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Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Late Ordovician strophomenide brachiopods (superfamilies Strophomenoidea and Plectambonitoidea) from the upper Changwu Formation (mid Ashgill, late Katian) of Jianglütang, Chun’an County, western Zhejiang Province, consist of ten genera and 12 species. Five new species of three new genera are recognized: Chunanomena triporcata, Chunanomena sembellina, Cheramomena subsolana, Lateriseptomena modesta, and Lateriseptomena rugosa. The strophomenide brachiopods from the upper Katian strata described in this study and those from the border region of Zhejiang and Jiangxi provinces reported in previous work contain 16 strophomenoid and 12 plectambonitoid genera, and most of the strophomenoids are endemic to South China. Numerical analysis of well-documented late Katian strophomenide brachiopod faunas indicates a strong provincialism, characterized by the highly distinct North American province (Laurentia), the South China-Kazakhstan province, and the Avalonia-Baltica province (Wales, Belgium and Sweden). Surprisingly, the Girvan district of Scotland, which was a peri-Laurentian terrane during the Ordovician, contains a late Katian brachiopod fauna that is more closely related to the contemporaneous brachiopods of Avalonia-Baltica than to those of North America. [ABSTRACT FROM AUTHOR]

Brachiopods from the lower Tonggao Formation (Floian, late Early Ordovician) of Sandu, southeastern Guizhou Province, represent a deep-water benthic shelly fauna from the Jiangnan Slope facies of the South China paleoplate. The fauna contains 16 brachiopod taxa, with orthides, lingulates, and pentamerides being the common groups. Concurrent graptolites confine the brachiopod fauna to the Tetragraptus approximatus and the Acrograptus filiformis biozones (early Floian). The first appearance datum (FAD) of several brachiopod genera, such as Paralenorthis, Protoskenidioides, and Nereidella, in the Sandu slope facies is one or two graptolitic biozones lower than their FAD in shallower water facies on the Yangtze Platform. Later in the late Floian, these genera became major components of the Sinorthis fauna that flourished over much of the Yangtze Platform, suggesting a migration of the benthic shelly fauna from slope to platform facies during the Floian radiation in South China. Compared to the platform fauna, the deep-water brachiopod fauna of the Sandu area has a lower level of richness, diversity, and community organization. Three brachiopod associations are recognized: the Paralenorthis–Nereidella, the Palaeoglossa longa, and the Lingulella–Protoskenidioides associations. An upsection decrease in shell size, faunal richness, and species diversity in the Tonggao Formation indicate a deteriorating environment towards hypersalinity in the Sandu area, resulting in the ultimate disappearance of the deep-water brachiopod fauna. [ABSTRACT FROM AUTHOR]

Sixteen species from the Lower Silurian (mostly Aeronian and rarely Telychian) of South China have been assigned previously to the brachiopod family Pentameridae, mainly to the genus Pentamerus. Study of intrapopulation variation suggests that 13 species from the upper Aeronian Lojoping Formation of the Yichang area, western Hubei Province, can be synonymized with Sulcipentamerus dorsoplanus, the most abundant pentamerid species of South China but confined to the Yichang area. The conspicuously high and obtuse ventral umbo, strong ventribiconvexity and a sulcate anterior commissure warrant genus status for Sulcipentamerus, independent of Pentamerus. True Pentamerus is rare in South China, known only from upper Aeronian rocks of Guizhou Province. Multivariate analyses indicate that Aeronian pentameride brachiopods of South China are characterized by a high level of provincialism, distinct from those of Laurentia. Also, the Aeronian pentamerides of South China or Laurentia have a low degree of similarity to those of Baltica, Siberia, Avalonia, Kazakhstan and other palaeotropically located plates or terranes. Besides South China and Laurentia, the pentamerides of other palaeotropical regions constituted a relatively tight cluster. This suggests that the palaeogeographical positions of South China and Laurentia only allowed limited or periodic faunal exchange of these generally large-shelled brachiopods adapted to living in relatively shallow, warm waters. [ABSTRACT FROM AUTHOR]

Systematic and statistical study of brachiopods from the Dawan Formation of the Yichang area, western Hubei Province, central China, indicates that, at generic and specific levels, the α diversity of Early to Mid Ordovician brachiopods in the study area reached the first acme at the beginning of the Corymbograptus deflexus Biozone, marked by the diverse Sinorthis typica Community. This diversity maximum of brachiopods occurred approximately one biozone later than that of the Upper Yangtze Platform. In taxonomic constituents, the main contributors to the diversity maximum were orthoids, which experienced a major increase in the number of genera in the upper Didymograptellus eobifidus Biozone and the lower C. deflexus Biozone. In brachiopod communities or associations, orthoids and pentameroids were the dominant elements. Analyses of Early–Mid Ordovician brachiopods from the Upper Yangtze Platform indicate that a high level of brachiopod community organization, with temporal and spatial stability, was achieved by the Sinorthis Community, which persisted from the D. eobifidus to the Azygograptus suecicus biozones (early Arenig). In the D. eobifidus Biozone, the Sinorthis Community thrived across a wide ecological range (BA3 to upper BA4) in the siliciclastic facies of the central part of the Upper Yangtze Platform and, by the latest D. eobifidus interval, invaded more carbonate-rich substrates in more offshore settings in the northeastern part of the platform (the present Yichang area). [ABSTRACT FROM AUTHOR]

The Upper Ordovician (mid-Ashgill) Xiazhen and Changwu formations in the Zhejiang-Jiangxi border region of southeastern China contain an abundant and diverse suite of brachiopods. A cluster analysis of 59 key samples from 180 collections (over 23 000 specimens) allowed delineation of eight distinct brachiopod communities, herein named the Ectenoglossa minor Community, the Eospirifer praecursor Community, the Ovalospira dichotoma Community, the Antizygospira liquanensis – Sowerbyella sinensis Community, the Kassinella shiyangensis Community, the Altaethyrella zhejiangensis Community, the Tcherskidium jiangshanensis Community and the Foliomena folium Community. These communities occur predominantly in limey, clayey, to silty mudstone facies, similar to Ziegler's Early Silurian brachiopod communities in the Welsh Borderland. On the basis of lithological, faunal, and paleogeographical evidence, the eight communities are interpreted to have distributed along an onshore–offshore gradient from BA1 to BA6 settings on the northeastern margin of the Zhe-Gan Platform. In a broad paleo-embayment and mixed carbonate–siliciclastic shelf setting, the distribution of the eight brachiopod communities appears to have been controlled primarily by water depth because a given brachiopod community can be found in different lithofacies. Substrate types, however, must have played an important role, as some of the communities show preferred lithofacies. This study shows that the ecological zonation and community organization of the Late Ordovician pre-extinction brachiopods were similar to those of Early Silurian post-extinction brachiopods, although pronounced brachiopod provincialism during the Ashgill makes it difficult to directly correlate these communities with coeval brachiopod communities reported from other paleo-plates.Les formations de Xiachen et de Changwu de l'Ordovicien tardif (Ashgillien moyen) dans la région de la frontière Zhejiang-Jiangxi du Sud-Est de la Chine contiennent une suite abondante et diversifiée de brachiopodes. Une analyse typologique de 59 échantillons clefs provenant de 180 collections (plus de 23 000 spécimens) a permis de délimiter huit communautés distinctives de brachiopodes nommées ici la communauté Ectenoglossa minor, la communauté Eospirifer praecursor, la communauté Ovalospira dichotoma, la communauté Antizygospira liquanensis–Sowerbyella sinensis, la communauté Kassinella shiyangensis, la communauté Altaethyrella zhejiangensis, la communauté Tcherskidium jiangshanensis et la communauté Foliomena folium. Ces communautés se retrouvent surtout dans des faciès de mudstone à chaux, d'argileux à silteux, semblable aux communautés de brachiopodes de Ziegler du Silurien précoce dans la Bordure Galloise (Angleterre). Selon les évidences lithologiques, fauniques et paléogéographiques, les huit communautés se seraient distribuées le long d'un gradient côtier et extracôtier dans des environnements BA1 à BA6 sur la bordure nord-est de la plate-forme de Zhe-Gan. Dans un environnement de grande paléobaie ouverte et de plate-forme à mélange de carbonates et de siliclastiques, la distribution des huit communautés de brachiopodes semble avoir été contrôlée surtout par la profondeur de l'eau puisqu'une communauté donnée de brachiopodes peut se retrouver dans différents lithofaciès. Les types de substrats ont cependant dû avoir joué un rôle important puisque quelques communautés présentent des lithofaciès préférentiels. La présente étude montre que la zonation écologique et l'organisation des communautés des brachiopodes avant extinction à l'Ordovicien tardif étaient semblables à celles des brachiopodes post-extinction du Silurien précoce, bien que le provincialisme prononcé des brachiopodes au cours de l'Ashgillien rende difficile la corrélation directe entre ces communautés et les communautés contemporaines de brachiopodes provenant d'autres paléoplaques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The Kuanyinchiao Formation (Hirnantian, Upper Ordovician), yielding the typical Hirnantia fauna, has commonly been accepted as representing cool-water sediments deposited during the glacial interval in the Hirnantian Global Boundary Stratotype Section and Point (GSSP) region of South China. Recent investigation reveals that the uppermost carbonate-dominated part of this formation yields a warm-water rugose coral fauna with Silurian affinities at many localities of northern Guizhou Province, which substantially differs from the underlying cool-water fauna. This suggests that these carbonates were probably postglacial warm-water sediments, rather than having formed during the Hirnantian glacial interval as previously thought. Such a conclusion is consistent with the evidence from the associated brachiopod fauna, i.e., the Dalmanella testudinaria - Dorytreta longicrura community, which is similarly distinct from the underlying typical Hirnantia fauna. The sedimentological data show warm-water features at the same level (e.g., the presence of oolitic grains), also supporting this new interpretation. [ABSTRACT FROM AUTHOR]

The distribution pattern of early Telychian ( turriculatus-crispus graptolite biozone) red beds in the Eastern Yangtze Platform of South China is reconstructed based on regional geologic data. The red beds are developed in three areas, which are separated by regions without red deposition. The distribution pattern indicates that the Cathaysian Oldland was the provenance of sediment rich in ferric oxides, which are essential for the formation of red beds. Silurian marine siliciclastic red beds, both in China and worldwide, tended to develop during times of relatively low sea level. Coeval hematitic oolites that formed far from the coast may record a change from reducing to oxidizing conditions in the ocean. Furthermore, it is likely that a fall in global sea level, a transition from reducing to oxidizing conditions in the ocean, and a cooling climate, all of which were closely related to the early Telychian Valgu Event, promoted the global development of marine red beds during this period. [ABSTRACT FROM AUTHOR]