The Research On Depositional Environments And Lithofacies Palaeogeography In Kuqa Basin

The papers are guided by sedimentology, stratigraphy, facies palaeogeography, clastic rocks and other theories, combining with outcrop observing, core description of the scene, and analysis with stratigraphic correlation, isotope geochemistry and so on, to research depositional environments, lithofacies palaeogeography.Based on the outcrops and well logs, we described the Paleogene's stratum in Kuqa Basin into two parts. The stratum includes Kumugeliemu Group and Suweiyi Formation in east, and the western group with Talake Formation, Xiaokuzibai Formation and Awate Formation; the east-west dividing line is Kezilenuer groove. The Rock types in Paleogene include: terrigenous rocks, evaporites rocks and carbonate rocks. Terrigenous rocks mainly include conglomerate, pebbly sandstone, sandstone, siltstone and mudstone. Carbonate rocks including limestone and dolomite, less distribution. Evaporites rocks mainly include gypsum rock and salt rock, widely distributed, and with the great thickness.In early Paleogene, Kuqa Basin had many multiple regression transgression, is the period when the Kuqa Basin transformed from a marine influenced to a non-marine influenced basin. The seawater of Paleotethyan re-entered this area. As the basin subsidence, there is intermittent transgression from the direction of southwest in Tethys, and with a sizable area of the shallow sea and the gulf deposition. The basin's rock characterize is Carbonate rocks in Paleocene. In early and middle Eocene, there is larger set of salt, gypsum rock and fine clastic sediments. The late Eocene - Oligocene epoch water drop out from the basin. The scope of the deposition is expand, and gradually change to the continental clastic sedimentary rocks. Development of the fan delta, tidal flat, cream Salt Lake, a shallow lake facies models.Kuqa Basin generally on a subtropical climate, but there are different stages in Paleogene. Cuban maintained the hot drought climate since the late Jurassic. Early-medium Eocene, climate became more humid and warm, and sedimentary area of a greenish gray, gray and white-gray sandstone, gravel-like limestone, limestoneand gray green, purple-brown red sandstone and mudstone. This reflects the environment with humid and semi-arid alternately changing. In late Eocene-Oligocene, that is red coarse sediment. Reflect its environment is turn the weak oxidation and reduction environment into hot dry oxidation environment.