Study On The Late Triassic-Early Jurassic Marine Bivalves In Southern China And Their Provincialism

Southern China was located in the overlap region of the Panboreal and the Tethys Superrealm, yielding mixed marine bivalve faunas during the Late Triassic-Early Jurassic. A total of 34 species, belonging to 22 genera bivalves from the Upper Triassic-Lower Jurassic of southern China are described in this paper. These bivalves belong to six assemblages. They in ascending order are:the Canian Guangdongella -Bakevellia, Carnian-early Norian Palaeopharus-Tosapecten or Bakevelloides -Jiangxiella, early-middle Norian Oxytoma-Asoella,? Late Norian-Rhaetian Unionites ? emeiensis-Yunnanophorus, Hettangian Hiatella minuta-H. curta, and the ? Hettangian, Sinemurian-Toarcian Parainoceramus-Teinonuculana assemblages. The correlation of the Upper Triassic-Lower Jurassic among southern China and its adjacent regions, including Japan, Indochina, and Yunnan province of China, are discussed.The Late Triassic-Early Jurassic marine bivalves from South China and adjacent areas, including the tectonic units of Qamdu, Qiangtang, Lhasa, Himalaya, Simao, and Indochina, representing three relevant and representative biogeographic regions, i.e. the western Tethys, Japan, and New Zealand, are rigorously analysed at the generic level. A dynamic palaeobiogeographic pattern is presented applying cluster analysis, and analysis of taxonomic diversity gradients and endemism to three time intervals, i.e. the Carnian, the Norian-Rhaetian, and the Early Jurassic. Three provinces, i.e. the North-Eastern Tethyan (NE), South-Eastern Tethyan (SE), and the Himalayan (HI) province, are recognised during the Carnian in the study area. The HI joined the SE and a new province, the Arctic-Pacific (AP) formed in the Norian-Rhaetian. Up to the Early Jurassic, the AP disappeared. The mixed Late Triassic-Early Jurassic bivalve faunas in southern China are ascribed to the having been existing ancient ocean currents.