Abstract:

The Indosinian structural features in the adjacent regions of Anhui (Wan)，Zhejiang (Zhe) and Jiangxi (Gan) in eastern Jiangnan Orogen were largely ignored due to the lack of directly structural age data. Based on regional geological information at scale of 1∶50,000 and field observation on southern Anhui，this study found and concluded some new evidences of Indosinian tectonic events in southern Anhui. Three-period distinct structural features have been identified in Liutang area of Xiuning in Anhui，and among which the angular unconformity between the Upper Triassic and the Lower Triassic belongs to the Indosinian event. The NE-trending fault developed in Lantian relict synclinal basin was formed during Indosinian，which experienced a process from slipping to collapse. The age of Triassic Dongkengkou quartz porphyry is about 245.2 Ma, implying that the Early Indosinian event had caused a partial extension. In addition，the age of sericites in Sanyangfault is (230.5±2.3) Ma(⁴⁰Ar-³⁹Ar)，indicating that the Jinningian fault had been affected by Indosinian movement. Upon these findings，this study discussed the evolution process of Indosinian movement，and provided important implications for understanding the Indosinian tectonic events of southern Anhui，even those of Wan-Zhe-Gan adjacent areas.

Key words: Indosinian, fault, southern Anhui, eastern Jiangnan Orogenic Belt