The Hirnantia Fauna is a globally-represented,cool water brachiopod fauna that originated and flourished in shallow marine environments at intermediate to low latitudes after the first episode of the end-Ordovician ma...The Hirnantia Fauna is a globally-represented,cool water brachiopod fauna that originated and flourished in shallow marine environments at intermediate to low latitudes after the first episode of the end-Ordovician mass extinction.It was well-developed,widely distributed,long in stratigraphical range,and complex in palaeoecological differentiation on the Upper Yangtze Platform of the South China paleoplate,where it has been extensively studied.Qualitative and quantitative analyses show that the FAD of the Hirnantia Fauna in South China becomes stratigraphically higher from nearshore to offshore localities on the Yangtze Platform,while the range of the fauna becomes shorter whereas the taxonomic diversity increases.Over its stratigraphical range the diversity of the Hirnantia Fauna at nearshore localities consistently decreases,but trends in the opposite direction at offshore,deeper water localities.The fauna was represented by different communities,subcommunities or associations with changing environmental factors(such as water depth and substrate) at different localities or horizons.展开更多
Ordovician conodonts representing 28 genera and 28 named and three unnamed species were identified from 740 chert and siliceous siltstone spot samples(>3000 thin sections)from deep-water turbiditic sequences of the...Ordovician conodonts representing 28 genera and 28 named and three unnamed species were identified from 740 chert and siliceous siltstone spot samples(>3000 thin sections)from deep-water turbiditic sequences of the Lachlan Orogen in central and southern New South Wales,Australia.Based on these faunas,a new conodont biozonal scheme has been established to divide the Ordovician turbiditic successions of the Lachlan Orogen into 12 superbiozones and biozones.They are(in ascending order)the Paracordylodus gracilis Superbiozone(including the Prioniodus oepiki Biozone),Periodon flabellum Superbiozone(including the Oepikodus evae Biozone in the lower part),Periodon hankensis Biozone,Periodon aculeatus Superbiozone(including the Histiodella labiosa,Histiodella holodentata,Histiodella kristinae,Pygodus serra and Pygodus anserinus biozones)and the Periodon grandis Biozone.The Pygodus anserinus Biozone is divided further into the lower and upper subbiozones.This new conodont biozonation scheme spanning the upper Tremadocian to middle Katian interval permits precise age-dating and correlation of deep-water siliciclastic rocks that characterize the Ordovician Deep-Sea Realm regionally and internationally.展开更多
基金supported by Chinese Academy of Sciences (Grant No. KZCX2-YW-Q05-01)National Natural Science Foundation of China (Grant No. 40825006)Ministry of Science and Technology of China (Grant Nos. 2006CB806402,2006FY120300-5)
文摘The Hirnantia Fauna is a globally-represented,cool water brachiopod fauna that originated and flourished in shallow marine environments at intermediate to low latitudes after the first episode of the end-Ordovician mass extinction.It was well-developed,widely distributed,long in stratigraphical range,and complex in palaeoecological differentiation on the Upper Yangtze Platform of the South China paleoplate,where it has been extensively studied.Qualitative and quantitative analyses show that the FAD of the Hirnantia Fauna in South China becomes stratigraphically higher from nearshore to offshore localities on the Yangtze Platform,while the range of the fauna becomes shorter whereas the taxonomic diversity increases.Over its stratigraphical range the diversity of the Hirnantia Fauna at nearshore localities consistently decreases,but trends in the opposite direction at offshore,deeper water localities.The fauna was represented by different communities,subcommunities or associations with changing environmental factors(such as water depth and substrate) at different localities or horizons.
文摘Ordovician conodonts representing 28 genera and 28 named and three unnamed species were identified from 740 chert and siliceous siltstone spot samples(>3000 thin sections)from deep-water turbiditic sequences of the Lachlan Orogen in central and southern New South Wales,Australia.Based on these faunas,a new conodont biozonal scheme has been established to divide the Ordovician turbiditic successions of the Lachlan Orogen into 12 superbiozones and biozones.They are(in ascending order)the Paracordylodus gracilis Superbiozone(including the Prioniodus oepiki Biozone),Periodon flabellum Superbiozone(including the Oepikodus evae Biozone in the lower part),Periodon hankensis Biozone,Periodon aculeatus Superbiozone(including the Histiodella labiosa,Histiodella holodentata,Histiodella kristinae,Pygodus serra and Pygodus anserinus biozones)and the Periodon grandis Biozone.The Pygodus anserinus Biozone is divided further into the lower and upper subbiozones.This new conodont biozonation scheme spanning the upper Tremadocian to middle Katian interval permits precise age-dating and correlation of deep-water siliciclastic rocks that characterize the Ordovician Deep-Sea Realm regionally and internationally.