Systematic palaeontology and biostratigraphy of two Early Cretaceous condensed sections from the Barents Sea

NILS ARHUS, SIMON R. A. KELLY, JOE S. H. COLLINS AND MICHAEL R. SANDY

hus, N., Kelly, S. R. A,, Collins, J. S. H. & Sandy, M. R. 1990 Systematic palaeontology and biostratigraphy of two Early Cretaceous condensed sections from the Barents Sea. Polar Research 8, 165- 194. Bivalve, brachiopod and cirripede faunas from the latest Jurassic and Early Crctaceous Barents Sea boreholes 7320/3-U-1 and 7425/9-U-l are systematically described and illustrated. Microfossils have also been studied and the cores are dated on the basis of the fossil recovery. The bivalve Rirchia whose zonal sequence has been used for correlation of boreal marine sections is the most important hiostratigrdphic marker group in the condensed Boreal Berriasian-Hautcrivian intervals of these cores. A new species of cirripede Zeugmatolepas? borealis Collins sp. nov. and dinoflagellate cyst Muderongia uequicurnus &hub sp. nov. are described. The Late Jurassic fine-grained clastics of core 7320/3-U-1 are overlain by about 3 m of grey dolomitic limestone of Valanginian and Hauterivian age. The lowermost part of 7425/9-U-l is represented by a latest Volgian-earliest Berriasian fossiliferous greyish green marl. It is followed by a reddish brown fossiliferous claystone of Berriasian and perhaps partly Valanginian age. Core 7425/9-U-l also contains a mainly Valanginian greyish green marly limestone which changes into a dark grcy ((1 black limestone of Early Barremian age in its upper part. The sedimentological change from condensation to dark grey clay deposition took place in the middle Barremian H. rude-fissicosfarurn ammonite Zone in 7425/9-U-l and probably slightly earlier in 7320/3-U-1. This was commenced at abut the same time as deposition of the inaccurately and only indirectly dated fluvio-deltaic Festningen Sandstone Member on Spitsbergen. The dark claystone may thus be a distal equivalent to this sandstone unit. Nils Arhus, IKU. N-7034 Trondheim, Norway; Simon R. A. Kelly. 47 Oyster Row. Cumbridge CB.5 8LJ. England; Joe S. H. Collins. 63 Oakhursr Grooe, E. Dulwich. London SE22 YA H, England; Michael R. Sandy, Deparrment of Geology, Unioersiry of Davron. Dayron. Ohio 45469. U.S.A.;January 1990 Irecjised A uglrsf I W).

In large parts of the Barents Sea the Jurassic/ stage names. Until the Jurassic-Cretaceous Cretaceous boundary is represented by an uncon- Boundary Working Group (IGCP) makes precise formity with Lower Cretaceous sediments pro- correlation between the regions, the terms Vol- grading on older strata, often on Volgian black gian and Boreal Berriasian (rather than Ryaz- shales. The two coreholes studied here (732013- anian) are recommended. U-1 and 7425/9-U-l, see Fig. 1) were drilled by Parts of these condensed sections are equiv- the drilling ship ‘Bucentaur’ in 1985 as part of alent to a 15 m thick white sandy bioclastic lime- the Norwegian Continental Shelf and Petroleum stone consisting mainly of bivalve debris in the Technology Research Institute’s (IKU’s) Barents lower part of the Tordenskjoldberget Member (as Sea Mapping Program. 7425/9-U-1 located on defined by Smith et al. (1976) in section D 833 on the structurally high Bjarmeland Platform (see Tordenskjoldberget on Kongscziya, Kong Gabrielsen et al. 1990) and on such highs the Karls Land), whereas thicker siliciclastics occur Boreal Berriasian to early Barremian is con- on Spitsbergen and in wells in the basins of the densed and incomplete. The cores both produced southwestern Barents Sea. This shows that macrofossils and the fauna and microflora are tectonics played an important role in facies described here together with a presentation of the distribution, but nevertheless the occurrence of lithological logs and a biostratigraphic inter- Valanginian and Hauterivian limestones on struc- pretation where also foraminifera data are taken tural highs both in the Barents Sea and further into consideration. south on the Norwegian shelf seems to be the Because of the Boreal nature of the fauna it is result of a sea-level rise. The transition from the not possible to use directly the standard Tethyan condensed interval to the overlying claystones 166 N. hhus et al.

-~ Boundaries of highs or basins LLLJa Faults affecting Cretaceous /Tertiary strata - Faults affecting Jurassic strata u Faults affecting Permo -Triassic strata on the Loppa High

-A Reverse faults Tags point downslope

Fig. I. Locations of thc two studicd corcholcs. Map modified after Gahriclscn el al. (1990) will be dealt with in a separate paper where data those from the Jurassic-Cretaceous boundary, from additional shallow cores are included. from the Barents Sea floor are very limited. Nagy (1973) described but did not illustrate mollusca, including buchiid bivalves, belemnites and ony- Macrofossil studies of Barents Shelf and chitids from grab samples taken on Svalbard- adjacent areas (S.R.A.K) banken. However, in adjacent Svalbard the Early Cretaceous macrofossil data, including sequence has been fairly well documented. The Systematic palaeontology and biostratigraphy 167 most important illustrated systematic studies The Buchia zonal sequence in comparison to relating to the present study have been by Stolley ammonite zones in Svalbard is being assessed (1912), Frebold (1930), Frebold & Stoll (1937) currently by the author. The distribution of and Sokolov & Bodylevsky (1931), mainly in the Buchia species in comparison to ammonite zones Isfjorden region, Birkenmajer & Pugaczewska in Svalbard has been given by Yershova (1983). (1975) in Torell Land, Frebold (1929) and Bir- She divided the genus into more species than used kenmajer et al. (1982) in Sabine Land, Bliithgen by Zakharov (1981) and all species recognized in (1936) on Kong Karls Land and Yershova (1983) the present work have also been identified by her in the Svalbard Archipelago. South of the Barents from Svalbard. Sea there is only limited exposure of Jurassic- Buchia okensis has been recommended by Zak- Lower Cretaceous strata on Andoya (Birkelund harov (1087) as the best bivalve for the rec- et al. 1978; Zakharov et al. 1981). The bio- ognition of the Jurassic-Cretaceous boundary in stratigraphy has been slightly revised by Aarhus Boreal regions. Its association on the Russian et al. (1986). To the east of the Barents Sea Platform, North and West Siberia and East Sokolov (1908) has described buchias from Tim- Greenland with the ammonite Hectoroceras kochi an-Pechora and Spitsbergen; Tullberg (1881) provides an important correlation event of the initially described the rich loose block fauna of Boreal Berriasian. Zakharov (1981) regarded the Novaya Zemlya whose stratigraphy has been most B. okensis Zone as appearing in mid-Chetaites recently revised by Cherkesov & Burdykina sibericus Zone and lasting until the middle of the (1981). The Jurassic-Cretaceous boundary sec- succeeding H. kochi Zone. Hoedemaeker (1987), tions on Frans Josef Land do not provide com- however, correlated the B. okensis Zone with parable faunas. To the west, in the Wandel Sea only the upper part of the H. kochi Zone and the Basin, HBkansson et al. (1981) have described lower part of the Tethyan Berriasella para- the Jurassic-Cretaceous boundary strata of Peary mimouna Subzone. He regarded the base of the Land, North Greenland. In East Greenland the Cretaceous as somewhat below (three zones) this Buchia sequence was illustrated by Surlyk & Zak- level at the boundary between the Pseudo- harov (1982). Further south the Boreal bivalve subplmites grandis and the Subthurmannia sub- faunas of the Jurassic-Cretaceous boundary in alpina Subzones. Zakharov’s broader concept of eastern England have been described by Kelly the B. okensis Zone commences only half a zone (1984). Kelly (1990) has also reviewed the Buchia above Hoedemaeker’s concept of the base of the sequence in Europe. Berriasian in the Boreal Realm at the base of the Chetaites SibiricuslPraetollia maynci Zone. Buchia and the Jurassic-Cretaceous boundary (S.R.A.K.) Description of core 732013-U-1 (205500.8E 735115.2N). - See Fig. 2 (N.A. on the basis of By far the most significant macrofossil relating to data from colleagues at IKU). the present study is the bivalve Buchia which has been the subject of a major monographic revision 36.2-33.3 m and stratigraphic assessment by Zakharov (1981), The lowermost 2.9 m of the core consist of a grey on whose work this article relies heavily. Zak- clayey and sandy siltstone with wood fragments harov (1981, table 3) proposed a full sequence of and numerous 1-5 mm thick horizontal fine sand eight Buchia biozones for the Russian Platform, and silt laminations. Some mainly horizontal bur- but only recorded four of them for the Early rows l-3mm in diameter occur. Faecal pellets Cretaceous of the arctic islands around the Bar- 0.24.5 mm in diameter are commonly pyritized ents Sea. A revised version of the table was given and/or sideritized, probably during early dia- by Surlyk & Zakharov (1982, table 3). The Buchia genesis, and a larger siderite nodule was also zones that are confirmed from the Barents Sea penetrated. boreholes are the B. okensis and B. keyserlingi Glauconite occurs as a few 0.2-0.5 mm green zones. The B. uolgensis, B. unschensis and B. grains and possibly replaces faecal pellets. Chert sublaevis zones are only provisionally identified. is observed in a few laminations and in concretions The Barents Sea Buchia zonal sequence is com- up to 3 mm in diameter. pared to that of northern Siberia in Fig. 5. For The unit is fairly homogeneous with respect to comparison with other regions see the tables of natural y-radiation except for positive K and U Zakharov (1981) and Surlyk & Zakharov (1982). anomalies in the uppermost decimetres of the 732013-u - 1

m Systematic palaeontology and biostratigraphy 169 unit. TOC values in 7 samples vary between 1.6 from where they are fairly constant. The average and 4.3 wt% (mean 2.7%), with lowest values for the whole unit is 3.2 wt%. Rock-Eva1 data above 34 m. The kerogen is of very poor hydrogen indicate an upward change in kerogen type from type IV up to 34.2 m where a strong increase in a hydrogen-poor type TI1 kerogen to a slightly hydrogen index is seen. more hydrogen-rich type 111, especially above 15 m. 33.3-29.95 m The next 3.3 m thick grey carbonate interval con- sists of 2.3 m of dolomitized limestone followed Biostratigraphy of core 732013-U-1,- See Fig. 3 by lm of limestone. The transition from the (N.A., S.R.A.K.). clastic interval below is abrupt and the lower 0.25 m of the dolomite is horizontally laminated 36.20-33.50 m Volgian - (Boreal Berriasian) and gradually changes into a wackestone. Glau- Four samples from this interval were processed conite mainly in the form of glauconitized faecal for palynology, and were found to contain the pellets occurs together with medium sized sand low diversity Pareodinia borealis dinoflagellate grains in the lower 0.7m of the dolomite. The cyst assemblage. Samples from the lower part of glauconite may contribute to 30% of the rock in the interval are dominated by tasmanitids, Sir- the richest horizons. miodinium grossii, representatives of the Gon- Most of the interval consists of intermingling yaulacysta cretacea/helicoidea group and a variety wackestones and packstones. The packstones are of Tubotuberella apatela similar to Tubotuberella very rich in both fragmented and unfragmented uncinata (Brideaux 1977) Davies 1983. Some of material of Buchia. In the wackestones the pro- the specimens of T. apatela bear a few small spines portion of Buchia is low relative to the presence along plate boundaries particularly antapically , of foraminifera, fragments of echinoderms and resembling Tubotuberella dangeardi subsp. pri- the bivalve Inoceramus. mitiva Sarjeant 1982, proving the need for Chert occasionally partly replaces both micrite revision of this complex. T. uncinata has pre- and fossil fragments. The average whole rock viously been recorded from the Barremian and T. TOC content is 0.2 wt%. dangeardii subsp. primitiua from the Bathonian. Poorly preserved specimens of Cribroperidinium 29.95-0 m spp. with variably developed horns are the dom- This upper part of the core consists of dark grey inant palynomorphs recorded at 33.50 m. Some silty claystone to clayey sandy siltstone except for of them may be referred to the C. granulatuml the lowermost 0.5 m which is developed as a black granuligerumlglobatum complex. shale poor in quartz and feldspar and rich in mica/ The recorded assemblages from this interval illite. In the lower part of the unit horizontally are not very age significant. Tasmanitids are par- laminated silty and clayey alternations occur. ticularly common in the late Portlandian i.e. Late From around 16 m and upwards very fine grained Volgian in the North Sea Basin (Davey 1982), sandstones occur at the base of thin fining upwards but in the Middle Volgian on Spitsbergen. Rep- beds. The income of sandy material seems to be resentatives of the G. cretacealhelicoidea group associated with an increased content of albite as have not been found consistently and commonly compared to alkali feldspar. below the Volgian on Spitsbergen. The absence of Bioturbation mainly occurs as 0.5-2 mm dia- Gonyaulacysta jurassica and Pareodinia capillosa meter horizontal burrows, although they may also also favours a Volgian dating, although this evi- be vertical and/or up to 1 cm in diameter. Ellip- dence is negative. P. capillosa occurs consistently tical to spherical faecal pellets of 0.2-1 mm dia- in the latest Kimmeridgian sensu gallico in the meter often comprise approximately 10% of the area. rock. These are sideritized, pyritized or glau- At 36.20m several specimens of Cribro- coni tized. peridinium cf. mamilliferum (Gitmez 1970) have Siderite also occurs as early diagenetic con- been observed. Gitmez found this form in the cretions approximately 3-5 cm in diameter. The basal Kimmeridgian of Normandy, but we have amount of macrofossils in the rock is low, but recorded it only in latest Kirnmeridgian sensu some lnocerarnus fragments occur. gallico in the Barents Sea borehole 7230/5-U-2, TOC values generally increase upwards to 20 m which does not penetrate the Volgian. 170 N. Arhus et al.

- 7 m 0. N mP

Y w LL !2 u0 - , 1 I I I I I .... I..,...... 0.00 ...... 2.47 ...... ,I,.,, l.. 5 , I I I. I I 1/11,. 5.53 ,.,. 8.42 ...... 0.47 ...... ,. 2.43 j/iii/ Early Barremian 4.45 ..... 6.14 ...... ii 8.46 ...... ::::I/,I,,...... 10.94 ,I .., 13.45 /Ill 25.44 27.44 28.94 ~arlyBarremiat 29.95 Haulelivian 29.98 30.04 30.20 Late Valanginiar 31.12 31.31 Valanginlan 32.10 33.50 Boreal Berriasiar 35.22 VOlgla" 35.73 36.20

Fig. 3. Palaeontological range chart corc 7320/3-U-1

32.70-31.37 m Valanginian 30.04-27.44 m Hauterivian - Early Barremian Buchia keyserlingi occurs throughout the interval The presence of rare and damaged represen- which has not yielded palynomorphs. In East tatives of the nannofossil Watznuueria biporta at Greenland (Surlyk & Zakharov 1982), on Andaya 30.04, 29.99 and 29.98m suggests an age not (Birkelund et al. 1978; Zakharov et al. 1981) and earlier than Hauterivian at these depths. the Russian Platform (Zakharov 1981) the species Relatively diverse dinoflagellate cyst assem- was reported as most abundant in the Early Val- blages occur in the dark claystone from immedi- anginian. Zakharov (1987, p. 146, table 2) tabled ately above the limestone and upwards. most numerous specimens in his late Early Val- Nelchinopsis kostromiensis has been recorded in anginian B. keyserlingi Zone. B. keyserlingi also the two lowermost samples at 29.95 and 28.94 m. ranges up into the Early Hauterivian, especially Duxbury (1977) and Riley & Fenton (1984) in northern Germany and eastern England. claimed that this species does not range above the Hauterivian, in contrast to Heilmann-Clausen (1987) and Leereveld (pers. comm. 1988) who 31.12-30.20 m Late Valanginian reported it also from the earliest Barremian S. B. sublaeuis has been found from 31.12 to variabilis Zone and as high as the middle Bar- 30.20m. The species is most typical of the Late remian H. rude-jissicostaturn Zone, respectively. Valanginian of And~ya,Norway (Zakharov et al. Muderongia australis is common at 29.95 m. 1981), East Greenland (Surlyk & Zakharov 1982) and the Russian Platform (Zakharov 1981), but 27.44-0 m Early Barremian extends from Early Valanginian to earliest Hau- The presence of Aptea anaphrissa in most samples terivian. from 27.44m to the top (common in the lower Systematic palaeontology and biostrutigraphy 171 part) favours a late Early Barremian dating. Dux- into four units. The lowermost 0.7m thick part bury (1977) and Davey (1979) found A. consists of a greyish green homogeneous marl anaphrissu in uppermost Lower and middle Bar- (wackestone) with abundant fragmented and remian strata, whereas Duxbury (1980) reported unfragmented shells of Buchia and fragmented it exclusively from top Lower Barremian, but Inoceramus in a micritic matrix. Terrigenous mat- there is some confusion due to a former three- ter may amount to more than 60 wt% and TOC fold division of this stage. Mutterlose & Harding content to an average of 0.3940. (19x7) recorded A. anuphrissa exclusively in the middle section of the Hauptblatterton of claypit 63.84-58 m Gott, northern Germany, which according to The overlying, about 5 m thick unit comprises them is an offshore anoxic warmwater facies. reddish brown, very fossiliferous, silty claystone These beds contain a belemnite fauna with with occasional reduction spots. Its base is sharp. Aulacoteuthis spp. and correspond to the late Complete and fragmented specimens of the Early Barremian fissicostatum Zone (lower part bivalve genera Buchia and lnoceramus are the of H. rude-jissicostatum Zone). most common fossils, but brachiopods, cirri- pedes, gastropods, belemnites, echinoderm frag- ments, foraminifera and wood fragments have Description of core 742519-U-1 (254619.3E also been recognized. 742925.3N). - See Fig. 4 (N.A. on the basis of data from Geir Elvebakk and others). 58-53.5 m 64.54-63.84 m The unit gradually changes into the greyish green Lithologically this 14.5 m long core can be divided marly limestone of the next unit and the transition

742519-u-1

Legend to the stratigraphical columns -~ Early Barremian LITHOLOGY SEDIMENTARY STRUCTURES Claystone - Horizontal lamination 0 Siltstone - Horizontal graded laminatioi dXC Ccquina bed Sandstone 0 5- III Bioturbation - intensity Limestone EARLY DlAGENETlC MINERALS Dolomite (Hauter ivian) - Siderite G Glauconite Valang i n ian a Till 0 Pyrite W Concretion V Chen s-siderite Indeterminate c-calcite SideritizedlPyritized pellets Boreal Berriasian Valanginian FOSSILS V Brachiopoda (L3 Calcisphere ~~ (Early)Boreal - 8, Buchia 0 Radiolaria 8, lnoceramus Gastropoda Berriasian T!? Echincderma m Wood fragment Latest Volgian Foraminifera 88 Unidentified fossil v Belemnite

Fig. 4. Sedimentological log core 7425/9-U-l, prepared by Geir Elvebakk 172 N. Arhus et al. zone is mottled. Colour changes often follow the and fragments in the unit is high. Buchia is the outlines of shells, suggesting that colour dif- most common fossil in the lower part whereas ferences are due to diagenesis. Light greyish/ Inoceramus is dominant in the upper part. greyish green mottling occurs in the lower 2.5 m Echinoderm fragments and foraminifera occur of this unit, whereas the upper couple of metres throughout the unit and belemnites and cal- consist of dark grey to black limestone. This lime- cispheres have been observed in the lower part. stone may be stromatolitic in part due to lami- Much of the shell material is bored, probably by nation of calcite and dark brown to black material sponges. Diameter and shape of the borings vary. of possible algal origin. The interval in general is lean in organic matter with an average TOC con- tent of only 0.06%. 53.5-49.72 m The amount and diversity of calcareous fossils The transition is abrupt to the overlying grey silty

19.72 iI .94 i3.78 i3.94 i i i i i i i i i i i iii i4.34 i5.00 i5.95 i5.98 i6.87 i7.00 i7.10 i7.34 i7.37 i7.85 i7.95 i8.20 i8.37 i8.41 i8.67 i8.83 $9.03 i9.10 i9.38 i9.62 19.80 iO.08 io.10 i0.2 $0.27 i0.65 iL.08 il.10 $1.33 il .hl $1.83 i2.35 i2.45 9.85 $3.25 j3.34 1 LEGEND 33.42 I Present 53.70 $3.76 Common j3.84 1 I j3.89 i4.30 $4.38 I l

Fig. 5. Mucrofuunul and pulynologicul runge chart core 7425/9-U-1 Systematic palaeontology and biostratigraphy 173 claystone, represented by 3.8 m of core. A 3 cm correlated a similar foraminifera assemblage from thick lag dep6sit of coarse sand containing some a thin interval at the base of the Rurikfjellet glauconite is developed between the units. Member in the Agardhfjellet section, Spitsber- Description is hampered by extreme fragmen- gen, to the Berriasian of Siberia, but a younger tation of the rock. Thin lamination occurs, but age cannot be excluded. locally, burrows 1-2 mm in diameter destroy this. Yellowish brown siderite concretions up to 15 cm 61.83-58.41 m indeterminate Boreal Berriasian- thick are observed. The rock has a fair to good Valanginian organic matter content with an average TOC con- Only one of the seven samples prepared for paly- tent of 1.0 wt%. Rock-eval data show that the nology from this interval was productive, con- samples contain a hydrogen-poor type III/IV taining a poor and low diversity dinocyst kerogen. The most organic-rich examined sample assemblage without precise biostratigraphic sig- from 51.94 m with a TOC content of 2.4% has a nificance. The bivalve fauna includes only epi- more hydrogen-rich type I11 kerogen. faunal or reclining filter feeders. Juveniles with clearly preserved prodissoconchs numerically dominate the age undiagnostic disarticulated Biostratigraphy of core 742519-U-1.- See Figs. Buchia fauna. Cirripede plates described below 5 and 6 (S.R.A.K., N.A.). are found between 61.05 and 59.28 m. 64.54-61.83 m latest Volgian - (Early) Boreal Berriasian 58.41-57.37 m (Early) Valanginian Buchia cf. unschensis (Pavlov) occurs at 64.3& Buchia keyserlingi (Trautschold) occurs from 63.89 m and suggests a late Late Volgian to ear- 58.41-57.37m. The species is a typical Boreal liest Early Boreal Berriasian age. Low diversity Early Valanginian to Early Hauterivian indicator, assemblages of foraminifera and dinoflagellate but most characteristic in the late part of the Early cysts are present and are not very age diagnostic. Valanginian (Zakharov 1987). The interval is The dinocyst assemblages consist of small spinose therefore most likely to be Early Valanginian. A species, probably reflecting some environmental single poorly preserved specimen of the dino- restriction. flagellate cyst Hystrichodiniurn furcaturn has Buchia cf. volgensis was recognized from a been recorded at 57.34 m. According to Riley & single specimen at 63.42 m. B. volgensis is a more Fenton (1984), this species has a total strati- widespread Boreal Berriasian indicator than B. graphic range of late Valanginian to early Bar- okensis, which occurs between 63.25 and 61.83 m. remian. B. okensis is most typical of the late Early Boreal Berriasian (Zakharov 1987), where it often occurs 57.10 m Late Valanginian - (Early Hauterivian) in association with the ammonite zonal index Buchia cf. sublaevis (Keyserling) occurs at this Hectoroceras kochi. In Barents Sea core 7430110- depth and is most likely evidence of a Late Val- U-1 the uppermost specimens determined as B. anginian age (see above). Records of similar cf. okensis have been found 10 cm above the last forms at 55.95 and 54.34 m are stratigraphically records of Lenticulina sossipatrovae and the first problematic. records of Marssonella oxycona (Skarb~pers. comm.). Bartenstein & Bettenstaedt (1962) 56.6249.72 m Early Barremian claimed that M. oxycona is suggestive of a Val- The foraminifera fauna, with the first record of anginian or younger age, but our evidence com- Gavelinella barrerniana at 56.62 m, indicates that plicates this. Also in 7425/9-U-1 M. oxycona most of the upper limestone unit in this core is appears slightly below the disappearance of B. Barremian in age. Uvigerina moesiana appears at okensis (at 62.50 and 61.83 m, respectively). 55.70m. Skarb0 (pers. comm.) has noted the Lenticulina spp. dominate the foraminifera income of these two species in the same sample assemblages at 63.76 and 63.38m. Basov & in the lower part of a limestone interval in Barents Ivanova (in Saks 1972) reported some new species Sea core 7430/1O-U-l, 0.25 m above the first rec- of Lenticulina to appear in the Berriasian of the ord of the dinocyst A. anuphrissa. The uppermost Urdyuk-Khaya and the Boyarka sections, north- record of Buchia sublaeuis at 55.95 m is conflicting ern Siberia, but a detailed correlation with Siberia and problematic evidence (see above). Inocer- is impossible at this stage. Nagy (pers. comm.) amids occur throughout the core, but between 174 N. hhus et al.

Fig. 6. Range chart prepared by Oddvar Skarh@showing distribution of foraminifera etc. in corc 74?5/9-U-l

53.85 and 53.78 m much larger shell fragments of tromiensis does not range above the Hauterivian. this group are common. The necessary characters But the species is rare in the upper part of its for species determinations have not been range. Since A. anaphrissa often has an acme observed and the fauna therefore cannot be used occurrence in the lowermost part of its range (e.g. for age interpretation. in the commercial Troms~yflaketwells 7120/9-1 A relatively diverse dinoflagellate cyst assem- at 1,761 m, in 7120/12-2 at 1,500 and 1,475 m and blage occurs at 53.94 m, about 0.5 m below the in 7120/12-3 at 1,81Om), this may be the best top of the limestone interval. Aptea anaphrissa, practical palynological criterion for distinguishing Dapsilidinium multispinosum and Disphaeria tes- Hauterivian and Barremian strata, although the selata dominate the assemblage. According to acme occurrence is probably situated in the Duxbury (1980), A. anaphrissa is a late Early middle Barremian H. rude-fissicostatum ammon- Barremian marker (see above). ite zone according to the literature (see above). Nelchinopsis kostromiensis is rare, with single The presence of Rhynchodiniopsis aptianu specimens recorded at 51.94 and 49.72 m, show- (synonymous with R. fimbriata and Gonyau- ing that N. kostromiensis and A. anaphrissa have lacysta anglese) is in accordance with the range overlapping ranges in this core. This is in contrast reported by Srivastava (1984). He found the taxon to the observations by Duxbury (1977) and Riley throughout the Barremian stage in the stratotype & Fenton (1984) who claimed that N. kos- and some paratype sections in contrast to Zahiri Systematic palaeontology and biostratigraphy 175

(1981), who reported it only from the lowermost indicators of a possible Jurassic age in this bore- Barremian. hole. The species was originally recorded from Spitsbergen by Sokolov & Bodylevsky (1931). Zakharov (1981, p. 116) recognized B. unschensis from the Craspedites okensis to Hectoroceras Systematic palaeontology kochi Zones in northern central Siberia and in Systematic annotations as indicated by the sym- the Pechora Basin on the Russian Platform in bols preceding the year in each synonymy entry strata of possibly the Craspedites subditus Zone follow the Richter system as modified by to those bearing Hectoroceras. Hikansson et al. Matthews (1973). Synonymy entries of buchiid (1981, p. 24) recorded the species from the Late bivalves are only included where they supplement Volgian and Early Ryazanian of Peary Land, the principal work of Zakharov (1981), or have North Greenland. Jeletzky (1984) also identified been figured or described from Svalbard. Citings the species in the Late Tithonian (i.e. Late Vol- are not mentioned unless significant. The figured qian - earliest Boreal Berriasian) of Arctic material is held in the collection of Paleontologisk Canada. The present occurrence is most likely to Museum, Oslo (PMO). be Early Boreal Berriasian, but it is also possible that it may be latest Volgian as recorded from Bivalves (S.R.A. K.) Svalbard by Yershova (1983). Class Bivalvia LinnC, 1758 Stratigraphic range. - C. subditus Zone, Late Subclass Pteriomorphia Beurlen, 1944 Volgian to H. kochi Zone, Early Boreal Order Pterioida Newell, 1965 Berriasian. Suborder Pectinina Waller, 1978 Buchia okensis (Pavlov 1907) Superfamily Buchiacea Waller, 1978 Fig. 7E-L Family Buchiidae Cox, 1953 Genus Buchia Rouillier, 1845 v. 1931 Aucelh okensis Pavlov: Siikolov & Bodylcvsky. p. 40, pl. 1. figs. 10, II (Festningcn, Spitshergcn, Janusfjcllct Buchia cf. unschensis (Pavlov 1907) Formation, Boreal Bcrriasian). 1937Aucelh sp. cf. okenub Pavlov; Frebold & Stoll, p. Fig. 7A-C 29 (Festningcn, Spitsbcrgen. Janusfjcllet Formation, Boreal Berriasian). 1931 Aucella cf. unschensis Pavlov; Sokolov & Bodylevsky, v. 1981 Buchia okensis (Pavlov); Zakharov. p. 116, pl. 31, figs. p. 42 (Festningen. Spitsbergen. Valanginian). 1-3; pl. 32, figs. 1-4: pl. 33, figs. 1-2: pl. 34, figs. 1-3; cf. 1YX3 Buchiu unschensis (Pavlov): Yershova, p. 25, pl. 27, pl. 35, figs. 1-4 (R. Boyarka and PdkSa, northern central fig. 4 (Agardhbukta, Spitsbergcn, nodiger Zone, Late Siberia. Boreal Berriasian). Volgian). , 1981 Buchia okensis (Pavlov); Hhkansson ct al. p. 24, pl. 4, cf. 1983 Buchia unschensis (Pavlov): Zakharov ct al.. p. 176, pl. figs. 3-8; pl. 5, figs. 1-3 (Pcary Land, North Grccnland, 23, figs. 46(northern central Siberia, Late Volgian). Boreal Berriasian). cf. 1989 Buchia unschensis (Pavlov): Paraketsov & Para- . 1982 Buchia okensis (Pavlov); Surlyk & Zakharov, p. 740, ketsova, p. 230, pl. 9, fig. 4 (northern U.S.S.K.,Late pl. 75, fig. I (South Jameson Land, East Greenland. Berriasian). Boreal Berriasian). . 1983 Buchia okensis (Pavlov); Ycrshova, p. 34, pl. 26, fig. 26 Type.- Lectotype: designated by Jeletzky (1966), (Agardhbukta. Svalhard, throughout the Berriasian). A. P. & M. V. Pavlov Museum, Moscow, No. . 1983 Buchia okensis (Pavlov); Zakharov ct al., p. 176, pl. 24, figs. 1-2 (northern central Siberia, Berriasian). VI, 341153, Late Volgian, ?nodiger Zone, River . 1984 Buchia okensis (Pavlov); Jeletzky, p. 203, pl. 3, fig. 2a- Unzha, near Ogarkov, Kostromsk Oblast, d (SW British Columbia, Boreal Berriasian). U.S.S.R. . 1986 Buchia okensis (Pavlov); Zakharov & Lcbcdev, p. 94, pl. 11. figs, 2,3 (western Siberia, Boreal Berriasian). Material. - Borehole 742519-U-1 at 64.3G , 1987 Buchia okensis (Pavlov): Zakharov. p. 147 (Berriasian; 63.89 m. defines base of Cretaceous in the Boreal and Subtethyan realms). (See Zakharov 1981, p. 116, for full Diagnosis. - Small to medium size, trigonal synonymy.) outline, moderate to close spaced commarginal . 1989 Buchia okensis (Pavlov); Paraketsov & Paraketsova, folds with fine lamellae. Growth curve curvoid to p. 228. pl. 10, figs. 1-5 (northeastern U.S.S.R.. Late Berriasian). ort hoid. Remarks. - These specimens are not well Type. - Lectotype designated by Pozhariskaya preserved. However, they are the only bivalve (1971, p. lls), original of Pavlov (1907, pl. 1, 176 N. Arhus et al. Systematic palaeontology and biostratigraphy 177 fig. lla-c), M. V. and A. P. Paviov Museum, Stratigraphic range. - H. kochi to B. mesezhnikovi Moscow, Ryazan Horizon, R. Pekhorka, Uly- Zones, Boreal Berriasian. anovsk Oblast, U.S.S.R. Buchia cf. uolgensis (Lahusen 1888) Material. - Borehole 7425/9-U-l at 63.25- Fig. 7D 61.83 m. Diagnosis. - Medium to large size buchiid with cf. 1983 Buchia uolgensis (Lahusen); Yershova, p. 34 (Sval- strong commarginal folds, moderately bard, Berriasian, up to spusskensis Zone). cf. 1989 Buchiu uolgemis (Lahusen); Pdraketsov & Parakct- compressed, broad valves, umbo of left valve *ova, p. 229, pl. 11. figs. 1-3 (northeastern U.S.S.R., moderately projecting. Growth curve curvoid to Early Valanginian). obliquoid. cf. 1990 Buchiu odgensb (Lahusen); Kelly, p. 138, pl. 2, fig. 2 (eastern England, Berriasian, S. icenii Zone). Remarks. - The species is most typical of the (See Zakharov (1981) and Kelly (1984) for full synonomy of Early Boreal Berriasian on the Russian Platform species.) where it occurs in association with Hectoroceras kochi (Zakharov 1981, p. 121). The stme asuoei- Types. - Syntypes from the Boreal Berriasian of ation is described from Peary Land, North Green- Kashpir, Simbirsk, Starayan and Ryazan. Lec- land (Hikansson et al. 1981). It also occurs in totype: designated Glazunova (1973), Gorni East Greenland where it is recorded by Surlyk & Museum, Leningrad, No. 11/40, Kashpir, Kuyby- Zakharov (1982, p. 740) as rarely occurring in the shev Oblast, U.S.S.R. Muslingeelv Member of the Hesteelv Formation. Material. - Borehole 7425/9-U-1 at 63.42 m. But the basal conglomerate of this same member yielded abundant specimens of this species to the Diagnosis. - Medium to large, tall buchiid, with author in 1973. However, it is not known in the low regular commarginal folds. Growth curve H. kochi Zone from eastern England. B. okensis orthoid to inversoid. is widely distributed in the Northern Hemisphere Remarks. - B. volgensis is a longer ranging Boreal (see Zakharov, 1981, fig. 62). Jeletzky (1984, fig. Berriasian indicator than B. okensis, which 5) considered the species sensu strict0 appeared becomes most abundant in the Late Boreal at the true Tithonian-Berriasian boundary in Berriasian, but also occurs in the Early Boreal Western British Columbia, but also recognized B. Berriasian. The species is widely recorded from n. sp. aff. okensis occurring considerably earlier the Boreal Berriasian of Spitsbergen (Yershova within the Late Tithonian. However, on the em- 1983). It is particularly widespread on the Russian tral Russian Platform the species IS recorded from Platform (Zakharov 1981), Andoy, Norway the Late Volgian (Zakharov 1B1, table 3) where (Birkelund, et al. 1978; Zakharov et al. 1981), it is associated with B. uncitoides and in Svalbard East Greenland (Surlyk & Zakharov 1982), it ranges throughout the Berriasian overlapping ?Peary Land, North Greenland (Hikansson et al. with B. keyserlingi (Yershova 1983). 198l), and eastern England (Kelly 1984). (See

Fig. 7. A-C: Buchiu cf. unschensb (Pavlov 1907) A, PMO 116.481, right valve, 63.89111, X1.5; B, PMO 116.482, left valve, 64.03111, X1.5; C, PMO 116.483, left valve, 64.30111,Xl. D: Buchia cf. uolgensis (Lahusen 18x8) PMO 116.484. left valve, 63.42111. XI. E-L: Buchia okensh (Pavlov 1907) E. PMO 116.485, right valve interior, 63.25 m, X3; F, same specimen, PMO 116.485, X 1; G,PMO 116.486, right valve, 63.02 m, X1.25: H. PMO 116.487, left valve, anterior view, 62.74m. XI;I, PMO 116.488, left valvc. 62.50m, XI; J, PMO 116.489, left valves, 62.25m. XIS; K. PMO 116.490. leftvatvc. 61.83m. xl; L. PMO 116.491, right valve, 62.40m, XI. M-R: Buchiu keyserlingi (Trdutschold 1868) M,PMO 116.492, right valve, 58.4111~.XIS; N, PMO 116.493. left valve, 57.37111. XIS: 0,P. 0,PMO 116.494. left valve, dorsal. lateral and anterior views, 57.62 m, x 1; R. PMO 116.495, left valve, 57.52 m, X I. All specimens from Barents Sea Borehole 7425/9-U-1. Depths given in metres below sea floor. All specimens in external lateral view unless stated otherwise. 178 N. Afrhus et al. Systematic palaeontology and biostraiigraphy 179

Zakharov 1981, fig. 66, and Kelly 1984, p. 60, for Lcbedev, p. 95, pl. 14, figs. 8, 9 (western Siberia. late more widespread geographical distribution.) Early Valanginian). 1987 Buchia keyserlingi (Trautschold); Zakharov, p. 150 Stratigraphic range. - Boreal Berriasian. (Boreal and Subtethyan regions, Early Valanginian to Early Hauterivian). Buchia keyserlingi (Trautschold 1868) (See Zakharov 1981 for full synonymy.) Fig. 7M-R, Fig. 8A-D Type. - Holotype by monotype, Gorni Museum, Leningrad, No. 266/46, River Yusy, Volga River v. 1930 Aucellu keyserlingi Lahusen: Frebold, p. 43, pl. 15, fig. I (Festningen, Spitsbcrgcn, Janusfjellet Formation, Basin. Originally figured by Keyserling (1846, pl. Valanginian). 16, fig. 6) as AucelEa concentrica var. rugosa. 1931 Aucrlla keyserlingi Lahusen; Sokolov & Bodylcvsky, p. 43 (Fcstningcn, Spitsbergen, Janusfjcllct Formation, Material. - Borehole 7320/3-U-1 at 32.70- Valanginian). 31.37 m; 7425/9-U-1 at 58.41-57.37 m. v. 1936 Aucellu keyserlingi Lahuscn: Bluthgen, p. 13, pl. 2, fig. 2 (Johnsenberget, Kong Karls Land, Early-Middle Diagnosis. - Inflated, moderately sized buchiid, Valanginian). commarginal ribs regular, but sometimes smooth. 1937 Aucella keyserlin~iLahusen; Frebold & Stoll, p. 28 Left valve beak weakly to moderately projecting. (Festningen, Spitsbergen, Janusfjellct Formation, Val- Growth curve inversoid. anginian). v. 1981 Bucliin keyserlingi (Trautschold); Zakharov, p. 141, pl. Remarks. - The species is a typical Boreal Val- 50, figs. 2-5: PI. 51, figs. 1-7; PI. 52. figs. 1-3; PI. 53. anginian indicator, and is widely recognized in figs. 1-3; pl. 54. figs. 1-2; pl. 55. figs. 1-4 (Svalbard. British Columbia. Kussian Platform. northern central Svalbard. It is most abundant in the Early Val- Siberia, Valanginian). anginian of East Greenland (Surlyk & Zakharov ? 1981 Buchia sp. indet. cf. keyserlingi (Lahusen): 119kansson 19821, Andoy, Norway (Birkelund et al. 1978; et al.. p. 26, pl. 5. fig. 6 (Peary Land, North Greenland, Zakharov et al. 1981), and the Russian Platform Valanginian). . 1981 Buchia kevserlingi (Trautschold): Zakharov et al.. p. (Zakharov 1981). The species, however, does 264, PI. 2. figs. 3, 4 (Andoy, Norway, Early Valan- range up into the Late Valanginian where it occurs ginian). with, but is subordinate to, 3. sublaevis (Key- v. 1982 Buchia keyserlinp (Trautschold); Surlyk & Zakharov, serling) and also into the Early Hauterivian, the p. 741, pl. 76, figs. 2.3: pl. 77, fig. 1 (Wollaston Forland. latter occurrence especially in northern Germany East Greenland, Early Valanginian). . 1983 Buchiu keyserlingi (Lahuwn); Kempei-, p. 366. pl. 1. and eastern England. Yershova (1983) recorded fig\. 7, 8 (Axel Hcibcrg and Ellesmcre Islands. B. keyserlingi as early as the latest Late Berri- Canadian Arctic, Latc Valanginian). asian. 19x3 Buchia keyserlingi (Lahusen); Bogdanova in Luppov el id.. p. 77, pl. 11. figs. 9-15: pl. 12, figs. 1-3 (Man- Stratigraphic range. - Latest Berriasian to Early guyschlak. southern U.S.S.R.,Early Valanginian). Hauterivian. . 1983 Buchia keyserlingi (Lahusen); Ycrshova. p. 34. pl. 37. fig. 2 (Svalbard, Latc Bcrriasian (Beds with Tollia and Bojurkiu) to latc Early Valanginian (rarnulicostu Buchia sublaeuis (Keyserling 1846) Zone)). Fig. 8G-I . 1983 Buchiu keyserlingi (Trautschold): Zakharov ct al.. p. 176, pl. 23, figs. 1-6 (northern central Siberia, Early v. 1931 Aucella sublami.\ Keyscrling; Sokolov & Bodylcv5ky. Valanginian). p. 45. pl. 2. figs. 6, 7 (Festningen. Spitsbcrgcn. . 1986 Buchiu keyserlingi (Trautschold); Zakharov & Janusfjellet Formation. Valanginian).

Fig. 8. A-D: Buchia keyserlingi (Trautschold 1868) A, PMO 116.496, latex cast of left valve, 31.37111, X2: B, PMO 116.497, left valve, 31.421~1,X2; C, PMO 116.498, internal mould, left valve, 31.79m, x2; D, PMO 116.498, same specimen, latex cast, X2. E,F,J: Buchia cf. sublaeuis (Keyserling 1846) E, PMO 116.499, lcft valve, 55.95111, x1.5; F, PMO 116.500. left valve. 57.101~1,X1.S: J. PMO 116.503. lcft valve. 54 34,. x 1. G.H,I: Buchia sublaeuis (Keyserling 1846) G. PMO 116.501, right valve, internal mould, 31.12m. X2: 1I. PMO 116.501. same specimen, latcx cast. x2: 1. PMO 116.502. left valve, 30.20m, x1.5. K-M: Inoceramus? sp. K, PMO 116.504, right valve, 53.85111, Xl: L. PMO 116.505, '?left valve, 53.78111, X1.2; M, PMO 116.506. '?right valve. 53.80111, Xl. Specimens A-D, G-I from Barents Sea Borehole 7320/3-U-1, E, F, J-M, 7425/Y-U-1. Depths given in metres below sea floor. All spccimens in external lateral vicw unless stated otherwise. 180 N. hhzu et al.

1975 Buchia d. sublaevis (Keyserling); Pugaczewska in to smooth cornmarginal ornament and certainly Birkenmajer & Pugaczewska, p. 66, pl. 5, fig. 1 lack the very regular, quite strong cornmarginal (Treskelen, Spitsbergen, TirolarpassetMember?, Val- ornament of B. jischeriana. B. sublaevis is most anginian?). v. 1981 Buchia sublaevb (Keyserling); Zakharov, p. 149, pl. typical of the Late Valanginian of AndBy, Norway 56, figs. 1-5; pl. 57, figs. 1--4; pl. 58, figs. 1-4; pi, (Zakharov et al. 1981), East Greenland (Surlyk 59, figs. 1-4 (Russian Platform and northern central & Zakharov 1982) and the Russian Platform Siberia, Late Valanginian to Early Hauterivian). (Zakharov 1981) but also extends from Early . 1981 BuchiasubLaeuh (Keyserling); Zakharovetal., p. 264, Valanginian to Early Hauterivian, the latter pl. 2, figs. 5, 6 (Andoy, Norway, Late Valanginian, ?Early Hauterivianf. especially in eastern England and northern Ger- . 1982 Buchia fischerimo (d’orbigny); Pugaczewska in Bir- many. kenmajer et al., p. 124, PI. 41, figs. 1-7 (Mykle- gardfjellet, Spitsbergen, Rurikfjellet Member, Stratigraphic range. - Early Valanginian to Early probably Late Valanginian). Hauterivian. v. 1982 Buchin sublaeuis (Keyserling); Surlyk & Zakharov, p. 742, pl. 76. figs. 2-7 (Kuhn Island and Wollaston Forland, East Greenland, Early and Late Valan- Inoceramus? sp, ginian). Fig. 8K-M . 1983 Buchia sp. (cx gr. sublaeuis Keyscrling); Yershova, p. Material. - Borehole 7425/9-U-l at 53.85- 43, (Svahdrd. early Early Hauterivian). . 1983 BUC~UIsublamis (Keyserling); Yershova. p. 38, pl. 53.78 m. 39, fig. 2 (Svalbard. Late Valanginian). cf. 1983 Buchiasublneuis (Keyserling); Zakharov et al.. p. 176, Diagnosis. - Large prismatic shell with broad pl. 27, figs. 1-2 (northern central Siberia, Late Val- commarginal folds; a juvenile shell shows sub- anginian). ovate outline and moderate obliquity. . 1986 Buchia sublaeub (Keyserling); Zakharov, p. 95, pl. 11, figs. 12, 13 (western Siberia, Late Valanginian). . 1989 Buchia subkieuis (Keyserling); Paraketsov & Parak- Remarks. -The specimens originally described as etsova, p. 237, pl. 10, figs. 5-7 (northeastern U.S.S.R., I. spitsbergensis by Stolley (1912, p. 20, pl. 1, Late Valanginian). figs. 5,6) were in association with Inoceramus . 1990 Buchiasublaevis (Keyserling); Kelly, p. 138, pl. 2, figs. 3-5 (Federal German Republic, Early Hauterivian). labiatiformis Stolley and crioceratid ammonites (See Zakharov 1981, p. 149, for full synonomy.) in a block from the ‘Ditrupa Sandstein’. I. lab- iatiformis differs from I. spitzbergensis by its much Type. - Syntypes: Gorni Institute, Leningrad, narrower umbones and more narrow, oblique nos. 267/46,268/46, originals of Keyserling 1846, shape. Sokolov & Bodylevsky (1931, p. 47) rec- p. 300, pl. 16, figs. 13-15, Late Valanginian, R. orded I. cf. spitzbergensis from bed 32 of the Izhma, tributary of R. Pechora, Shel’skaya, Arch- Festningen Section, which they dated as Early angel’sk Oblast, U.S.S.R. Aptian. They also stated that the specimen cited Material. - Borehole 7320/3-U-1 at 31.12- by Zhirmunskiy (1927, p. 104), which was seen 30.20 m. by them in the Marine Institute Collections, Leningrad, bore radial ornament and was not an Diagnosis. - Moderately inflated, with left valve inoceramid. Pchelina (1965) listed I. spitzber- beaks weakly to moderately projecting. Com- gensis also in association with I. cf. labiatiformis, marginal ornament usually becoming smooth. but together with Arcthoplites from the Middle Growth curve inversoid Albian of Van Keulenfjorden, Spitsbergen. Remarks. - The specimens figured by Puga- Pchelina (1967) recorded Inoceramus sp. associ- czewska (in Birkenmajer & Pugaczewska 1975) ated with Hauterivian Simbirskitid ammonites in were from loose concretions, thus the precise age S~rkappLand, and gave several species from the cannot be established. The specimens that she Albian. In Svalbard Yershova (1983) recorded figured (in Birkenmajer et al. 1982) as B. fisch- Early Hauterivian Inoceramus sp. and Late Hau- eriana occur very high in the section, probably at terivian I. aff. aucella Trautschold and I. sp. ex. the level of the B. crassicollislunschensis assem- gr. colonicus (Anderson). She also identified I. blage recorded by Pchelina (1967). Yershova spitzbergensis Stolley and I. labiatiformis from (1983) showed the B. sublaevis group in Svalbard Aptian and I. anglicus from the Middle Albian. to extend from the Late Valanginian to Early The present borehole specimens are left in open Hauterivian time. It represents the final appear- nomenclature and the age cannot be precisely ance of Buchia. The specimens have suppressed given at this stage. Systematic palaeontology and biostratigraphy 181

Brachiopods (M.R.S.) Elongate-oval outline, rounded anterior margin. Prominent beak, gently rounded hinge- Articulate and inarticulate brachiopods have been line. Numerous growth lines. recovered from the calcareous reddish brown silty claystone unit of core 7425/9-U-1 of inde- Remarks. - The specimens are small in com- terminate Berriasian-Valanginian age (between parison to Lingulu ovalis from the Upper Kim- 61.50 and 60.08 m depth). The brachiopods are meridge Clay Formation of Dorset, England, but not numerous and are generally poorly preserved, have a similar elongate-oval outline and com- being crushed and/or incomplete. A number of parable beak position. We have not been able to distinctive shell morphologies are present, compare the specimens from core 742519-U-1 however, which do allow some generic assig- directly with juvenile growth line patterns of Lin- nations. The lack of abundant and suitably pre- gufa ovalis J. Sowerby and Lingula subovalis served material does not allow full taxonomic Davidson. Such comparison may clarify the affin- description of this material. The internal struc- ities of the Barents Sea material. These specimens tures that are available for study (of Terebratulina may be juveniles. They are not preserved in life sp. and Cheirothyris sp.) are due to fortuitous position. preservation. Records of Early Cretaceous Lingula are rare. Representatives of the genera Lingula, Dis- The genus is typically interpreted in the fossil cinisca, Terebratulina and Cheirothyris are rec- record as an indicator of shallow-water marginal orded for the first time from the northern high marine to intertidal environments (e.g. Ferguson latitudes, providing new information on Early 1986). Living species of Lingula are found mainly Cretaceous brachiopod palaeobiogeography. A in tropical to subtropical seas. The presence of single valve referred to the rhynchonellid genus Lingula antarctica Buckman in the Eocene La P lilorhynchia, an element of the distinctive north- MesetaFormation of Seymour Island, Antarctica, ern Siberian brachiopod fauna described by has been interpreted as indicating that shelf water Dagys (1968), has been identified. temperatures were warmer in the southern high Only a few brachiopods have been recovered latitudes during the Eocene than they are today from core 7425/9-U-1 and the chances of (Owen 1980; Lee 1986; Wiedman et al. 1988). recovering and identifying large ‘Siberian’ tere- The occurrence of Lingula in core 7425/9-U-1 bratulids (e.g. Siberiothyris and Taimyrothyris) may allow a similar inference, that water tem- from a 54 mm diameter core would be remote. peratures were warmer in the northern high lati- The possibility of homoeomorphy between the tudes during the Early Cretaceous than present- Barents Sea articulate brachiopods and the genera day. In this Barents Sea core, however, Lingula to which they are assigned has to be considered. occurs in a sequence that contains a characteristic Specimen numbers prefixed B. are present in Boreal bivalve Buchia (which need not imply the collections of the Department of Palaeonto- ‘cold water’). The ecological tolerances of taxa logy, British Museum (Natural History), London. (genera and species) may vary through geological time and this needs to be kept in mind when Phylum Brachipoda DumCril, 1806 relating modern and fossil distributions to each Class Inarticulata Huxley, 1869 other. Order Lingulida Waagen, 1885 Superfamily Lingulacea Menke, 1828 Order Acrotretida Kuhn, 1949 Family Lingulidae Menke, 1828 Superfamily Discinacea Gray, 1840 Genus Lingula Bruguikre, 1797 Family Discinidae Gray, 1840 Subfamily Disciniscinae Schuchert and Le Vene, Lirigula cf. ooalis J. Sowerby 1929 Fig. 11A Genus Discinisca Dall, 1871 Material. - One complete and two fragmentary valves at 60.10 m. Dimensions (approximate) of Discinisca sp. complete specimen (Fig. 11A): length 4.2 mm, Fig. 11B width 2.6 mm. Approximate dimensions of Material. - One crushed specimen at 60.08 m. incomplete external mould: length 4.5 mm, width Dimensions of the damaged specimen: length 3.1 mm. 2.4 mm, width 1.8 mm. The specimen has a cir- 182 N. Arhus et al. cular outline. At least 12 growth lines can be assic and Cretaceous northern high latitudes of distinguished. The specimen is attached to the the Boreal Realm (Dagys 1968; Owen 1972) and posterior lateral margin of the pedicle valve of an also from Cretaceous southern high latitudes indeterminate terebratulid(?). (Thomson & Owen 1979). If Thomson & Owen’s (1979) record of Ptilorhynchia australis from the Class Articulata Huxley, 1869 Lower Aptian of Alexander Island, Antarctic Order Rhynchonellida Kuhn, 1949 Peninsula, is a true Ptilorhynchia, it suggests that Superfamily Rhynchonellacea Gray, 1848 either the genus had a bipolar distribution, or a Family Rhynchonellidae Gray, 1848 cosmopolitan distribution (it should therefore be Subfamily Cyclothyridinae Makridin, 1955 found in mid- and low palaeolatitudes), possibly Genus Ptiforhynchia Crickmay, 1933 migrating from northern to southern high latitude regions. The record of Ptilorhynchia from the Ptilorhynchia sp. Lower Cretaceous of Mexico (Sandy in press) Fig. 11C suggests a cosmopolitan distribution and a North- South migration for the genus. Material. - Internal cast of an incomplete pedicle The internal structures of the type species P. valve at 60.20m. Dimensions of the specimen: Crickmay 1933, originally described length 7.9 mm, width 7.8 mm. The specimen is plumasensis from the Jurassic of California, are not yet known crushed and incomplete. It has a sub-triangular in detail. Knowledge of these would be valuable outline with a rounded anterior commissure. In in understanding the relationship between the lateral profile the specimen is very gently convex occurrences of the genus in Siberia, British Col- except in the umbonal area (posterior third of umbia, Mexico and Antarctica. length), where the maximum convexity is devel- oped. The internal cast is smooth, with the traces Order Terebratulida Waagen, 1883 of a few growth lines visible. A shallow sulcus extends from the umbo to the anterior Suborder Terebratulidina Waagen, 1883 Superfamily Cancellothyridacea Cooper, 1973 commissure, where the sulcus is approximately Family Cancellothyrididae Thomson, 1926 2 mm in width. Two parallel straight muscle scars (c. 2 mm long) are present in the umbonal area. Subfamily Cancellothyridinae Thomson, 1926 Genus Terebratulina d’Orbigny, 1847 A hinge tooth appears to be present where the cast is damaged in the umbonal area, suggesting that it is a pedicle valve. Terebratulina sp. Fig. llD, E Rerriarks. - The shape of the outline and the smooth shell and sulcus suggested by the internal Material. - Terebratulina sp. Interior of a brachial cast are characters displayed by Ptilorhynchia and valve at 61.10 m. Dimensions: length 3.2 mm, some species of Lacunosella. The valve is most width 3.1 mm. likely to be the pedicle valve of a Ptilorhynchia. Brachial valve interior (Fig. 11D, depth The outline of the sulcate valve is comparable 61.10 m), the brachidium is not preserved. The to P. glabra Dagys recorded from the Valanginian socket is visible on the left-hand side. A eusep- of northern Siberia (Dagys 1968). Two other toidum approximately 1 mm in length is present. species from northern Siberia, P. seducta Dagys The interior of the valve is relatively smooth. The (Berriasian-Hauterivian) and P. obscuricostata traces of a few of the costae can be seen along Dagys (Lover Volgian), also have broadly sulcate the length of the specimen but are most noticeable pedicle valves but with costae developed towards at the margin of the specimen where they are the anterior commissure. Costae have not been expressed as grooves on the valve interior. seen on the specimen recovered from core 7425/ Terebratulina? sp. Internal cast of brachial(?) 9-U-1, but due to its probable juvenile status valve at 60.10 m. Dimensions (approximate) of these would not be expected. It is not possible to incomplete specimen: length 3.0 mm, width provide a specific identification for the specimen 3.5 mm. The specimen has a circular outline apart apart from commenting on its similarity to the from the posterior hinge-line which is straight. above species. The internal structures of the speci- An estimated 17 costae are present at the margin men are unknown. of the damaged specimen. It can be estimated that Ptilorhynchia is currently recorded from Jur- approximately 20 costae were originally present. Systematic pakzeontology and biostratigraphy 183

Terebratulina? sp. Valve exterior (Fig. ZlE, well marked. The right-hand deltidial plate of the depth 60.10 m). Dimensions: length 3.3 mm, pedicle valve appears to be in place, sticking out width 3.0mm. The specimen has a subcircular and resembling a socket tooth. outline, tapering posteriorly to a sub-straight Remarks. - The specimen of Cheirothyris from hinge-line. The umbo protrudes posteriorly core 7425/9-U-l may be an immature specimen beyond the hinge-line, suggesting a pedicle valve. or belong to a diminutive species. It is smaller Costae radiate from the neanic stage of the valve. than adult specimens figured by Gerasimov (1955) Eighteen costae are present at the margin of the and Makridin (1964) or specimens of the type valve, some originating from the bifurcation of species Cheirothyris fleuriausa (d’orbigny) in the other costae. The intersection of growth lines and British Museum (Natural History), London costae leads to the development of concentrically (specimens reach over 20mm in length, e.g. B. arranged isolated rugae. 37312, B. 86223). The possible immature status Remarks. - The specimens from core 7425/9-U-l of the specimen could account for the long median may be juveniles or representatives of micro- septum which would become relatively shorter as rnorphic brachiopod species. Contemporaneous the valves grew longer and/or the septum became genera sharing similar external and internal mor- partially resorbed. phological characters include Symphythyris Smir- Cheirothyris has previously been recorded from nova and Crurafina Smirnova. The specimens the Jurassic of the Russian Platform. The Pechora lack the posterior elongation of Symphythyris. In Basin may have acted as a migration route for the brachial valve interior (Fig. 11D) there is Cheirothyris between the Russian and Svalbard no sign of the ventrally concave hinge-plate-like Platforms, suggesting a South-North pattern of structures on the inner side of the socket ridges colonization. seen in Cruralina (as illustrated by Nekvasilova The brachiopod genera Cheirothyris (Late 1978, plate IV), or of their former attachment. Jurassic-Early Cretaceous), Cheirothyropsis Two small scars are present where the brachidium (Jurassic) and Tetractinella (Triassic) provide a has broken off. classic example of homoeomorphy (e.g. Rudwick The relatively coarse costae on the internal 1970, p. 110). Another homoeomorphic brachio- cast (Terebratulina? sp., depth 60.10 m) and the pod to add to this list is represented by a single circular outline of its valve are atypical of specimen from the Upper Cretaceous Flysch Terebratulina, which tends to have relatively Zone of Austria (F. A. Middlemiss Collection). smooth valve interiors (e.g. Cooper 1973). In the The specimen is from Dambachgraben, Austria, absence of additional material and details of the probably Campanian in age and appears to be a brachidium the specimen is tentatively referred homoeomorph of Cheirothyris (Middlemiss pers. to Terebratulina. comm.; pers. observ.). Suborder Terebratellidina Muir-Wood, 1955 Stratigraphic range. - Gerasimov (1955) and Mak- Superfamily Zeiileriacea Allan, 1940 ridin (1964) record species of Cheirothyris from Family Zeilleriidae Allan, 1940 the Jurassicof the U.S.S.R. This is the first record Genus Cheirothyris Rollier, 1919 of the genus from the Cretaceous. Cheirothyris sp. Fig. 11F Cirripedes (J.S.H. C.) Material. - Interior of a single brachial valve at Hitherto, only two species of cirripedes, Archae- 61.08 m. Dimensions of the incomplete valve: olepas decora Harbort (1905) and Zeugmato- length 4.2 mm, width 4.3 mm. The valve has four lepas? hausmanni (Koch & Dunker 1837) have characteristic prominent carinae which extend been described from the Lower Cretaceous. The anteriorly. The anterior commissure appears to new species described here is the first to be be rectimarginate. Marginal grooves are pre- described from the Berriasian and may be com- served along part of the anterior commissure. pared with Z.? hausmanni. At least five regularly spaced growth lines are Capitular and lateral valves occur spasmodi- present. A median septum can be traced for two- cally through 59.38-59.03 m of core 7425/9-U-1. thirds of the length of the valve, the brach- The valves are very fragile, frequently shattering idium is not preserved. Shell endopunctation is as the core-thickness was reduced. The moulds, 184 N. Arhus et al. Systematic palaeontology and biostratigraphy 185 however, are sufficiently well preserved to allow at the tergo-basal angle. The occludent margin is adequate description of inner surface details slightly arched in the lower part and forms almost where not otherwise available. Predominant a right angle with the weakly siiiuous lower valves are terga, followed by scuta, rostra and margin. The tergal margin is weakly convex to then single examples of a carina and several dif- almost straight and the tergo-lateral angle is ferent lateral valves. This proportion of valves bluntly rounded. The lateral margin is straight, would seem to compare favourably with the pres- as long as the tergal margin, and forms a right ence of valves of various Gault species in a similar angle with the basal margin. The ridges of the bulk sample. Unfortunately, the carina, an apical surface ornament are coarser on the occludent fragment, is not sufficiently well preserved to be side of the apico-basal ridge and themselves selected as type. become coarser towards the occludent margin. Series Cirripedia Burmeister, 1834 Some ridges bifurcate, others are intercalated at Order Thoracica Darwin, 1851 an early growth-stage. Intermediate stages of Suborder Lepadomorpha Pilsbry, 1907 growth are marked by very faint lines, whereas temporary terminal stages are marked by rather Family Scalpellidae Pilsbry, 1916 broad shingle-like ridges knotting the apicobasal Genus Zeugmatolepas Withers, 1913 ones. On the inner surface a moderately deep adduc- Type species. - Zeugmatolepas rnockleri Withers tor muscle pit is overlain by another pit - 1913 by original designation. some Range. - Late Jurassic - Late Cretaceous. internal moulds show only a very shallow division between these two pits. Several growth ridges line Zeugmatolepas? borealis sp. nov. the tergal edge; the occludent edge is sharp to Fig. 9A-F, Fig. 10A-F within a short distance of the apex. Tergum (Fig. 10B, C) is sub-rhomboidal in Derivation of name. A northern species. outline, thin, rather bowed towards the carinal side and about one third as long as wide. The Diagnosis. - A Zeugrnatolepas with the umbo of the scutum apical and the basal tergal angle apicobasal ridge, situated about two thirds from moderately rounded. Tergum with the upper and the carinal margin, is obscure, but broadly devel- lower carinal margin rounded or forming an oped basally and there is a shallow depression on obtuse angle, the apico-basal ridge is developed the carinal side of it. The occludent margin is basally. weakly concave, shorter than the scutal margin, raised and bounded by a depression; the scutal Material. - All specimens from borehole 742519- angle is broadly rounded. The scutal margin is U-1. Holotype, a right scutum (Fig. 9F) from sinuous in its upper half and in its lower half 59.38m. Paratypes, 3 terga, carina, rostrum, 7 almost straight to the broadly rounded basal latera or lower latera, ?peduncle plate from angle. The convex upper part of the carinal mar- 59.8 m, 3 terga, rostrum from 59.03 m, 3 scuta gin is rather longer than the concave lower part from 59.28111, 7 terga, 2 scuta from 59.35m, 2 and the carinal angle is generally broadly terga, 1 lateral valve from 59.37 m. rounded, though may be sharp. The longitudinal Scutum (Fig. 9F) is subtrapezoidal in outline, ridges are much flatter and broader than those on moderately convex transversely and slightly cur- the scutum; a somewhat stronger ridge extends ved towards the tergum. The width is about two from the apex to about midway along the scutal thirds of the length. The umbo is apical and the margin. The knotted arrangement of the growth- curved apico-basal ridge, which is only a little lines appears only on the carinal side and its full wider than the ornamental ridges, is not produced development is retarded to a late growth-stage.

Fig. 9. Zeugrnafolepas? borealis Collins sp. nov. Barents Sea Borehole 7425/9-U-l at depth 59.38-59.03 m. A: Paratype, PMO 116.470 (Stub SK18); apical portion of carina, x36. B: Paratype, PMO 116.478 (Stub SK20); lower latus L3, x33. C: Paratype, PMO 116.471 (Stub SK18); rostrum, ~24. D: Paratype, PMO 116.472 (Stub SK18); lower latus L4, ~36. E: Paratype, PMO 116.473 (Stub SK18); lower latus L3, x43. F: Holotype, PMO 116.475 (Stub SK19); scutum, x20. 186 N. Arhus et al. Systematic palaeontology and biostratigraphy 187

On the inner surface a broad area of the upper the apex a little to one side of the midline causing carinal and occludent edges is marked with a slight difference in length of the lateral margins. growth-lines; no ridges pending from the apex on The longer margin is convex towards the base and the occludent side have been observed. the basal margin is divided by apicobasal ‘ridges’ Carina (Fig. 9A). A fragmentary apical portion into three parts each with a concave margin, the seen only from the photograph; narrow, flat to part on the side of the longer lateral margin equals concave on either side of a broadly rounded the length of the median part. The surface orna- median ridge. The basal angle is acute and the ment is more prominent on the median and ‘short’ apex rounded. Weak growth lines are knotted at side of the valve. the intersection with rather stronger apicobasal Latus 5 (Fig. 10E) is subtriangular in outline ridges. with the surface strongly deflected to one side of Rostrum (Fig. 9C) is equilaterally triangular, an apicobasal ridge; on the deflected side the almost as wide as high and strongly convex trans- lateral margin is convex and the basal margin versely with a strong apicobasal ridge; the apex slightly upturned. A fragment of another form is rounded. The lateral margins are weakly convex (Fig. 10A) partially overlaps the basal part of a apically and concave basally; the basal margin is right scutum. nearly straight with sharp basilateral angles. The A possible peduncle plate has the outer surface surface ornament of coarse ridges is similar to sharply inclined with the base in which is a distinct that of the scutum; the growth lines are vague. pit; vertical ridges on the outer surface are con- Latus 1 (Fig. 10D) is almost isoceles-triangular tinued partway onto the base. in outline with the basal margin rounded; a small portion of the apical area shows the growth lines Discussion. - In ornament and broad outline the in chevron. scuta and terga of Z.? borealis are not unlike Latus 2 (Fig. 10F) is almost equilaterally tri- those of the Jurassic Z. concinna (Morris 1845) angular in outline with the apex rounded; the from the Oxford Clay of central England. Of basal margin forms almost a right angle to one known Cretaceous species Z.? borealis is closest side and is moderately rounded on the other to Z.? hausmanni, which has been recorded from towards which the apicobasal ridges are directed; the Lower Cretaceous Hilston of Germany (Har- the ridges are almost absent (?eroded) on the bort 1905) and Speeton Clay of England. The inflected side and rather broad, sometimes bi- scutum of Z.? hausrnanni which also retains the furcate on the other. The valve figured by Withers apical position of the umbo is much smoother (1935, pl. 3, fig. 5s, after Koch & Dunker 1837) than that of Z.? borealis and on the inner surface is very similar, but from the opposite side of the has a ridge limiting the pit above the adductor capitulum. muscle pit. The underside of the tergum of Z.? Latus 3 (Fig. 9B, E) ?left and right valves, in hausmanni has 3-4 short apical ridges on the outline subtriangular with the apex rounded and occludent side which appear not to be developed more or less medial, the height is about two thirds in Z.? borealis. The rostrum of Z.? borealis is of the width. Of the two weak apicobasal ‘ridges’ essentially similar to that considered by Withers one is rather nearer one side, reducing the length (1935. p. 82) to belong to Z.? hausmanni, but of that part of the basal margin, the growth lines differs in having a rather more triangular base are deflected upwards on the opposite side. and stronger median ridge. Ridges similar to those on the scutum form the But for two exceptions the lateral valves here surface ornament. assigned to Z.? borealis show the greatest devi- Latus 4 (Fig. 9D) is rather damaged along the ation to any figured by Withers (1928, 1935) in lateral margins; about twice as wide as high with Zeugmatolepas; ‘latus l’, herein, approaches a

- Fig. 10. Zeugmarolepas? borealis Collins sp. nov. Barents Sea Borehole 7425/9-U-l at depth 59.3b.59.03 m A: Paratypc. PMO 116.479 (Stub SK20): latus overlapping right scutum. x24. B: Paratypc, PMO 116.469 (Stub SK17): left tergum, x30. C: Paratype. PMO 116.480 (Stub SK20): left tergum. x22. D: Paratype. PMO 116.476 (Stub SK19): latus 1. x20. E: Paratypc. PMO 116.474 (Stub SK18): latus 5. x30. F: Paratype. PMO 116.477 (Stub SK19): latus 2. x33. 188 N. Arhus et al. Systematic palaeontology and biostratigraphy 189 typical upper latus, while ‘latus 2’ approaches that antapical horns of M. asymmetrica are of unequal figured by Koch & Dunker as remarked above. length. The others are peculiar in having a tripartite basal Stratigraphic range. -Known only from the Lower margin. Barremian. Muderongia australis Helby 1987 Dinoflagellate cysts (N.A.) Fig. 12C Muderongia Cookson & Eisenack emend. Stover & Evitt 1978 1958 Muderongia macwhaei Cookson & Eisenack, p. 41, pl. 6, figs. I, 4 (partim). Type species. - Muderongia macwhaei Cookson 1975 Muderongia sp. cf. M. rnacwhaei Cookson & Eisenack; & Eisenack emend. Stover & Evitt 1978 Wall & Evitt. pl. 3. figs. 1, 2, 4,s. text-fig. 9. 1980 Muderongia sp. cf. M. macwhaei Cookson & Eisenack: Muderongia aequicornus sp. nov. Wiseman, pl. 1. fig. 2. Fig. llJ, Fig. 12B, G, H (holotype) 1980 Muderongiasimplex Alberti; Morgan, PI. lY, fig. 8,9, 10 (partim). Derioution of name. - With reference to the equal 1YW Muderongia macwhaei Cwkson & Eisenack; Jain & lengths of the right and left lateral horn and also Khowdja-Ateequuaman. pp. 37-38, pl. 1, figs. 1, 3; pl. 2, figs. 1, 2,4. 5; pi. 3, figs. 3-9. to the two equal antapical horns. 1987 Muderongia australis Helby, pp. 300-303, figs. 2, 3, 5.

Material. - Borehole 7320/3-U-1 at 27.440 m. A few specimens recorded per slide from seven Holoiype. - Geological Survey of Western samples, but more commonly in one sample from Australia, Perth. Investigator-1, 1,419 m. Slide F the top of the core. 11824, co-ordinates LO7.1+07.2. Fig. 2A-C. Description. - Proximate cyst, cornucavate. Material. -Common at 29.95 m in borehole 7320/ Endophragm rounded, more or less protruding 3-U-1. 7430/10-U-l. Present in the uppermost into the five horns. The apical and two straight part of the Rurikfjellet Member, Janusfjellet, antapical diverging horns are about 50 Vrn long Spitsbergen, where it is common 10 m below the and gently tapering throughout their length. top of the member, but also present somewhat Stout, blunt lateral horns, in the order of 15 bm lower in the section in the Hauterivian S. uer- long with paracingular notches. Operculum usu- sicolor ammonite Zone. ally detached. Paraplates not discernible. Remarks. - This species belongs to a plexus Remarks. - In spite of the often difficult dis- including M. macwhaei Cookson & Eisenack tinction of species within this genus, the mor- 1958, M. staurota Sarjeant 1% and M. australis phology of this species shows little variation in Helby 1987. Helby (1987) distinguished a form core 7320/3-U-l. included in M. macwhaei by Cookson & Eisenack Muderongia testudinaria Burger 1980 and Mud- and named it M. australis. Jain & Khowaja-Atee- erongia asymmetrica Brideaux 1977 are the most quzzaman (1984) illustrated the variation in the similar species, but both have relatively long post- plexus, but their forms are more similar to M. cingular extensions of their cingular horns. The australis and M. staurota than to the holotype of

Fig. 11. A-F: Brachiopods fro-m core 7425/9-U-1, Barents Sea. Undifferentiated Boreal Berriasian-Valanginian. Depth and magnification as indicated. A: Lingula cf. ouah J. Sowerby. PMO 116550, 60.10m. x5. B: Discinisca sp. PMO 116551. 60.08111.x10. C: Pfilorhynchia sp. PMO 116552, 60.20m. x5. D: Terebrafulina sp. PMO 116553, 61.10 m, X 10. Interior of brachial valve. E: Terebrafulina? sp. PMO 116554, 60.10m. x10. F: Cheirorhyris sp. PMO 116555, 61.08111,X5. Interior of brachial valve. G-K: Dinoflagellate cysts from cores 7320/3-U-l and 7425/9-U-1, Barcnts Sea. Lower Barremian. X500. Depth as indicated G: Batioladinium shaflesburiensis sensu N0hr-Hansen, PMO 116556. 7320/3-U-1, 28.94 m. Slide Ox,. England finder W22/1. H: B. shaftesburiensis sensu N0hr-Hansen. PMO 116557. 7320/3-U-1. 20.94 m. Slide Ox3, England finder C40. 1: Pseudoceratium nudum Gocht 1957. PMO 116558. ?425/Y-U-l, 49.72111.Slide Ox,, England finder F21/4. J: Muderongia aequicornus sp. nov. PMO 116559. 7320/3-U-l, 4.45 m. Slide Oxlr England finder Y27. K: Muderongia fefracanfha(Gocht) Alberti 1961. PMO 116560. 7320/3-U-l, 23.45 m. Slide Ox,, England finder M25/4. 190 N. Arhus et a/. Systematic palaeontology and biostratigraphy 191

M. macwhaei. Their PI. 2, fig. 9 resembles M. Stratigraphic range. - The species is too rare to tetracantha. No specimens with the extreme be useful for dating in the Lower Cretaceous of lateral horns of the holotype of M. macwhaei have the Barents Sea, but does at least occur in the been observed in our material. Barremian. In Morocco and England it is also known from the Aptian and Albian and the Stratigraphic range. - This species occurs in the species seems to be more common in these areas. Hauterivian and Barremian of Australia and in beds close to the Hauterivian/Barremian bound- ary in the Barents Sea, Spitsbergen and East Acknowledgements. -We arc indebted to the crew on hoard Greenland. An acme of this species observed both M/S ‘Bucentaur’ for providing the cores and to the scven oil in the Barents Sea and Spitsbergen and also in companies that financed this drilling project; to Gcir Elvebakk, East Greenland by Ncjhr-Hansen (pers. comm. Jacob Verdenius and Oddvar Skarb@ who provided sedi- mentological, calcareous nannoplankton and foraminifci-a1 1989) may be of stratigraphic importance. This data, respectively, and to the tcchnical staff at IKU for various acme is not observed in 7430/10-U-1, where the kinds of assistance. species occurs consistently in low numbers from 25.10 to 11.94111(top of the core). In 7425/9-U- 1 M. australis has not been found. References Muderongia perforata Alberti 1961 Aarhus, N., Verdenius, J. & Birkelund, T. 1986: Bio- Fig. 12E stratigraphy of a Lower Cretaceous section from Sklinna- banken, Norway, with some comments on the Andeya I961 Muderongiu perform Alberti, p. 13, pl. 2, figs. 8. 9. exposure. Nor. Geol. Tidsskr. 66, 17-43. 1974 Muderongia cf. sraurora Saricant: Davey & Verdier. p Bartenstein, I1. Xr Bcttenstacdt, F. 1962: Marine Unterkreidc 644, PI. 91, figs. 4, 8. (Boreal und Tcthys). Pp. 225-297 in Simon. W. Xr Betten- 1976 Muderongiu simplex Alberti: Brideaux, pl. 44.2, tig. 1. stacdt, H. (eds.): Lri!fos.silirn der Mikropuluontologie. 1979 Muderotijiiu srmpfex Alhcrti: Ashraf, p. 136, pl 6, fig. 10 Bcrlin. 1981 Muderorigru perforutu Alhcrti: Below, pp. 16-17, pl. 2 Birkelund,T.,Thusu, B. Xr Vigran, J. 1978: Jurassic~Crctaccoiia fig. 7, text-tig. 11. hiostratigraphy of Norway, with comments on the British 1983 Muderongia puricrtu Duxhury, pp. 36-37. pl. 2. figs. 5, 8 Rasenia cymodoce Zonc. Pulueontology 21, 31-63. tcxt-fig. 16. Birkcnmajer, K. & Pugacawska, H. 1975. Jurassic and Lower 19x7 Muderongiu pur.iutu Duxhury: I Icilrnann-Clauscn, pi. I, Cretaceous marine fauna of SW Torell Land. Spitshergcn. lig. 6. Stud. Geol. Pol. 44, 45-89. Birkcnmajcr, K., Pugacrcwska, H. & Wicrrhowski. A. 1982: Holotype. - Geologischen Institut der Universitat The Janusfjcllct Formation (Jurassic-Lower Crctaccous) at Tubingen. Borehole Pirna, Sachsen. Slide A9, Myklegardfjellct, east Spitshcrgcn. Pulueonr. Polonicu 4.7. 107-140. PI. 2, fig. 8. Bliithgen. J. 1936: Die Faunu und Strutigruphie dr~OOerjuru urtd der Unterkreide LJOI~Kiiriig KcirlA Land. Grirnrncn. 92 Mulerial. - Borehole 7425/9-U-1 at 53.94 m. PP. Chcrkesov. 0. V. & Burdykina. M. D. 1981: 0 \tratigrafikatsiy Rmnarks. - Alberti described this species as hav- mezozoya Novoy Zemli po nakhodkam pcrcotlixhcnnoy ing two antapical horns, one of which can be fauni (On the stratification of thc Mesozoic (if Novaya Zcmlya strongly reduced. His figures, however, do not from discovcrics of rcdepositcd fo\sil\). Pp. 85-99 in Hond- show more than one antapical horn except the arev, V.I. (ed.): Paleonrologicheskrrya osnova stratigru- specimen in PI. 2, fig. 7, which he only with doubt ficheskikh skhem palaeozoyu i mesozoyu ostroooo Sooimkoy Arktiki (Palaeontological basis for the Palacozoic and Mcso- assigned to this species. The lack of two antapical zoic stratigraphic schemes of thc islands of the Sovict Arctic). horns led Duxbury to describe his specimens as a PGO Scvmorgeologiya, Leningrad (in Russian) new species. Chopcr, G. A. 1973: Fossil and Recent Cancellothyridacca

Fig. 12. Dinoflagellate cysts from Lower Barremian sections in corcs 7320/3-U-I and 7425/9-U-l, Barents Sea. XSOO. Depth as indicated. A: Pseudoceratium nudum Gocht 1957. PMO 116561. 7425/Y-U-I, 51.94 m. Slide Ox,, England finder M18/1. B: Muderongia aequicornus sp. nov. PMO 116562. 7320/3-U-l, 2.47 m. Slide Ox3, England finder V21. C: Muderongiu ausrralis Helhy 1987. PMO 116563, 7320/3-U-l, 29.95 m. Slide Ox,, England finder N16. D: Muderongia cf. asymmetrica Brideaux 1977. PMO 116561. 7425/9-U-l, 51.94m. Slide Oxz, England finder G34/4. E: Muderongia perforata Alberti 1961. PMO 116564. 7425/9-U-1, 53.94 m. Slide Oxz, England finder Z22/3. F: Muderongia cf. usymmetrica Brideaux 1977. PMO 116561. 7425/9-U-l, 51.94 m. Slide Ox2,England finder K24/3. G: Muderongia aequicornus sp. nov. PMO 116565. 7320/3-U-l, 10.47rn. Slide Ox,, England finder 023/2. H: M. aequicornus sp. nov. Holotype. PMO 116566. 7320/3-U-l, 0 m. Slide Ox,, England finder 024/2. 192 N. Arhus et al.

(Brachiopoda). Tohoku Uniuersiry, Sci. Rep., 2nd set. Hoedemaeker, P. J. 1987: Correlation possibilities around the (Geol.). Special Volume 6 (Harai Memorial Volume). 371- Jurassic/tretaceous boundary. Scripto Geuiojircu 84. 55 pp. 390, PIS. 42-46. HBkansson, E., Birkelund, T., Piasecki, S. & Zakharov, V. A. Crickmay, C. H. 1933: Attempt to zone the North American 1981: Jurassic-Cretaceous boundary strata of the extreme Jurassic on the basis of its brachiopods. Geological Society Arctic (Pcary Land, North Greenland). Geological Sociefv of of America, Bulletin 44, 871-894. Denmark, Bulletin 30. 11-42. Dagys, A. S. 1968: Yurskiye i rannemelovyye brakhiopody Jain, K. P. Khowaja-Atccquzzaman 1984: Reappraisal of the severa Sibiri (Jurassic and Lower Cretaceous brachiopods genus Muderongia Cookson & Eiaenack, 1958. Journal ofthe from northern Siberia). Izdarelstoo Nauka, Sibinkoye otde- Palaeontological Society of India 29. 34-42. leniye 41. 126 pp, (in Russian). Jeletzky, J. A. 1966: Upper Volgian (latest Jurassic) ammon- Davey, R. J. 1974: Dinoflagellate cysts from the Barremian of ites and buehias of Arctic Canada. Geological Survey of the Speeton Clay, England. Birbal Sahni Institute of Canada, Bulletin 128. 51 pp. Palaeoborany, Special Publication 3, 41-75. Jeletzky. J. A. 1984: Jurassic-Cretaceous boundary beds of Davey, R. 1979: The stratigraphic distribution of dinocysts in western and Arctic Canada and the problem of the Tithonian- the Portlandian (latest Jurassic) to Barremian (Early Cre- Berriasian stages in the Boreal Realm. Pp. 175-255 in Wcs- taceous) of northwest Europe. American Association of Strati- termann, C. E. G. (cd.): Jurassic-Cretaceous hiochronolog)] graphic Palynologisrs, Contribution Series 5B,4W1 und palaeogeography of Norrh America. Geological Associ- Davey. R. J. 1982: Dinocyst stratigraphy of the latest Jurasslc to ation of Canada, Special Paper 27. Early Cretaceous of the Haldager no. 1 borehole, Denmark. Kelly, S. K. 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Zakharov, V. A., Surlyk, F. & Dalland, A. 1981: Upper Jur- melovykh otlozhcniy o. Shpitsbergena (Fauna of the Upper assic-Lower Cretaceous Buchia from Andeya. northern Nor- JUrdSSiC and Lowcr Crctaccous dcposits of thc island of way. Nor. Geol. Tidsskr. 61, 261-269. Spitsbergen). Trudy plou. mursk. nauch. insf. 2(3), 91-115 Zhirmunskiy. A. M. 1927: Fauna vcrkhne-yurskikh i nizhne- (in Russian, Frcnch summary).