Disintegration of the Xiangshan Group and Its Age Determination
The age and stratigraphic sequence of the Xiangshan Group in the Ningxia region have been disputed. The debata centers on the stratigraphic structure and sedimentary tectonic environment of the Xiangshan Group. According to new field observation and analysis of previously published data, it is proposed that the Xiangshan Group does not occur as a monoclinal plunge as thought before. Instead, each stratigraphic subunit in the Xiangshan Group has different characteristics. Combined with regional stratigraphic analysis, the new data provide a stratigraphic framework and infilling model of the Helanshan Rift Basin.