Acritarchs from the Lower Cambrian Buen Formation in North Greenland GEUS Report file no.

22316

Gonzalo Vidal and John S. Peel

GRØNLANDS GEOLOGISKE UNDERSØGELSE

Bulletin 164 1993 GRØNLANDS GEOLOGISKE UNDERSØGELSE Bulletin 164

o Acritarchs from the Lower Cambrian Buen Formation in North Greenland .. ~ ~ f)

Gonzalo Vidal and John S. Peel

1993 Vidal, G. & Peel, J. S. 1993: Acritarchs from the Lower are particular1y important and relevant with classical Cambrian Buen Formation in North Greenland. Bull. Lower Cambrian rock successions in Baltoscandia, vari­ Grønlands geol. Unders. 164, 35 pp. ous areas of the East European Platform, Svalbard, Scotland and North-East Greenland. In all, the reco­ vered acritarch assemblage conclusively confirms the AcritafGhs (organic-walled phytoplankton) are de­ previously proposed late Ear1y Cambrian age for the scribed from the siliciclastic rocks of the Buen Forma­ Buen Formation, most likely corresponding to the He­ tion. A total of 52 form taxa are reported from a small liosphaeridium dissimilare - Skiagia ciliosa (= Vergale number of extremely fossiliferous samples from the 'horizon') and perhaps the Volkovia dentifera - Lie­ deeper shelf portion of the formation. The preservation paina plana (= Rausve 'horizon') acritarch zones in the of acritarchs is excellent and, in the light of their abun­ East European Platform and counterparts in Baltoscan­ dance, the taphonomy and palaeobiology of the Buen dia. Formation are discussed. Three new acritarch form taxa are erected and two more., obviously also new, are left under open nomenclature. Large-size acanthomorphic Authors' addresses: acritarchs represented by extremely rare finds of two G. V., Institute of Earth Sciences - Micropalaeontol­ new taxa (Comasphaeridium? densispinosum n. sp. and ogy, Uppsala University, Norbyvagen 22, S-751 22 Comasphaeridium longispinosum n. sp.) are recorded Uppsala, Sweden. for the first time in Lower Cambrian strata. Large acan­ J. S. P., Geological Survey of Greenland, øster Vold­ thomorphs are otherwise important in Neoproterozoic gade 10, DK-1350 Copenhagen K, Denmark. Present strata and the significance of the present finds is dis­ address: Institute of Earth Sciences - Dept of Historicai cussed. The remaining acritarchs are known from nu­ Geology and Palaeontology, Uppsala University, Nor­ merous wor1d-wide earlier occurrences. Comparisons byvagen 22, S-751 22 Uppsala, Sweden.

Grønlands Geologiske Undersøgelse Ujarassiortut Kalaallit Nunaanni Misissuisoqarfiat Geological Survey of Greenland The Geological Survey of Greenland (GGU) is a research institute affiliated to the Mineral Resources Administration for Greenland (MRA) within the Danish Ministry of Energy. As with all other activities involving the non-living resources in Greenland, GGU's investlgations are carried out within the frarnework of the policies decided jointly by the Greenland Home Rule Authority and the Danish State.

© GGU, Copenhagen, 1993 ISSN 0105-3507 Contents

Dansk sammendrag - Imaqarnersiuineq ., ...... 4 Goniosphaeridium ~p. A...... 23 Introduetion...... 5 Goniosphaeridium varium (Volkova, 1969) Geological framework ...... 5 Downie, 1982 ...... 23 Sample register...... 7 Goniosphaeridium volkovae Hagenfeldt, 1989 ...... 25 Material and methods ...... 9 Granomarginata squamacea Volkova, 1968...... 25 Acritarch preservation...... 9 Heliosphaeridium sp...... 25 Taphonomy and palaeobiology 9 Heliosphaeridium coniferum (Downie, 1982) Large acanthomorphic acritarchs...... 11 Moczydlowska, 1991 ...... 25 Biostratigraphy ...... 12 Heliosphaeridium dissimilare (Volkova, 1969) Conc1usions ...... 13 Moczydlowska, 1991 ...... 25 Taxonomy 15 Heliosphaeridium lubomlense (Kirjanov, 1974) Archaeodiscina umbonulata Volkova, 1968...... 15 Moczydlowska, 1991 ...... 25 Asteridium Moczydlowska 1991...... 15 Heliosphaeridium notatum (Volkova, 1969) Moczydlowska, 1991 ...... 25 Asteridium lanatum (Volkova, 1969) Moczydlowska, 1991 ...... 15 Heliosphaeridium obscurum (Volkova, 1969) Asteridium ordensis (Downie, 1982), comb. nov. .... 15 Moczydlowska, 1991 ...... 27 Asteridium tornatum (Volkova, 1968) Leiosphaeridia Eisenack, 1958 emend. Downie & Moczydlowska, 1991 ...... 17 Sarjeant, 1963...... 27 Leiovalia tenera Kirj anov, 1974...... 27 ?Celtiberium geminum Fombella, 1977...... 17 Lophosphaeridium dubium (Volkova, 1968) Comasphaeridium sp. A Downie, 1982 "...... 17 Moczydlowska, 1991 ...... 27 Comasphaeridium agglutinatum Moczydlowska, 1988. 19 Lophosphaeridium tentativum Volkova, 1968 ...... 27 Comasphaeridium mackenziana Baudet, Aitken & Vanguestaine, 1989 19 Lophosphaeridium truncatum Volkova, 1969 ...... 27 Lophosphaeridium sp...... 29 Comasphaeridium molliculum Moczydlowska & Vidal, 1988...... 19 Multiplicisphaeridium dendroideum Comasphaeridium? densispinosum Vidal n. sp...... 19 (Jankauskas, 1976)...... 29 Pterospermella Eisenack, 1972...... 29 Comasphaeridium longispinosum Vidal n. sp. 19 Retisphaeridium dichamerum Staplin, Jansonius & Comasphaeridium strigosum (Jankauskas) Downie, 1982 .,...... 21 Pocock, 1965...... 29 Skiagia Downie, 1982 '" ...... 29 Comasphaeridium cL strigosum (Jankauskas) Downie, 1982 ...... 21 Skiagia ciliosa (Volkova, 1969) Downie, 1982 ...... 29 Cymatiosphaerapostii (Jankauskas, 1976) Skiagia compressa (Volkova, 1968) Downie, 1982. ... 29 Jankauskas, 1979 ...... 21 Skiagia orbiculare (Volkova, 1968) Downie, 1982. ... 31 Cymatiosphaera sp. 21 Skiagia ornata (Volkova, 1968) Downie, 1982 ...... 31 Dictyotidium Eisenack, 1955 emend. Staplin, 1961 ... 21 Skiagia scottica Downie, 1982 ...... 31 Dictyotidium perforatum Vidal n. sp...... 21 Tasmanites bobrowskae Wa:i:ynska, 1967 ...... 31 Elektoriskos sp. A...... 23 Tasmanites tenelIus Volkova, 1968...... 31 Fimbriaglomerella Loeblich & Drugg, 1968 23 Tasmanites volkovae Kirjanov, 1974...... 31 Globosphaeridium cerinum (Volkova) Trachysphaeridium timofeevi Vidal, 1976...... 31 Moczydlowska, 1991 ... :...... 23 Acknowledgements ...... 33 Goniosphaeridium primarium (Jankauskas) References...... 33 Downie, 1982 ...... 23 Dansk sammendrag

Dette arbejde beskriver acritarcher (fytoplankton forekomster verden over. Det er især vigtigt at sammen­ med organisk væg) fra Buen Formationen (nedre Kam­ ligne med de klassiske aflejringer fra nedre Kambrium i brium) i Nordgrønland. I alt rapporteres der om 52 Baltoscandia, forskellige områder på den østeuropæiske arter fra få men særdeles fossilrige prØver, der repræ• platform, Svalbard, Skotland og Nordøstgrønland. senterer den dybere del af shelfen i Buen Formationen. Acritarch-sammensætningen bekræfter fuldtud den ti­ På baggrund af det store indhold af velbevarede acri­ dligere foreslåede datering af Buen Formationen til den tarcher diskuteres formationens tafonomi og palæobio• sene del af tidlig Kambrium, højst sansynligt svarende logi. Tre nye arter af acritarcher opstilles, mens to til Heliosphaeridium dissimilare - Skiagia ciliosa (= andre, tydeligvis også nye, placeres under åben nomen­ Vergale 'horizon') og måske Volkovia dentifera - Lie­ klatur. Store acantomorfe acritarcher er for første gang paina plana (= Rausve 'horizon') acritarch-zonerne på registreret i lag fra nedre Kambrium. Disse former er den østeuropæiske platform og tilsvarende zoner i Bal­ ellers kun beskrevet fra neoproterozoiske aflejringer. toscandia. De resterende acritarcher kendes fra talrige tidligere

Imaqarnersiuineq

Nalunaarusiami uvani imaani naasuaqqat, acritarchit, taamaattut ujaqqani pisoqaanerusuni taamaallat siorna­ Avannaarsuani ujaqqani immikkoortuni Buen Forma­ tigut allaaserineqartarsimagamik. Acritarchit sinneri si­ tionimeersut ukiut immikkoortut Kambriumip aallartin­ larsuarmi ujaqqani allarpassuarni siornatigut allaatigi­ nerani pinngorsimasut eqqartorneqarput. Ujaqqani neqarsimasuni ilisimaneqarput. Ujaqqat architarchiqar­ amerlanngikkaluartutuni naasuaqqanilli ujaranngorsi­ fiusut pingaarnerit 570 milliunit missaanni masunik amerlaqisunik akulinni, architarchit immik­ pisoqaassusillit Baltoscandiami, Europami kangilliup koortut 52-t siumorneqarsimapput, taakkulu Buen For­ nunavissuani, Svalbardimi, Skotlandimi Tunumilu mationip atsinnerusortaani nassaarineqarsimapput. Ar­ Avannaarsuani sanilliussallugit pingaartorujussuuvoq. chitarcherpassuit ujaranngorsimagaluarlutik ilusaat Architarchit assigiinngitsorpassuit ataatsimoortut tunn­ allanngorsimanngitsut tunngavigalugit qangarsuaq sumi gavigalugit ujaqqat imikkoortut Buen Formationip piso­ inuusimanerat eqqartorneqarpoq. Architarchit immik­ qaassusaasa Kambriumip aallartinnerani pinngorsima­ koortut nutaat pingasut suunerat aalajangerneqarsima­ sutut aalajangerneqarsimanerat maannakkut erseqqis­ voq, allaIli marluk qularnanngitsumik nutaajusut suli sumik uppernarsineqarsimavoq. erseqqissumik taaguuserneqarsimanngillat. Aatsaat si­ ullerpaamik acritarchit annertoqisut ukiut 570 milliunit matuma siornatigut pinngorsimasut allaaserineqarput, Introduetion

The organic-walled envelopes of presu,mably motile Early Phanerozoic radiation evenfs. In addition, orga­ and/or encysted life stages of Early Palaeozoic protists nic-walled phytoplankton provide valuable information (Dale, 1977; Tappan, 1980) are among the most abun­ about conditions of deposition and organic diagenesis. dant fossils in shallow to moderately deep shelf deposits In this paper folIowing previous preliminary reports (Downie, 1973). Near the ProterozoiclPhanerozoic (Vidal & Peel, 1984; Moczydlowska & Vidal, 1986) we boundary eukaryotic plankton underwent a radiation deaJ with the palaeobiology, taxonomy and biostrati­ (Moczydlowska & Vidal, 1986) comparable in magni­ graphy of the abundant acritarchs of the Buen Forma­ tude to that formerly reported among ichnofossils tion of North Greenland. ane additional point of in­ (Crimes, 1987) and skeletised faunas (Conway Morris, terest circles around the taphonomic significance of 1987). Assemblages of acritarch taxa which in a geologic acritarchs in the Buen Formation in the light of the perspective, arose and declined rapidly, are becoming previously reported occurrence of an exceptionally pre­ increasingly well-known in numerous regions (see Moc­ served fauna of poorly skeletised macrofossils from the zydlowska, 1991 for a recent review). Together with same formation (Conway Morris et al., 1987; Conway shelly faunas, they provide the basis for increasingly Morris & Peel, 1990; Peel, 1990; Peel et al., 1992). refined biostratigraphy which allows the correlation of

Geological frarnework

The Buen Formation forms part of a southern shelf most of central and eastern North Greenland. Strata sequence within the Lower Palaeozoic Franklinian Ba­ assigned to these groups form a complex of prograding, sin succession of the Canadian Arctic Islands and north­ diachronous carbonates and subordinate siliciclastic ern Greenland (Higgins et al., 1991; Surlyk, 1991). This sediments. Shelly macrofossils are conspicuous at many carbonate-dominated shelf sequence unconformably horizons within the two groups and indicate an age from overlies crystalline basement of the Greenland Shield late Early Cambrian to earliest Ordovician. and Proterozoic sedimentary basins to the south. To the The Buen Formation varies in thickness from about north, the shelf sequence passes into an equivalent 425-500 m in its southern outcrop in Peary Land but deep-water trough sequence but the northern margin of thins to about half this amount in the small outcrops in this Franklinian Basin succession is poorly constrained. northern Freuchen Land and northern Wulff Land (Fig. The Buen Formation contrasts with most units within 1). Farther north, the succession thickens greatly as the the Franklinian shelf sequence of northern Greenland formation grades into the turbidite trough sequence of in being composed of siliciclastic sediments. This silici­ the Polkorridoren Group. Typically, the formation can clastic interval can be traced east-west across northern be divided into a lower sandstone-dominated unit and Greenland, either as the Buen Formation itself (Fig. 1) an overlying recessive unit dominated by mudstones. or as the correlative Dallas Bugt Formation and Hum­ The sandstone-dominated unit is most prominent in boldt Formation of the area around Kane Basin, to the southern outcrops from Wulff Land to southern Peary west (Peel 1982; Peel & Christie, 1982). Land but mudstones dominate in north-east Peary Land In central and eastern North Greenland (Fig. 1) the and outcrops along the northern coast of Greenland, to Buen Formation overlies marine platform carbonate the west. The characteristic transition from sandstone­ sediments of the Portfjeld Formation. The latter forma­ dominated inner shelf deposits to finer grained outer tion is poorly fossiliferous but has yielded the cyanobac­ shelf deposits reflects a regional rise in sea level within teria SpirelIus Jiang, 1982, Obruchevella Reitlinger, Buen time. 1948 and Jiangispirellus Peel, 1988 of probable Early A section through the formation at its type locality is Cambrian age (Peel, 1988). shown in Fig. 2 and most samples processed for acri­ The Buen Formation is overlain by a progradational tarchs in the present study were either derived from this shelf sequence referred to the Brønlund Fjord Group section or from outcrops close by. The lower sandstone­ and the overlying Tavsens Iskappe Group throughout dominated unit contains strata interpreted as inner shelf 6

.... -~'-I:...... ,..--~ \", \_-

Wandel Valley Formation (Ordovician)

Ordovician U Tavsens Iskappe Group 40km M C o;:

Portfjeld Formation

Fig. 1. Outcrops of the Buen Formation in central North Greenland showing the derivation of fossiliferous samples. and tidal deposits. The abrupt sedimentological change abundant macrofossils occur within the deep shelf mud­ from sandstone domination to mudstone at about 270 m stones from the same samples as those yielding acri­ above the base ofthe section indicates maximum trans­ tarchs in the present investigation (e.g., GGU samples gression of the shelf and the establishment of a deep 184002-184004; GGU 270591-270592). Olenellacean shelf environment. Subsequent strata are mudstone­ trilobites include OlenelIus hyperboreus (Poulsen, dominated, with thin beds of storm deposited sand­ 1974), associated with hyolithids, bradoriids. Pelagiella, stones; they represent a sequence shaIlowing to inner Hyolithellus and inarticulate brachiopods (cf. Poulsen, shelf environments but not as shaIIowas the sandstone­ 1974; Palmer & Peel, 1979). OlenelIus is also reported dominated lower unit of the formation. A detailed sedi­ from the highest beds of the formation in eastern Peary mentary profile through the lower part of the formation Land (Palmer & Peel, 1979), while Bergstrom & Peel in the un-named land area south of Nares Land (locality (1988) described trace fossils from the same interval in for GGU 316941 in Fig. 1) was presented by Bryant & southern Peary Land. Pickerill (1990, fig. 2). In north-western Peary Land (Fig. 1, GGU 340103) The lower sandstone-dominated unit ofthe Buen For­ outer shelf mudstones in the lower part of the Buen mation in southern outcrops has not yielded macro­ Formation have yielded a rich fauna of poorly skeletised fossils, although trace fossils have been described by macrofossils associated with the nevadiid olenellacean Bryant & Pickerill (1990). In the vicinity of the type BuenelIus higginsi Blaker, 1988. The fauna is dominated locality in southern Peary Land, well preserved and by arthropods and worms, the latter including artic- 7 ulated halkieriids (Conway Morris et al., 1987; Conway Morris & Peel, 1990; Peel, 1990; see also Blaker, 1988). ·274573 Acritarchs have not been recovered from this locality. • ~ ·274570 Sample register .274800 The relative stratigraphic pOSitIOn of samples pro­ • ~ cessed for acritarchs is indicated in Fig. 2. • GGU 184002-184004: Buen Formation at Brillesø, east side of the valley of Børglum Elv, southern Peary Land, a few kilo­ ·274795 metres north-east of the type locality of the formation (cf. Figs 1, 2). Samples collected by J. S. Peel, 1974.

GGU270591, 270592: Buen Formation on the northern side of Sæterdal, southern Peary Land, about 20 km west of the type ( 184002-4) locality (cf. Figs 1, 2). Samples collected by J. S. Peel, 1978. (270591,2) GGU 274793-274800, 274570-274573: Buen Formation at its type locality, north side af Jørgen Brønlund Fjord, immedi­ ately west of the mouth of BØrglum Elv in southern Peary Land (Figs 1, 2). Samples collected by H. A. Armstrong and J. R. ~f+1 Ineson, 1980. ;.•••• :::- .. :.'.:-\::::1 ," . GGU 340103: Lower Buen Formation, Sirius Passet, north­ .... ',' " ,,:,' west Peary Land (Fig. 1). Collected by S. Conway Morris and ....~~ J. S. Peel, 1989. GGU 316941: 54.8 m above the base of the Buen Formation, ii-y~< 200 un-named land area south of Nares Land (see Figs 1, 2).

Collected by I. D. Bryant, 1984 (see Bryant & Pickerill, 1990). . .. ' '. '.:. : ' ',:: : ...... , ..' .. ' .'. : :.: :: ',::.: ~~'.: .:. :'. '•. F=:2zzi2:z:~ .. I-:::::/:::;?~-~/_~/-~'/;...,:hI ./././././ ..• :~: •... ~~ :... ~~~·.i·.·~ .-'/./ ~ . '...... J .1 .:',' O".:

: •.. : ~ .•: J JJJJ./""'" I- - ..

Fig. 2. Section through the Buen Formation at its type locality, 100 west of the mouth of Børglum Elv on the northern shore of Jørgen Brønlund Fjord, southern Peary Land, showing the 274794 location of GGU samples. Numbers in brackets indicate sam­ I- _ ...... :-. ples collected at other localities (see Fig. 1) and correlated with 274793 the type section. The succession shows two shallowing-up cy­ des. The lower part of the section (1l-270 m) represents an ?(316941) inner shelf succession characterised by storm beds which are IX succeeded at about 120 m by sediments showing a tidal infJu­ ence. Deep shelf mudstones (c. 271l-325 m) represent the pe­ ...... 30 2 /fF riod of maximum transgression of the shelf; subsequent sedi­ .. ,. .... :: ~~~~~_>:::J ments indicate shallowing to inner shelf conditions, but not as shallow as the lower cyde. 8

G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) G) c c c c c c c c c c c c c c c c ~ ..... ~ ~ ~ ~ ~ '"..... '"..... ~ ~ ~ '";;! ;;!'" ~ ... ;;!'" '"o o ...... en en ;a .....en ~ IB ~ ~ § § ~ ~ ..... ~ iS 8 ~ ~ ;j '" '" ~ '" le LeiospI7aeridia sp. • • •• • • ••••• Trachysphaetidium timofeevi •• •• Skiagia omata •• •• •••• •••• Comasphaeridium maekenzlåna • •• •• ComaspI7aeIidiummo/Iieulum • • Leiovalia tenera • • • Skiagia el7iosa type A • •• • ••••••••• Skiagia ei/iosa type B • • ••• Comasphaeddium ? densispliJosum n. sp. •• • Comasphaeridlum IongispliJosum n. sp. • ComaspI7aeIidium sp. A Downie • • •• Comasphaeddiumstrigosum • •• • ••• • • Cymatiosphaem sp. ••• • Granomarginata squamaeea • • Heliosphaen"dium disslillilare •• ••• • •• • Heliosphaeridlum obseumm • :. He!lOSphaeridiumsp. LophosphaeridiumbUncatum • • • Ptemsperme/Ia sp. • Retisphaeridium dlchamerufi! •• • • ••• Comasphaeridium cf. SIJiJosum • • • ComasphaeIidium spp. • • • Goniosphaeridium vanum • Skiagia seoUiea •• •• ••••• • Asterid!um ordensis • • Asteridium lanatum • • ••• CymatiosphaerapostIl • • Elektoriskos sp. A • Goniosphaeridlum sp. A • Goniosphaeddium vo&ovae • Heliosphaeridium eOfillemm • • Lophosp/7aeridlumtentativum • • "oV Skiaglå orblculare • ••• • • Skiagia eompressa ••• •• ••• Archaeodi>cinaumbonu/ata • Fimbdaglomerellamembranaeea • Aillbdaglomerellaminuta • Globosphaeridium eerinum •• Goniosphaeridiumprimanum • Lophosphaeridiumdubium ••• MultljJlicisphaeddium dendroideum • •• Tasmanites bobrowskae • • •••• Tasmanites tene//us • • Heliosp/Jaeridlum /ubom/ense • Tasmanites vo&ovae • • Heliosphaeridium notatum • ? Ce/tibenumgeminum • OictyotidJumpertoratum n. sp. •• Oictyotidiumpriseum • Skiaglå ei!lOsa type C • ComasphaeridliJm agg/utlilatum • Asteridiumtomatum • • Ga7bsphaeridium sp. • • Lop7asphaeridlum sp. Fig. 3. Chart showing the occurrence of acritarchs in processed samples from the Buen Formation. 9

Material and methods

Spot samples and samples collected from stratigra­ fully described by Vidal (1988). Sixteen samples proved phic sections through the Buen Formation are included fossiliferous, a figure that by any accounts is to be in this study. Acid-resistant organic-walled residues considered as a very high yield. were isolated from a total of 20 samples using a method

Acritarch preservation

The preservation of acritarchs and other organic mi­ and amorphous organic matter ranges from light yellow crofossils in the investigated samples is generally good to brown and this suggests thermal alteration index to excellent. The most productive samples (e.g. GGU (TAI) values around 2 to 2+ (immature to mature; samples 184002-184004, 274570-274572, 274795­ Pearson, 1984). These data are in agreement with a 274799) are rich in yellowish to brown, granular or thermal alteration corresponding to temperatures be­ flaky, organic sapropel. Compaction and flattening of tween 50 and <150°C. Exceptionally, one sample microfossils is moderate and certain samples (notably (GGU 340103) of thinly laminated black pyritous shale GGU 184004 and 274571, 274796, 274797) yielded yielded dark-grey to black bacterial microfossils and three-dimensionally preserved acritarchs. The reason sapropel-like organic debris indicating thermal alter­ for this is unclear, but comparable preservation has ation (TAI 4- to 4) in the order of 200°C or higher.This been observed e!sewhere in Lower Cambrian rocks with sample, collected from the locality in Sirius Passet, high phosphate contents (Mcczydlowska & Vidal, northern Peary Land, which yield the poorly skeletised 1992). It cannot be excluded that the investigated black fauna described by Conway Morris et al. (1987) and mudstones and shales may include early diagenetic Conway Morris & Peel (1990) lies on the southern mar­ phosphatised portions, thus accounting for the unusu­ gin of the North Greenland fold belt (Dawes, 1976; ally good preservation of acritarchs. but such intervals Higgins et al., 1991). The higher degree of thermal have not been detected. alteration reflects metamorphism associated with the The colour of acritarchs, cyanobacterial microfossils fold belt.

Taphonomy and palaeobiology

It appears possibie that the accumulation of Early As pointed out above (see Geological frarnework) an Palaeozoic acritarchs may have followed patterns abrupt sedimentological change is observed from the comparable to those of the geologicaIly more recent lower sandstone to the upper mudstone-dominated por­ phytoplankton groups (Knoll, 1985), such as dinoflagel­ tion of the Buen Formation. These changes correlate lates (Evitt, 1985; Vidal & Nystuen, 1990a). well with the recorded lack, respectively abundance, of Despite generally low Total Organic Carbon (TOC) macrofossils and microfossils. Thus, except for ichno­ values around 0.1%, (except the above mentioned sam­ fossils (Bryant & Pickerill, 1990), the dominantly arena­ ple 340103 with TOC 2.0%) finely laminated and car­ ceous portions of the investigated section (Fig. 2) are bon-rich rocks from the Buen Formation yield large barren, whereas the deeper shelf mudstones (samples amounts of organic saprope! and acritarchs that seem to GGU 274796, 274797, 274800, 274570; Figs 2, 3) yield bear witness of quiet water conditions and slow deposi­ abundant acritarchs (Vidal & Peel, 1988); rich shelly tion. Thus for example, sapropel A is believed to form faunas are best known from the deepest part of the in low energy lacustrine or marine environments where succession (e.g. GGU samples 184002-4; Poulsen, abundant organic matter accumulates under restricted 1974; Palmer & Peel, 1979). Furthermore, the fre­ circulation and dysaerobic conditions (Staplin et al., quency of discrete palynomorph taxa varies consider­ 1973, cited in Venkatachala, 1981). ably in the investigated samples and certain taxa (e.g. 10

SPECIES ACRITARCH TAXA FROM THE BUEN FORMATION

\li CD \li ~ S:'c ~ gj

~ d§~~!llC .~~ ~ ~ ~ ~a!l ~ ~i~·;s IH~~~nH!iUH... {Ii"" ~hH~iJ ... •. z hUiH O Na: O ;C Illilillllllllllllllllllillllllllllll I~ ~ ~, ... RAUSVE I

VERGAI..E

TALSY

LONTOVA

ROVNO

KOlUN

Fig. 4. Stratigraphic ranges of acritarchs in samples from the Buen Formation according to previous occurrences in various parts of the East European PIl/tform (Volkova el al., 1983; Moczydlowska, 1991). Taxa with stratigraphically poorly constrained ranges are omitted.

Skiagia ornala, S. ciliosa, S. scottica form the bulk of the Rocks of the Buen Formation at Sirius Passet in total palynomorph population in most samples. In terms north-western Peary Land (GGU 340103 in Fig. 1) yield of the taxonomic diversity among acritarchs, the Buen a fauna of arthropods, worms, sponges and halkieriids Formation is roughly comparable to the diversity rec­ (Conway Morris et al., 1987; Conway Morris & Peel, orded in time-equivalent Early Cambrian rock units in 1990; Peel, 1990; Peel et al., 1992). ane single pro­ Baltoscandia (Eklund, 1990; Hagenfeldt, 1989; Moc­ cessed sample (GGU 340103) from this important local­ zydlowska & Vidal, 1986; Moczydlowska, 1991). itYyielded only thermally altered possibly bacterial mi­ Lower Cambrian units in Baltoscandia represent dep­ crofossils attributed to Sphaerocongr!!gus variabilis osition in pericratonic basins under generally shallow Moorman, 1974 that have been interpreted as probable water conditions as demonstrated by the abundance of cyanobacteria (Knoll & Swett, 1985; Moorman, 1974; sedimentary rocks displaying various features indicating Mansuy & Vidal, 1983) or photosynthetic anoxygenic shallow shelf to littoral deposition (cf. Eklund, 1990; bacteria (Vidal & Nystuen, 1990a). Interestingly, and Vidal & Nystuen, 1990b). Although abundant phyto­ parallel to well-studied dysaerobic late Neoproterozoic plankton can be recovered from generally shallow ma­ basins in Spain (Palacios, 1989) and Baltoscandia (Vidal rine sequences (Moczydlowska & Vidal, 1992), a gen­ & Nystuen, 1990a), acritilfchs are also absent from this eral trend towards decreasing taxonomic diversity is fossiliferous Buen sall}ple (GGU 340103). Other rec­ pervasive in littoral sequences (Vidal & Nystuen, 1990a; ords of exceptionally preserved Cambrian faunas share Palacios & Vidal, 1992) as compared to contemporane­ with the Buen Formation the probably significant fea­ ous deeper shelf settings. Depositional settings and ture of occurring in 'deeper water shales' (Conway Mor­ post-burial degradation processes are of extreme impor­ ris, 1987). A detailed study of organic, non-mineralising tance for the preservation potential of delicate organic­ organisms in the Burgess Shale (Butterfield, 1990) re­ walled remains (Butterfield, 1990). vealed that the Burgess Shale, contrary to the present 11 case, yields abundant leiosphaerid and rare papillose of the Buen Formation in more southern outcrops is (Butterfield, 1990) and small spiny acritarchs (Vidal, here seen as indicating a preserved sample of accumu­ unpublished observation). Furthermore, Butterfied lated encysted and/or motile life stages of algal protists. (1990) concluded that carbon isotopic values for the This feature may indicate accumulation in organic-rich Burgess Shale reflect normal conditions. No such data sediments overlain by nutrient-rich oxic waters in the are available for the Buen Formation. The investigated mixed layer or, alternatively represent the accumulated Buen sample comes from a succession where bioturba­ phytoplankton that occupied productivity 'hot spots' in tion is present in certain beds, but the soft bodied fauna denitrified anoxic waters along the narrow chemical is collected from laminated horizons with only a few gradients at the boundary of the oxygen-minimum zone horizontal burrows in part of the section where biotur­ (Berry et al., 1989). The latter has existing parallels in bated and non-bioturbated horizons alternate. It ean be blooms produced by dinoflagellates under conditions concluded that the presence of abundant organic matter suitable to denitrification (Eppley et al., 1969). and pyrite in the investigated sample from north-west­ Proposed anoxitropy, implying anoxic conditions be­ ern Peary Land and the recovered biotas are consistent neath the wind-mixed surfaee layer, in Early Palaeozoic with sparse bioturbation, enhanced carbon burial and oceans could accommodate conditions involving high perhaps oxygen-depleted bottom water. productivity (as implied by the rich acritarch record) In this context, the contrasting abundance of acri­ and a fair preservation potential in the offshore 'black tarchs in the mudstone-dominated deeper shelf portion shale' facies (Berry et al., 1989).

Large acanthomorphic acritarchs

Rare specimens of large (9{}-180,um in vesicle diame­ vast numbers of accompanying 'normal size' (c. 5-70 ter) acanthomorphic acritarchs (Fig. 6a, c, d) occur in ,um) typical Early Cambrian taxa. GGU samples 184002-184004 from the Buen Formation Certain Proterozoic and Early Palaeozoic acritarchs (Fig. 3). Generally, acritarchs average between 50 and (e.g. Tasmanites, Baltisphaeridium and Veryhachium) 100,um (Tappan, 1980), although the normal range of were compared to the phycoma stages of prasinophy­ Early Palaeozoic non-tasmanitid acritarchs is about 5­ cean green algae (Jux, 1971; 1975) on the basis of their 100 ,um. By contrast, morphologically diagnostic large wall ultrastructure. Such studies have not been applied (>100 ,um) acanthomorphic acritarchs, although gener­ to Neoproterozoic and Early Cambrian acritarchs, al­ ally rare, appear widespread in Neoproterozoic se­ though the incremental growth pattern of the prasi­ quences (Awramik et al., 1985; Butterfield et al., 1988; nophycean phycomata from an initial size of about 10 Jankauskas, 1979; Keller & Jankauskas, 1980; Knoll & ,um to about 1O{}-175,um at a mature stage (Tappan, Ohta, 1988; Knoll, 1984; Knoll & Calder, 1983; Knoll et 1980), as compared to the dimensions and growth pat­ al., 1991; Pjatiletov & Rudavskaya, 1985; Vidal, 1990; terns of some Neoproterozoic species of large acantho­ Yin, 1985; Zang, 1988; Zang & Walter, 1989). In gen­ morphs, are supposed to indicate possibie prasinophy­ eral (although often imprecisely expressed) the within­ cean affinity (Knoll et al., 1991; Vidal, 1990). sample numbers of large acanthomorphs in late Prote­ The large acanthomorphs from the Buen Formation rozoic occurrences are low (Zang Wenlong, V. A. Ru­ (Fig. 6a, c, d) have processes and other morphological davskaya, personal demonstration, 1990; M. Moczy­ features that are present among typically Lower Cam­ dlowska, G. Vidal & V. A. Rudavskaya, unpublished brian smaller counterparts. Here, because they display data), often amounting to a few specimens in a normal distinctive morphologic attributes (apart from their palynological sample. This feature has a parallel in the larger dimensions), they are attributed to different taxa. notable rarity of large acanthomorphs in the present Their presence in only three of the investigated samples Early Cambrian material. Small or large, acanthomor­ that apparently do not differ from other processed sam­ phic acritarchs are generally rare in Late Proterozoic ples is puzzling, but probably not more so than the successions but the rarity of the large acanthomorphs presence or absence of 'normal' Cambrian-type taxa in must be considered as puzzling when compared with the the same samples (see Moczydlowska & Vidal, 1992 for a discussion on related subjects). 12

Biozones (after Moczydtowska, 1989) Rock units

USSR aeritareh Poland S. Sweden Poland Blozones Seandinavia 'horizonS' Lublin slope OstergtStland

OELANDICUS mudst () ECCAPARADOXIDES Kibartai E. OELANDICUS Kostrzyn Fm glauconite sst :i OELANDICUS ------

Lingulid Sandstone PROAMPYX L1NNARSSONI Rausve PROTOLENUS Radzyn & <:: ------l'll HOLMIA KJERULFI grp Vergale MICK WITZIA '- Kaplonosy Fms .c HOLMIA E HOLMIA INUSITATA 11111111 Sandstone l'll U '- MOBERGELLA Q) 3: o SCHMIDTIELLUS l=c=J:c Talsy SCHMIDTIELLUS ....J RUSOPHYCUS IIIII ------PLATYSOLENITES Lontova Mazowsze Fm PLATYSOLENITES ANTIQUISSIMUS ------Wrodowa Fm () SABELLIDITES Rovno Q) '- SABELLlDITI::S- a. CAMBRIENSIS ------'Kotlin' VENDOTAENIA Lublin Fm

Biostratigraphy

From previously reported macrofossil finds (Palmer inated deep shelf portion are also poorly fossiliferous & Peel, 1979; Poulsen, 1974), the age of the Buen (particularly GGU samples 270591-270592; Figs 2, 3). Formation can be conclusively established as late Early In the light of the distribution of acritarchs in the above Cambrian (Bryant & Pickerill, 1990). The acritarch as­ mentioned areas, most of the upper mud-dominated semblage recovered from the Buen Formation com­ member thus appears to be of Vergale age (Heliosphae­ pares well with assemblages from Early Cambrian suc­ ridium dissimilare - Skiagia ciliosa acritarch zone; Moc­ cessions in the East European Platform, Baltoscandia zydlowska, 1991). However, this assumption may imply (Eklund, 1990; Hagenfeldt, 1989; Moczydlowska, 1991; stratigraphic extended ranges for three species (Tasma­ Moczydlowska & Vidal, 1986; Vidal & Nystuen, 1990b; nites tenellus, Goniosphaeridium primarium, and per­ Volkova et al., 1983), Scotland (Downie, 1982), Spain haps Comasphaeridium mackenziana (as indicated in (Palacios & Vidal, 1992; Gamez et al., in press); Sval­ Fig. 4). In the case of the latter species the previously bard (Knoll & Sweet, 1987), central East Greenland established range is poorly constrained. (Downie, 1982; Moczydlowska & Vidal, 1986) and Can­ The 3 specimens of H. notatum in GGU sample ada (Baudet et al., 1989; Figs 3-5). 274798 could perhaps suggest that a part of the in­ No age diagnostic microfossils were recovered from vestigated succession mayas well be of Rausve age samples from the lower arenaceous part of the Buen (equivalent to the Volkovia dentifera - Liepaina plana Formation. Investigated samples from the upper part of acritarch zone; Moczydlowska, 1991), although it could the Buen Formation are generaIly richin phytoplank­ alternatively have an earlier appearance in the Buen ton, although some samples from the mudstone-dom- Formation. 13

Rock units Fig. 5. Suggested biostratigraphic correlation of the Buen Formation in the context of Lower Cam­ brian biozonation for the East European Platform Southern Norway North-East and Baltoscandia and suggested correlations of North Gree[lland Lake Mjøsa Greenland rock successions in North-East Greenland.

limestone, shale, conglomerate .LU L111J~ lU Ul Lil Brønlund Fjord ? Group

Evjevik Limestone

HOLMIA Shale Ella Island Fm BUEN FM ------Bråstad sst & sh ------Bastion Fm Brennsæter shale Portfjeld Fm

Ringsaker Quartzite Mbr Kløftelv Fm ? f------? Vardal Sandstone Mbr I -- -- ? -- - -?

Ekre Shale Spiral Creek & Canyon Fms

Conc1usions

Acritarchs are extremely abundant and quite well­ dant organic matter, perhaps under restricted circula­ preserved in deeper shelf mudstones (Figs 2, 3) of the tion and dysaerobic conditions (see above). Buen Formation. Individual abundance and taxonomic Large-size (vesicle diameter 90-180 ,um) acanthomor­ diversity are substantially 'lower folIowing a shallow­ phic acritarchs occur in small numbers (GGU samples ing-up trend to alternating fine-grained sandstone and 184002-184004) in the deep shelf portion of the Buen siitstone of inner shelf facies (Figs 2, 3). By contrast, Formation. These acanthomorphs are here described as GGU samples 274793-274794 from mudstones, inter­ two new species of the acritarch genus Comasphaeri­ preted as inner shelf storm beds (Figs 2, 3), are totally dium. As it is the case with large Neoproterozoic acan­ barren. This seems in agreement with previously ob­ thomorphs, they are rare components among the small served trends of decreasing taxonomic diversity in litto­ to normal size (vesicle diameter 5-70,um) characteristic ral sequences as compared to contemporaneous deeper Early Cambrian acritarch taxa in the Buen Formation. shelf settings. By inference with the stratigraphic ranges of acri­ High taxonomic diversity (as recorded in GGU sam­ tarchs elsewhere, the investigated upper mud-dom­ ples 274570-274571, 274796-274800, 184002-184004) inated member of the Buen Formation may be corre­ correlates positively with the presence of organic sapro­ lated with rocks of the Heliosphaeridium dissimilare ­ pe!. This latter feature appears to be in agreement with Skiagia ciliosa acritarch zone (Vergale 'horizon') and suggested quiet water conditions and slow deposition perhaps the Volkovia dentifera - Liepaina plana acri­ resuiting in the accumulation and preservation of abun- tarch zone (Rausve 'horizon'; Fig. 5). 14

- 15

Taxonomy

The Buen Formation has yielded a rich and diverse Archaeodiscina umbonulata Valkova, acritarch assemblage including species of Arehaeodis­ 1968 eina, Asteridium, Comasphaeridium, ?Celtiberium, Cy­ Fig. Ile matiosphaera, Dietyotidium, Elektoriskos,· Fimbriaglo­ merelIa, Globosphaeridium, Goniosphaeridium, Helio­ This is represented by a single well-preserved speci­ sphaeridium, Leiosphaeridia, Leiovalia, Lophosphaer­ men recovered from GGU sample 274796. Previous idium, Multiplieisphaeridium, Pterospermella, Reti­ occurrences are given in Hagenfeldt (1989) and Moc­ sphaeridium, Skiagia and Tasmanites. These form zydlowska & Vidal (1986). genera comprise 52 form taxa, of which 9 are only identified at the form-genus level (Fig. 3). The taxonomy of Early Cambrian acritarchs is based on gross morphologicalfeatures and elements of orna­ Asteridium Moczydlowska 1991 mentation such as processes. Recent work on EarlY Cambrian acritarchs (e.g. Downie, 1982; Moczydlow­ The genus Asteridium Moczydlowska, 1991 is repre­ ska, 1988, 1991; Moczydlowska & Vidal, 1988; Volkova sented in the Buen Formation by Asteridium lanatum et al., 1983) has resulted in a satisfactory state of taxo­ (Volkova, 1969) Moczydlowska, 1991, A. (= Mierhys­ nomic stability and understanding. Consequently, to tridium) ordensis (Downie, 1982) comb. nov. and A. avoid unnecessary repetition, in this paper we refrain tornatum (Volkova, 1968) Moczydlowska, 1991. from providing a complete taxonomic treatment of pre­ viously known taxa; these are only briefly described. More or less complete and recent synonymies, taxo­ nomic information and geographic and stratigraphic dis­ Asteridium lanatum (Valkova, 1969) tributions can be retrieved from papers by Downie Moczydlowska, 1991 (1982), Hagenfeidt (1989), Knoll & Sweet (1987), Moc­ Asteridium lanatum (Volkova, 1969) Moczydlowska, zydlowska & Vidal (1988), Moczydlowska (1988), Vol­ 1991 occurs in small numbers in several samples from kova (1968, 1981a, 1981b) and Volkova et al. (1983). the Buen Formation (Fig. 3). The dimensions of well The most recent and complete source of information preserved specimens indicate vesicle diameter x = 10.8 can be found in Moczydlowska (1991). ,um (N = 8) and process lengthx = 0.7,um (N = 8). This Collection numbers prefixed by GGU refer to sam­ taxon was selected by Moczydlowska (1991) as type ples collected by the Geological Survey of Greenland. species of the new form-genus Asteridium, thus trans­ Figured specimens with numbers prefixed MGUH are ferring several species previously attributed to the form­ kept in the Geological Museum, University of Copen­ genus Mierhystridium (Deflandre, 1937) Sarjeant, 1967 hagen. to the new form-genus. Previous occurrences were re­ Dimensions are generally based on measurements of cently listed by Hagenfeldt (1989) and Moczydlowska the best preserved material available and are given as (1991). the number of specimens (N), mean (x) for vesicle diameter and process length and (a) for standard devia­ tion. Asteridium ordensis (Downie, 1982), comb. nov. Fig.9b Fig. 6. Acritarchs from the Buen Formation, North Greenland. a, Comasphaeridium longispinosum n. sp., MGUH 21.516: 1982 Micrhystridium ordensis sp. nov. Downie, p. 262, figs H/46 from GGU sample 184004-B: 1, holotype. b, Comas­ 6ff-hh, 7a. phaeridium cf. strigosum (Jankauskas) Downie, 1982, MGUH 21.517: Y/35-4 from GGU sample 184003: 1. c, d, Comasphae­ Material. Four well-preserved specimens. ridium? densispinosum n. sp., specimen at c, MGUH 21.518: E/36-4 from GGU sample 184002: 1; specimen at d, MGUH 21.519: Z/47-3 (below) from GGU sample 184003: 1, holo­ Emended diagnosis. Organic-walled spheroidal vesicle type. Bar under c represents lO,um for a, c; 4,um for b and 16 with numerous medium length, straight, thin processes ,um for d. of equal width withblunt distal ends. 16 17 Remarks. The morphotype attributed by Downie (1982) ?Celtiberium geminum Fombella, 1977 to Micrhystridium ordensis displays morphological attri­ Fig. 8d, e butes established to the form-genus Asteridium Moc­ zydlowska, 1991. A. ordensis differs from other species A single acritarch specimen from GGU sample of the genus by its straight, widely-spaced and more 274799 is attributed to ?Celtiberium geminum Fombella, robust processes, with blunt distal ends. 1977. It has a spherical central vesicle (6.um in diame­ ter) whose cavity seems to be in communication with Dimensions. Vesicle diameter 7-8 .um, process length tapering conicai processes (2-2.5 .um in length) with 1.5-4.um . rounded apical ends. C. geminum is formerly known from Middle Cambrian rocks in northern Spain (Fom­ Occurrence and stratigraphic range. Lower Cambrian bella, 1977) and was recently reported by Eklund (1990) Buen Formation ofNorth Greenland (Figs 3, 4). Lower from the lower Middle Cambrian glauconite sandstone Cambrian Fucoid Beds in Scotland, Bastion Formation unit in Ostergotland, southern Sweden. in North-East Greenland, Gog Formation and Mt. Whyte Formation in Alberta, Canada.

Comasphaeridium Sp. A Downie, 1982 Asteridium tornatum (Volkova, 1968) Fig. 8j Moczydlowska, 1991 Fig.9a 1982 Comasphaeridium sp. A. Downie, p. 260, fig. 6m. 1989 Comasphaeridium sp. A in Downie, 1982 Baudet, Aitken & Vanguestaine, p. 140, pI. 1, figs 18-19. Asteridium tornatum (Volkova, 1968) Moczydlowska, 1991 is rare in the investigated samples from the Buen Formation (Fig. 3). It consists of organic-walled circular Material. Eight well-preserved specimens. to oval vesicles 8-21 .um in diameter covered by evenly distributed short, thorn-like processes 1-2.um in length. Description. Organic-walled sphaeroidal vesicle with Previous occurrences were listed by Volkova (1969a, b), numerous clearly defined processes tightly arranged and Volkova et al. (1979) and Moczydlowska (1991). tapering towards the sharp tips.

Remarks. This species of Comasphaeridium differs form C. velvetum Moczydlowska, 1988 and C. agglutinatum Moczydlowska, 1988 by having free-standing and un­ pasted, longer and tapering, sharp pointed processes. It also differs from Comasphaeridium strigosum (Jankaus­ kas) Downie, 1982 through its clearly defined, not pasted and longer processes, and by the clearly delim­ ited outline of the vesicle.

Dimensions. Vesicle diameter: N = 6, i= 8.6 .um, pro­ Fig. 7. Acritarehs from the Buen Formation, North Greenland. cesses: N = 6, i = 5.5 .um. a-b, Comasphaeridium molliculum Moezydlowska & Vidal, 1988, two foeal leveis, MGUH 21.520: Kl46-4 from GGU Occurrence and stratigraphic range. Lower Cambrian sample 274795: Al. c, h, Comasphaeridium cf. strigosum (Jan­ Buen Formation ofNorth Greenland (Figs 3, 4). Lower kauskas) Downie, 1982, specimen at c, MGUH 21.521: U/41-3 Cambrian Fucoid Beds in Scotland, Holmia Shales in from GGU sample 274797: GI; specimen at h, MGUH 21.526: southern Norway and Gog Formation in Alberta, Cana­ U/50-3 from GGU sample 274571: G2. d, e Comasphaeridium da (Downie, 1982); upper part of Lower Cambrian mackenziana Baudet, Aitken & Vanguestaine, 1989, specimen at d, MGUH 21.522: S/47 from GGU sample 274796: GI; Vampire Formation and Sekwi Formation in north­ specimen at e, MGUH 21.523: Kl27 from GGU sample western Canada (Baudet et al., 1989). 274571: G2. f, Comasphaeridium sp., MGUH 21.524: D/43 Acritarchs clearly belonging to the genus Comasphae­ from GGU sample 274799: Al. g, Comasphaeridium strigosum ridium, but not being clearly attributable to any known (Jankauskas) Downie, 1982, MGUH 21.525: Z/32 (below) form species of this genus, are here referred to Co­ from GGU sample 184003: l. Bar under f represents 10 ,um. masphaeridium spp. in Fig. 3. 18 b c

h

Fig. H. Acritarchs from the Buen Formation, North Greenland. a, b, Heliosphaeridillm lubomlense (Kirjanov. 1974) Moczyd/ow­ ska, l YY l, MGUH 21.527: W/30-4 and MGUH 21.528: R/43-1/3 from GGU sample 274797: G l. c, f-lelio.vphlleriililll'll obsclIrllll1 (Volkova. 1969) Moczydlowska. IYYL MGUH 21.529: N/42-3 from UUU sample 184002: J. d. e, ?Celliberilll7l gelllilllllll Fombella. 1977 allwo focallevels. MGUH 21.530: K/2fi from GGU samplc 27479\!: Al. f. du tcrccl spccimcns ol' COlllasplweri­ dillllllllackellZialla Bauclet. Aitken & Vanguestaine. 1989. MGUH 21.531: T/48-4 from GGU sample 184002: I. g. k, Jleliosplllle­ rir/hml colllfentlll (Dem'nic. 1(82) Moczydlowska. 1991. spccimcn at g. MGUH 21.532: R/45-3 from UUU sample 274796: GI: specimcn at k; MGUH 2.1.533: R/45-3 from GGU sample 27479fi: GI. h. COlliosphaeridi/ll1l vo/kovae Hagcnfelclt. 198Y. MUUH 21.534: Z!48---3 (bclow) from GG samplc IH4002: l. i, COlliosp!laeridillll1 sp. A. MGUH 21.535: Z!49 3 (bclow) from GGU s:lmplc 27479fi: G I. j. C()/}wsp!l{wridiwll sp. A Downic, 19H2. MGUH 21.536: 1:::/40 from UGU samplc 27·H%: U I. l. COlllasplweridilll1l agglll(illllllllll Moczydlowska. 1988. MGUIl 21.537: Z/43-2 from GGU sample 274571: G2. Bar undcr I reprcsenls 13/1111 for a IO 1'111 for b-I. 19 Comasphaeridium agglutinatum ous occurrences were listed by Moczydlowska & Vidal Moczydlowska, 1988 (1988), Hagenfeldt (1989) and Vidal & Nystuen (1990b). Fig. 81

Two specimens recovered from GGU sample 274571 Comasphaeridium? densispinosum Vidal (Fig. 3) are attributed to Comasphaeridium agglutina­ n. Sp. tum. They consist of a spheroidal vesicle ranging 6-8,um Fig. 6c, d in diameter and surrounded by densely arranged agglut­ inated processes. The species is previously known only Derivation of name. Latin densum, dense, and spina, from the lower part of the Wlodawa Formation and the spine; relating to the densely arranged crown of pro­ Mazowsze Formation in Poland (Moczydlowska, 1991). cesses covering the vesicle.

Material. Eight well-preserved specimens. Comasphaeridium mackenziana Baudet, Aitken & Vanguestaine, 1989 Diagnosis. An acritarch species with spheroidal vesicle Fig. 7d, e densely covered with short, minute, simple ciliar-like processes. The processes are generally simple, but may 1989 Comasphaeridium mackenziana n. sp. Baudet, Aitken in some instances display a distinct, low, conicai, proxi­ & Vanguestaine, p. 138-140, pI. 1, figs 14-17. mai attachment to which a ciliar-like portion of the process is attached. Excystment by median split. Material. Thirteen well-preserved specimens; abundant in GGU sample 184002 from the Buen Formation (Figs Description. The generic assignation of this taxon is 3, 4). uncertain, being attributed with certain reservations to Comasphaeridium? This is because most specimens dis­ Description. Small acritarchs conslstmg of a central play process dimorphism, possessing abundant ciliar­ spherical vesicle having a smooth outer surface covered like short processes together with few processes that by numerous, well-defined, closely arranged, filiform display a conical-shaped basal attachment, a feature and flexible processes of equal thickness. absent among species of Comasphaeridium.

Dimensions. Vesicle diameter: N = 8, i= 94.1 ,um, a = Dimensions. Vesicle diameter: N = 12, i= 8.08 ,um, 36.9,um. Process length: i = 1 ,um. Width of process processes: N = 12, i = 3.08 ,um. attachment i = 1,um, height of process attachment i = 1,um. Occurrence and stratigraphic range. Lower Cambrian Buen Formation, (Figs 3--4), North Greenland. Previ­ Occurrence and stratigraphic range. Lower Cambrian ous occurrences are 14 m above the lower junction of Buen Formation in North Greenland (Figs 3--4). the Lower Cambrian Sekwi Formation and 2 and 8 m below tht? upper junction of the Vampire Formation in the central Mackenzie Mountains, north-western Cana­ Comasphaeridium longispinosum Vidal da (Baudet et al., 1989). n. Sp. Fig. 6a

Comasphaeridium molliculum Derivation of name. Latin longum, long and spina, Moczydlowska & Vidal, 1988 spine; relating to the extremely Iong processes covering Fig. 7a, b the vesicle.

For synonyms see Moczydlowska & Vidal (1988) and Material. A single specimen from GGU sample Hagenfeldt (1989). Acritarchs consisting of a central 184004-B. spherical vesicle (vesicle diameter: N = 6, 65-70,um) with smooth outer surfaee covered by numerous, closely Description. Acritarch with large spheroidal to ovoidal arranged filiform and flexible processes (process length: vesicle covered by densely interwoven and, in relation 5-7,um). Excystment (not seen in the present material) to the vesicle diameter, long, slender and very thin by median split (Moczydlowska & Vidal, 1988). Previ- processes. 20 a b c

d

h

.. 21 Dimensions. The single recovered specimen has a ves­ Cymatiosphaera postii (Jankauskas, icle diameter of i = 180 ,um, whereas the sub-micron 1976) Jankauskas, 1979 wide processes are i = 20,um in length.

Only 2 specimens of C. postii were recovered (Fig. 3). Occurrence and stratigraphic range. Lower Cambrian Overall dimensions range from 20-25 ,um whereas the Buen Formation in North Greenland (Figs 3, 4). diameter of the inner body is 16 ,um. Synonymy and previous occurrences in Lower Cambrian strata were listed by Hagenfeldt (1989) and Moczydiowska (1991). Comasphaeridium strigosum (Jankauskas) Downie, 1982 Fig. 7g Cymatiosphaera Sp. Fig. lOc, d

Acritarchs attributed to C. strigosum are rare, but occur through most of the sampled succession of the Acritarchs here attributed to Cymatiosphaera sp. Buen Formation. The vesicle diameters range from (sensu Volkova et al., 1979) are very rare and restricted 18-22 ,um, whereas the length of processes is 3-6 ,um. to 4 samples (Fig. 3). They are comparable to forms For synonymies and previous occurrences see Hagen­ from the Vergale 'horizon' in Latvia illustrated by Vol­ feldt (1989) and Moczydlowska (1991). kova et al. (1979, pI. 15, figs 1-2) under the name Cymatiosphaera div. sp. Four specimens recovered have a mean vesicle diameter of 33 ,um. Comasphaeridium cf. strigosum (Jankauskas) Downie, 1982 Dictyotidium Eisenack, 1955 emend. Figs 6b, 7c, h Staplin, 1961

Acritarchs attributed to this species consist of a cen­ Type species. Leiosphaera (= Dictyotidium) dictyotum tral spherical vesicle (diameter i = 20.3 ,um, a = 5.0 Eisenack, 1938, p. 27-28, pI. 3; figs 8a-c. ,um, N = 13) surrounded by densely arranged simple processes (process length i = 6.1 ,um, a = 2.2 ,um, N = 13). Dictyotidium perforatum Vidal n. Sp. Fig. lOa

Derivation of name. Latin perforatum, perforated; re­ Fig. 9. Acritarchs from the Buen Formation, North Greenland. lating to the perforations observed on the fieIds limited a, Asteridium tornatum (Volkova, 1968) Moczydlowska, 1991, MGUH 21.538: C/42 from GGU sample 274571: G2. b, Asteri­ by the reticular ornamentation of the vesicle. dium (= Micrhystridium) ordensis (Downie, 1982) comb. nov., MGUH 21.539: V/45-2 from GGU sample 184002: 1. c, He­ Material. Three specimens from GGU samples 274799 liosphaeridium dissimilare (Volkova, 1969) Moczydlowska, and 274800. 1991, MGUH 21.540: R/45-2 from GGU sample 274799: Al. d, Pterospermella sp., MGUH 21.541: S/43 from GGU sample Diagnosis. Spheroidal vesicle with reticular surface 184004: Al. e, Retisphaeridium dichamerum Staplin, Jansonius sculpture. The areas limited by reticula have clearly & Pocock, 1965, MGUH 21.542: B/43-4 from GGU sample 274798: Al. f, Retisphaeridium dichamerum Staplin, Jansonius defined circular pores. & Pocock, 1965, MGUH 21.543: L/49 from GGU sample 274796: GI. g, Lophosphaeridium dubium (Volkova, 1968) Dimensions. The overall dimensions are derived from Moczydlowska, 1991, MGUH 21.544: K/43--4 from GGU sam­ the measurement of 3 deformed specimens and suggest ple 274571: G2. h, Lophosphaeridium tentativum Volkova, a diameter of >60->80 ,um. The lumina of the reticular 1968, MGUH 21.545: J/26-4 from GGU sample 274573B: GI. sculpture are i = 1-2,um wide. Diameter of pores

This species of Elektoriskos Loeblich, 1970 is repre­ Goniosphaeridium primarium sented by a single distinctive specimen in GGU sample (Jankauskas) Downie, 1982 184002 (Fig. 3). It consists of a small (4.5,um in diame­ Fig. Ila ter) spherical vesicle densely covered with slender, meandering processes 5 ,um in length that stand on Microfossils here attributed to the acritarch genus slightly infiated proximal attachments. The specimen Goniosphaeridium Eisenack, 1969 emend. Kjellstr6m, differs substantially from other species of small acri­ 1971 are here referred to G. primarium (Jankauskas) tarchs such as Heliosphaeridium and Asteridium by the Downie, 1982 recorded as 2 specimens (vesicle diameter character of the processes and their proximal attach­ 28--48,um, process length 20-30 ,um, width of process ments. base 7-9,um) in GGU sample 274796. Previous occur­ rences were listed by Volkova et al. (1979) and addi­ tional occurrences in the Lower Cambrian of Baltoscan­ Fimbriaglomerella Loeblich & Drugg, dia were reported by Vidal & Nystuen (1991b). 1968 One specimen uncertainly identified as Goniosphaeri­ Fig. 14e, f dium sp. was also recovered from GGU sample 274571.

This genus is represented by two species, Fimbriaglo­ merelIa membranacea (Kirjanov, 1974) Moczydlowska & Vidal, 1988 (Fig. 14e) and F. minuta (Jankauskas, Goniosphaeridium Sp. A 1979) Moczydlowska & Vidal, 1988 (Fig. 14f), both of Fig. 8i which are represented by single well-preserved speci­ mens in GGU sample 274796. Contrary to specimens Rare acritarchs uncertainly attributed to genus Go­ reported by Moczydlowska & Vidal (1988), the present niosphaeridium are here referred to Goniosphaeridium specimens are fiattened by sediment compaction. sp. A. The conicai nature of the compressed processes is evident and may suggest original connection between processes and the inner vesicle cavity. However, this feature cannot be ascertained in the specimens avail­ able. Fig. 10. Aeritarehs from the Buen Formation, North Green­ land. a, Dictyotidium perforatum Vidal n. sp., MGUH 21.549: F/37 from GGU sample 274799: Al, holotype. b, Dictyotidium priscum Kirjanov & Volkova, 1979, MGUH 21.550: J/50-3 Goniosphaeridium varium (Volkova, from GGU sample 274800: Al. c-e, Cymatiosphaera sp., spee­ 1969) Downie, 1982 imen at c, MGUH 21.551: R/43-l from GGU sample 274796: GI; specimen at d, MGUH 21.552: E/38-l from GGU sample 274795: Al; specimen at e, MGUH 21.553: 0/50-2 from GGU This is represented by a single poorly preserved speci­ sample 274800: A-l. Bar under c represents 10 flm for a, c, e; men about 44 ,um in diameter (Fig. 3, GGU sample 15.5 flm for b; 25 flm for d. 184003). ,

24 b

d

f 25 Goniosphaeridium volkovae Hagenfeldt, Heliosphaeridium coniferum (Downie, 1989 1982) Moczydlowska, 1991 Fig.8h Fig. 8g, k

Acritarchs here attributed to Goniosphaeridium vol­ Heliosphaeridium coniferum (vesicle diameter 5-9 kovae Hagenfeldt, 1989 (Hagenfeldt, 1989, pI. 3; fig 1) ,um, process length <2-2,um) was recently emended by consist of 20 variably preserved specimens in GGU Moczydlowska (1991) who provided a list of previous sample 184002. They consistently possess a central ovoi­ citations. The species is present in smaIl numbers in dal to spherical vesicIe tightly covered by discrete con­ GGU sample 184002 and more abundantly in GGU icai, sharp-pointed, processes, apparently in communi­ sample 274496. Specimens from the Buen Formation cation with the inner cavity of the vesicIe. The maximal cIosely correspond to specimens from eastern Poland vesicIe diameter ranges from 7-8,um, (x = 7.2,um), and iIlustrated by Moczydlowska (1991), whereas they seem the length of processes ranges from 1.5-4,um (x = 2.8 quite different from specimens from the lower part of ,um). the 'Fucoid' Beds in Scotland illustrated by Downie Hagenfeldt (1989) Iisted occurrences in the USSR (1982). and in Scandinavia, where the species occurs in beds attributed to the Lower Cambrian Vergale and Rausve 'horizons', the lower Middle Cambrian Kibartai 'hori­ zon' and Eccaparadoxides oelandicus Zone. Heliosphaeridium dissimilare (Volkova, 1969) Moczydlowska, 1991 Fig.9c Granomarginata squamacea Volkova, 1968 The species (vesicIe diameter 7-10 ,um, x = 1O.7,um, a = 3.2, N = 36; process length 2-4 ,um, x = 3.6 ,um, a A few specimens placed here show a central vesicIe = 1.03, N = 58) was also emended by Moczydlowska diameter of 20 ,um and outer wing diameter ranging (1991), who listed previous occurrences (see also Vidal 30-40,um. Synonymies and previous occurrences were & Nystuen, 1990b). mentioned by Hagenfeldt (1989) and Moczydlowska (1991).

Heliosphaeridium Sp. Heliosphaeridium lubomlense (Kirjanov, 1974) Moczydlowska, 1991 Acritarchs identified as Heliosphaeridium sp. occur in Fig. 8a, b two samples (Fig. 3); they are smaIl forms which ean not be identified at the specific level. Heliosphaeridium lubomlense consists of acritarchs with a distinctive spherical vesicIe 12-15 ,um in diame­ ter, with irregular circular outline and possessing nu­ merous straight and equally distributed processes. The processes (5-7,um in length) have conicai proximal por­ tions tapering in the central part and are sIightly wid­ Fig. 11. Acritarchs from the Buen Formation, North Green­ ened at the distal portion. land. a, Goniosphaeridium primarium (Jankauskas) Downie, 1982, MGUH 21.554: Z/36-3 from GGU sample 274796: GI. b, c, Multiplicisphaeridium dendroideum (Jankauskas, 1976) Jankauskas & Kirjanov, 1979, specimen at b, MGUH 21.555: Heliosphaeridium notatum (Volkova, Z/36 from GGU sample 274796: GI; specimen at c, MGUH 1969) Moczydlowska, 1991 21.556: X/39-1 from GGU sample 274796: GI. d, Leiovalia tenera Kirjanov, 1974, MGUH 21.557: H/37--4 ftom GGU This species is extremely rare in the present material, sample 184002: 1. e, Archaeodiscina umbonulata Volkova, 1968, MGUH 21.558: Z/29 from GGU sample 274796: GI. f, being only represented by 3 specimens unsuitable for Leiosphaeridia sp., MGUH 21.559: 0125 from GGU sample illustration (vesicIe diameter 22-24 ,um; process length 274799: Al. Bar under f represents 15.5.um for a, d; lO.um for >2-3,um) in GGU sample 274798. Synonymy and pre­ b--c, e-f. vious occurrences were Iisted by Hagenfeldt (1989). 26 b

c d 27 Heliosphaeridium obscurum (Volkova, Leiovalia tenera Kirjanov, 1974 1969) Moczydlowska, 1991 Fig. lId Fig.8c Leiovalia tenera is represented by 2 well-preserved Heliosphaeridium obscurum is a rare component in specimens (Fig. 3). It consists of elongated, oval shaped GGU sample 184002 (6 specimens; vesicle diameter 5-6 flattened vesicles with smooth surface, often displaying ,11m; process length 1.5-2,um). Synonymy and former thin compactional folds; the length ranges 87-90 ,11m, occurrences were listed by Hagenfeldt (1991) and Moc­ whereas the vesicle width ranges 34-40 ,11m. Previous zydlowska (1991). occurrences were mentioned by Hagenfeldt (1989) and Eklund (1990).

Leiosphaeridia Eisenack, 1958 emend. Lophosphaeridium dubium (Volkova, Downie & Sarjeant, 1963 Fig. IH 1968) Moczydlowska, 1991 Fig.9g The genus Leiosphaeridia is here represented by sphaeromorphic acritarchs that are not identified to the This consists of sphaeroidal vesicles tightly covered specific level since morphological features are restricted by small and short conicai protuberances. Five reco­ to vesicle dimensions and relative wall thickness. The vered specimens indicate a vesicle diameter 19-36,um, microfossils have circular tb oval vesicles with smooth whereas process length is <1 ,11m. The species was trans­ surface. The wall of the vesicle is generally sturdy and ferred to the genus Lophosphaeridium by Moczydlow­ thick, and displays compression folds that are irregular ska (1991), who also listed synonymies and former oc­ both in shape and distribution. Excystment, when pre­ currences (see also Hagenfeldt, 1989). The species is sent, is by median split. The diameter of the vesicle extremely rare in GGU samples 274570, 274571, ranges x 20-80 ,11m. 274796). Specimens recorded in the Buen Formation (Fig. 3) may consist of soiitary, discrete vesicles or more or less regular coenobial cell clustersof up to 8 cells (Fig. IH). Lophosphaeridium tentativum Volkova, The latter are usually within the lower recorded diame­ 1968 ter range of the discrete cells. Fig. 9h In general, microfossils attributed to Leiosphaeridia constitute one of the most common and abundant acri­ Lophosphaeridium tentativum is represented in 2 tarch taxa in Neoproterozoic and Cambrian strata. On samples (Fig. 3) from the upper part of the sampled account of a lack of diagnostic features, an apparent interval of the Buen Formation. It consists of spherical, stratigraphic range from Proterozoic to Tertiary has flattened vesicles 11-45 ,11m in diameter and covered been recorded (Downie & Sarjeant, 1964; Tappan, with tightly arranged small granulae. For syncinymy and 1980; Lindgren, 1982a, b). previous occurrences see Hagenfeldt (1989) and Moc­ zydlowska (1991).

Lophosphaeridium truncatum Volkova, 1969 Fig.9j Fig. 12. Acritarchs from the Buen Formation, North Green­ land. a, c, Skiagia ciliosa (Volkova, 1969) Downie, 1982 (mor­ This species occurs in very small numbers in 3 sam­ photype A), specimen at a MGUH 21.560: Z/39-1 from GGU ples (Fig. 3) of the Buen Formation. It consists of spher­ sample 274796: GI; specimen at c, MGUH 21.562: Z/31 from icai vesicles (N = 6, vesicle diameter 26-36,um) covered GGU sample 274570: 1. b, Skiagia ciliosa (Volkova, 1969) Downie, 1982 (morphotype B), MGUH 21.561: Y/32 from by rounded, clavate, coarse grains and discrete granulae GGU sample 184003: 1. d, Skiagia ciliosa (Volkova, 1969) (< 1-1 ,11m in diameter). Previous occurrences and syn­ Downie, 1982 (morphotype C), MGUH 21.563: Zl30 from onymies were given by Hagenfeldt (1989) and Moc­ GGU sample 274570: 1. Bar under d represents 10 ,/tm. zydlowska (1991). 28 29

28-40.um in diameter (N = 4) with psilate or very fine Lophosphaeridium sp. granular ornamentation displaying a transversal reticu­ Fig.9i lar pattern of folds. Synonymy and previous occurrences were given by Hagenfeldt (1989). Acritarchs attributed to Lophosphaeridium sp. consist ofsphaeroidal vesicles ranging around 40.um in diameter which are densely covered by small sub-micron gran­ ulae. Skiagia Downie, 1982

Multiplicisphaeridium dendroideum Acritarchs attributed to the form-genus Skiagia form (Jankauskas, 1976) Jankauskas & the bulk of the acritarch remains recovered from the Buen Formation. Synonymies and previous occurrences Kirjanov, 1979 of the various species of this form-genus were treated by Fig. Ub, c Downie (1982), Hagenfeldt (1989), Moczydlowska (1991) and Vidal & Nystuen (1990b). Multiplicisphaeridium dendroideum, although found in 3 samples, is represented in the present material by 2 well-preserved specimens consisting of a central vesicle in communication with numerous (>15) conicai, di­ Skiagia ciliosa (Volkova, 1969) Downie, morphic, evexate processes, often with ramified termi­ 1982 nal portions. The overall dimensions are 18-26 .um, Fig. 12a-d processes included, whereas the length and basal width of the processes is 3-4.um and 2-3 .um, respectively. As is the case in former occurrences, three distinctive morphotypes of Skiagia ciliosa (Volkova, 1969) Downie, Pterospermella Eisenack, 1972 1982, A, B and C, co-occur in discrete samples. Type A Fig.9d (Fig. 12a, c) has narrow process attachments and thin and siender process stems, whereas Skiagia ciliosa type Acritarchs attributed to the genus Pterospermella Ei­ B (Fig. 12b) possesses wider conicai process attachments senack, 1972 are rare and consist of forms with a solid and processes stems, the processes being longer and circular central body ranging 25-30.um in diameter sur­ provided with funnel-shaped apical ends. Shorter, less rounded by a translucent, 10-15 .um wide extremely numerous and clearly evexate processes ornament the delicate aia. Various gradings in the density of the cen­ vesicle of morphotype C (Fig. 12d). tral body are observed. Acritarchs here referred to the three distinguished morphotypes (Fig. 12a-d) consist of circular to ovoidal vesicles (vesicle diameter: N = 100, i = 32.9.um) with Retisphaeridium dichamerum Staplin, numerous cylindrical processes (process length: N = Jansonius & Pocock, 1965 100, i = 3.9.um). In the present, relatively abundant Figs ge, f, lOe material, the processes appear hollow and are clearly isolated from the vesicle cavity by aplug. The proximal This species was recovered in generally small num­ attachments of the processes are generaIly conicai, bers from several samples of the Buen Formation. It whereas the apical portions are funnel-shaped. consists of ellipsoidal to circular compressed vesicles

Skiagia compressa (Volkova 1968) Fig. 13. Acritarchs from the Buen Formation, North Green­ Downie, 1982 land. a, Skiagia ornata (Volkova, 1968) Downie, 1982, MGUH Fig. 14g 21.564: F/29 from GGU sample 274796: GI. b, Elektoriskos sp. A., MGUH 21.565: K/33-4 from GGU sample 184002: 1. c, Rare acritarchs here attributed to Skiagia compressa Globosphaeridium cerinum (Volkova) Moczydlowska, 1991, possess an oval-shaped vesicle (vesicle diameter: N = MGUH 21.566: R/25-3 from GGU sample 274570: 1. d, e, Skiagia orbiculare (Volkova, 1968) Downie, 1982, specimen at 35, i = 32.6.um) that bears numerous, proximally wide d, MGUH 21.567: T/5D-4 from GGU sample 274795: Al; and conical-shaped processes (process length: N = 35, i specimen at e, MGUH 21.568: X/42-3 from GGU sample = 5.7 .um), thus resulting in diagnostically 'crenulated' 274571: G2. Bar under crepresents lO,um for a-d; 15.6,um for e. periphery. Distally, the processes are funnel-shaped. 30

c

f . 31

Skiagia orbiculare (Volkova, 1968) Tasmanites bobrowskae Wazynska, 1967 Downie, 1982 Fig. 15b-c Fig. Bd, e Rare organic-walled spheroidal microfossils placed Acritarchs attributed to Skiagia orbiculare are com­ here are often compressed, having vesicles which are mon in the Buen Formation (Fig. 3) and have ovoidal to circular to oval in outline (N = 7, i = 90.4 ,um) and spheroidal vesicles (vesicle diameter: N = 50, x = 31.7 possessing a thick vesicle wall perforated by irregularly ,um) with numerous medium-Iength processes (process distributed large pores. For synonymy and previous oc­ length: N = 50, i = 7.1,um) that are slender, tapering currences see Hagenfeldt (1989) and Moczydlowska from the proximal part along their total length. Their (1991). distal portions are funnel-shaped.

Tasmanites tenellus Volkova, 1968 Skiagia ornata (Volkova, 1968) Fig. ISa Downie, 1982 Fig. 13a This species is very rare in the present material. It comprises organic-walled microfossils having circular to Skiagia ornata is an extremely abundant acritarch oval compressed vesicles (vesicle diameter: N = 7, i = species in the Buen Formation (Fig. 3) that possesses an 90 ,um) with a thin vesicle wall perforated by small, spheroidal vesicle (diameter: N = 140, x = 33.7 ,um) irregularly distributed pores. Synonymy and occur­ with very numerous, long, siender cylindrical processes rences were recently listed by Hagenfeldt (1989) and (process length: N = 140, i = 13.6,um) that are wid­ Moczydlowska (1991). ened proximally and distally (funnel-shaped).

Tasmanites volkovae Kirjanov, 1974 Skiagia scottica Downie, 1982 Fig. 15d Fig. 14a-d

This is extremely rare in samples from the Buen For­ Together with S. ornata, this species is among the mation. The circular, organic-walled vesicle (vesicle di­ most abundantly occurring acritarchs in the Buen For­ ameter: 60-70 ,um) possesses a thick perforated wall mation (Fig. 3). It has a spheroidal to ovoidal vesicle with abundant, regularly distributed pores located in (vesicle diameter: N = 140, x = 27.5 ,um) with numer­ funnel-like wall depressions, a diagnostic feature that ous, tightly arranged processes that are of variable results in the irregular periphery of the thick vesicle length (process length: N = 140, i = 6.1,um), slender wall. For synonymy and previous occurrences see Ha­ and cylindrical, proximally slightly widened and distally genfeldt (1989) and Moczydlowska (1991). opened into a wide funnel-shape, being often attached to one another at the distal funnel-shaped ends. Trachysphaeridium timofeevi Vidal, 1976 Fig. 14. Acritarchs from the Buen Formation, North Green- land. a-d, Skiagia scottica Downie, 1982, specimen at a, Trachysphaeridium timofeevi is a rare component in MGUH 21.569: Q/2fr-3 from GGU sample 184004-B; speci­ men at b, MGUH 21.570: Z/29 from GGU sample 274796: GI; samples of the Buen Formation (Fig. 3). The ovoidal to specimen at c, MGUH 21.571: 0/51-4 from GGU sample ellipsoidal, walled and scabrate sculptured vesicle 274571: G2; specimen at d, MGUH 21.572: L/34-2 from GGU ranges 50-62 ,um by 20-40,um. Previous occurrences sample 274797: GI. e, Fimbriaglomerella membranacea (Kir- were listed by Hagenfeldt (1989). janov, 1974) Moczydlowska & Vidal, 1988, MGUH 21.573:_ Z/29-1 from GGU sample 274798: Al. f, Fimbriaglomerella Various tubular sheaths, possibly cyanobacterial, oc­ minuta (Jankauskas, 1979) Moczydlowska & Vidal, 1988, MGUH 21.574: Z/49-3 from GGU sample 274796: GI. g, cur in the investigated samples of the Buen Formation Skiagia compressa (Volkova, 1968) Downie, 1982, MGUH (Fig. 9k). The sheaths are of quite variable length and 21.575: K/48-2 from GGU sample 274796: GI. Bar under f range in width from 2-10 ,um. These fossils were rec­ represents 10 pm for a-f; 11 pm for g. orded ih variable numbers in most processed samples. \

32 b

Fig. IS. Acritarchs from the Buen Formation, Norlh Greenland. a, Tasmanires ref/el/us Volkova, 1968, MGUH 21.576: J/40-2 frol11 GG sample 274800: A I. b. c, Tasmaf/ire.~ bobrolVskae Wai:ynska, 1967. specimen at b. MGUH 21.577: Z139-4 from GGU sample 27~797: (j I; specimcn at c, MG H 21.578: /33-1 from GGU sample 274797: G I. d, Tasmallires lIo/kovae Kirjanov, 1974. MG UH 21.579: Z1~3 from GGlJ sample 274797: G I. Bar under e repre enls IO lim for a-b. u; I~ ,um for c. 33 Acknowledgements

G. Vidal acknowledges grant support from the Swedish Nat­ marks Geologiske Undersøgelse) is thanked for discussion of ural Science Research Council (NFR). Jon R. Ineson (Dan- Buen environments and for providing Fig. 2.

References

Awramik, S. M., McMenamin, D. S., Yin Chongyu, Zhao Norway, Greenland and Canada. Trans. Roy. Soc. Edin­ Ziqiang, Ding Qixiu & Zhang Shusen 1985: Prokaryotic and burgh, Earth Sci. 72, 257-282. eukaryotic microfossils from a ProterozoiclPhanerozoic tran­ Downie, C. & Sarjeant, W. A. S. 1964: Bibliography and index sition in China. Nature 315, 655-658. of fossil dinoflagellates and acritarchs. Mern. Geol. Soc. Baudet, D., Aitken, J. D. & Vanguestaine, M. 1989: Palynol­ Arner. 94, 180 pp. ogy of uppermost Proterozoic and lowermost Cambrian for­ Eklund, C. 1990: Lower Cambrian acritarch stratigraphy of the mations, central Mackenzie Mountains, northwestern Cana­ Bårstad 2 core, Ostergotland, Sweden. Geol. Foren. Stock­ da. Can. J. Earth Sci. 26, 129-148. holm Forhandl. 112, 19-44. Bergstrom, J. & Peel, J. S. 1988: Lower Cambrian trace fossils Eppley, R. W., Rogers, J. N. & McCarthy, J. J. 1969: Half from northem Greenland. Rapp. Grønlands geol. Unders. saturation constants for uptake of nitrate and ammonium by 137,43-53. marine phytoplankton. J. Phycol. 5, 912-920. Berry, W. B. N., Wilde, P. & Quinby-Hunt, M. S. 1989: Evitt, W. R. 1985: Sporopollenin dinoflagellate cysts. Their Paleozoic (Cambrian through Devonian) anoxitropic bio­ morphology and interpretation, 333 pp. Texas: Arner. Assoc. topes. Palaeogeog. Palaeoclimatol. Palaeoecol. 74, 3-13. Stratigraphic Palynologists Foundation. Blaker, M. R. 1988: A new genus of nevadiid trilobite from the Fombella, M. A. 1977: Acritarcos de edad Cambrico Medio­ Buen Formation (Early Cambrian) of Peary Land, central inferior de la provincia de Leon, Espaiia. Rev. Espafiola North Greenland. Rapp. Grønlands geol. Unders. 137, Micropaleont. 9:1, 115-124. 33-41. Gamez, J. A., Nieto, C., Gozalo, R., Liiian, E. Mandado, J. Bryant I. D. & Pickerill, R. K. 1990: Lower Cambrian trace & Palacios, T. (in press): Bioestratigrafia y evoluci6n del fossils from the Buen Formation of central North Green­ Cambrico de Borobia, Provincia de Soria. Cadenas Ibericas land: preliminary observations. Rapp. Grønlands geol. Un­ Orientaies. Cuad. lab. xeologico de Laxe 16,251-271. ders. 147, 44--62. Hagenfeldt, S. 1989: Lower Cambrian acritarchs from the Bal­ Butterfieid, N. J. 1990: Organic preservation of non-mineraliz­ tic Depression and south-central Sweden, taxonomy and ing organisms and taphonomy of the Burgess Shale. Paleo­ biostratigraphy. Stockholm Contr. Geol. 41, 1-176. biology 16, 272-286. Higgins, A. K., Ineson, J. R., Peel, J. S., Surlyk, F. & Sønder­ Butterfield, N. J., Knoll, A. H. & Swett, K. 1988: Exceptional ho1m, M. 1991: Lower Palaeozoic Franklinian Basin of preservation offossils in an Upper Proterozoic shale. Nature North Greenland. Bull. Grønlands geol. Unders. 160, 71­ 334, 424-427. 139. Conway Morris, S. 1987: The search for the Precambrian­ Jankauskas, T. V. 1979: [Middle Riphean microbiota from the Cambrian boundary. Arner. Scientist 75, 156-167. southern Urals and the Bashkirian Urals.] Akad. Nauk SSSR Conway Morris S. & Peel, J. S. 1990: Articulated halkieriids 248,190--193. [In Russian.] from the Lower Cambrian of North Greenland. Nature 345, Jux, U. 1971: Uber den Feinbau der Wandungen einiger paliio­ 802-805. zoischer Baltisphaeridiacean. Palaeontographica B 136, 115­ Conway Morris, S., Peel, J. S., Higgins, A. K., Soper, N. J. & 128. Davis, N. C. 1987: A Burgess Shale-like fauna from the Jux, U. 1975: Phytoplankton aus dem mittleren Oberdevon Lower Cambrian of North Greenland. Nature 326, 181-183. (Nehden-Stufe) des siidwestlichen Bergischen Landes (Rhei­ Crimes, T. P. 1987: Trace-fossils and the Precambrian-Cam­ nisches Schifergebirge). Palaeontographica B 149, 113-138. brian boundary. Geol. Mag. 124,97-119. Keller, B. M., & Jankauskas, T. V. 1980: [Microfossils from Dale, B., 1977: New observations on Pterdinium faeroensis the Riphean stratotype of the southern Urals.] Akad. Nauk Paulsen (1905), and ciassification of small orthoperidinioid SSSR 12, 58--67. [In Russian.] dinoflagellates. Brit. Phycol. J. 2, 241-253. Knoll, A. H. 1984: Microbiotas of the Precambrian Hunnberg Dawes, P. R. 1976: Precambrian to Tertiary of northem Green­ Formation, Nordaustlandet, Svalbard. J. Paleont. 58, 131­ land. In Watt, W.S. & Escher, A. (ed.) Geology ofGreen­ 162. land, 248-303. Copenhagen: Geol. Surv. Greenland. Knoll, A. H. 1985: The distribution and evolution of microbial Downie, C. 1973: Observations on the nature of the acritarchs. life in the Late Proterozoic Era. Ann. Rev. Microbiol. 39, Palaeontology 16, 239-259. 391-417. Downie C. 1982: Lower Cambrian acritarchs from Scotland, Knoll, A. H. & Calder, S. 1983: Microbiotas of the Late 34

Precamhrian Ryssø Formation. Nordaustlandet. Svalbard. Peel. J. S. 1990: Sludying the early histo,ry ol' life in Greenland. PalacolllOlogl' 26, -167-490. Rapp. Grpnlmlds geol. Unders. 14l:!. 5-1-56. Knoll. A. H. & Ohta. Y. 19 : Microfossils in metascdimcnts' Peel. J. S. & hri tie. R. L. 1982: Cambrian-Ordovieian plat­ from Prin~ Karl Forland. w~stern Svalbard. Polar Re.>. 6, form stratigraphy: correlalions around Kane Basin. Mede/r :CJ-07. Grøn/lIlld Geosci. 8, 117-135. Knoll. A. Il. & Swett. K. 19 '5: Mieropalaeontology uf Ihe late Peel, J. S.. Conway Monis. S. & Ineson. J. R. 1992: A seconel I'roterozoie Veteranen Group, Spitsbergen. Palaeomology glimpse of Early Cambrian life: new colleclions from Sirius 28. rl-473. Passet. orth Greenland. Rapp. Gr(~nl{/nd.~ geol. Ullders. Knoll A. II. & Swett. K. 19R7: Micropaleontology aeross thl: 155.48-50. Preeamhrian-Cambrian boundary in Spitsbergen. J. Pa/e­ PjalilclOv. V. G. & Rudavskaya. V. A. 1985: IAcritarchs from 0111. 61, R98-926. the Yudomian Complex.) III Sokolov. B. S. & Ivano\'~ky. Knoll. A. f-l.. Swell. K. & Mark. J. 1991: Paleobiology of a A. B. (eel.) Vendian Sys/em I, Pulaeoll/oloqy. 151-158. Neoprolerozoie tidal fiat/lagoonal complex: the Draken Mo cow. lin Russian.J Conglomeratc Formation. Spilsbergen. J. Pa/eoll/. 65, 531­ Poul en. V. 1974: Olenellacean trilobites from easlcrn North 570. Gr~enland. Bul!. ge%~~ Sor. Dcnmurk 23, 79-101. I.indgren. S. 19 2a: '(i!Xonomie review of Lciosphaeridia from Staplin. F. L.. Bailey. . J. L.. Pocock. S. A. & Evans. C. R. the Mesozoic and Teniary. S/ockholm COII/r. Geol. 3M. 1973: Diagenesis and metamorphism of sedimentary organic 21-33. mal lers. Unpublished paper presenled at the Ameriean As­ Lindgren. S. 1982b: Algal coenobia and leiospheres from the sociation of Petroleum Geology ymposium. Anaheim. Cali­ Upper Riphean of the Turukhansk region. eastern Siberia. fornia. 1973 (not seen; referred to in Venkataehala. B. S. Stockho/III COII/r. Geol. 38. 35--15. 1981. see helow). Mansuy. c.. & Vidal. G. 1983: Lale Proterozoic Brioverian Surlyk. F. 1992: Tectonostratigraphy of l"onh Greenlanel. RIII!. microfossils from France; laxonomic affinity and implica­ Grønlallds gcn{. Unders. 160,25-47. lions of plankton produetivity. NarlIre 302, 006-007. 'Ulppan, H. 191\0: The pa/eobi%gy nf p/Wl/ pro/iMs. 1028 pp. Moczydlowska. M. 1988: New Lem'er Cambrian aeritarch • an Francisco: rreeman & Co. from Poland. NCI·. Palaeobo/. PlI/YIIO/. 54, l-JO. Venkataehala. B. S. 19 l: Differentiation of amorphous Olga­ 'v1oczydlowska. M. 1991: Aerilareh biostratigraphy of the nic maller type in sediments. /n Brooks. J. (ed.) Organie Lower Cambrian and lhe Precambrian-Cambrian boundary mw/ml/ioll sIl/dies and fossil fl/el eXplOl"(flioll. 177-200. Lon­ in soulheastcrn Poland. Fn.uil.> & SIra/a 29, 127 pp. don: Academie Press. Moczydlowska. M. & Vidal. G. 19116: Lower Cambrian aeri­ Vidal. G. 1988: A palynological preparaliun rnethod. Pa/Yllo/­ t... reh zOJlalion in southern Scandinavia and southcastern og)' 12, 21:-220. Poland. Geol. Forell. S/ockhollll Fijrhalldl. 1Ol:!, 201-223. Vidal. G. 1990: Giant aeanthomorph aeritarchs from the Up­ 10ezydlowska. M. & Vidal. G. 19 arly Cambrian acri- per Proterozoic in southern orway. Palaeoll/ology 33, '287­ tarehs from Scandinavia aml Poland. PalYllology 12, I-IO. 298. Moczycllowska. M. & Vidal. G. IY91: Phytoplankton from the Vitta I. G. & Nystucn, J. P. Il)

sian platform.} In Rozanov, A. Yu. et al. [Tommotian Stage Volkova, N. A., Kirjanov, V. V., Piskun, L. V., Pashkev­ and the Cambrian lower boundary problem], 224-236. Mos­ iciene, L. T. & Jankauskas, T. V. 1983: Plant microfossils. cow: Nauka. [In Russian.] In Urbanek, A. & Rozanov, A. Yu. (ed.) Upper Precam­ Volkova N. A. 1981a: Distribution of acritarchs in sections of brian and Cambrian palaeontology of the East-European northeastem Poland. In Raaben M. E. (ed.) The Tommo­ Platform, 5--46. Warszawa: Wydawnictwa Geologiczne. tian Stage and the Cambrian lower boundary problem,'86-88. Yin Leiming 1985: Microfossils of the poushantuo Formation New Delhi: Amerind Publishing Co. in the Yangtze Gorge district, and Western Australia. Proc. Volkova, N. A. 1981b: Acritarchs of the northwestern Russian Roy. Soc. Victoria 83, 211-234. Platform. In Raaben, M. E: (ed.) The Tommotian Stage and Zang Wenlong 1988: Ediacaran plankton. Abstr. 7th Interna­ the Cambrian lower boundary problem, 259-273. New Delhi: tional Palynological Congress, Brisbane 1988, 184 only. Amerind Publishing Co. Zang Wenlong, & Walter, M. R. 1989: Latest Proterozoic Volkova, N. A., Kirjanov, V. V., Piskun, L. V., Pashkev­ plankton from the Amadeus Basin in Central Australia. iciene, L. T. & Jankauskas, T. V. 1979: [Plant microfos­ Nature 337, 642--645. sils.] In Keller, B. M. & Rozanov, A. Yu. (ed.) [Upper Precambrian and Cambrian palaeontology of the East-Eu­ ropean Platform], 4-38. Moscow: Nauka. [In Russian.] GRØNLANDS GEOLOGISKE UNDERSØGELSE Geological Survey of Greenland ISSN 0105 3507 øster Voldgade 10, DK-1350 Copenhagen K AiO Print Ud., Denmark Odense, Denmark