Zhan Renbin (詹仁斌)

Late Ordovician to earliest Silurian graptolite and brachiopod biozonation from the Yangtze region, South China, with a global correlation

Late Ordovician to earliest Silurian is an important geological period marked by large geological and biological events. However, the strata and fossils of this interval are not complete in many parts of the world. Based on studies of 43 sites in South China, in particular the continuous sections on the Yangtze platform, we recognize a complete succession including seven graptolite zones and two shelly faunas. In ascending order, the graptolite zones are the Dicellograptus complanatus , Dicellograptus complexus , Paraorthograptus pacificus (including Lower Subzone, Tangyagraptus typicus Subzone and Diceratograptus mirus Subzone), Normalograptus extraordinarius–Normalograptus ojsuensis , Normalograptus persculptus , Akidograptus ascensus and Parakidograptus acuminatus zones. The shelly faunas are the Foliomena–Nankinolithus and Hirnantia faunas, which may be correlated with D. complanatus Zone and N. extraordinarius–N. ojsuensis to part of N. persculptus zones respectively. The biozonation through this interval from the Yangtze region can be correlated with that of other parts of the world such as Dob’s Linn in Scotland, Spain and Portugal, Thuringia–Saxonia–Bavaria, Bohemia, Poland, Kazakhstan, Kolyma, Malaya Peninsula, Yukon, Canadian Arctic Islands, Nevada, Argentina, Niger and Victoria, Australia. The Hirnantian Substage, which has been proposed by us recently, includes the N. extraordinarius–N. ojsuensis Zone, Hirnantia fauna and N. persculptus Zone. The base of the Hirnantian Substage is marked by the First Appearance Data (FADs) of N. extraordinarius and N. ojsuensis , which have been determined to be synchronous on a global scale.

Late Ordovician Articulate Brachiopods from the Red River and Stony Mountain Formations, Southern Manitoba

The Late Ordovician Epoch was marked by one of the two greatest global sea-level rises and inundations of the North American paleocontinent during the Phanerozoic (last 544 million years), accompanied by rapid diversification of invertebrate faunas in shallow, epicontinental seas. Toward the end of the Late Ordovician, continental glaciation in the southern hemisphere (Gondwana landmass) caused a major sea-level drawdown and marine regression from North America, bringing about one of the five major mass extinction events in life history. The diversity of marine life in the inland seas would be particularly sensitive to global sea-level fluctuations caused by the growth and decay of the Gondwana ice cap. This monograph is part of an ongoing comparative study of the biodiversity changes of the Late Ordovician – Early Silurian brachiopods (the most abundant and diverse group of shelly benthos at that time) in continental-margin basins and inland seas of Canada. Study of the brachiopod faunas helps us understand many aspects (duration, extent, intensity, and timing) of the climatic changes and their effects on marine environments far from the site of the glaciation. The Late Ordovician carbonate deposits now preserved in the Williston Basin contain a rich and diverse benthic shelly fauna that lived in the ancient equatorial epicontinental seas just before the Late Ordovician mass extinction event, and this work deals with the taxonomy, biostratigraphy, paleoecology, and paleobiogeography of the brachiopod fauna. The authors described a total of 16 genera and 22 species and discussed their ancient living environments and faunal provincialism.

Late Ordovician Orthide and Billingsellide Brachiopods-from Anticosti Island, Eastern Canada: Diversity Change through Mass Extinction

This monographic study deals with a major marine faunal turnover during the Late Ordovician global greenhouse/icehouse episodes. The Late Ordovician was marked by one of the two greatest global sea-level rises and inundations of the North American paleocontinent during the Phanerozoic (last 544 million years), accompanied by a rapid diversification of invertebrate faunas in shallow, tropical, epicontinental seas. Toward the end of the Late Ordovician, continental glaciation in the southern hemisphere (Gondwana landmass) caused a major sea-level drop and marine regression from North America, bringing about the first of the five major mass extinction events in life history. Anticosti Island was part of the larger Anticosti basin, located on the eastern continental shelf of the North America paleocontinent, and was covered by a shallow, tropical sea in the Late Ordovician epoch. During the latest Ordovician global mass extinction event, the marine shelly benthos (bottom) of the Anticosti basin experienced a significant local radiation. This provides a great opportunity for us to investigate the response of marine life to a major environmental crisis. This monographic study aims to document the diversity change of brachiopods (one of the major groups of marine life during the Ordovician Period) from pre-extinction to extinction times.

THE OLDEST KNOWN EOSPIRIFER (BRACHIOPODA) IN THE CHANGWU FORMATION (LATE ORDOVICIAN) OF WESTERN ZHEJIANG, EAST CHINA, WITH A REVIEW OF THE EARLIEST SPIRIFEROIDS

ABSTRAC- Eospiriferpraecursor n. sp. is the oldest known eospiriferine, probably ancestral to the entire Spirifer group. It is described here based on external and internal mold material from the uppermost part of the Changwu Formation (mid-Ashgill, Late Ordovician), Hejiashan, Jiangshan, western Zhejiang, East China. A study of the ontogeny of E. praecursor n. sp. suggests that the cardinalia of early growth stages are more similar to those of early atrypoids rather than to those of the orthoids but the brachidia in these earliest Eospirifer are still unknown. The possibility that eospiriferines were derived from an atrypoid stock cannot be excluded. All early eospiriferine species recorded from the Ashgill, Rhuddanian, and early Aeronian are reviewed for comparison. Their morphological diversification reveals early evolutionary experimentation. Based on the Ashgill occurrence of Eospirifer, it is likely that East Asia may be considered as one of the eospiriferine source areas.

Late Cambrian brachiopods from Jingxi, Guangxi Province, South China

The brachiopod fauna of the upper Cambrian (upper Furongian) Guole Formation, northwestern Jingxi County, southwestern Guangxi Province, southern China, comprises six genera and seven species, including one new genus, three new species and two indeterminate species (Obolidae gen. et sp. indet, Acrotretidae gen. et sp. indet., Billingsella guangxiensis, B. costata sp. nov., Guoleella lata gen. et sp. nov., Palaeostrophia jingxiensis, Plectotrophia imparicostata sp. nov.). This is the first systematic description of an upper Cambrian brachiopod fauna composed mainly of calcareous-shelled individuals from China. Brachiopod and trilobite faunal analyses suggest that this fauna has a prominent North American (Laurentian) affinity. It is notably different from the coeval, lingulate-dominated brachiopod fauna of South China, particularly of the Yangtze Platform, but shares some similarity with those of the North China Platform. Preliminary analysis reveals that this brachiopod fauna, named the Billingsella-Palaeostrophia Fauna, lived in a nearshore, shallow water benthic regime with a calcareous muddy substrate.

Discovery of the late Middle Ordovician Saucrorthis fauna (Brachiopoda) from the Sibumasu palaeoplate, western Yunnan, SW China

A relatively diverse Saucrorthis brachiopod fauna is reported for the first time from the Sibumasu palaeoplate in the Shihtien Formation (Darriwilian, upper Middle Ordovician) at Laojianshan of Baoshan, western Yunnan Province, southwest China. It contains 25 brachiopod genera, amongst which orthides, strophomenides and billingsellides are predominant, but quantitatively Saucrorthis and Leptestiina are the most abundant. Numerical analyses of 23 global Darriwilian brachiopod faunas show two major clusters, the Saucrorthis Group and the Aporthophyla Group, representating two major palaeobiogeographical regions developed during the Darriwilian, corresponding to lower and higher palaeolatitudinal habitats, respectively.

A New Noncalcified Thallophytic Alga from the Lower Silurian of Anticosti Island, Eastern Canada

An exceptionally preserved noncalcified thallophytic alga, Menieria minuta gen. nov. et sp. nov. from the uppermost Gun River Formation (middle Aeronian, Lower Silurian) of Anticosti Island, eastern Canada, is characterized by a relatively delicate thallus with a central axis, lateral branches, and helically arranged, regularly and closely spaced, elongate-linguoid appendages. The algae locally constitute an important portion of the biomass in a brachiopod-dominated paleocommunity, forming an algal meadow on a relatively deepwater subtidal setting within the photic zone. This rare fossilization window suggests that such soft algal meadows may have been common during the Early Paleozoic, resembling modern sea grass meadows that are part of the carbon sink.An exceptionally preserved noncalcified thallophytic alga, Menieria minuta gen. nov. et sp. nov. from the uppermost Gun River Formation (middle Aeronian, Lower Silurian) of Anticosti Island, eastern Canada, is characterized by a relatively delicate thallus with a central axis, lateral branches, and helically arranged, regularly and closely spaced, elongate-linguoid appendages. The algae locally constitute an important portion of the biomass in a brachiopod-dominated paleocommunity, forming an algal meadow on a relatively deepwater subtidal setting within the photic zone. This rare fossilization window suggests that such soft algal meadows may have been common during the Early Paleozoic, resembling modern sea grass meadows that are part of the carbon sink.

Conodont diversification during the Ordovician: A perspective from North China and Tarim (Northwestern China)

Review of the literature on Ordovician conodont diversification in palaeoplates of North and Western China reveals that four diversity peaks are present in North China, occurring in the middle Tremadocian, early Floian, late Floian, and late Darriwilian, with three of these peaks (excepting that in the late Floian) also being recorded in Tarim. Three diversification intervals are present in North China, during the Tremadocian, late Floian, early and middle Darriwilian; comparable intervals are observed in the early and late Tremadocian, early Floian, and the Middle Ordovician in Tarim. The main conodont diversification episode in both palaeoplates took place in the Darriwilian, at the time of the Great Ordovician Biodiversification Event. A comparison of conodont diversity patterns in different palaeoplates (North China, Tarim, and South China) demonstrates that conodont radiation events mainly occurred within the Tremadocian, Floian, and Darriwilian. Conodont diversifications in these paleoplates also display some differences. In contrasting with Tarim and South China, North China witnessed a rapid conodont diversification during late Floian time. Conodont diversity in North China and Tarim increased continually and reached a peak in the late Darriwilian, concurrent with a prominent decreasing trend in South China. Differences of conodont diversification in these three palaeoplates may be related to their palaeogeography and tectonic history. When conodont diversifications in North China and Tarim are analysed on the background of palaeoenvironments, the main episodes are seen to be partly coincident with second order sea-level changes, particularly in North China. In general, conodont radiation correlates with large scale transgressions.

Evolution and paleogeography of Eospirifer (Spiriferida, Brachiopoda) in Late Ordovician and Silurian

Eospirifer, the oldest known genus of the spiriferide group (Brachiopoda), first appeared on the Zhe-Gan Platform of South China paleoplate during late Katian (Late Ordovician) represented by E. praecursor. It survived the end-Ordovician mass extinction, and reappeared on the Upper Yangtze Platform of South China paleoplate by the end of Ordovician near the upper part of the Normalograptus persculptus Biozone. Starting from the beginning of Silurian, Eospirifer experienced some morphological innovations and expanded its geographical distribution substantially. It reached its species diversity acme and the widest geographic distribution in Wenlock (middle Silurian), with the diversity hotspots in Laurentia, Avalonia, and Baltica. Various shell size frequency curves of E. praecursor under different paleogeographic settings suggest that this pioneer species of Eospirifer, with several macroevolutionary novelties, adopted a range of life strategies to adapt to the changing environments during early spiriferide evolution. There are also some morphological macroevolutionary trends during the evolutionary history of Eospirifer from Late Ordovician to the end of Silurian, such as the ever enlarging shell sizes and the width/length ratios from late Katian to Wenlock, but decreasing apparently of both parameters from Wenlock to Pridoli.

Permian integrative stratigraphy and timescale of China

A series of global major geological and biological events occurred during the Permian Period. Establishing a highresolution stratigraphic and temporal framework is essential to understand their cause-effect relationship. The official International timescale of the Permian System consists of three series (i.e., Cisuralian, Guadalupian and Lopingian in ascending order) and nine stages. In China, the Permian System is composed of three series (Chuanshanian, Yansingian and Lopingian) and eight stages, of which the subdivisions and definitions of the Chuanshanian and Yangsingian series are very different from the Cisuralian and Guadalupian series. The Permian Period spanned ∼47 Myr. Its base is defined by the First Appearance Datum (FAD) of the conodont Streptognathodus isolatus at Aidaralash, Kazakhstan with an interpolated absolute age 298.9±0.15 Ma at Usolka, southern Urals, Russia. Its top equals the base of the Triassic System and is defined by the FAD of the conodont Hindeodus parvus at Meishan D section, southeast China with an interpolated absolute age 251.902±0.024 Ma. Thirty-five conodont, 23 fusulinid, 17 radiolarian and 20 ammonoid zones are established for the Permian in China, of which the Guadalupian and Lopingian conodont zones have been served as the standard for international correlation. The Permian δ13Ccarb trend indicates that it is characterized by a rapid negative shift of 3–5‰ at the end of the Changhsingian, which can be used for global correlation of the end-Permian mass extinction interval, but δ13Ccarb records from all other intervals may have more or less suffered subsequent diagenetic alteration or represented regional or local signatures only. Permian δ18O{ainpatite} studies suggest that an icehouse stage dominated the time interval from the late Carboniferous to Kungurian (late Cisuralian). However, paleoclimate began to ameriolate during the late Kungurian and gradually shifted into a greenhouse-dominated stage during the Guadalupian. The Changhsingian was a relatively cool stage, followed by a globally-recognizable rapid temperature rise of 8–10°C at the very end of the Changhsingian. The 87Sr/86Sr ratio trend shows that their values at the beginning of the Permian were between 0.70800, then gradually decreased to the late Capitanian minimum 0.70680–0.70690, followed by a persistent increase until the end of the Permian with the value 0.70708. Magenetostratigraphy suggests two distinct stages separated by the Illawarra Reversal in the middle Wordian, of which the lower is the reverse polarity Kiaman Superchron and the upper is the mixed-polarity Illawarra Superchron. The end-Guadalupian (or pre-Lopingian) biological crisis occurred during the late Capitanian, when faunal changeovers of different fossil groups had different paces, but generally experienced a relatively long time from the Jinogondolella altudensis Zone until the earliest Wuchiapingian. The end-Permian mass extinction was a catastrophic event that is best constrained at the Meishan section, which occurred at 251.941±0.037 Ma and persisted no more than 61±48 kyr. After the major pulse at Bed 25, the extinction patterns are displayed differently in different sections. The global end-Guadalupian regression is manifested between the conodont Jinogondolella xuanhanensis and Clarkina dukouensis zones and the end-Changhsingian transgression began in the Hindeodus changxingensis-Clarkina zhejiangensis Zone. The Permian Period is also characterized by strong faunal provincialism in general, which resulted in difficulties in inter-continental and inter-regional correlation of both marine and terrestrial systems.