Microbialites in the Permian-Triassic boundary interval in central China : Structure, age and distribution

摘要: A carbonate crust, with a principally digitate structure, caps latest Permian reef complexes in east Sichuan, China. The crust contains the conodontHindeodus parvus, confirming its age as earliest Triassic; it therefore closely postdates end-Permian mass extinction, and is related to associated palaeoenvironmental change. Although branches have lobate margins, internal structures of radial fabrics different specimens, an organic origin cannot be confirmed, because fabric largely recrystallised. Therefore we apply term ?microbialite reflect uncertainty nature. co-eval (within theparvus Zone) confirmed microbial biostromes mounds Guizhou Province, south Sichuan. sum evidence, assembled by workers several sites worldwide, indicates sea-level rise occurred boundary interval, this corroborated facies Sichuan crust. Abrupt appearance disappearance formed precipitated carbonates, represents short-lived unusual post-extinction marine conditions which were switched abruptly on, then off. Microbial deposits overlying P/T other locations Tethys Ocean (Iran Japan) support view that oceanic had at least regional distribution. Because terminates, not succeeded fossil-rich deposits, application disaster biota concept inappropriate; environmentally-driven control on precipitation better supported whether or was biotically-mediated.