalbard; Butterfield et al. 1994). also made from each sample. Thin sections of mud­ Only four taxa, Leiosphaeridia spp., Navifusa majensis, stones, siltstones, shales and carbonates were cut parallel Stictosphaeridium spp. and tubular fossils, Siphonophycus to bedding. Thin sections of small drill cores of carbon­ spp., were recovered in examined petrographic thin sec­ ate rocks were cut at an approximately 45° angle to the tions. As with the macerated samples, Leiosph�eridia bedding. spp. is also the most common microfossil in the exam­ ined thin sections. The specimens of Leiosphaeridia spp. appear to be randomly distributed in all thin sections, an observation that was taken to indicate a planktonic Preservation of microfossils (taphonomy) mode of life for these organisms (Vidal & Knoll 1983; The majority of the fossiliferous samples derive from Butterfield & Chandler 1992). black to dark-grey mudstones and shales. The total organic carbon (TOC) content is generally high, with average values of approximately O.l g TOC per g of rock Systematic micropalaeontology for the Murmansk Coast area (n = 42; Samuelsson; un­ published data). The average H/C ratio for the Mur­ The Proterozoic micropalaeontology was impaired by mansk Coast kerogens is 0.49 (n = 13; Samuelsson; numerous poorly described taxa and burdened with taxo­ unpublished data), a figure that indicates moderate kero­ nomic inconsistencies. This problem was more recently gen preservation (Hayes et al. 1983; Strauss et al. 1992), dealt with in a number of publications (e.g. Xing et al. whereas in the Chapoma Formation, the average TOC is 1985; Yin 1987; Jankauskas et al. 1989; Fensome et al.

0.14 g per g sample (n = 20; Samuelsson, unpublished 1990; Schopf 1992; Butterfield et al. 1994), resulting in a data). The corresponding average H/C ratio for the more unified classification system. 172 J. Samuelsson NORSK GEOLOGISK TIDSSKRIFT 77 (1997)

KILDINSKA VA GRO UP VOLOK EIN

lernov C her p Poropelonskaya Kar Pumanskaya M Pe Skarbeev

r- 00 "' Ill .... Q .... N ..". Ill < r- 00 "' Q N N .., \C <'l .., .., .., .... <'l =:i 00 "' .... Q \C N N� � � �\C '9 '9 ";' ";' ";' ";' � � '? '? � � Ill .., '? ..". .... ";' ";' � .... '9 '9 �...... �.... ";' ...... ";' ...... ,..!...... ,..!. 'o:t � ...... ,..!."' ...... "' "' ...."' "' "' "'...... "' "' "'"'"' "' "' "' !:n rn "' .... ,..!. "' MICROFOSSIL TAXA "' "'.... rn rn � � � � � � � � � � � � � � � � � � � � � � � � < < < < � � � C/maria circularis • Leiosphaeridia spp. •••• •• • ••••••••••••• ••• ••• • •••• Lophosphaeridium laufeldii •• Loplwsphaeridium ? laufeldii •• Na vifusa majensis • • •• • ••••• Oscillatoriopsis spp. • • • • Satka sp. • ••• • Satka colonialica •• • • • • Simia sp. •• • •• • •• • Simia annulare •• • • •• • • •• • Sip/wnophycus spp. • • •• • •• • Sp haerocongregus sp. • Sp haerocon�re�us variabilis • Stictosphaeridium spp. •••• • • ••••• ••••• ••• • • • • Symphaeridium spp. •• • • ••••• • • Tasmanites rife_iicus • Tra chysphaeridium laminaritum • • Valeria lophostriata •• Va ndalosphaeridium sp. • Va ndalosphaeridium ?varangeri • Total forms present 6 6 2 2 1 11 7 1 7 5 4 5 7 1 1 8 3 2 11 12 4 3 4 5 3 2 1 4 1 2 1

Fig. 4. Stratigraphic distribution of microfossil taxa recovered from Kildin Island and the Sredni and Rybachi Peninsulas. Filled circles denote presence of taxa. For the geographic position of rock units see under 'Geological setting'. Abbreviations: Volok = Volokovaya Group; Ein = Einovskaya Group; Iernov = Iernovskaya Formation; Cher = Chernorechenskaya Formation; P= Pestzovozerskaya Formation; Kar = Karuyarvinskaya Formation; M = Motovskaya Formation; Pe = Perevalnaya Formation; Skarbeev = Skarbeevskaya Formation.

Traditionally, pre-Phanerozoic carbonaceous micro­ number of taxa previously known from Proterozoic suc­ fossils have been examined in either chemical macerates cessions in Scandinavia, Svalbard, Greenland, Russia, or petrographic thin sections. Usually, fine-grained detri­ Yakutia and North America (e.g. Vida! 1976a; Knoll & tal rocks were examined in macerates, and phosphorite Swett 1985; Jankauskas et al. 1989; Butterfield et al. nodules and cherts in thin sections. In addition, micro­ 1994; Hofmann & Jackson 1994). fossils recovered in phosphorite nodules and cherts are The wall thickness of acritarchs, particularly of usually hetter preserved, often three-dimensionally (e.g. Leiosphaeridia spp., and tubular microfossils is usually Moczydlowska & Vidal 1992 and references therein). expressed as 'opaque', 'trans1ucent' or 'medium-walled', These differences might result in taxonomic misidentifi­ etc., without being properly defined (e.g. Hofmann & cation when dealing with different lithologies for micro­ Jackson 1994; Butterfie1d et al. 1994). These characters are fossils (Schopf 1992). Lately, this problem has attracted subjective because the wall was not measured. Here, the increased attention and papers dealing with Proterozoic following criterion has been followed: In light of a systematic palaeonto1ogy often incorporate both petro­ virtually constant thermal altera ti on index (TAl), the graphic thin section and macerate examinations (e.g. wall-thickness was expressed in relation to the transpar­ Knoll et al. 1991; Butterfie1d et al. 1994; Hofmann & ency or translucency of the wall. The term 'opaque' refers Jackson 1994), although, admitted1y , this demands sig­ to the object being nearly impenetrable to transmitted nificant concentrations of microfossils per rock volume, light, whereas 'translucent' implies an object that to a at !east for thin-section examination. minimum extent transmits the light. 'Medium-walled' thus The present material consists of forms referred to 23 indicates an intermediate position between both extremes. form-taxa, consisting of two groups, acritarchs (includ­ In the descriptions below, size is given with the maxi­ ing possible prasinophytes and clustered forms), and mum diameter of the measured specimen. Owing to tubu1ar microfossils, most probably abandoned cyano­ compression, these values were not obtained accurately bacteria1 sheaths. The taxa are arranged in a1phabetic in some cases as many specimens were distorted and order. One previous1y described species is transferred to deformed. another form-genus (i.e. Lophosphaeridium laufeldii Vida1 With the exception of figured cerebroid Chuaria, de­ comb. nov.). Taxonomically, the assemb1a ge includes a posited at the Institute of Earth Sciences, Lund Univer- NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 173

1994 Leiosphaeridia wimanii (Brotzen)-Butterfield comb. TIERSKY COAST- SOUTHERN KOLA Chapoma Formation nov. in Butterfield et al., p. 42, figs. 13: D-F � N o � N m o Q c o o o o � � � � � � � � l l l l l l l l l l l l l l 1994 Chuaria circularis Walcott-Yin & Sun, pp. 99-100, TAXA N N N N N N N N N N N N N N m ; � æ m m m m� ø ø m m� m m m m � � � � � � � � � � � � � � fig. 4b I i i l l l l i I I I I I l Chuariasp. 1994 Chuaria circularis Walcott-Steiner, pp. 95-101, • Chuaria circularis figs. 1: 4-17; 3: 1-7; 4: 1-4; 8: 2; 9: l-2; 11: 8, lO; 12: • • • Leiosphaeridia 4, Il 1995 Chuaria circularis (Walcott) Vidal & Ford­ spp. •••••••••••••• Hofmann & Rainbird, p. 724, figs. l: 1-6 Navifusa majensis • Simia . sp • • • Material. - Five complete specimens. One additional Simla annulare •• •• • deformed specimen is attributed to Chuaria sp. Siphonophycus spp. • • ••••••• • Stictosphaeridium Description. - Acid-resistant, robust, single-walled, car­ sp. • ••••• Synsphaeridium bonaceous vesicle, flattened and circular to subcircular in spp. ••••••••• • Trachysphaeridium outline after compaction. Surface psilate, often shows ?laminaritum • Valeriasp. diagenetically introduced wrinkles, textures and compres­ • sional folds . Valeria lophostriata • 2 1 3 2 9 5 4 4 5 6 5 3 3 4 Total forms present Dimensions. - Vesicle diameter ranges from 266 to 313

Fig. Stratigraphic distribution of microfossil taxa recovered from the Jim. Mean diameter= 292.5 J..Lm (s.d.= 16.7 Jim, n = 5). 5. Chapoma Formation, Tiersky Coast. Filled circles denote presence of taxa. Remarks. - The extremely simple morphology of these sity, Sweden, all figured specimens are deposited in col­ flattened spherical microfossils presents a significant lections of the Institute of Earth Sciences, Uppsala Uni­ problem for sound taxonomic treatment. In this paper, I versity, Sweden, to which collection numbers make have attributed all larger (> 250 Jim; Hofmann & reference and indicate the location of specimens in mi­ Jackson 1994) smooth, spheroidal acritarchs to Chuaria croscopic slides given by an England Finder. Micro­ circularis following the emendation of the taxon by Vidal graphs of figured specimens were taken under inter­ & Ford (1985) where C. circularis is distinguished from ference contrast microscope, using a Leitz Wetzlar the genus Leiosphaeridia on the sole basis of its relatively microscope with an automatic Nikon UFX-IIA micro­ larger size and, in some cases, its relatively thicker vesicle photography attachment, Ilford XP2 black and white wall. The current use of C. circularis involves various film exposed at l00 ASA. unrelated, possibly biogenic objects (Vidal et al. 1993), The results from the microfossil examination are sum­ and because the biological affinities of C. circularis are marized and accounted for in Fig. 4 for the formations unknown, I have avoided a non-biological form-taxon­ on the Murmansk Coast and in Fig. 5 for the Chapoma omy with a finer subdivision into genera and species of Formation on the Tiersky Coast. these larger smooth spheroidal acritarchs. Admittedly, for a detailed morphological description of fossil micro­ Group Acritarcha Evitt, 1963 biota, artificial form-taxonomy might prove useful (e.g. Butterfield et al. 1994). Genus Chuaria Walcott, 1899 emend. Vidal & Ford, Larger specimens of Leiosphaeridia jacutica (Timofeev) 1985 Mikhailova & Jankauskas described in the literature fall under Chuaria circularis as defined by Vidal & Ford Type species. Chuaria circularis, Walcott, 1899 emend. (1985). Vidal & Ford, 1985 Occurrence. - Chuaria circularis is well known from Chuaria circularis Walcott, 1899 emend. Vidal & Ford, numerous Neoproterozoic settings around the globe, e.g. 1985 Fig. 7A, D the Chuar Group, Arizona, USA (Walcott 1899; Ford & Breed 1973; Vidal & Ford 1985); the Visingso Group, See Vidal et al. (1993, p. 390) for earlier synonymies. Sweden (Vidal 1976a); the Uinta Mountain Group, Utah, USA (Vidal & Ford 1985); the Little Dal Group, Canada 1993 Chuaria circularis (Walcott) Vidal & Ford-Vidal et (Hofmann & Aitken 1979); the Eleonore Bay Group al., p. 390, figs. 3A-D; 4D (Vidal 1979) and the Wolstenholme and Dundas Forma­ 1994 Leiosphaeridia jacutica (Timofeev) Mikhailova & tions of the Thule Group, Greenland (Vidal & Dawes Jankauskas-Hofmann & Jackson, p. 22, figs. 16; 17: 1-4 1980); Pendjari Formation, Benin and Burkina-Faso, 1994 Chuaria circularis Walcott-Butterfield et al., p. 32, West Africa (Amard 1992); Feishui and Huinan Group, figs. 8G-H; 13: G-I China (Zang & Walter 1992b); Miroedikha, Khatyspyt, 1994 Cerebrosphaera buickii Butterfield et al., p. 30, figs. Mastakh, Khajpakh and Debengdin Formations, Siberia 12: A-H (Vidal et al. 1993); Svanbergfjellet Formation, Spitsbergen NORSK GEOLOGISK TIDSSKRIFT 174 J. Samuelsson 77 (1997)

(Butterfield et al. 1994); Arctic Bay, Fabricius Fiord, chosen in, e.g., Jankauskas et al. (1989) are purely arbi­ Society Cliff, Victor Bay, Athole Point, Strathcona Sound trary. Additionally, transitional forms between different and the Elwin Formations of the Bylot Supergroup, dimensional clusters and vesicle wall thicknesses do oc­ Canada (Hofmann & Jackson 1994); Wynniat Formation cur. In the present material, specimens belonging to the of the Shaler Supergroup, Canada (Hofmann & Rainbird genus Leiosphaeridia have not been identified to the 1994); Dengying Formation, Yangtze Platform and Liu­ species level, mainly because of the limited number of laobei, Jiuliqiao, Xiamaling and Changlongshan Forma­ true biogenic characters associated with the taxon and its tions and the Changcheng Group, North China Platform, limited biostratigraphic value (Moczydlowska 1991). China (Steiner 1994). In the present material C. circularis Larger leiosphaerid acritarchs, however, are attributed to was found in the Chernorechenskaya Formation of the Chuaria circularis. Kildinskaya Group of the Kildin Island and the Chapoma Clusters of Leiosphaeridia-Iike microfossils are herein Formation of the Tiersky Coast. One specimen attributed described under the genera Stictosphaeridium spp. Timo­ to Chuaria sp. derives from the Chapoma Formation feev and Synsphaeridium spp. Eisenack. (See 'Additional (Figs. 7, 8). microfossils' below).

Stratigraphic range. - Most likely Early Neoproterozoic, Occurrence. - Leiosphaeridia spp. has been reported but see Vida! et al. (1993) for a discussion on the from numerous and world-wide occurrences (e.g. Vida! & biostratigraphical implications of the taxon. Ford 1985; Jankauskas et al. 1989; Zang & Walter 1992a; Moczydlowska 1991, 1992b; Hofmann & Jackson Genus Leiosphaeridia Eisenack, 1958 emend. Turner, 1994; Butterfield et al. 1994) and in the present material 1984. the taxon occurs in all fossiliferous samples and greatly outnumbers other microfossil taxa (Figs. 4, 5). Type species. Leiosphaeridia baltica, Eisenack, 1958 Stratigraphic range. - Late Proterozoic to Tertiary Leiosphaeridia spp. Fig. 7B, C, E (Moczydlowska 1991).

See Jankauskas et al. (1989, p. 69) for synonymies. Genus Lophosphaeridium Timofeev, 1959 ex Downie, 1963 emend. Lister, 1970. Material. - Thousands of specimens in various stages of preservation. As in many other Early Neoproterozoic Type species. Lophosphaeridium rarum Timofeev, 1959 ex settings, this taxon is by far the most abundant taxon Downie, 1963 within the assemblage. Lophosphaeridium laufeldii Vida!, 1976 comb. nov. Fig. Description. - Acid-resistant, isolated, circular to subcir­ 7F, H, I cular, compressed, commonly folded vesicles. Surface smooth to psilate in most cases, but a variety of sculp­ 1976a Trachysphaeridium laufeldi Vida! sp. nov-Vida!, ture patterns are known (e.g. chagrinate, granulate, ver­ pp. 36-38, figs. 21: A-N rucate). Opaque, robust-walled, thin-walled, single or 1976b Trachysphaeridium laufeldi Vida!-Vida!, fig. 2A double-walled forms occur. Elongated compressional 1985 Trachysphaeridium /aufeldi Vidal-Vidal & Ford, folds often present, thus indicating a somewhat rigid pp. 375-376, figs. 7: A-B; D, F vesicle wall. Median splits observed on some specimens. Material. - Four moderately well-preserved specimens. Dimensions. - Vesicle diameter 10-249 J.Lm. Mean dia­ Three more poorly preserved specimens are here at­ meter= 21.7 J.Lm (s.d.= 11.3 J.Lm, n = 100). tributed to e.f. Lophosphaeridium laufeldii.

Remarks. - The chaotic systematics of acritarchs is Diagnosis. - A species of Lophosphaeridium with vesicle especially inextricable among Leiosphaeridia spp. as most wall covered by numerous small hair-like spines. of them do not possess any diagnostic features other than surface sculpture, size and wall thickness. Further­ Description. - Acid-resistant vesicle, circular to subcircu­ more, taphonomically introduced features have in some lar in outline. Compactional folds present on some spee­ instances been taken as diagnostic (Hofmann & Jackson imens. The surface of the vesicle displays numerous 1994). This has created much confusion, and some recent tightly arranged, small conical spines that are visible as attempts have been made to revise the systematics of this evenly distributed small hairs at the outer edge of the taxon (Jankauskas et al. 1989; Schopf 1992). However, specimens. even though the number of leiosphaerid taxa has sub­ stantially decreased, the definition of species of Leio­ Dimensions. - Vesicle diameter 28-51 J.Lm. Mean diame­ sphaeridia depends often only on two biologically inade­ ter= 33 J.Lm (s.d. = 3.6 J.Lm, n = 4). The conical projec­ quate characteristics; size and wall thickness. Size ranges tions are approximately l J.Lm long. NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 175

Remarks. - In his original designation of the spedes 140 Trachysphaeridium laufeldi Vidal (1976a) noted that the vesicle surface is tightly covered with very short, conical 120 spines. These short spines are herein interpreted as small - • tubercles, part of the texture of the vesicle surface. The l l 100 genus Lophosphaeridium is characterized by its solid tu­ E - - � bercles (Downie 1963). Hence, I transfer the species from ::l l • the genus Trachysphaeridium to the genus Lophosphae­ 80 - ridium (Trachysphaeridium was earlier placed in syn­ ..c onymy with the genus Leiosphaeridia by Jankauskas et +-' • C> 60 - � 4 •• al. (1989, p. 70). The orthography of the specific epithet, c· • laufeldi, is corrected according to ICBN (Tokyo Code) Q) l . �l 40 - Articles 32.6 and 60.11.

20 Occurrence. - Lophosphaeridium laufeldii has been re­ - Navifusa majensis ported from the Visingso Group, Sweden (Vidal 1976a); o the Eleonore Bay Group, Greenland (Vidal 1976b); the l l l l l Andersby Formation of the Vadsø Group, Norway o 10 20 30 40 50 60 (Vidal 1981a); the Awatubi Member of the Kwagunt width J..Lm Formation, Chuar Group, Arizona and the Mount Wat­

son and Red Pine Shale of the Uinta Mountain Group in Fig. Relationship between vesicle length and width for Navifusa majensis 6. Utah, USA (Vidal & Ford 1985). In the present material including thin sections (n =52). the species was recovered in the Karuyarvinskaya For­ mation of the Kildinskaya Group on Sredni (Fig. 4). tive. Looking at the two-dimensional size distribution diagram (Fig. 6), all measurements plot within a unimo­ Stratigraphic range. - Upper Riphean (Vidal & Ford dal, single duster. Therefore, only one species is recog­ 1985) nized here. The size range as proposed by Jankauskas (in Jankauskas et al. 1989) suggests that specimens recovered Genus Navifusa Combaz, Lange & Pansart, 1967. in the present material fall closest to Navifusa majensis.

Type species. Navifusa navis (Eisenack 1938) Combaz et Occurrence. - Navifusa majensis is known from the al., 1967 Zilmerdak Formation of the Southern Ural foreland in Bashkiria, Russia (Jankauskas et al. 1989); the Strathcona Navifusa majensis Pyatiletov, 1980 Fig. 7G, J, K Sound, Society Cliffs and Arctic Bay Formations of the Baffin Island, Canada (Hofmann & Jackson 1994) and the See Hofmann & Jackson (1996, p. 14) for synonymies. Dundas Formation within the Thule Group, northwest Greenland (Hofmann & Jackson 1996). The present sped­ Material. - Thirty well-preserved and measured sped­ mens derive from the Poropelonskaya and Karuyarvin­ mens, more than 50 specimens observed in macerations. skaya Formations within the Kildinskaya Group and the Including those in thin sections, 52 spedmens were mea­ Pumanskaya Formation within the Volokovaya Group sured. (Fig. 4). One spedmen was recovered from the Chapoma Formation in the Tiersky Coast (Fig. 5). Description. - Solitary, acid-resistant, ellipsoida1, non­ septate, smooth, medium-walled vesicles with rounded Stratigraphic range. - Jankauskas et al. (1989) report a tips. They occasionally occur in chain-like clusters, flat­ Late Riphean age for the taxon, although similar forms tened due to compaction. are known from Mesoproterozoic up to Midd1e Devo­ nian strata (Eisenack et al. 1979). Dimensions. - Vesicle width 16-60 ,um, and vesicle length 41-120 ,um. Mean width= 24.7 ,um (s.d.= 4.84 Genus Satka Jankauskas, 1979.

,um, n = 29). Mean 1ength = 67.2 ,um (s.d.= 18.7 ,um, n = 30). Type species. Satka favosa Jankauskas, 1979

Remarks. - This species has an extremely simple mor­ Satka colonialica Jankauskas, 1979 Fig. 9A, B phology and a smooth surface. Jankauskas et al. (1989) placed the genus within the Order Osdllatoriales. How­ 1979 Satka colonialica Jankauskas sp. nov., pp. 192-193, ever, given the limited amount of characters presently figs. 1: 4, 6 known to be associated with Navifusa, all attempts to 1985 Satka colonialica Jankauskas-Vidal & Ford, p. compare it with recent taxa must be regarded as specula- 369, figs. 6: A-F 176 J. Samuelsson NORSK GEOLOGISK TIDSSKRIFT 77 (1997)

1985 Satka colonialica Jankauskas-Knoll & Swett, p. Genus Simia Mikhailova & Jankauskas, 1989. 468, figs. 53: 4-6, 8 1992a Satka compacta Zang & Walter sp. nov., p. 93, Type species. Simia simica Mikhailova & Jankauskas, figs. 69: F-H 1989 1994 Satka colonialica Jankauskas-Yin & Sun, p. 107, figs. 5: G, 7: K-L Simia annulare ('Fim9feev) Mikhailova, 1989, Fig. 9C-F

Material. - Twenty-nine well-preserved specimens, a 1969 Pterospermopsimorpha annulare Timofeev, sp. nov. number of poorer preserved specimens are attributed to 1989 Simia annulare (T imofeev), emend. comb. nov. Satka sp. Mikhailova in Jankauskas et al., p. 66, figs. 6: 5-8 1993 Simia annulare (T imofeev) Mikhailova-Vidal et al., Description. - Acid-resistant, single-walled, flattened en­ p. 395; fig. 5: A velopes with variable wall thickness. The overall shape is ellipsoidal, circular or complex with an uneven outline. Material. - Thirty-nine moderately well-preserved speci­ On parts of the envelope, irregularly distributed separate, mens and an additional twenty, more poorly preserved contiguous, round, quadrate or tetragonal cell-like struc­ attributed to Simia sp. tures or imprints of cell-like structures occur. Description. - Acid-resistant, rounded to ovoid vesicle, surrounded by an outer thin, spongy equatorial mem­ Dimensions. - Dimensions of envelope 32-200 ,um. Size brane. The inner body is smooth, not folded, generally of cell-like structures 9-41 ,um. opaque, although forms with less pronounced thickness and more translucent walls also occur. The outer mem­ Remarks. - Within the present material, at least two brane is translu�ent, psilate to fine-granular. The outer forms of the taxon occur; one that is circular in outline, layer is less dense than the inner and of a somewhat and a second that shows an irregular contour that is variable thickness among some specimens whose outer inconsistent and variable among the specimens. The ir­ layer is thinner. regular shape is here viewed as being a compressed, deformed and degraded variety of the original spherical Dimensions. - The diameter of the inner body is 14-63 form. For this reason, I have chosen to place all speci­ ,um, the diameter of the entire vesicle is 23-73 ,um. Mean mens belonging to the genus Satka within the same diameter of inner body= 29.9 .um (s.d.= 10.4 ,um, species, S. colonialica Jankauskas. n= 39). Mean diameter of whole vesicle= 36.7 ,um The species Satka compacta was erected by Zang & (s.d.= 10.6 ,um, n= 39). Walter (1992a) to comprise Satka-like microfossils with spongy lamellae. Judging from their description and their Remarks. - The genus Simia was introduced by accompanying illustrations, it seems that the 'sponginess' Mikhailova & Jankauskas (in Jankauskas et al. 1989). of the lamellae most probably is due to degradation. The Their definition of Simia is dose to that of the genus species is here placed in synonymy with S. colonialica Pterospermopsimorpha Timofeev emend. Mikhai1ova & Jankauskas. Jankauskas. After having examined the type material, G. Vida1 (pers. comm. 1996) arrived at the conclusion that Occurrence. - Satka colonialica is known from Upper the two taxa are separated primarily by the arrangement Riphean strata in Bashkiria, Russia (Jankauskas et al. of the outer envelope. Simia, in principle a double-walled 1989); the Chuar Group, Arizona, USA (Vidal & Ford sphaeromorph, is entirely surrounded by the outer wall 1985); the Veteranen Group in Spitsbergen (Knoll & in all directions, whereas Pterospermopsimorpha has its Swett 1985); the Bitter Springs Formation of the outer wall on1y present in the equatorial position (com­ Amadeus Basin in Australia (Zang & Walter 1992a) and pare the planet Saturn with its rings). However, it is the Liulaobei Formation in China (Yin & Sun 1994). In sometimes difficult to identify and recognize whether the the present material, the species is found in the Ier­ specimen recorded belongs to Simia or to Pterospermop­ novskaya, Chemorechenskaya, Poropelonskaya and simorpha. It may therefore be noted that among the Karuyarvinskaya Formations of the Kildinskaya Group microfossils attributed to Simia annulare herein, some on Kildin Island and Sredni Peninsula. Two specimens might in fact belong to Pterospermopsimorpha insolita attributed to Satka sp. were found within the Cher­ (T imofeev) Mikhailova. Most of the specimens here at­ norechenskaya and Karuyarvinskaya Formation of the tributed to S. annulare have a thick inner body (compare Kildinskaya Group on Sredni and within the Puman­ Figs. VI: 7-8 in Jankauskas et al. 1989). skaya Formation of the Volokovaya Group on Sredni The relationship between the overall (= outer) diame­ (Fig. 4). ter and the diameter of the inner body is directly propor­ tional (Fig. 8). All observed Simia fall on the same Stratigraphic range. - Upper Riphean (Jankauskas et al. correlation line, indicating that all of the recovered fos­ 1989). sils belong to the same taxonomic unit (Fig. 8). NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 177 8 c

F

H l

•

K

Fig. Chuaria circularis Walcott emend. Vida! Ford, Leiosphaeridia spp. (Eisenack ) Turner, Lophosphaeridium laufeldii (Vidal ) comb. nov. and Navifusa majensis 7. & Pyatiletov. A, D. Chuaria circularis Walcott emend. Vida! Ford. A. Eastern Coast of Visingsii Island, Sweden. Middle/Upper Visingsii unit, Upper Riphean. & Specimen V70-317A-I (C39-4). Specimen showing 'cerebroid' features on part of vesicle (Butterfield et al. 1994). Scale bar = 208 pm. D. Kumlaby borehole. Upper Visingsii unit. Specimen BV 4: 33-1 (R28-2). Another specimen showing 'cerebroid' features on part of the wall. Scale bar =210 pm. B, C, E. Leiosphaeridia spp. (Eisenack ) Turner. B. Sredni Peninsula. Karuyarvinskaya Formation. Specimen K91-23-l (F 34.-4). Thinwalled Leiosphaeridia spp. Scale bar =20 pm. C. Kildin Island. Chernorechenskaya Formation. Specimen K91-04-l (B52-4). Specimen showing median split. Scale bar = 20 pm. E. Sredni Peninsula. Karuyarvinskaya Formation. Specimen K91-23-2 (Q30). Thick-walled Leiosphaeridia spp. Scale bar = 13 pm. F; H, I. Lophosphaeridium laufeldii Vida! comb. nov. F. Sredni Peninsula. Karuyarvinskaya Formation. Specimen K91-22-l (T39). Scale bar =20 pm. H. Sredni Peninsula. Karuyarvinskaya Formation. Specimen K91-23-l (T35-3). Scale bar = 20 pm. I. Sredni Peninsula. Karuyarvinskaya Formation. Specimen K91-23-2 (C29-l ). Scale bar =20 pm. G, J, K. Navifusa majensis Pyatiletov. G. Sredni Peninsula. Pumanskaya Formation. Specimen K91-26-l (H45). Scale bar =20 pm. J. Sredni Peninsula. Poropelonskaya Formation. Specimen K91-l l-2 (S53-3). Scale bar = 20 pm. K. Sredni Peninsula. Karuyarvinskaya Formation. Specimen K91-23-l (042-3). Scale bar =17 pm. 178 J. Samue/sson NORSK GEOLOGISK TIDSSKRIFT 77 (1997)

80 1991 Sphaerocongregus variabilis Moorman-Moczyd­ lowska, p. 126, fig. 15: I 70 Simia annulare 1992a Sphaerocongregus variabilis Moorman-Zang & e Walter, p. 106, figs. 65: A-H ::t 60 1992b Sphaerocongregus variabilis Moorman-Zang & Walter, pp. 310-311, figs. 6: C-J, 14: G J-.4 .....Q) 50 Q) Material. - Twenty-one well-preserved and measured s 40 specimens. Twenty additional, poorly preserved spect­ ro ·� mens are referred to as Sphaerocongregus sp. "C 30 - - ro Description. - Acid-resistant, spherical or subspherieal 20 J-.4 duster of numerous tightly, sometimes irregularly packed Q) micrometer-sized spheroidal vesicles. The vesicles are o 10 homogeneous in size and appearance. Some of the dus­ ters are surrounded by a thin membrane. o o 10 20 30 40 50 60 70 Dimensions. - Diameter of aggregates ranges 13-26 pm. The diameter of the spheroidal vesicles is 0.5-1.2 pm. Diameter of inner body Jlm Mean diameter of aggregate= 17.3 pm (s.d.= 3.95 pm,

Fig. Relationship between the diameter of the inner body and the overall n = 21). 8. diameter of 39 measured Simia annulare. Remarks. - The specimens of Sphaerocongregus variabilis Occurrence. Simia annulare was reported by observed herein oeeur within a single sample, deriving Jankauskas et al. (1989) from Siberia and the Urals, from the Skarbeevskaya Formation, a deposit inter­ Russia. Vidal et al. (1993) reported the species from the preted as turbiditic (Siedlecka 1975; Lyubtsov et al. 1989; Khajpakh Formation, Yakutia. In the present material, Siedlecka 1995). Interestingly, specimens of S. variabilis Simia annulare was recovered from the Iernovskaya, observed by Mansuy & Vidal (1983) derive from tur­ Chernoreehenskaya, Pestzovozerskaya, Poropelonskaya biditie deposits, too, as do other observed S. variabilis and Karuyarvinskaya Formations of the Kildinskaya (e.g. Vidal 1981a; Vidal & Siedlecka 1983; Palacios Group on the Sredni Peninsula and Kildin Island and Medrano 1989; Vidal & Nystuen 1990a). Thus, the spee­ the Pumanskaya Formation of the Volokovaya Group imens found in the present material might be interpreted on Sredni (Fig. 4). The taxon was also found within the in agreement with the idea set forth by Mansuy & Vidal Chapoma Formation on the Tiersky Coast. Speeimens (1983) and other authors (e.g. Knoll et al. 1981; Palaeios attributed to Simia sp. were recovered from the same Medrano 1989; Vidal & Nystuen 1990a) that these mi­ geologieal units as S. annulare (Fig. 5). erofossils were planktonie and grew under harsh environ­ mental conditions. As an alternative, S. variabilis was Stratigraphic range. - Upper Riphean (Jankauskas et al. interpreted as an anoxygenie photosynthetie bacterium 1989; Vida1 et al. 1993). occupying S-rich waters of certain stratified suboxic H2 basins (Vidal & Nystuen 1990a), a view that may gain an Genus Sphaerocongregus Moorman, 1974. additional foothold considering reeent appreciation about the environmental conditions of the Proterozoic Type species. Sphaerocongregus variabilis Moorman, (Logan et al. 1995). 1974 Recently, Zang & Walter (1992a) established two new taxa, Sphaerocongregus ediacarus Zang & Walter and Sphaerocongregus variabilis Moorman, 1974 Fig. 9G Sphaerocongregus pertatatakus Zang & Walter. The spee­ imens depieted show an irregular aggregate shape sug­ See Vidal (1976a) and Palacios Medrano (1989) for gesting a variable level of degradation, even within a earlier synonymies. partieular specimen. These two species are here regarded as preservational variants of the type species. Zang & 1985 Bavlinella faveolata (Shepeleva)-Knoll & Swett, p. Walter (1992) also illustrated some objects in connection 462, figs. 51: 3-4 with their description of S. variabilis that clearly do not 1987 Bavlinel/a faveolata (Shepeleva) Vidal-Knoll & belong to this taxon, figs. 67H-J (not S. variabilis); figs. Swett, p. 910, figs. 5: 2-3 20: M-N (probably a non-biogenie object). 1989 Bavlinel/a faveo/ata Shepeleva-Jankauskas et al., p. 54, figs. 18: 7-8 Occurrence. - Sphaerocongregus variabilis is well known 1990a Sphaerocongregus variabilis Moorman-Vi dal & from occurrences world-wide. For references see Nystuen, p. 193, figs. 9: A-B, D-E, G-L Moorman (1974); Vidal (1976a); Knoll et al. (1981); NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 179

B c

D E

G H l

•

Fig. Satka colonia/ica Jankauskas, Sphaerocongregus variabilis Moonnan and Vandalosphaeridium ?varangeri Vida!. A, B. Satka co/onia/ica Jankauskas. A. Kildin 9. Island. Chernorechenskaya Formation. Specimen K91-0l-18 pm-4 (M33-l). Scale bar= 29 pm. B. Kildin Island. Chernorechenskaya Fonnation. Specimen K91-0l-18 pm-3 (L43-2). Scale bar= 56 pm. C-F. Simia annulare (Timofeev) Mikhailova. C. Kildin Island. Chernorechenskaya Fonnation. Specimen K91-0l-18 pm-4 (J42-4). Scale bar= 45 pm. D. Sredni Peninsula. Karuyarvinskaya Fonnation. SpecimenK91-22-l (G46). Scale bar= 20 pm. E. Kildin Island. Chernorechenskaya Fonnation. Specimen K91-0l-18 pm-3 (Z47-4). Scale bar= 20 pm. F. Sredni Peninsula. Karuyarvinskaya Fonnation. Specimen K91-23-l (Q47). Scale bar= 20 pm. G. Sphaerocongregus variabilis Moorman. Rybachi Peninsula. Skarbeevskaya Fonnation. Specimen K91-16B-2 (123-2). Scale bar= 28 pm. H, Vandalosphaeridium l. ?varangeri Vida!. H. Kildin Island. Chernorechenskaya Fonnation. Specimen K91-0l-18 ,um-3 (Z37-3). Scale bar= 20 pm. Kildin Island. Chernorechenskaya l. Fonnation. Specimen K91-0l-18 pm-3 (R38). Scale bar= 20 pm.

Mansuy & Vidal (1983); Knoll & Swett (1987); Palacios Vendian assemblages throughout the Northern hemi­ Medrano (1989); Jankauskas et al. (1989); Fensome et al. sphere but it is also found, although more scarcely, in the (1990); Vidal & Nystuen (1990a, 1990b) and Zang & Upper Riphean (Vidal 1976a; Vidal & Nystuen 1990a) Walter (1992b). Within the present material, a single and the Lower Cambrian (Knoll et al. 1981; Knoll & sample from the Skarbeevskaya Forrnation of the Ry­ Swett 1987; Vida! & Nystuen 1990b). bachi Peninsula yielded S. variabilis Moorrnan and spee­ imens referred to as Sphaerocongregus sp. (Fig. 4). Genus Tasmanites Newton, 1875.

Stratigraphic range. - According to Knoll & Swett (1987), Sphaerocongregus variabilis is characteristic of Type species. Tasmanites punctatus Newton, 1875 NORSK GEOLOGISK TIDSSKRIFT 180 J. Samuelsson 77 (1997)

Fig. Tasmanites rifejicus Jankauskas. Valeria Jophostriata Jankauskas and Trachysphaeridium laminaritum Timofeev. A. Tasmanites rifejicus Jankauskas. Sredni JO. Peninsula. Karuyarvinskaya Formation. Specimen K91-23-2 (K39-4). Scale bar= 52 pm. A'. Detail of vesicle surface showing pores. Scale bar= 1.36 pm. B, C. Valeria /ophostriata Jankauskas. B. Sredni Peninsula. Karuyarvinskaya Formation. Specimen K91-22-2 (G42). Scale bar= Il pm. C. Tiersky Coast. Chapoma Formation. Specimen K92-06-l (T50-2). Scale bar= 15 pm. D. Trachysphaeridium /aminaritum Timofeev. Kildin Island. Pestzovozerskaya Formation. Specimen K91-04-l (J53-3). Scale bar = 20 pm. 1983 Tasmanites rifejicus Jankauskas-Vidal & Siedlecka, Tasmanites rifejicus Jankauskas, 1978 Fig. lOA, A' figs. 5: A-B 1985 Tasmanites rifejicus Jankauskas-Knoll & Swett, p. 1978 Tasmanites rifejicus Jankauskas sp. nov. 465, fig. 53: Il Jankauskas, p. 914, figs. 1: 6-7 1989 Tasmanites rifejicusJankauskas-Jankauskas et al., p. 1981 Tasmanites rifejicus Jankauskas-Vidal, pp. 49-50 131 NORSK GEOLOGISK TIDSSKRIFT Early Neoproterozoic strata, Kola Peninsula 181 77 (1997)

Material. - A single moderately well-preserved specimen. tightly arranged roughly hemispherical shallow deptes- sions.

Description. - Acid-resistant, spherical, thick-walled vesicle. Owing to compaction, the vesicle is flattened and Dimensions. - Vesicle diameter 25-51 pm. the wall folded. The surface of the vesicle is covered in closely arranged pores, giving the vesicle a wavy appear­ Remarks. - The most prominent characteristic of Tra­ ance. The pores are rounded or slightly elliptical; varying chysphaeridium laminaritum is the alveolar, pseudo-retic­ between 0.5 pm and 1.5 pm in diameter and spaced at ular surface texture. Jankauskas (in Jankauskas et al. 2-3 pm intervals. 1989) transferred the species to the genus Leiosphaeridia. Concerning the alveolar vesicle wall structure, two alter­ Dimensions. - The diameter of the vesicle is 130 pm. natives are plausible: Either the structure is a tapho­ nomic imprint or a diagnostic feature. In regard to the Remarks. - Mainly based on ultrastructural evidence, similarity of the alveolar depressions of these specimens several authors were able to demonstrate that Tasmanites to pores of, for example, Tasmanites, the latter alterna­ is in fact a prasinophyte (e.g. Jux 1968, 1969; Boalch & tive seems to be the most probable. Until a taphonomic Parke 1971; Guy-Ohlson 1988; Boalch & Guy-Ohlson origin of the alveolar structure is demonstrated, these 1992). Regrettably, no ultrastructural investigations were palynomorphs should in my opinion not be grouped hitherto performed on Neoproterozoic specimens. There­ together with Leiosphaeridia spp., but retained within the fore, Tasmanites rifejicus is here kept within the original genus Trachysphaeridium Timofeev. acritarchs. Occurrence. - Trachysphaeridium laminaritum has been Occurrence. - Tasmanites rifejicus occurs in the Inzer reported from the Awatubi Member of the Kwagunt Formation in the southern Urals (Jankauskas 1978); the Formation and Red Pine Shale of the Uinta Mountain Klubbnasen and Andersby Formations of the Vadsø Group (Vidal & Ford 1985); the Visingso Group (Vidal Group in East Finnmark, Norway (Vidal 198 la; Vidal & 1976a); the Vadsø Group, Norway (Vidal 198 la); the Siedlecka 1983); the Jupiter Member of the Galeros Liulaobei, Shijia and Zhaowei Formations, China and Formation and the Red Pine Shale of the Uinta Moun­ the Gouhou Formation, China (Zang & Walter 1992b). tain Group (Vidal & Ford 1985) and the Veteranen For occurrences within Russia and surrounding areas see Group, Svalbard (Knoll & Swett 1985). The single speci­ Vidal (1976a). The two specimens recovered within the men recovered here derives from the Karuyarvinskaya present material derive from the Pestzovozerskaya For­ Formation of the Kildinskaya Group on Sredni (Fig. 4). mation of the Kildinskaya Group on Kildin Island, and from the Poropelonskaya Formation within the Kildin­ Stratigraphic range. - Upper Riphean sensu stricto skaya Group on Sredni (Fig. 4). (Vidal & Ford 1985). Stratigraphic range. - Upper Riphean and Vendian Genus Trachysphaeridium Timofeev, 1966. (Jankauskas et al. 1989).

Type species. Trachysphaeridium laminaritum Timofeev, Genus Valeria Jankauskas, 1982. 1966 Type species. Valeria lophostriata (Jankauskas 1979) Trachysphaeridium laminaritum Timofeev, 1966 Fig. JOD Jankauskas, 1982

See or (1985, p. 373) for earlier synonymies. Valeria lophostriata (Jankauskas, 1979) Jankauskas, 1982 Vida! & F d Fig. JOB, C 1989 Leiosphaeridia laminarita (Timofeev) Jankauskas See Hofmann & Jackson (1996, p. 16) for synonymies. comb. nov. in Jankauskas et al., p. 78, figs. 11: 11-13 1992 Leiosphaeridia laminarita (Timofeev) Jankauskas­ Material. - Eight well-preserved specimens, and one Zang & Walter, 1992a, p. 64, figs. 52: H; 54: C poorly preserved specimen attributed to Valeria sp. 1992 Leiosphaeridia laminarita (Timofeev) Jankauskas­ Zang & Walter, 1992b, p. 295 figs. 10: H-J Description. - Acid-resistant, circular to subcircular, or­ ganic vesicles with medium wall thickness. The vesicle is Material. - Two moderately well-preserved specimens. covered in a diagnostic polarly arranged, hemispherical One poorer preserved specimen is here attributed to sculptural pattern, which consists of parallel, tightly Trachysphaeridium ?laminaritum. packed striae. The striae are extremely thin, probably less than 0.25 pm. Description. - Acid-resistant organic-walled vesicles cir­ cular to ovoid in outline. The vesicle is thick and dense Dimensions. - Vesicle diameter is 16-100 pm. Mean and displays an alveolar wall structure, which consists of diameter= 70.9 .um (s.d. = 25.9 .um, n = 8). 182 J. Samuelsson NORSK GEOLOGISK TIDSSKRIFT 77 (1997)

Remarks. - The characteristic surface scu1pture of Vale­ Description. - Acid-resistant organic microfossil consist­ ria lophostriata makes it readi1y recognizab1e and very ing of a thick, massive smooth inner body surrounded by significant from a biostratigraphica1 point of view an outer spongy membrane. The membrane is supported (Butterfie1d & Chand1er 1992). However, among the by simple processes. smaller specimens it is sometimes rather difficult to rec­ ognize the individual granulae that seem to build up the Dimensions. - Diameter of inner body is 17-21 fliD. striated pattern on larger, fragmentary specimens. Diameter including membrane 21 -22 11m.

Occurrence. - Valeria /ophostriata occurs within the Zi­ Remarks. - Two of the specimens show clear similarities galgi and Zigazino - Komarovo Formations, southern to the type species, Vandalosphaeridium varangeri. Owing Urals, Bashkiria (Jankauskas 1979); the Klubbnasen and to their poor preservation, however, these specimens of Andersby Formations of the Vadsø Group, Norway Vanda/osphaeridium are uncertainly determined to the (Vidal 1981a); the Båsnæring and Båtsfjord Formations species level. of the Barents Sea Group, Norway (Vidal & Siedlecka 1983); the upper Visingso Group, Sweden (Vidal & Occurrence. - Vandalosphaeridium varangeri was hitherto Siedlecka 1983); the Galeros and Kwagunt Formations reported from the Dundas and Nassiirssuk Formation of of the Chuar Group, Arizona, USA (Vidal & Ford the Thule Group in East Greenland (Vidal & Dawes 1985); the Wolstenholme and Dundas Formations of the 1980); the Ekkerøy, Dakkovarre and Grasdal Forma­ Thule Group, Greenland (Dawes & Vidal 1985); the Agu tions in Varanger Peninsula, northern Norway (Vidal Bay Formation of the Fury and Hecla Group, Canada 1981 a) and the Biskopåsen Formation and Moelv Tillite (Butterfie1d & Chandler 1992); the Arctic Bay Formation of the Hedmark Group, southern Norway (Vidal & of the Eqalulik Group, the Fabricius Fiord Formation Nystuen 1990a). The specimens in this material derive and the Society Cliffs Formation of the Uluksan Group, from the Chernorechenskaya Formation within the all of the Bylot Supergroup, Canada (Hofmann & Jack­ Kildinskaya Group on Kildin Island (Fig. 4). son 1994) and the White Pine Shale of the Nonesuch Formation, central USA (Vidal, unpublished data). In Stratigraphic range. - Upper Riphean and Lower Ven­ the present material, the species is known from two dian (= Terminal Riphean R4; Vidal & Nystuen 1990a). samples from the Karuyarvinskaya Formation of the Kildinskaya Group on Sredni and from one sample of the Chapoma Formation on the Tiersky Coast (Figs. 7, Additional microfossils 8). The specimen attributed to Valeria sp. was recovered from one sample from the Chapoma Formation. Clustered sphaeromorphs are common in the present material. Most of them are morphologically simple, and Stratigraphic range. - Valeria lophostriata is known from seem to be the clustered counterparts to individually Upper Riphean localities world-wide (Jankauskas et al. preserved Leiosphaeridia spp. Eisenack (196 5) erected the 1989). Additionally, Hofmann & Jackson (1994) re­ genus Synsphaeridium to incorporate smooth leiospheres ported it from the somewhat older (1270-750 Ma) Bylot Supergroup, Canada. The correct stratigraphic range is probab1y upper Midd1e Riphean to Upper Riphean 20 (Butterfie1d & Chandler 19 92). . robustum 18 Siphonophycus Ill 16 Genus Vanda/osphaeridium Vidal, 1981. r:: cu 14 .....a �S.rugosum V Type species. Vandalosphaeridium reticulatum (Vidal, 12 cu l �.kestron 1976 ) Vidal, 1981 ø.ø - 10 l l Vandalosphaeridium ?varangeri Vidal, 1981 Fig. 9H, I �o 8 l cu ..0 6 l a 1981 Vandalosphaeridium varangeri Vi dal sp. nov.-Vi dal, 4 l = S. capitaneum 1981a, pp. 38-39, figs. 18: A-I z l 1990 Vandalosphaeridium varangeri Vidal-Vidal & 2 l Nystuen, 1990a, pp. 197-198, figs. 12: C-C' o o 10 20 30 40 50 Material. - Two poorly preserved specimens are at­ Measured width of compressed filament (J.llll) tributed to Vandalosphaeridium ?varangeri. Another Fig. Size distribution of tubular microfossils assigned to Siphonophycus spp. specimen in an extremely poor state of preservation 11. Subdivision of the taxon to species leve! made according to Hofmann Jackson & is attributed to Vandalosphaeridium sp. (1994). NORSK GEOLOGISK TIDSSKRIFT Early Neoproterozoic strata, Kola Peninsula 77 (1997) 183

that are aggregated without any identifiable order. Other mens of Siphonophycus within the present assemblages to taxa have been described that also incorporate the species level in the size-distribution diagram of sphaeroidal microfossils of the leiosphaerid type (e.g. Siphonophycus spp. (Fig. 11). Symp/assosphaeridium spp.). Symplassosphaeridium is dis­ Specimens of Siphonophycus are common in benthic tinguished from Synsphaeridium on the basis of its rela­ mat communities (Hofmann & Jackson 1994). Within tively smaller spheroids and its more regular overall the samples examined herein, they are found together appearance (Hofmann & Jackson 1994). Stictosphaerid­ with presumably planktonic acritarchs, and are at times ium Timofeev is another genus consisting of small (20- clustered into balls. Thus, they are most probably not in 80 Jl.m across; Jankauskas et al. 1989), thin-walled situ, an interpretation that might explain why almost all aggregated spheroids without surface sculpture (Vidal Siphonophycus spp. are fragmentary. 1976a; Vidal & Ford 1985). Vidal (1976a) regarded Stic­ tosphaeridium spp. as a wastebasket group. As a conse­ quence, Stictosphaeridium spp. might be regarded as Palaeoenvironmental distribution of synonymous with Leiosphaeridia spp., as no feature ex- microfossils • cept for the clustering habit of Stictosphaeridium separate the two genera. In the Early Neoproterozoic, the ecosystems were proba­ Within the present material, aggregates that are made bly already complex, but for taphonomic reasons only a up of thick-walled smooth spheroids with crescent­ minor part of the contributing taxa is preserved in the shaped longitudinal folds are attributed to Synsphaerid­ fossil record (Vidal 1994). Nevertheless, Neoproterozoic ium spp. (Fig. 14A, B), and aggregates made up of rocks representing substantially all marine sedimentary thin-walled smooth spheroids are attributed to Stic­ palaeoenvironments contain well-documented and di­ tosphaeridium spp. (Fig. 12C-E). Whenever the same verse organic-walled microfossil assemblages, including spheroids are found isolated they are attributed to cyanobacteria (Vidal & Knoll 1983; Knoll 1984; Vidal & Leiosphaeridia spp. The taxon Symplassosphaeridium spp. Nystuen 1990a; Knoll et al. 1991). Present-day organisms is here regarded as conspecific with Synsphaeridium spp. have specific preferences concerning habitat, and this is As stated by Hofmann & Jackson (1994), both Syn­ also inferred to exist in the past and demonstrated by sphaeridium spp. Eisenack and Symplassosphaeridium spatia! relationship between the distribution of microfos­ spp. Timofeev have long stratigraphic ranges which sil taxa and lithologica1 facies (e.g. Vidal & Knoll 1983; make them of less value for biostratigraphy. However, Mansuy & Vida! 1983; Knoll et al. 1991; Butterfield & they are significant components in pre-Varangerian Chandler 1992; Butterfield et al. 1994). This feature must acritarch assemblages and are rare in younger strata (G. be considered before the biostratigraphic significance of Vidal, pers. comm. 1996). recovered microfossil assemblages can be estimated The present assemblage contains numerous tubular (Knoll & Swett 1985; Butterfield & Chandler 1992). microfossils, interpreted as sheaths of a bacterial or However, the correlation between microfossil distribu­ cyanobacterial origin. All are compressed and un­ tion, facies and depositional environment ('palynofacies') branched, and the majority are fragmentary and non­ is not straightforward. The factors affecting the distribu­ septate. These are attributed to the form-genus tion and preservation of fossil microbiotas can be di­ Siphonophycus Schopf 1968 (Fig. 12F, G). Some of the vided into two broad categories; primary {including sheaths within the present assemblage are septate (Fig. physical, chemical and biological effects) and secondary 12H), and are attributed to the genus Oscillatoriopsis (taphonomic) factors. Schopf 1968. Butterfield et al. (1994, p. 56) emended the In present-day environments, primary factors that af­ genus Oscil/atoriopsis Schopf and excluded 'pseudo-sep­ feet the distribution of micro-organisms are related to tate' filaments. The specimens observed herein, however, climatic beits, water depth, co2 and oxygen concentra­ show no signs of being anything other than truly septate. tions, nutrient supply, wave and current actions, intra­ In the case of Siphonophycus spp., five different form and interspecific competition and physical barriers. The species were recognized in the Bylot Supergroup, Baffin interaction of these factors is comp1ex, and they certainly Island, Canada by Hofmann & Jackson (1994) on the were important for the pattern of distributions of basis of arbitrarily chosen sheath widths (see also Knoll micro-organisms in the remote past (Knoll et al. 1991; et al. 1991). Butterfield et al. (1994) recognized six differ­ Moczydlowska & Vidal 1992). Therefore, the evaluation ent species of Siphonophycus based on somewhat differ­ of microfossil distributions (especially planktonic) is as­ ent criteria than Hofmann & Jackson (1994). Zang & sociated with considerable uncertainties (Moczydlowska Walter (1992b) attributed similar tubular fossils to three & Vidal 1992). Additionally, the fossil record of bacteria different genera, as opposed to different species. In this and protists is, and must be, incomplete and severely paper, the division by Hofmann & Jackson is followed. distorted through burial and preservational factors Siphonophycus spp. and Oscillatoriopsis spp. are well (Vidal & Moczydlowska 1992; Vida! 1994). For instance, known from Late Proterozoic settings world-wide, and not all micro-organisms produce preservable structures; are of limited biostratigraphic importance (Hofmann & thus some organisms and parts of organisms are more Jackson 1994). Therefore, I have only attributed speci- likely to be preserved than others. Certain organic-walled NORSK GEOLOGISK TIDSSKRIFT 184 J. Samuelsson 77 (1997)

A B

D

Fig. Synsphaeridium spp. Eisenack, Stictosphaeridium spp. Timofeev, Siphonophycus spp. Schopf and Oscillatoriopsis spp. Schopf. A, B. Synsphaeridium spp. 12. Eisenack. A. Kildin Island. Chemorechenskaya Formation. Specimen K91-0l-18 pm-4 (K42). Scale bar= 45 pm. Sredni Peninsula. Karuyarvinskaya Formation. B. Specimen K91-22-2 (H5 1-3). Scale bar= 20 pm. C-E. Stictosphaeridium spp. Timofeev. C. Tiersky Coast. Chapoma Formation. Specimen K92-06-l (Z4 1). Scale bar= 36 pm. D. Sredni Peninsula. Poropelonskaya Formation. Specimen K91-l l-l (J55-l). Scale bar= 12 pm. E. Tiersky Coast. Chapoma Formation. Specimen K92-12-l (P29-2). Scale bar= 16 pm. F, G. Siphonophycus spp. Schopf. F. Tiersky Coast. Chapoma Formation. Specimen K92-06-l (E44-3). Scale bar= 26 pm. G. Kildin Island. Pestzovozerskaya Formation. Specimen K91-04-l (Z42-4). Scale bar= 25 pm. H. Oscillatoriopsis spp. Schopf. Kildin Island. Chernorechenskaya Formation. Specimen K91-0l-94 pm-2 (K31-4). Scale bar= 21 pm. NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 185

microfossils are composed of a sporopollenine-like mate­ Sredni Peninsula and Kildin Island as constituting various rial that is mechanically resistant and chemically inert, parts of a deltaic system. The microfossil assemblages except to oxidation and carbonization (Martin 1993). recovered from these units (i.e. the Iernovskaya, Poro­ The envelopes of other micro-organisms are made of pelonskaya, Karuyarvinskaya and Pumanskaya Forma­ more perishable materials, such as cellulose, which is less tions on Sredni and the Chernorechenskaya and likely to be incorporated in the fossil record. This feature Pestzovozerskaya Formations on Kildin Island) are gener­ tends to distort the record of microbial life (Vidal 1994). ally more diverse and derive from more fossiliferous The preservational potential of the palaeoenvironment is samples than those from the turbiditic and shallow-marine another important factor to consider. Certain environ­ settings (Figs. 4-5). In fossiliferous samples, on average ments (i.e. anoxic) are more favourable for the preserva­ 4.84 microfossil taxa were preserved per sample in the tion of organic-walled micro-organisms and organic deltaic settings in comparison to 1.83 and 4.00 microfossil matter than others (Farrimond & Eglinton 1990; Knoll taxa on average for the turbiditic and shallow-marine et al. 1991). The sedimentation rate is also important for settings respectively. Apart from the dominating taxa the preservational potential of a sediment (Butterfield et Leiosphaeridia spp., the assemblages obtained from the al. 1994). In some instances, the preservation of the deltaic settings yielded a reasonable, if not large, variety of sediments themselves is the most constraining factor for pteromorphic and sphaeromorphic acritarchs and tubular survival of buried fossils (Veizer 1992). The preserva­ microfossils. Interestingly, the tubular microfossil Oscilla­ tional potential of different facies is highly variable. For toriopsis spp. was exclusively recovered in the deltaic type example, recrystallized carbonate-dominated facies usu­ of setting. The modem Oscillatoriaceaean genus Oscillato­ ally yield very few or no microfossils (Horodyski 1993; ria occupies a wide variety of environments, ranging from Hofmann & Jackson 1994), whereas siliciclastic facies planktonic freshwater to marine benthic saltmarshes (Carr very often contain both diverse and exceptionally pre­ & Whitton 1982), but just like other cyanobacteria, served microbiota (Zang & Walter 1992a; Jankauskas et individual species generally occur in a relatively restricted al. 1989; Knoll et al. 1991; Horodyski 1993; Martin range of environments (Knoll & Golubic 1992). It is an 1993). My results are consistent with this observation. open question, however, whether the Oscillatoriopsis spp. It should be noted, however, that diagenetic chert recovered herein belong to the same species. and phosphorites often contain exceptionally preserved The greatest taxonomic diversity among the sections microbiotas (see Moczydlowska & Vidal 1992 and refer­ examined is in the Karuyarvinskaya Formation, inter­ ences therein). Other taphonomic factors negatively af­ preted by Siedlecka et al. (1995a) as sabkha-type tidal fecting the preservation of micro-organisms include flats associated with deltaic environments. In the Bylot biodegradation, mechanical fragmentation and photoly­ Supergroup, Canada, Hofmann & Jackson (1994) ob­ sis (Butterfield et al. 1994). For micro-organisms, none of served a similar pattern, as microfossil species diversity these taphonomic processes are random or even uniform was greatest in shallow-water, i.e. intertidal to supratidal, (Knoll & Golubic 1992). evaporitic settings. They interpreted their observations as Despite the uncertainties associated with the estimation partly reflecting taphonomic factors such as the preserva­ of factors affecting the spatia! distribution and preserva­ tive effects of saline waters. tion of microfossils, it is generally agreed that Proterozoic The stratigraphic section on the Rybachi Peninsula microfossil assemblages are facies dependent (Knoll & was interpreted by Siedlecka et al. (1995b) as represent­ Vidal 1983; Knoll 1984; Knoll & Swett 1985; Vidal & ing a basinal turbidite system overlain by upper slope Nystuen 1990a; Knoll et al. 1991; Butterfield & Chandler deposits. Vidal (1979, 1981b) noted a direct correlation 1992; Hofmann & Jackson 1994; Butterfield et al. 1994), between the state of preservation and the energy of the although some examples are known where no clear litho­ environment and the associated potential for reworking. and palynofacies relationships can be explained Thus, if the turbiditic system on Rybachi represents the (Moczydlowska 1991; Moczydlowska & Vidal 1992). environment with the predominantly high, and by com­ The sequences on the Sredni and Rybachi Peninsulas, parison the overall highest energy level, the turbiditic the Kildin Island and Tiersky Coast examined here can sediments should contain relative1y fewer and more broadly be categorized into three different depositional poorly preserved microfossils than the lower energy en­ environments; deltaic, deep-water turbiditic and shallow­ vironments do. Six samples from turbiditic settings, marine. It was on1y the fine-grained siliciclastic samples mudstones of the Motovskaya (interpreted as a turbidite­ that yielded microfossils (with the sole exception of a associated olistostrome) and Perevalnaya Formations of phosphorite; see 'Appendix'). Comparison of assem­ the Einovskaya Group and the Skarbeevskaya Forma­ blages from the three environments was thus influenced tion on Rybachi yielded microfossils. The recovered mi­ by energy level and not affected by other sedimentologi­ crofossils in these samples show few microfossil taxa, in cal parameters. a poor state of preservation. However, this might mainly Generally, microfossil preservation has been observed be due to the stronger lithification and more intense to be relatively good in deltaic settings (Horodyski et al. folding of the rocks on Rybachi than the rocks on 1992 and references therein). Siedlecka et al. (1995a) Sredni, Kildin and Tiersky Coast (see 'Geological set­ tentatively interpreted the Late Riphean sequences on the ting'). Nevertheless, the nature of the recovered micro- 186 J. Samuelsson NORSK GEOLOGISK TIDSSKRIFT 77 (1997) fossils from Rybachi is as the reasoning above predicts, eies-dependent. However, in disparate sedimentary which makes the lithification and falding to be the sole basins, the same conditions might occur. The question is factors affecting the composition less probable. Note­ thus whether there is a correlation between microfossil worthy, for example, is the Jack of tubular microfossils in distribution and large-scale, palaeogeographic settings in the fossiliferous samples from the turbiditic settings on the Early Neoproterozoic. the Rybachi Peninsula. Well-preserved fossils of this type To illustrate the distribution of microfossil taxa in the usually occur in near-shore environments and thus Late Riphean, a simplified and taxonomically somewhat should be absent from turbiditic settings (Knoll et al. revised summary of the microfossils obtained from 42 1991; Butterfield & Chandler 1992; Hofmann & Jackson formations within the proximity of Baltica is illustrated 1994). The Skarbeevskaya Formation, also interpreted as (Fig. 13). The data set is roughly divided into passive turbiditic, is separated from the Einovskaya Group by a 'continental margin' and 'intracratonic settings' respec­ fault and it is uncertain whether it is part of the same tively. The division was made under the assumption that turbidite system. One sample from the Skarbeevskaya an intracratonic setting represents a more restricted envi­ Formation contained Sp haerocongregus variabilis Moor­ ronment than a continental margin does. Thus, if the man, a characteristic fossil from other turbiditic settings Early Neoproterozoic micro-organisms were provincial, (see further discussion under S. variabilis in the section the distribution of microfossils should be different in the on 'Systematic micropalaeontology'). two types of settings. The Chapoma Formation is tentatively interpreted as However, of the reported taxa in Fig. 13, one-third an intracratonic shallow-water deposit (see 'Geological were recovered from a single formation. Of the remain­ setting'). In comparison to the other units examined ing two-thirds, only six taxa did not occur in both a herein, it contains an intermediate diverse microfossil passive continental margin and intracratonic settings. assemblage (Fig. 5). Same taxa recovered from the Taking into consideration that passive continental mar­ deltaic settings on the Sredni Peninsula such as Lopho­ gin environments dominate on Baltica in comparison to sp haeridium laufeldii, Satka colonialica, Tasmanites rifeji­ intracratonic settings, no specific microfossil assemblage cus and Vandalosphaeridium ?varangeri were not can be considered as characteristic of any of the two recovered from the Chapoma Formation. A possible settings (leaving the possibility apen that certain taxa exp1anation for this observation can be that the sedimen­ might be). This observation is in agreement with the tary conditions of the Chapoma Formation did not inferred cosmopolitan nature of most Late Proterozoic favour preservation of these taxa, or that the taxa were microfossils (Vidal & Ford 1985). simply absent in this particular environment. No taxa were found in the Chapoma Formation that were not also recovered from the other settings. Stratigraphy and correlation In summary, the correlation between facies, deposi­ tional environment and microfossil distribution is partly The taxonomic evaluation indicates that the recovered in accordance with previous observations and suggested microfossils constitute associations comparable with mi­ models (Vida! & Knoll 1983; Knoll 1984; Palacios crobiotas reported from Upper Riphean ( = Riphean 3 Medrano 1989; Vida! & Nystuen 1990a; Knoll et al. 1991; and 4) rock units of the North Atlantic region and Butterfield & Chandler 1992; Hofmann & Jackson 1994). elsewhere (e.g. Vida! 1976 a, 1979; Dawes & Vidal 1985; The most general models of palaeoecological distribu­ Knoll 1981, 1982b; Knoll & Calder 1983; Knoll & Swett tion of microbiota suggest only that low-diversity assem­ 1985; Jankauskas et al. 198 9; Butterfield et al. 1994). blages of microfossil taxa occur in inshore coastal With but a few exceptions, most other authors that have environments, while higher diversity assemblages indicate worked in this area have reported similar ages (e.g. more apen shelf conditions (Vida! & Knoll 1983). Other Timofeev 1969; Siedlecka 1975, 1995; Vida! 1981a; Vidal general models attempt to explain differences between & Siedlecka 1983; Lyubtsov et al. 1989). An outline of microfossil distribution in basinal non-turbiditic and tur­ the stratigraphic positions of the examined Lower biditic sequences (Palacios Medrano 1989; Vida! & Neoproterozoic strata of the Murmansk and Tiersky Nystuen 1990a). The most detailed models recognize a Coasts and the correlation with same of the most impor­ number of distinct biofacies zones (Knoll et al. 1991; tant Neoproterozoic sequences in the proximity of Butterfield & Chandler 1992). The assemblages examined Baltica are depicted in Fig. 14. herein are best compared with the more general models, On Sredni Peninsula and Kildin Island, the presence of partly because of the limited number of fossiliferous biostratigraphically significant microfossils in samples samples and the preservation of the fossil assemblages. from the Kildinskaya Group, i.e. Lophosphaeridium laufeldii (Vidal) Samuelsson comb. nov., Satka colonial­ ica Jankauskas, Simia annulare (Timofeev) Mikhailova, Tasmanites rifejicus Valeria lophostriata Microfossil provincialism in the Early Neoproterozoic Jankauskas, Jankauskas and Vandalosphaeridum ?varangeri Vida!, As discussed above, the distribution of Late Riphean supports Siedlecka's (1995) interpretation of a Late microfossil assemblages is palaeoenvironment- and fa- Riphean R3 age for the Kildinskaya Group. The pres- NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 187

PASSIVE CONTINENTAL MARGIN INTRACRATON Murmansk Coast BSR NyFriesland Nordaust Greenland EFinnmark Ti SE Nor Swed TAXA Kildin V Ein Bar Sea Veteranen A kad Fran Cels Ro L U Eleonore Vadsø Tana Heamark Visingsi:i l 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

Bracl!yplega•wn klumdanum • CTwaria CJrcularis • •••• •• • ? • ? •••••• •• •• • ••• Cymatiosplraeroides spp. • • Dictvotidium {ullerene • auosospl�aenawm spp. • • Germinosplraera spp. • I..eiosplraeridia spp. •••• • •• • • • •••• •• •• ••• • •• ••• ••• • ••• ••• Lop�;{,�pl!aeridium laufeldii • •••• •• Naui 1sa majensis •• • ? • Octoedryxium trzmcatum • •• • Oscu/ospl!aera l!yalina • Peteinospltaeridium reticulatum • Plranerosplraerops capita11s • Podolina minuta • rotosplraeridi�m tu�erw erum !y, • Pterospernwpszmorpl!a mogzleuzca • • • Pterospernwpszmorplra concmtrzca • Pterospernwpsimorpl!a cf. densicoroiiQta •• • • •• Satka colonia/ica •••• • •• mua annu are •••• • • Splraeroconff,regus variabilis •• •• ••• •••• • cf. Stietosp Jaeridium spp. •••• • • • •• • •• ••• ••• •••• • • •• �nsplraeridium spp. • ••• ••• •• •• • •••• ••• • • •• asmani les �ifejicus ? •• rac zy zystrzc wspl!aera azmika •• Traclzysplzaeridium sp. •• • • Traclzysphaeridium apertum • Traclzyspal!eridillm limzinaritum • •••• • .: . Tracliyspl!aeridillm Ievis •• • • •••• ••• Trachysr,haeridium timofeeuii • cf. •• ••• ••• Valerza 'thostriata • • • Valkyria area/is • Vandalosphaeridium uarangeri ? •••• SPHAEROMORFHS INDET • •••• •••• ••• CLUSTERED SPHERES • ••• SPINY ACRITARCHS • • CHROOCOCCALEAN •• • • TUBULAR FILAMENTS ••• • •••• •• • • • • •

Fig. 13. Diagram showing presence of microfossil taxa in a number of Late Riphean formations in the proximity of Baltica. Filled circles denote presence of microfossil taxa, question-mark uncertainty, e.f. denotes provisional identification. Data have been adopted from various sources. The taxonomy of the reported microfossils from the respective fo rmations has been slightly revised mainly according to Jankauskas et al. (1989) and Hofmann & Jackson (1994). Abbreviations: BSR = Barents Sea Region; Nordaust=Nordaustlandet; Ti= Tiersky Coast; S E Nor= Southeastem Norway; Swed = Sweden; V=Volokovaya Group; Ein = Einovskaya Group; Bar Sea= Barents Sea Group; Akad= Akademikerbreen Group; Fran = Franklinsundet Group; Cels = Celsiusberget Group; Ro = Roaldtoppen Group; L= Lower Eleonore Bay Group; U Eleonore= Upper Eleonore Bay Group; Tanafj =Tanafjorden Group. The numbers on the figure refer to the following fo rmations (reference within parentheses): l. lernovskaya (this paper), 2. Chemorechenskaya (thls paper), 3. Poropelonskaya and Pestzovozerskaya Formations (this paper), 4. Karuyarvinskaya (this paper), 5. Pumanskaya (this paper), 6. Motovskaya (this paper), 7. Perevalnaya (this paper), 8. Skarbeevskaya (this paper), 9. Kongsfjord (Vida! & Siedlecka 1983), 10. Båsnæringen (Vida! & Siedlecka 1983), Il. Båtsfjord (Vida! & Siedlecka 1983), 12. Kortbreen (Knoll & Swett 1985), 13. Kingbreen (Knoll & Swett 1985), 14. Glasgowbreen (Knoll & Swett 1985), 15. Oxfordbreen (Knoll & Swett 1985), 16. Svanbergfjellet (Butterfield et al. 1994), 17. Draken (Knoll et al. 1991), 18. Westmanbukta (Knoll 1982b), 19. Kapp Lord (Knoll l982b), 20. Flora (Knoll l982b), 21. Norvick (Knoll l982b), 22. Hunnberg + Rysso (Knoll l982b), 23. Lower Eleonore Bay Group (Vida! 1979), 24. Quarzite series (Vida! 1979), 25. Multicoloured series (Vida! 1979), 26. Lower Limestone-Dolomite series (Vida! 1979), 27. Upper Limestone-Dolomite series (Vida! 1979), 28. Klubbnasen (Vida! 198Ia), 29. Andersby (Vida! 198la), 30. Golneselv (Vida! 198la), 31. Ekkerøy (Vida! 198la), 32. Stangenes (Vida! 198la), 33. Dakkovarre (Vida! 198la), 34. Grasdal (Vida! 198la), 35. Chapoma Formation (thls paper), 36. Brøttum (Vida! & Nystuen 1990a), 37. Biskopåsen (Vida! & Nystuen 1990a), 38. Biri (Vida! & Nystuen 1990a), 39. Ring (Vida! & Nystuen 1990a), 40. Lower Visingso Group (Vida! 1976a), 41. Middle Visingso Group (Vida! 1976a), 42. Upper Visingso Group (Vida! 1976a).

ence of less biostratigraphically important taxa, i.e. Stic­ earlier proposed Terminal Riphean R4 age for the tosphaeridium spp. in this unit further corroborates the Volokovaya Group cannot therefore be ruled out Late Riphean age. The acritarch Valeria lophostriata (Siedlecka 1995). The presence of these two taxa in the deserves special attention, as it most characteristically Pumanskaya Formation is here interpreted as indicative occurs during the first one-third of the Late Riphean of a minimum Late Riphean R3 age for the Volokovaya (Butterfield & Chandler 1992 ). In the Kildinskaya Group. Group, it was recovered only from the stratigraphically Regrettably, the microfossils recovered from the two youngest unit on Sredni, the Karuyarvinskaya Forma­ fossiliferous samples of the Einovskaya Group on Ry­ tion. In a preliminary report, Samuelsson (1995) inferred bachi did not yield any biostratigraphically useful taxa the Karuyarvinskaya Formation as being of Terminal (Fig. 4). The same applies to the microfossil assemblage Riphean ( = Kudashian R4) age. Subsequently, Siedlecka of the Skarbeevskaya Formation, although the presence (1995) followed this interpretation. However, the pres­ of the microfossil taxa Stictosphaeridium spp. and Sp hae­ ence of Valeria lophostriata within the Karuyarvinskaya rocongregus variabilis Moorman is weakly indicative of a Formation points at a younger, Late Riphean R3 age. Terminal RipheanjVendian age. The Pumanskaya Formation of the Volokovaya The biostratigraphically significant microfossils recov­ Group on Sredni yielded biostratigraphically significant ered from the Chapoma Formation, Tiersky Coast, acritarchs attributable to Satka sp. and Simia annulare Simia annulare (Timofeev) Mikhailova and Valeria (Timofeev) Mikhailova. Based on lithostratigraphy, the lophostriata Jankauskas, suggest a Late Riphean R3 age 188 J. Samuelsson NORSK GEOLOGISK TIDSSKRIFT 77 (1997)

TANAFJORD- LBARD ARD BARENTS SOUTH- � �; � EAST 50\JTHERN onostr SREDNI KILDIN RYBACHI TIERSKY VARANGER- SOUTH R � SEA EAST GREENLAND M PENINSULA PENINSULA COAST SWEDEN URALS a units ISLAND REGION FJORD NORWAY FRIESLAND AUSTLANDE1 Z � BER!.O- SALUM OSLO ? GAISSA HfMALE BREEN KAPPE 510 GRO UP i;2 SPARKE OWOVlCIANCAMBRD­ LØKVIK­ KlSTEDAL FORMATION "'1-----t 'HOl.MIA 540-550 ROCKS FJELLET � DUOLBAS SERIES� Ma GROUP GAISSA 0.. BREIVIKA 560 >640 �1-ST-AP-P0---1 V � ? �ÅS i!j :ii'G� ZIGAN Ma Z ill[612±18 DRA OISEN ., ��GlEDDE "' C '-' � SPCANYONIAALCR �--KUK· MOELVFM � � � R ��E � =��L ? § r----- 8 SVFANO � �±7 � SKARilEEV� r------t>==s�==�=o=w� � B �N-;;:- =uffi!C � H 650 KAYA ��J-����r-�EL�OO�BRE�rn�_Es�ACKA�B��G1FJjEtv�æø�f��KUu ����RG FM UPPER LRING FM VISINGSO TANA p.. ;;;) slRI GROUP VOLO­ ? FJORD FM....":;[:"',...-.., KOVAYA GROUP 2 fl 707±37 � A GROUP tJ Ma ? Q �;rnON .!... ..: FORMA 830±68 1------1� �----i,_Z'TB::-':"A:::CCKL::-':"U::":ND::-1� BLS��åiEN Ø tJ Ma ::E RY S EKKERØYA FM I.IJ � S ffi1-----t o �t-:.lli-TOPPEN i!i FORMA TION UPPER < W co t ELEONORE � UK TYVJOFJELL :X: � FMDRAKEN e FORMATJON MIDDLE t'; 9 c:�iJP 688±10 BATS- GSO ::!:: SvANBERGFJELLET <- -- Ma FJORD vg�UP as_ � _ fil 0.. FM §l BRØT- O 680 ;2 HUNNBERG MIN'YAR CHAPOMA 5 -- TUM G�\:i��v FORMATION � KILDIN FM gf-OLN -Lv-1ES-E fM FORMATION KILDIN P:: Cl Y FM < 680-802 GROUP PADDEB . GROUP l-::-:-::==-11----i � BÅSNÆR �� 1-----tiiJ 0i.'i'.",." 1----tB-�- INGEN FIJGLE- CE S � .... � c�... ��"ei":LSRJ oo: 1050-619 FM > -o w Fo RMAnON l 1015-849 BERGET 00: .N - "-+-;:RAN:::-;:::KUN:-;::--l g- - Ill Ma � F LO ER � ��R'� BARGOUT- O ER W Ma L- - N-W - ..- -l� � ;;; s=: 1-V IS I GSO -----+-- -! ELE�..t;,ORE � PO��.'i�N � KONGS- K�== ? � ,..J ���� ? 1-L...;BOTN=��M"807±119'-- -=---t GROUP ---- � "" FJORD ------t ? GROUP :.0: m'MEWAK EINOVS- 000- KAYA 810±19 ;•-==� PORMATION950-1000 basementbasement 88�Ma � basement lbasement Ma

Fig. 14. Stratigraphic correlation diagram of important Late Riphean-Early Ordovician outcrop areas in the North Atlantic Region. The correlations are based on: this paper for the Tiersky Coast and the Skarbeevskaya Formation (Rybachi Peninsula); this paper and Siedlecka (1995) for the Sredi Peninsula, Kildin Island and the Rybachi Peninsula; Siedlecka (1995) for the Barents Sea Region and the Tanafjorden-Varangerfjorden Region; Vida) & Moczydlowska (1995) for the South Central Norway and South Sweden; Hambrey (1982) for Ny Friesland and Nordaustlandet in Svalbard; Vida) (1979), Vida) & Siedlecka (1983) and Vida) (1985) for East Greenland; Chumakov & Semikhatov (1981) and Semikhatov (1991) for the southem Urals. for this unit. On basis of the presence of V. /ophostriata on Sredni as Terminal Riphean R4 in age. Based on in both the Chapoma Formation and the Karuyarvin­ lithostratigraphy, her age assignment is not directly in skaya Formation of the Kildinskaya Group on Sredni, conflict with micropalaeontological data that suggest the Chapoma Formation and the upper part of the that the Pumanskaya Formation of the Volokovaya Kildinskaya Group are interpreted as broadly time­ Group is of a minimum Late Riphean R3 age. On the equivalent. Tiersky Coast, the recovered microfossil assemblage from the Chapoma Formation yielded the biostrati­ graphically significant Simia annulare and Valeria lopho­ striata. Of these, V. lophostriata probably has the highest Summary correlative potential (Butterfield & Chandler 1992). Mu­ On basis of the recovered microfossil assemblages, the tual presence of V. /ophostriata has herein served as the investigated successions can be broadly correlated with basis for a tentative correlation of the Chapoma Forma­ Upper Riphean units in Baltica and elsewhere. All recov­ tion with the Karuyarvinskaya Formation of the Kildin­ ered microfossils, with the possible exception of Van ­ skaya Group on Sredni. Together with results based on dalosphaeridium ?varangeri, are cosmopolitan in their other methods (Siedlecka 1995), the biostratigraphically distribution. On the Sredni Peninsula and Kildin Island, inferred Late Riphean age of the investigated Kola units samples from the Kildinskaya Group yielded the follow­ is fairly well-constrained. Hence, the deposition of these ing acritarchs of biostratigraphical importance: Lopho­ sedimentary successions predate the Varanger lee Age in sp haeridium /aufeldii, Satka colonialica, Simia annulare, the North Atlantic Region. Tasmanites rifejicus, Valeria /ophostriata and Van ­ On basis of its possession of short conical spines, dalosphaeridium ?varangeri. With the exception of Valeria Tr achysphaeridium laufeldi Vidal is transferred to /ophostriata and Vandalosphaeridium ?varangeri, all of Lophosphaeridium laufeldii Vidal 1976, comb. nov. these taxa are exclusively known from the Late Riphean Palaeoenvironmentally, the successions examined R3. Siedlecka (1995) interpreted the Volokovaya Group herein are considered as deltaic (Sredni Peninsula and NORSK GEOLOGISK TIDSSKRIFT 77 (1997) Early Neoproterozoic strata, Kola Peninsula 189

Kildin Island), deep-water turbiditic (Rybachi Peninsula) Evitt, W. R. 1963: A discussion and proposals conceming fossil dinoflagellates, and shallow-water (Chapoma Formation). The taxo­ hystrichospheres and acritarchs, Il. Proceedings of the National Academy of Sciences USA 49, 298-302. nomic diversity and the preservation of the microfossil Farrimond, P. & Eglinton, G. 1990: The record of organic components and the assemblages differ between the settings. The highest taxc nature of source rocks. In Briggs, D. E. G. & Crowther, P. R. (eds.): onomic diversity was obtained from the deltaic setting, Palaeobiology, a Synthesis, 217-222. Blackwell Scientific Publications. Fensome, R. A., Williams G. L., Barss, M. S., Freeman, J. M. & Hill, J. M. 1990: whereas the shallow-marine setting yielded an intermedi­ Acritarchs and fossil prasinophytes: an index to genera, species and infraspe­ ate number of taxa, and the turbiditic settings yielded cific taxa. American Association of Stratigraphic Palynologists Fo undation, very few taxa and poorly preserved specimens. Contributions 25, 771 pp. Ford, T. D. & Breed, W. J. 1973: The problematical Precambrian fo ssil Chuaria. Palaeontology 16, 535-550. Acknowledgements. - This research would have been impossible without the Føyn, S. 1985: The Late Precambrian in northern Scandinavia. In Gee, D. G. & support and encouragement of Professor Gonzalo Vida! and Dr Malgorzata Stur!, B. A. (eds.): The Caledonide Orogen - Scandinavian and Related Areas, Moczydlowska-Vidal, Institute of Earth Sciences, Micropalaeontological Labora­ 233-245. Wiley, Chichester. tory, Uppsala. Professor Vida! also initiated the project and introduced me to the Golubic, S. & Hofmann, H. J. 1976: Comparison of Holocene and mid-Precam­ fascinating world of Proterozoic microfossils. Professor Anna Siedlecka and Dr brian Entophysalidaceae (Cyanophyta) in stromatolitic algal mats: cells divi­ David Roberts, Geological Survey of Norway, Trondheim, are thanked for sion and degradation. Journal of Palaeontology 50, 1074- 1082. invaluable help and advice. Dr Ulf Sturesson, Bjom Blix (M. Se.) and Magnus Green, J. W., Knoll; A. H., Golubic, S. & Swett, K. 1987: Paleobiology of Silfversparre (M. Se.), Uppsala, kindly assisted in preparing some of the illustra­ distinctive benthic microfossils from the Upper Proterozoic Limestone­ tions. Dr Graham E. Budd, Uppsala, improved the English in parts of the Dolomite 'series', central East Greenland. American Journal of Bo tany 74, manuscript. Dr V. V. Lyubtsov and Dr V. Z. Negrutsa, Russian Academy of 928-940. Sciences, Kola Branch, Apatity, Russia, are thanked for assistance in the field. Green, J. W., Knoll, A. H. & Swett, K. 1988: Microfossils in oolites and pisolites Professor David L. Bruton, Professor Anna Siedlecka and Dr Nicholas J. from the Upper Proterozoic Eleonore Bay Group, central East Greenland. Butterfield carefully reviewed and commented on the manuscript. To them, I Journal of Paleontology 62, 835-852. express my sincere thanks. My research was made possible by grants from the Gumis, M & Torsvik, T. H. 1994: Rapid drift of large continents during the Late Swedish Institute, Otterborgsfonden and the Swedish Natura! Science Research Precambrian and Paleozoic: Paleomagnetic constraints and dynamic models. Council (NFR; grants to G. Vida!). Geology 22, 1023-1026. Guy-Ohlson, D. 1988: Developmental stages in the life cycle of mesozoic Tasman ­ Manuscript received January 1996 ites. Botanica Marina 31, 447 -456. Hambrey, M. J. 1982: Late Precambrian diamictites of northeastern Svalbard. Geological Magazine 119, 527-642. Hambrey, M. J. 1988: Late Proterozoic Stratigraphy of the Barents Shelf. In References Harland, W. B. & Dowdeswell, E. K. (eds.): Geological Evolution of the Barents Shelf Region, 49-72. Graham & Trotman. Amard, B. 1992: Ultrastructure of Chuaria (Walcott) Vida! and Ford (Acritarcha) Hayes, J. M., Kaplan, L R. & Wedeking, K. W. 1983: Precambrian organic from the Late Proterozoic Pendjari Formation, Benin and Burkina-Faso, West geochemistry, preservation of the record. In Schopf, J. W. (ed.): Earth's Africa. Precambrian Research 57, 121-133. Ear/iest Biosphere; its Origin and Evolution, 93-134. University Press, Prince­ Boalch, G. T. & Guy-Ohlson, D. 1992: Tasmanites, the correct name for lon. Pachysphaera (Prasinophyceae, Pterospermataceae). Ta xon 41, 529-531. Hofmann, H. J. & Aitken, J. D. 1979: Precambrian biota from the Little Dal Boalch, G. T. & Parke, M. 1971: The prasinophycean genera (Chlorophyta) Group, Mackenzie Mountains, northwestern Canada. Canadian Journal of possibly related to fossil genera, in particular the genus Tasmanites. In Fari­ Earth Sciences 16, 150-166. nacci, A. (ed.): Proceedings of the lind Planktonic Conference, Roma 19 70, Hofmann, H. J. & Jackson, G. D. 1994: Shale-facies microfossils from the 99- 105. Proterozoic Bylot Supergroup, Baffin Island, Canada. The Paleontological Brotzen, F. 1941: Några bidrag till visingsoforrnationens stratigrafi och tektonik. Society Memoir 37, 39 pp. Geologiska Fo reningens i Stockholm Fo rhand/ingar 63, 245-261. Hofmann, H. J. & Jackson, G. D. 1996: Notes on the geology and micropalaeon­ Butterfield, N. J. & Chandler, F. W. 1992: Palaeoenvironmental distribution of tology of the Proterozoic Thule Group, Ellesmere Island, Canada and north­ Proterozoic microfossils, with an example from the Agu Bay Formation, Baffin west Greenland. Geological Survey of Canada Bulletin 495, 26 pp. Island. Palaeontology 35, 943-957. Hofmann, H. J. & Rainbird, R. H. 1994: Carbonaceous megafossils from the Butterfield, N. J., Knoll, A. 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Journal of Paleontology 58, 131-162. the Arctic In stitute 80, 74-80. (In Russian with an English summary). Knoll, A. H. 1992: Vendian microfossils in metasedimentary cherts of the Scotia Pyatiletov, V. G. 1980: On findings of microfossils of the genus Navifusa in Group, Prins Karls Forland, Svalbard. Palaeontology 35, 751-774. Lakhandinskoy Suite. Paleontologicheskiy Zhurnal 3, 143-145. (In Russian). Knoll, A. H., Blick, N. & Awramik, S. M. 1981: Stratigraphic and ecologic Raaben, M. E., Lyubtsov, V. V. & Predovsky, A. A. 1995: Correlation of implications of Late Precambrian microfossils from Utah. American Journal of stromatolitic formations of northern Norway (Finnmark) and northwestern Science 281, 24 7-263. Russia (Kildin Island, Kanin Peninsula). Norges Geologiske Undersøkelse Sp e­ Knoll, A. H. & Calder, S. 1983: Microbiotas of the Late Precambrian Ryssø cia/ Publication 7, 233-246. Formation, Nordaustlandet, Svalbard. Palaeontology 26, 467-496. Ragozina, A. L & Stepkin, Ye. S. 1979. Formation attribution and correlation of Knoll, A. H. & Golubic, S. 1992: Proterozoic and Living Cyanobacteria. In the Late Precambrian deposits of the Kola Peninsula. In Keller, B. M. & Schidlowski, M. et al. (eds.): Early Organic Evolution: lmp/icalions fo r Mineral Semikhatov, M. A. (eds.). Stratigrafiya verkhnego Proterozoya SSSR (Rifey i and Energy Resources, 450-462. Springer Verlag. Berlin Heidelberg. Vend), 129-132. Nauka, Leningrad. (In Russian). Knoll, A. H. & Swett, K. 1985: Micropalaeontology of the Late Proterozoic Roberts, D. 1995: Principal fe atures of the structural geology of Rybachi and Veteranen Group, Spitsbergen. Palaeontology 28 (3), 451 -473. Sredni Peninsulas, and some comparisons with Varanger Peninsula. Norges Knoll, A. H. & Swett, K. 1987: Micropaleontology across the Precambrian-Cam­ Geologiske Undersøkelse Sp ecial Pub/ication 7, 247-258. brian boundary in Spitsbergen. Journal of Paleontology 61 (5), 898-926. 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Timofeev, B. V. 1966: Micropaleophytological Investigations of Ancient Fo rma­ Zang, W. & Walter, M. R. 1992a: Late Proterozoic and Cainbrian microfossils lions, 147 pp. Academy of Sciences USSR. (In Russian). and biostratigraphy, Amadeus Basin, central Australia. Memoirs of the Associ­ Timofeev, B. V. 1969: Proterozoic Sp haeromorphs, 146 pp. NAUKA. (In Rus­ ation of Australasian Palaeontologists 12, 1-132. Brisbane. sian). Zang, W. & Walter, M. R. 1992b: Late Proterozoic and Early Cambrian Turner, R. E. 1984: Acritarchs from the type area of the Ordovician Caradoc microfossils and biostratigraphy, northern Anhui and Jianfsu, central-eastern Series, Shropshire, England. Palaeontographica B /90(4-6), 87-157. China. Precambrian Research 57, 243-323. Veizer, J. 1992: Recycling and preservation probabilities of sediments. In Schopf, J. W. & Klein, C. (eds.): The Proterozoic Biosphere - A Multidisciplinary Study, 63-65. Cambridge University Press. Cambridge. Vida!, G. 1976a: Late Precambrian microfossils from the Visingso Beds in southern Sweden. Fossi/s and Strata 9, 57 pp. Oslo. Vida!, G. 1976b: Late Precambrian acritarchs from the Eleonore Bay Group and Appendix - details of investigated samples m Tillite Group in East Greenland. A preliminary report. Grønlands Geologiske ascending order Undersøge/se Rapport 78, 19 pp. Vida!, G. 1979: Acritarchs from the Upper Proterozoic and Lower Cambrian of Numbers within parentheses refer to Thermal Alteration Index (TAl) according East Greenland. Grønlands Geologiske Undersøge/se Bulletin /34, 1-55. to the scale by Pearson (1984). The lower number represents the minimum value Vida!, G. 1981a: Micropalaeontology and biostratigraphy of the Upper Protero­ in the sample, the higher number maximum value. Most T AI values were zoic and Lower Cambrian Sequences in East Finnmark, Northern Norway. obtained on specimens of the Leiosphaeridia spp. Data on the fossil con tent of the Norges Geologiske Undersøkelse Bulletin 362, 53 pp. respective samples are given in Figs. 4 and 5. Vida!, G. 1981b: Aspects of problematic acid-resistant, organic-walled microfos­ The majority of the samples from Murmansk Coast used in this study were sils (acritarchs) in the Upper Proterozoic of the North Atlantic region. Precam­ collected during the summer of 1991 by Dr M. Moczydlowska-Vidal and Profes­ brian Research /5, 9-23. sor G. Vi dal. Samples from this collection round were given identification prefixes Vida!, G. 1982: In Wikman, H., Bruun, Alucflcal., Dahlman, B. & Vida!, G: K9 1-. The remainder of the samples were collected by Professor A. Siedlecka in Beskrivning till berggrundskartan Hjo NO. Sveriges Geo/ogiska Undersiikning, the summer of 1993, and were given the prefix AS-. Two phosphoritic conglomer­ 52-76. Uppsala. ates from the Kuyakanskaya Formation were collected in 1990, also by Professor Vida!, G. 1985: Biostratigraphic correlation of the Upper Proterozoic and Lower A. Siedlecka. Prefix given was K90-. Cambrian of the Fennoscandian Shield and the Caledonides of East Greenland and Svalbard. In Gee, D. G. & Stur!, B. A. (eds.): The Ca/edonide Orogen ­ K90-01A Kuyakanskaya Fm. Phosphorite. Barren. Scandinavia and Related Areas, 331-338. John Wiley & Sons Ltd. K90-01B Kuyakanskaya Fm. Phosphatic conglomerate. Vida!, G. 1988: A palynological preparation method. Palyno/ogy /2, 215-220. K91-01 Middle Chernorechenskaya Fm. Southern coast of the eastern part of Vida!, G. 1994: Early ecosysterns: Limitations imposed by the fossil record. In Kildin Island. Thin layer of black shale at lower part of exposed sequence. Bengtson, S. (ed.): Early Life on Earth. Nobel Symposium No. 84, 298-311. Synsphaeridium spp. observed in thin section. (3 - , 3 + ). Columbia University Press, New Y ork. K91-02 Middle Chemorechenskaya Fm. Southem coast of the eastem part of Vida!, G. & Dawes, P. R. 1980: Acritarchs from the Proterozoic Thule Group, Kildin, l km from previous spot. Greenish finely laminated mudstone with Northwest Greenland. Grønlands Geologiske Undersøge/se Rapport /00, 24- calcareous concretions laminated as the mudstone. Barren. 29. K91-03 Middle Chemorechenskaya Fm. Southern coast of the eastern part of Vida!, G. & Ford, T. D. 1985: Microbiotas from the Late Proterozoic Chuar Kildin, 2 m above previous sample. Thick-bedded greenish and red shale. (2 +, Group (Northern Arizona) and Uinta Mountain Group (Utah) and their 3+). chronostratigraphic implications. Precambrum Research 28, 349-389. K91-04 Lower Pestzovozerskaya Fm. Southern coast of the eastern part of Vida!, G. & Knoll, A. H. 1983: Proterozoic plankton. Geological Society of Kildin, at cliff section of previous locality. Shale. (3, 4- ). America Memoir /6/, 265-277. K91-05 Upper lemovskaya Fm. Southem coast of the eastern part of Kildin. Vida!, G. & Moczydlowska, M. 1992: Patterns of phytoplankton radiation across Thin-bedded mudstone with 'trails'. (3 + ). the Precambrian-Cambrian boundary. Journal of the Geological Society 149, K91-06 Upper Bezymyannaya Fm. Southern coast of the eastern part of Kildin. 647-654. Oncolithic and oolithic dolostone. Vida!, G. & Moczydlowska, M. 1995: The Neoproterozoic of Baltica - stratigra­ K91-07 Iernovskaya Fm. Sredni, Kutovaya Bay. Mudstone within unclear part of phy, palaeobiology and general geological evolution. Precambrian Research 73, unit. Synsphaeridium spp. observed in thin section. (3-, 3). 197-216. K91-08 lemovskaya Fm. Sredni, stream section running into Kutovaya Bay. Vida!, G., Moczydlowska, M. & Rudavskaya, V. A. 1993: Biostratigraphical Mudstone. Synsphaeridium spp. observed in thin section. (3, 3 + ). implications of a Chuaria -Tawuia assemblage and associated acritarchs from K91-09 Upper lernovskaya Fm. Sredni, stream section running into Kutovaya the Neoproterozoic of Yakutia. Palaeontology 36, 387-402. Bay. Thin bed of shale between sandstone. (2 +, 4- ; on kerogen). Vida!, G. & Nystuen, J. P. 1990a: Micropaleontology, depositional environment, K91-10 Poropelonskaya Fm. Sredni, inland outcrop. Shale. (3). and biostratigraphy of the Upper Proterozoic Hedmark Group, Southern K91-11 Poropelonskaya Fm. Sredni, inland outcrop. Shale. (3 -, 3 + ). Norway. American Journal of Science 290-A, 170-211. K91-12 Poropelonskaya Fm. Sredni, inland outcrop. Shale. Siphonophycus spp. Vida!, G. & Nystuen, J. P. 1990b: Lower Cambrian acritarchs and the Protero­ observed in thin section. (3 -, 3 + ). zoic-Cambrian boundary in southern Norway. Norsk Geologisk Tidsskrift 70, K91-l3 Zemlepakhtinskaya Fm. Sredni, inland outcrop. Conglomerate with 191-222. intraformational phosphorite conglomerate. Vi dal, G. & Siediecka, A. I 983: Planktonic, acid-resistant microfossils from K9t-14 Poropelonskaya Fm. Sredni, Bolshoe Ozerko Bay. Mudstone. Synsphae­ the Upper Proterozoic strata of the Barents Sea region of Varanger Peninsula, ridium spp. observed in thin section. (2 +, 4- ). East Finnmark, Northern Norway. Norges Geologiske Undersøkelse 382, 45- K91-15 Poropelonskaya Fm. Sredni, Bolshoe Ozerko Bay. Mudstone. (3 -, 3+). 79. K91-16A Poropelonskaya Fm. Sredni, Bolshoe Ozerko Bay. Mudstone. (3, 3+). Walcott, C. D. 1899: Precambrian fossiliferous formations. Bulletin of the Geo/og­ K91-16B Skarbeevskaya Fm. Northern coast of Rybachi at Cape Kijski near the ical Society of America JO, 199-244. Skarbeevskaya River. Mudstone within the conglomeratic part of the formation. Wegmann; C. E. 1928: Sur un nouveau gisement de roches morainiques prequa­ (4 -, 5; on kerogen, Sp haerocongregus TAl = 3, 3 + ). ternaires. C. R. Societe Geologique de France Il, 274-276. K91-17 Skarbeevskaya Fm. Northem coast of Rybachi at Cape Kijski near the Wegmann, C. E. 1929: Zur Kenntnis der tektonischen Beziehungen metallo­ Skarbeevskaya River. Phosphatic pebble in conglomerate facies. Barren. genetischer Provinzen in der nordlichsten Fennoskandia. Zeitschrift for prak­ K91-18 Skarbeevskaya Fm. Northern coast of Rybachi at Cape Kijski near the tisch Geo/ogie 37(l l), 193-208. Skarbeevskaya River. Thin laminated mudstone. Barren. Xing, Y.-SH. et al. 1985: Late Precambrian palaeontology of China. Geo/ogical K91-19 Skarbeevskaya Fm. Northern coast of Rybachi at Cape Kijski near the Memoirs 2(2), 288 pp. Ministry of Geology and Mineral Resources, Geological Skarbeevskaya River. Thin bedded mudstone. Barren. Publishing House, Beijing. (In Chinese). K91-20 Skarbeevskaya Fm. Northern coast of Rybachi at Cape Kijski near the Yin, L.-M. 1987: Microbiotas of Lates! Precambrian sequences in China. In Skarbeevskaya River. Mudstone. Barren. Nanjing Institute of Geology and Palaeontology, Academia Sinica (compil.), K91-21 Skarbeevskaya Fm. Northerncoast of Rybachi at Cape Bezimienny. Thin Stratigraphy and Palaeontology of Systemic Boundaries in China. Precambrian­ layer of phosphorites. Barren. (5 on kerogen). Cambrian Boundary, 415-522. Nanjing University, Nanjing. K91-22 Karuyarvinskaya Fm. Northwestem part of Sredni, opposite the Aynov Yin, L.-M. & Sun, W. 1994: Microbiota from the Neoproterozoic Liulaobei Islands. Black micaceous shale. (3, 3 + ). Formation in the Huainan region, northern Anhui, China. Precambrian Re­ K91-23 Karuyarvinskaya Fm. Northwestern part of Sredni, opposite the Aynov search 65, 95-114. Islands. Black micaceous shale. (3, 4-). 192 J. Samuelsson NORSK GEOLOGISK TIDSSKRIFT 77 (1997)

K91-24 Upper Kuyakanskaya Fm. East of Mt. Pummanki, near military installa­ K92-0I Altemating red and greyish mudstone. Almost barren. No organic matter tions above cliff, Sredni. Shales and phosphate clasts. Barren. observed in thin section. (3). K91-25 Upper Kuyakanskaya Fm. East of Mt. Pummank:i, near military installa­ K92-02 Altemating red and greyish mudstone, about l m above previous. tions above cliff, Sredni. Phosphatic pebbles. Barren. Leiosphaeridia spp. observed in thin section. (2 +, 3-). K91-26 Pumanskaya Fm. East of Mt. Pummanki, near military installations K92-03 Thinly laminated organic-rich shale with pyrite, l m above previous. above cliff, Sredni. Black siliceous mudstones. Siphonophycus spp. observed in Leiosphaeridia spp. observed in thin section. (3 -, 3 + ). thin section. (3, 4-). K92-04 Thinly laminated organic-rich shale with pyrite, 120 cm above previous. K91-27 Poropelonskaya Fm. Near Ozerko village, Korobielnyi stream, Sredni. Leiosphaeridia spp. observed in thin section. (3 + ). Mudstone. (3 + ). K92-05 Laminated carbonate-cemented sandstone (strike N32'W; dip Il'E). K91-28 Upper Poropelonskaya Fm. A few metres above sample K9 1 -27. Mud­ Barren. stone. (3, 3 + ). K92-06 Greyish laminated shale. Leiosphaeridia spp. observed in thin section. (3, K91-29 Poropelonskaya Fm. Coast near to Cape Vestnik, Sredni. Mudstone. (3, 3+). 4-). K92-07 Carbonate. Pyrite abundant in thin section. Poropelonskaya Fm. Coast near to Cape Vestnik, Sredni. Phosphorite. (3, K91-30 K92-08 Carbonate. Pyrite abundant in thin section. 4-). K92-09 Stromatolite oriented perpendicular to shoreline N30'W. No organic Motovskaya Fm. Cape Vestnik area, Sredni. Mudstone in olistrostome. K91-31 matter observed in thin section. (3, 3 + ). (3, 5). K92-10 Mudstone, about l m above the stromatolites. Leiosphaeridia spp. ob­ Poropelonskaya Fm. Eina Bay, Zelezny Stream, Rybachi. Mudstone. K91-32 served in thin section. (3, 3 + ). (3 +, 4- ). K92-11 Locality 784 in Lyubtsov et al. (1991). Grey shale in altemating mud­ AS 2/93 Middle Pumanskaya Fm. Exposures in cliffs 1.5 km SSW of Cape cracked mudstone; interbed of abo ut 160 m thickness. (3 -, 3 + ). Zemljanoy, Sredni. Mudstone. (3 +, 4-). K92-12 Same as previous, on top of bed. (3 -, 3+). AS 3/93 Middle Purnanskaya Fm. Exposures in cliffs 1.5 km SSW of Cape Locality as previous. Carbonate cemented sandstone. Some parts phos­ Zemljanoy, Sredni. Mudstone. (3, 4- ). K92-13 phoritic. AS 4/93 Lowermost Pumanskaya Fm. Coastal exposures at a ba y WSW of Cape Locality as previous. Carbonate, 60 cm above previous. Pyrite abundant Zemljanoy, Sredni. Mudstone. Siphonophycus spp. and Navifusa majensis ob­ K92-14 served in thin section. (3, 3 + ). in thin section. Phosphoritic parts. No organic matter observed in thin section. Locality 785 in Lyubtsov et al. (199Jb). Carbonate. AS 5/93 Lowermost Pumanskaya Fm. Coastal exposures at a ba y WSW of Cape K92-15 Zemljanoy, Sredni. Mudstone. Siphonophycus spp. and Navifusa majensis ob­ K92-16 Locality as previous. Dark grey shale. Pyrite and hematite observed in served in thin section. (3 + , 4- ). thin section. (2 +, 3 + ). AS 10/93 Zubovskaya Fm. E of Little Cape Skarbeevsky, Rybachi. Mudstone. K92-17 New locality. Thinly bedded dark-grey shale. Leiosphaeridia spp. and Barren. (5, on Kerogen). organic matter observed in thin section. (3, 3 + ). AS 14/93 Upper Perevalnaya Fm. Cape Sharapov, Rybachi. Mudstone. (5). K92-18 Locality as previous. Black shale interbed. Phosphoritic parts. Pieces of larger sphaeromorphic acritarchs observed in thin section (3, 4- ). All samples from the Chapoma Formation on the Tiersky Coast were collected K92-19 Locality as previous. Black shale. Leiosphaeridia spp. observed in thin by myself and Professor Vida! during the summer of 1992, and have been given section. Phosphoritic parts. the prefix K92-. The samples were laken at the same locality, the Chapoma River, K92-20 Locality as previous. Phosphate. Leiosphaeridia spp. and abundant or­ a few kilometers upstream from the mouth of the river at the White Sea. ganic matter observed in thin section. (3 -, 3 + ).