Onset of the Kwangsian Orogeny as evidenced by biofacies and lithofacies.

The onset timing of the Kwangsian Orogeny might differ among localities across South China. Refined stratigraphic works at different localities are necessary to reveal the details of this likely distinction. Recently, we recollected some graptolite specimens from the Ordovician Shixing and Longtouzhai formations (corresponding to the Longxi Formation of southern Jiangxi Province) at many localities in Guangdong Province. The palaeontological and biostratigraphical studies of these graptolite faunas indicate that the facies change from graptolitic shale to nearshore shallow-water, coarse clastics in Guangdong is slightly earlier than that in southern Jiangxi. This timing difference may imply a northward progression of the Kwangsian Orogeny. Based on the biostratigraphy and palaeontology of the Ordovician in the Zhujiang Basin (western part) and Chiangnan Slope Belt (including western Fujian, eastern Guangdong, northern Guangxi, northern Hunan, northeastern Jiangxi, southern Anhui, and western Zhejiang), the Sandbian to late Katian distribution and replacement of biofacies and lithofacies in the two regions are proposed and discussed, which display distinct features at different stages of the Kwangsian Orogeny. [ABSTRACT FROM AUTHOR]