Wang Cheng-Yuan

Conodont survival and low iridium abundances across the Permian-Triassic boundary in south China

The Permian-Triassic sedimentary sequence of China includes one of the most complete and fossiliferous Paleozoic-Mesozoic boundaries known. Closely spaced sampling across the boundary, which is an important extinction event for most organisms, has produced good conodont faunas that show little diversity change. A drop in conodont abundance is the only apparent response to the extinction event. A low concentration of iridium in the boundary clay (0.002 part per billion �20 percent), as well as in samples immediately below and above, that range from 0.004 to 0.034 part per billion do not support the proposal of an extraterrestrial impact event at this boundary in China.

Continental island from the Upper Silurian (Ludfordian Stage) of Inner Mongolia: Implications for eustasy and paleogeography

An unconformity between the Silurian Xibiehe Formation and Ordovician igneous rocks marks the perimeter of a small paleoisland near Bater Obo in north-central Inner Mongolia, 180 km northwest of the provincial capital of Hohhot. The stratigraphic position of the lower part of the Xibiehe Formation is correlated by means of conodonts with the upper part of the Ancoradella ploeckensis Zone in the basal Ludfordian Stage (corresponds to mid-Ludlovian Epoch, ca. 421 Ma). Elongate in plan (610 m × 200 m), the exhumed diorite core rises 30 m above the lowest elevations of surrounding Silurian strata. Paleoshores along the principal axis of the inlier delineate contrasting facies. Robust stromatoporoids are in growth position within silty limestones, some directly encrusting the unconformity surface of the sheltered southeast margin. A basal conglomerate of diorite cobbles and boulders characterizes the high-energy northwest margin. The depositional constraints and timing of transgressive facies associated with this continental paleoisland have implications for the eustatic and paleogeographic history of the parent Sino-Korean plate. Burial of the island corresponds to the beginning of a global rise in sea level that peaked in late Ludlovian time. Our interpretation of windward and leeward facies requires an approximate 90° clockwise rotation of the parent plate to accommodate the dominant pattern of low-latitude trade winds and storms.

The frasnian-famennian conodont mass extinction and recovery in South China

AbstractsConodonts are most important for the study of the Frasnian/Famennian Late Devonian mass extinction and recovery. Conodont mass extinction occurred stepwise (poly-episodes) in the latest Frasnian (latelinguiformis Zone) and was of very short timespan and global scale. Five steps of the conodont mass extinction can be recognized, with the same as in other sections in the world. Conodont recovery occurred in the earliest Famennian marked by the first appearance ofPalmatolepis triangularis. The timespan of the conodont recovery interval can be estimated as much less than 0.5 m.y. An independent survival interval cannot be determined. All of the Early- and Middletriangularis Zone should be assigned to the recovery interval, in which conodonts recovered also in a stepwise pattern and on a global scale.Pal. praetriangularis, Pal. triangularis andIcriodus alternatus, I. praealternatus, I. deformatus asymmetricus are crisis progenitor taxa, which are important for conodont recovery in the pelagic and neritic facies respectively. Some species ofPolygnathus andIcriodus are ecological generalists.KurzfassungConodonten sind sehr wichtig bei Untersuchungen des Frasnium/Famennium-Massenaussterbens und der — Wiederherstellung. Das Conodonten-Massenaussterben geschah schrittweise im spätesten Frasnium (spätelinguiformis-Zone), war sehr kurzfristig und global. Fünf Schritte können in Profilen weltweit erkannt werden. Die Conodonten-Wiederherstellung passierte im frühesten Famennium beim ersten Auftreten vonPalmatolepis triangularis und dauerte schätzungsweise weniger als 0,5 m.y. Ein unabhängig auftretendes Überlebensintervall kann nicht bestimmt werden. Die Frühe und Mittleretriangularis-Zone insgesamt wird zum Wiederherstellungsintervall gerechnet, während dem sich die Conodontenfaunen schrittweise und global wieder erholten.Pal. praetriangularis, Pal. triangularis undIcriodus alternatus, I. praealternatus, I. deformatus asymmetricus sind Krisenvorgänger-Taxa, die wichtig sind für die Conodontenwiederherstellung in der pelagischen and neritischen Fazies. Einige Arten vonPolygnathus undIcriodus sind ökologische Generalisten.

PERMIAN NEOGONDOLELLIDS FROM SOUTH CHINA - SIGNIFICANCE FOR EVOLUTION OF THE SERRATA AND CARINATA GROUPS IN NORTH-AMERICA

The Neogondolella serrata (Clark and Ethington) group was originally reported as a North American provincial conodont lineage. More or less complete Permian sequences now recognized in China include species originally thought to be part of the North American provincial fauna as well as species reported previously from other parts of the world. Comparison of Chinese and North American species may be useful in correlation of series and stage boundaries between the two areas. The Chinese conodont succession demonstrates that most Permian neogondolellids were not provincial but attained worldwide distribution. Late Permian ancestors of Early Triassic Neogondolella species were apparently widespread in the Tethyan Sea and the sudden appearance of Triassic Neogondolella species in North America without Permian ancestors is only the consequence of the absence of the latest Permian marine rocks in North America. Of particular regional stratigraphic interest is the occurrence of the North American species N. wilcoxi Clark and Behnken in the Chinese late Guadalupian-Dzhulfian. This occurrence supports a late Guadalupian (post-Lamar) age for the uppermost Gerster Formation in Utah.

Some Problems on the Guryul Ravine Section of Kashmir as Permian-Triassic Boundary Stratotype

The selection of a Global Boundary Stratotype Section and Point (GSSP) should be strictly treated on the basis of the requirements of International Commission on Stratigraphy (ICS). This is espicially necessary for the Permian-Triassic boundary which is not only an intersystem boundary but also the boundary between the Palaeozoic and the Mesozoic.

Conodont Biofacies and Paleoecology of the Carboniferous of China

Serious study of Carboniferous conodonts in China has been in progress only during the last ten years and encouraging achievements, especially in conodont biostratigraphy, have been made. A complete Carboniferous conodont sequence has been recognized and a preliminary biofacies framework has been established. It is now possible to recognize at least three broadly defined conodont biofacies at positions along an environmental gradient that includes basinal, outer shelf and inner shelf facies. Basinal facies are limited in distribution to South China. Outer shelf facies occur over most of the area of the platform of South China and inner shelf facies are distributed over a limited area of South China as well as the vast area of the platform of North China.