黑龙江省东北部绥滨地区东荣组最上部的沟鞭藻组合--兼论该地区侏罗-白垩系界线

黑龙江省东北部绥滨地区海相东荣组最上部产丰富或较丰富的沟鞭藻类,经鉴定达20属30余种,其中有些在我国为首次发现,包括一新种Leberidocysta suibinensis sp．nov.。文中详细地讨论沟鞭藻Oligosphae-ridium pulcherrimum组合的特征及其地质时代,包括侏罗-白垩系界线等;认为该组合的时代为Berriasian—Valanginian期。这一组合是我国白垩纪最早期的海相沉积,也是白垩系底部的第一个化石组合;首次提出黑龙江省东北部绥滨地区侏罗-白垩系界线应置于Tithonian阶的沟鞭藻Amphorula delicata组合与Berriasian-Valanginian阶的Oligosphaeridium pulcherrimum组合之间,即岩石地层上的东荣组上部与最上部之间。这条沟鞭藻类生物地层界线与双壳类的下、中伏尔加阶的Buchiamosquensis-B．rugosa带与上伏尔加阶的B．fischeriana带之间的分界完全吻合,与目前国际地科联地层委员会建议的侏罗-白垩系界线位于中伏尔加阶与上伏尔加阶之间亦完全一致。     

The Hunneberg Stage (Ordovician) in the area east of St. Petersburg, north-western Russia

The bio- and lithostratigraphy of the poorly known early Ordovician (Arenig) Hunneberg Stage is described from the area east of St. Petersburg (Putilovo Quarry and Lava river), where the Lakity Beds (Leetse Fm.) consist of glauconitic sands and silty clays. The described fauna includes graptolites, conodonts, brachiopods, acritarchs, foraminifers, and several problematic groups. The Lakity Beds are unique within the lower Ordovician sequence of the East Baltic in the abundance of graptolites, co-occurring with conodonts. The conodonts from the lower part of the Lakity Beds belong to the uppermost subzone (Oelandodus elongatus — Acodus deltatus deltatus) of theParoistodus proteus Zone, coinciding with the lower part of theTetragraptus phyllograptoides Zone. This suggests that there is a hiatus between the Lakity Beds and the underlying Nazya Formation. The lower Lakity Beds also contain the brachiopodsLeptembolon lingulaeformis andEosiphonotreta cf.acrotretomorpha, which suggest that they may be correlated with the Joa Member of the Leetse Formation in North Estonia. In the upper part of the Lakity Beds, conodonts of thePrioniodus elegans Zone co-occur with graptolites indicating the upper subzone of theTetragraptus phyllograptoides Zone in the Scandinavian sections. There are still problems of defining and correlating the base of the Billingen Regional Stage, which are outside the scope of this paper.     

Silurian (Ludlow) acastid trilobites from Gotland and Scania,Sweden

Acastid trilobites from Ludlow strata on Gotland include three stratigraphically non-overlapping species ofAcastella Reed:Acastella madidipes n. sp. (Hemse Marl and Eke Beds),A. breviceps (Angelin 1851) (Burgsvik Beds), andA. amatrix n. sp. (Hamra Beds, and probably Burgsvik Beds). Type and other material ofA. breviceps (Angelin) from the Klinta Formation, Scania, is revised. Meraspid and early holaspid material ofAcastella is described. Some characters supportAcaste and allied taxa of mostly Wenlock age as a monophyletic subfamily Acastinae.Acastella as widely recognized is a grade with Devonian species more closely related to Asteropyginae than to the Ludlow type species. Baltic Ludlow-P?00ED;dolí species previously placed inScotiella Delo form a distinct group,Ewacaste n. gen., that includes a species from the uppermost Eke Beds on Gotland.     

New graptolite,chitinozoan and acritarch records from the Pascha-Incamayo area,Cordillera Oriental,Argentina

A new fossil assemblage bearing graptolites, chitinozoans and acritarchs is analyzed based on material collected in the Pascha-Incamayo area, Salta Province, NW Argentina. The occurrence of Hunnegraptus copiosus (Lindholm, 1991), associated with specimens of the genus Tetragraptus (Salter, 1863), is highly relevant to improve the age assignment and correlate the fossil-bearing levels previously assigned to the Devendeus Formation. Different stages in the development of the index species of the Upper Tremadocian H. copiosus Biozone are described and illustrated. The precise stratigraphic ranges of the associated chitinozoans and acritarchs are discussed, according to the biostratigraphic analysis, and the stratigraphic relationships for the studied section are considered.     

Magnetostratigraphy of the Sherwood Sandstone Group (Lower and Middle Triassic), south Devon, UK: detailed correlation of the marine and non-marine Anisian

The Sherwood Sandstone Group in south Devon consists of the Budleigh Salterton Pebble Beds and the Otter Sandstone Formation. The Otter Sandstone Formation comprises four lithostratigraphic sub-units, from the base labelled A-D, and contains tetrapods corresponding to the Perovkan land vertebrate faunachron, and is consequently a key European non-marine Anisian succession. A total of 181 palaeomagnetic specimens from 92 horizons were measured to determine the palaeomagnetic signal. The magnetic properties and characteristic remanence is predominantly carried by haematite, most of which probably formed early in the depositional and diagenetic history. The lower part of the Sherwood Sandstone Group (Budleigh Salterton Pebble Beds and Otter Sandstone Formation, unit A, lower part of unit B) has predominantly normal polarity (magnetozones BS1, BS2 and BS3n) with three thin reversed polarity magnetozones. The lower part of unit B to the lower part of unit C of the Otter Sandstone Formation is predominantly reverse polarity (magnetozones BS3r, BS4 and BS5), but includes three short normal polarity intervals. The upper ca. 50 m of unit C shows a mix of normal and reverse polarity (BS6, BS7) with normal dominating. The ca. 15-m-thick unit D is entirely of normal polarity (BS8n). The magnetostratigraphy allows unambiguous comparison with conodont and ammonite calibrated magnetostratigraphies from elsewhere in Europe. These show that the BS2 and BS3n magnetozones of the Otter Sandstone Formation are lower Aegean to middle Pelsonian (lower to middle Anisian). The BS3r to BS5r magnetozone interval, is middle Pelsonian to lower Illyrian (middle to upper Anisian), and the BS6 to BS8n magnetozone interval is middle Illyrian to lower Fassanian. The top of unit D is correlated to an interval in the middle of the Nevadites Zone (close to the Anisian-Ladinian boundary). Consequently, the Otter Sandstone Formation correlates with the Muschelkalk in the Polish Basin, but is equivalent to only part of the Germanic Basin Muschelkalk. The continuous magnetostratigraphy from the Sherwood Sandstone Group, provides additional details of the polarity pattern through the Pelsonian to Illyrian interval, which appears to be lacking in discontinuous marine sections. A synthesis of adjacent European sedimentary basins in combination with the magnetostratigraphy, suggests that the Budleigh Salterton Pebble Beds are probably Late Spathian to lower Aegean.     

Environmental changes reflected by palynomorphs in the early Middle Ordovician Hanadir Member of the Qasim Formation, Saudi Arabia

Core samples from the QASIM-801 (QSIM-801) water well in the Qasim Region of central Saudi Arabia were investigated palynologically. The interval studied contains the transgressive succession from the Sajir Member of the Saq Formation to the Hanadir Member of the Qasim Formation, and yields well-preserved and abundant cryptospores, microphytoplankton (acritarchs and chlorophycean algae), and chitinozoans, indicative of a Darriwilian (Llanvirn) age. The lowermost portion of the cored interval from the upper Sajir Member consists of fine-grained sandstones deposited in tidal flat, and shallow-marine settings. It is characterized by abundant and diverse cryptospores (permanent tetrads, dyads, monads), cuticle-like phytoclasts, and a low diversity assemblage of marine palynomorphs. The upper part of the cored interval from the Hanadir Member is composed of hemipelagic to pelagic, organic-rich, graptolitic shales, and micaceous shales, of middle- to outer-shelf depositional settings, which yield abundant marine palynomorphs (acritarchs and chitinozoans). Cryptospore-bearing horizons are interspersed in the succession. Changes in the composition of palynomorph assemblages reflect higher frequency environmental changes within an overall transgressive succession. Four new acritarch species are described in open nomenclature, Tyrannus sp. A, Clypeolus sp. A,?Pulvinosphaeridium sp. A, and?Tinacula sp. A.     

Cretaceous angiosperm pollen from the Kachaike Formation,south-western Santa Cruz Province,Argentina

Thirty-three angiosperm pollen species are here reported from mid-Cretaceous deposits of the Kachaike Formation, Austral Basin, southern Argentina. Clavatipollenites is the most abundant angiosperm genus, with six well-defined morphological groups recognised on the basis of their reticulum morphology and sculpture. Pollen of eudicots are scarce, represented by tricolpate (Psilatricolpites spp. and Tricolpites spp.), tricolporoidate and tricolporate morphotypes (Dryadopollis spp.). Increasing complexity in the aperture structure is seen throughout the sequence; tricolpate and tricolporoidate forms are recorded in almost all samples, while tricolporate pollen grains are restricted to the middle and upper levels of the unit. The high species richness and abundance of monocolpate-ulcerate angiosperm related to monocots or magnoliids sensu lato recorded in the unit is comparable to that previously recognised in other assemblages from the early and middle Albian of the southern (e.g. Australia) and northern hemispheres (e.g. Western Portuguese basin, Europe). The recorded increase in the number of angiosperm species towards the middle and upper parts of the Kachaike Formation, with the presence of monocolpate, tricolpate, tricolporoidate and tricolporate pollen, suggests an early-early middle Albian age for these parts of the unit, in agreement with the early Albian age proposed for its basal levels on the basis of dinoflagellates.     

Microplankton changes through the early Silurian Ireviken extinction event on Gotland, Sweden

This paper documents and analyses the extinction and origination patterns of acritarchs and prasinophyte algae at the Llandovery/Wenlock boundary transition in the Lower Silurian on the island of Gotland, Sweden. Closely spaced samples were collected from two parallel sections: Lusklint 1 and Lickershamn 2, spanning the upper part of the Lower Visby Beds and almost all of the Upper Visby Beds (i.e. the uppermost Llandovery and lowermost Wenlock).

At least eight extinctions affecting the conodont record have been reported at these levels. This turnover (named the Ireviken Event) has been interpreted as an example of the change from a P to an S climate state, reflecting large changes in the ocean/atmosphere system.

The palynomorph data show a significant turnover in the phytoplankton, with most of the extinctions at the end of the event (85.3% in the top 4 m of the Lusklint 1 section). The originations are more numerous than the extinctions and they are distributed through the whole of the Ireviken Event. There is an uneven distribution across the event with more originations in the Lower Visby Beds forming a convex pattern.

Comparison of these data to other palynological studies suggests that there was a slightly higher number of migrations out of Gotland than in. The P and S model does not successfully explain all the changes recorded, but is the model most inclusive of all the climatic variables available at this time.     

Miospore assemblages from the Silurian–Devonian boundary,in borehole A1-61, Ghadamis Basin,Libya

Well preserved and diversified miospore assemblages have been recorded from a relatively continuous sequence in borehole A1-61 which spans the Silurian–Devonian boundary in the northwestern part of the Ghadamis Basin, Libya. The sequence is represented by early Devonian Lochkovian beds of the Tadrart Formation that transgress onto the Silurian Ludlow-Pridoli beds of the upper part of the ‘Alternances Argilo-gréseuses’ Formation. The present work demonstrates a succession of miospore assemblages from closely sampled layers that have been stratigraphically dated as Ludlow–middle Pridoli and early Lochkovian by chitinozoans and acritarchs. Over 80 species of cryptospores and trilete spores have been identified. Modified detailed morphological interpretations are given. The miospore assemblages are correlated with miospore zonation schemes established for the type sequences of the Welsh Borderland, and those previously described from Libya. Early occurrences of some species as Streelispora newportensis on the western Gondwana plate, are put forward by comparison with the Old Red Sandstone continent. Phytogeographic and palaeobotanic implications based on these observations are discussed.     

A re-evaluation of Cercidiphyllum-like plant fossils from the British early Tertiary

The occurrence of Cercidiphyllum -like leaves, infructescences, fruits and seeds in the British early Tertiary is reviewed. Material previously described from the London Clay Formation, Lower Headon Beds (upper Barton Formation), Oldhaven Formation, and Woolwich and Reading Formation, are evaluated along with specimens from a new late Palaeocene locality in the Reading Beds. The leaves are assigned to Trochodendroides prestwichii; and infructescences, fruits and seeds, previously assigned to Carpolithus gardneri and Jenkinsella apocynoides , are united as a single species Nyssidium arcticum. The evidence that Trochodendroides and Nyssidium are parts of a single kind of fossil plant is supported, and the reconstructed ' Nyssidium plant' is compared with extant taxa, particularly extant Cercidiphyllum. The fossil plant shows a combination of characters not seen in any living genus, and the structure of the infructescence, as well as other features, precludes placing it within Cercidiphyllum. 'Nyssidium' and Cercidiphyllum are closely related. The morphological and sedimentological evidence indicates that 'Nyssidium' was an important colonizer of a variety of open flood-plain environments during the early Tertiary.     

The importance of Precambrian microfossils for modern biostratigraphy

A new model of the distribution of Proterozoic microorganisms is developed, based on studies of Riphean and Vendian silicified and organic-walled microfossils from the reference sections of northern Eurasia, and on their comparison with other known microfossil assemblages. Within the interval from 2.0 to 0.535 Ga, seven successive informal global microphytological units (referred to as proterohorizons) are determined: (1) Labradorian proterohorizon occupies the upper part of the Lower Proterozoic (Paleoproterozoic), 2.0–1.65 Ga; (2) Anabarian proterohorizon, Lower Riphean-lower Middle Riphean (lower and middle Mesoproterozoic), 1.65–1.2 Ga; (3) Turukhanian proterohorizon, upper Middle Riphean (upper Mesoproterozoic), 1.2–1.03 Ga; (4) Uchuromayan proterohorizon, lower Upper Riphean (lower Neoproterozoic), 1.03–0.85 Ga; (5) Yuzhnouralian proterohorizon, upper Upper Riphean (upper Neoproterozoic without Ediacaran); (6) Amadeusian proterohorizon, Lower Vendian (Ediacaran), 0.6–0.55 Ga; and (7) Belomoryan proterohorizon, Upper Vendian (Ediacaran), 0.55–0.535 Ga.     

Cryptospore Assemblages from the Ordovician/silurian Boundary in the Puna Region, North-west Argentina

Palynomorph assemblages have been recovered from deposits believed to straddle the Ordovician/Silurian boundary, from the upper member of the Salar del Rincón Formation, in the Puna region of north-west Argentina. The palynomorph assemblages are dominated by terrestrial cryptospores, but also contain marine elements (acritarchs, prasinophycean algae and chitinozoans). The cryptospore assemblages are similar in composition to those described from coeval deposits worldwide, suggesting that the producers were cosmopolitan and tolerated a wide range of climatic conditions. They are correlated with the Imperfectotriletes spp. Interval Biozone (sub-biozone α) of the Imperfectotriletes spp.- Laevolancis divellomedia Assemblage Biozone, indicating a Hirnantian (latest Ordovician) age. Acritarchs include late Ordovician species such as Eupoikilosusa striata and Villosacapsula cf. setosapellicula , that coexist with the Llandovery species Dactylofusa estillis. Based on lithological and palynological evidence, an early Llandovery, or a late Hirnantian (post-glacial) age is proposed for the basal part of the upper member of the Salar del Rincón Formation.     

Progress in Irish lower palaeozoic palynology

Knowledge of Lower Palaeozoic palynomorphs in Ireland has improved greatly during the last decade, and acritarchs of most epochs from Vendian to Wenlock, together with Ordovician and Silurian chitinozoa and Silurian miospores, are now known. The present state of knowledge is summarised in terms of a number of distinctive palynological assemblages.     

Fungal spores of the genus Pesavis from the Lower Tertiary of Britain

Dispersed fungal spores from the Reading Beds (Palaeocene) near Newbury, Berkshire are referred to the genus Pesavis Elsik & Jansonius, and a possible affinity with aero-aquatic fungi is suggested. This highly distinctive Palaeogene sporomorph has not previously been described from the European Tertiary.     

Unteroligozäne Fische (Otolithen) aus dem Neuwieder Becken (Rheinisches Schiefergebirge,West-Deutschland)

On the basis of otoliths three fish species are described from the Maifeld Beds of the Neuwied Basin (Rhenish Massif/Western Germany):Dapaloides sieblosensis (Winkler),Umbra weileri Martini andThaumaturus sp. The fish assemblage indicates an early Oligocène age and a brackish environment in a shallow water. A marine connection during the Latdorfian between the Upper Rhinegraben and the Neuwied Basin on one side and the Sieblos/Rhön area on the other side seems possible.     

LATE PRECAMBRIAN TRACE FOSSILS FROM NEW SOUTH WALES

Seven trace-fossil species are described from the upper part of the Torrowangee Group (Upper Proterozoic) of western New South Wales, and a variety of other traces are illustrated. A few forms occur in the Fowlers Gap Beds, and a more diverse and abundant fauna is recorded from the stratigraphically higher Lintiss Vale Beds. Virtually all the traces are preserved in the plane of bedding, as semi-reliefs. The named trace fossils all come from the Lintiss Vale Beds, and are as follows: Planolites ballandus sp. nov., Planolites? sp., Cochlichnus serpens sp. nov., Gordia? sp., Torrowangea rosei gen. et sp. nov., Phycodes? antecedent sp. nov., and Curvolithus? davidis sp. nov. Three of these species are regarded as feeding burrows (endogene), and are thought to represent the activity of infaunal, worm-like deposit feeders. Others may be either feeding burrows or crawling trails. There are also a few impressions which seem to be rest marks. A discussion of the significance of the trace-fossil occurrences is presented.     

Triassic/Jurassic carbonates from the Hochfelln Mountain (Northern Calcareous Alps)—its facies, silicified fauna and implications for the end-Triassic biotic crisis

A suite of Early Mesozoic (Late Triassic, Norian to Early Jurassic) calcareous beds was studied from the Hochfelln Mountain in the Northern Calcareous Alps (NCA, South Germany). The Hauptdolomit Group consists of thick peritidal deposits and is overlain by basin deposits of the Rhaetian Kössen Formation and Rhaetian reefoidal limestone with corals. Unlike many other sections in the Tethys realm, coral growth seems to continue into the Jurassic or starts again relatively early within the Early Jurassic. Silicified corals and other marine invertebrates are present in the calcareous, micritic Hochfelln Beds. A re-examination of previously collected ammonite material indicates the presence of Coroniceras sp. which suggests an Early Sinemurian age for the Hochfelln Beds. Abundant sponge spicules (spiculites) suggest that sponges were the source for the silicification. The site produced one of the most diverse Early Jurassic (Sinemurian) gastropod faunas of the NCA (25–30 species, some undescribed). The relatively diverse Early Sinemurian gastropod fauna and coral growth indicate rapid recovery from the end-Triassic biotic crisis.     

Epitoniids (Gastropoda: Epitoniidae) from the late Eocene of Kazakhstan and Ukraine

Epitoniid assemblages from the Chegan Formation of Kazakhstan and the Mandrikovka Beds of Ukraine are revised. Members of five subfamilies, seven genera, and at least 14 species (nine in the Mandrikovka Beds and at least seven in the Chegan Formation) are recorded. A new species, Acirsa aralica sp. nov., from the Chegan Formation is described. Most of the other species are provided with the data on distribution, comparisons, remarks, and figures.     

Upper Ordovician microphytoplankton of the Bill's Creek Shale and Stonington Formation,Upper Peninsula of Michigan,U.S.A.: Biostratigraphy and paleogeographic significance

An abundant, diverse, and well-preserved organic-walled microphytoplankton assemblage is described from the Upper Ordovician Bill's Creek Shale and the lower Stonington Formation (Bay de Noc Member) in the Upper Peninsula of Michigan, U.S.A. Based on graptolite and conodont evidence, the Bill's Creek Shale and Stonington Formation are Richmondian (=Ashgill) in age. The assemblage is dominated by acritarchs, which comprise 29 species (including the enigmatic palynomorph Gloeocapsomorpha prisca) assigned to 20 genera. The prasinophyte phycomata are represented by undifferentiated species of Leiosphaeridia and Tasmanites. In addition, chitinozoans are abundant, and scolecodonts and graptolite fragments are common. Paleontologic-palynologic and sedimentologic evidence indicates that the Bill's Creek Shale was deposited in a low-energy, shallow, nearshore marine environment. The overlying Bay de Noc Member of the Stonington Formation also accumulated in a low-energy, normal marine environment, but in a more offshore, somewhat deeper water setting. Both formations experienced minor transgressive and regressive episodes as indicated by fluctuations in the composition of the palynoflora. The combined Bill's Creek/Stonington acritarch assemblage closely resembles those described from the Richmondian-aged Maquoketa Shale (Missouri and Kansas), Sylvan Shale (Oklahoma), and Vauréal Formation (Anticosti Island, Québec, Canada). The overall composition of the acritarch assemblage from these four formations reflects a distinctive, recognizably Laurentian character. Nonetheless, many of the Bill's Creek/Stonington acritarchs have been reported from Upper Ordovician localities elsewhere, providing additional evidence for Late Ordovician cosmopolitanism of the marine microphytoplankton community. Additionally, the restricted stratigraphic range of many of the taxa further enhances their biostratigraphic application, both regionally and globally, and reaffirms the Richmondian (=Ashgill) age of the Bill's Creek Shale and Stonington Formation.     

Bryozoans, corals, and microfacies of Lower Eifelian (Middle Devonian) limestones at Kierspe, Germany

The Lower Eifelian Meinerzhagener Korallenkalk (= upper Cultrijugatus Beds) at Kierspe, Sauerland, contains a rich reefal fauna. Eight bryozoan species are described, two of them are new: the cystoporate Fistuliporella kierspensis n. sp. and the trepostome Leptotrypella sophiae n. sp. The bryozoans from the Meinerzhagener Korallenkalk shows distinct similarities to the Lower–Middle Devonian of Spain (Santa Lucía Formation, Emsian–Eifelian), and to the Middle Devonian (Eifelian) of Transcaucasia. The coral fauna comprises five tabulate corals and one rugose coral that document a paleobiogeographic relationship between Central and Eastern Europe and Central Asia. The associated fauna is represented by brachiopods, ostracods, and echinoderms. The studied limestones also commonly contain calcimicrobes represented by three species. The faunal and microfacial characteristics indicate a shallow marine depositional environment just above the storm wave base, with a supposed depth of 20 m, within the photic zone. The nutrient regime was at least a mesotrophic. The upper boundary of the Cultrijugatus Beds coincides with the Chote?-Event that strongly affected brachiopods, whereas corals and bryozoans were insensitive to this event.