Tectonic Evolution and Upper Triassic Distribution in the Western Henan

Three eastwest,northwest and northeast trending Fault groups developed in the Western Henan as a result of structural movements during Indo - Chinese and early to middle Yanshan, late Yanshan, and Himalayan epochs respectively.They control the basin's boundary and local structures, and also control, to a certain degree, the denudation of the Upper Triassic. Xiashi - Chenzhaigou and Xiashi -shimen faults have relative large influence on the preservation of the Upper Triassic, which is well preserved in the lower blocks and is severely eroded in the upper thrust blocks. The Upper Triassic mainly distributs over the Pengpo Seg in the Yichuan Basin,and over the Louyang Seg and the Shilingci subseg of the Yiyang Seg in the Louyang Basin, while it is almost completely eroded in other areas.