The Late Permian to Late Triassic Great Bank of Guizhou: An isolated carbonate platform in the Nanpanjiang Basin of Guizhou Province, China

Abstract

The Late Permian to Late Triassic Great Bank of Guizhou (GBG) in southwest China is one of the few isolated carbonate platforms in the world that exposes an essentially complete record of initiation, development, and drowning across multiple platform-to-basin transects. The platform is exceptionally exposed in cross section at the surface by a faulted syncline that rotated strata to a dip angle of approximately 65°. Platform development spanned the end-Permian extinction and Triassic recovery that marks the transition from Paleozoic to Mesozoic styles of carbonate sediment production, providing a rare opportunity to assess the impact of global changes in carbonate factory types at a single locality. In addition, regional basin controls such as differential siliciclastic sediment input and varied antecedent topography provided mechanisms for lateral variability in platform morphology that can be investigated along exposures in several geographic sectors. Consequently, the GBG preserves a record of temporal and spatial variability in platform architecture that offers an unparalleled opportunity to investigate the controls on isolated carbonate platform morphology. A better understanding of these mechanisms is critical for improving predictive geologic models in exploration and field-development settings. The GBG also serves as a key outcrop analog for Early Triassic oolite reservoirs in the Middle East and China, the steep microbial-boundstone slopes of Carboniferous platforms in Kazakhstan, and the Permian platforms of Texas and New Mexico.