Stratigraphic Sequence of the Early-Middle Permian Reef in Western East Kunlun Mountains
东昆仑西段早—中二叠世生物礁相地层层序

Based on data of reefs and foraminifera fossils, the authors have reconstructed a stratigraphic sequence of the Early-Middle Permian reefs in the western section of the East Kunlun. The sequence consists of 5 lithologic formations. The Aqikekule formation is composed of carbonates and knoll reef buildups on clastic continental margin of the plateau. Fusulinids in the formation, which can make up the Chalaroschwagerina-Pseudofusulina parafecunda assemblage zone, prove that the age of the unit is middle-late Early Permian. The Chadertaq Formation consists mainly of block bedded framestones of the well reef and contains the Misellina claudiae fusulinid fauna, corresponding to Middle Permian Qixia period. The Qingshishan Formation and the Biyunshan Formation were formed under different conditions, but were synchronous in the early-middle Maokouan period of Middle Permian. The former was comprised mainly of reef-core framestone and reef breccia in great thickness. The latter resulted from the deposition of dark and organic-rich material in the back reef and the lagoon. Both contain the Polydiexodina-Neoschwagerina assemblage zone, belonging separately to the Cancellina liuzhiensis subzone, the Neoschwagerina simplex subzone and the Afghanella schencki subzone. The Karva Formation includes flyschoid sandstone and slate intercalated with mudmound limestone and yields fusulinids of the Afghanella schenck subzone. This formation is comparable with the mid-upper part of the Maokouan.