Permian transgression-regression sequences and sea-level changes of South China

As one of the low-lying microcontinents in the eastern Palaeotethyan ocean, South China develops continuous Permian marine sequences, from which three supersequences reflecting the second-order cycles and nine subordinate sequences corresponding to the third-order cycles have been recognised. These sequences correspond approximately to the Maping Formation, the Liangshan Formation, the Chihsia Formation, the Maokou Formation, the Wuchiaping Formation and the Changhsing Formation, respectively. Each sequence is bounded by regional unconformities produced by the interplay of eustatic sea-level drops and local tectonic uplift. Sequence stratigraphical analysis of the three supersequences, named respectively the Maping, Yanghsing and Loping Supersequences, reveals the following: the sea-level went down slowly during the Chuanshanian, then went through a period of slow-rising followed by rapid-falling during the Chihsian to Maokouan. During the Lopingian, while the other regions of the world were experiencing a great regression, the sea-level of South China eperic sea rose slowly from the Wuchiapingian to the Changhsingian and then rose rapidly at the end of the Permian. Because South China was a low-lying microcontinent and lacked a massive source of terrigenous influx during the Permian, we believe that the eustatic curve derived from this microcontinent is probably closer to the Permian global eustatic profile. This may also account for the significant differences between the Permian sea-level change curve proposed in this paper from that of Ross and Ross (1987, 1988, 1994) based on the Russian Platform and North America.