Permian of West Yunnan, Southwest China: a biostratigraphic synthesis

Recent progress in the study of Permian stratigraphy of western Yunnan, southwest China, is reviewed with particular references to the Tengchong and Baoshan blocks and the Changning-Menglian Belt. Where confusion or controversy exists in stratigraphical nomenclature and/or dating, we attempt to clarify the situation based on our recent field observations and newly obtained research results. The Permian within the Changning-Menglian Belt embraces different stratigraphic successions, suggesting different tectonic settings, ranging from passive margin and active margin, to oceanic basin and seamounts. Permo-Carboniferous faunas in the carbonate sequences of the Changning-Menglian Belt are of typical Cathaysian affinity, as demonstrated by abundant fusulinaceans and compound rugose corals. The Permian stratigraphy and faunas of the Tenchong and Baoshan blocks are markedly different from those of the Changning-Menglian Belt. The Baoshan Block lacks Upper Carboniferous deposits, and its subsequent Lower Permian sequence consists predominantly of siliciclastic strata yielding cool-water faunas and possibly glaciogene diamictites, overlain by thick basaltic lava and volcaniclastics of probably rift origin. The upper part of the Permian in the Baoshan Block is characterized by carbonates containing mixed Cathaysian and Gondwanan faunas. The Tengchong Block has a similar evolutionary history to the Baoshan Block, but completely lacks volcanic rocks. (C) 2002 Elsevier Science Ltd. All rights reserved.