奥陶三叶虫生物相和古地理.pdf

Available online at Palaeoworld 20 (2011) 15–45 Research paper Trilobite biofacies and palaeogeographic development in the Arenig (Ordovician) of the Yangtze Block, China Zhi-Yi Zhou a,∗, Jan Bergströmb , Zhi-Qiang Zhou c , Wen-Wei Yuan a , Yun-Bai Zhang a a State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, China b Department of Palaeozoology, Swedish Museum of Natural History, P.O. Box 5007, S-104 05 Stockholm, Sweden c Xi’an Institute of Geology and Mineral Resources, 166 East Youyi Road, Xi’an 710054, China Received 20 August 2010; received in revised form 6 December 2010; accepted 9 December 2010 Available online 22 December 2010 Abstract Cluster analysis was conducted using Pearson’s coefficient based on the relative abundance data of 73 trilobite genera and subgenera in 72 collections, and fourteen Arenig (Floian–early Darriwilian) trilobite biofacies are recognized from the inner shelf to deep outer shelf of the Yangtze Block. The biofacies patterns and faunal dynamics across the eight successive time intervals suggest that the progressive changes in generic composition, diversity, and dominant components may have been affected by bathymetric gradients and lithofacies transition along the palaeoramp of the block, and by temporal constraints on the different trilobite clades. On the whole, the total faunal diversity reached its peak in the shallow outer shelf, from which it decreased both seawards and shorewards. The benthic