The Relationship between Tectonic Evolution and Uranium Ore Formation of Sandstone Type in Shawabuqi Area, Xinjiang

The Relationship between Tectonic Evolution and Uranium Ore Formation of Sandstone Type in Shawabuqi Area, Xinjiang
　　Due to characteristics of low degree of uranium geological research and sandstone type uranium mineralization, which controlled by tectonic in Shawabuqi area, this dissertation discuss structural characteristics and the relationship between tectonic and uranium mineralization, finally propose tectonic-metallogenetic model of sandstone type uranium deposit in Shawabuqi area, mainly by study on tectonic evolution, Mesozoic and Cenozoic regional tectonic background of northern Trim Basin, uplifting epochs of Tianshan, basic characteristics of uranium ore-formation and the age of uranium ore-formation.From the west to east, the northern peripheral earth’s surface of Tarim Basin contain Keping thrust belt, Wushi thrust belt, and Kuqa thrust belt, each has its own rare earth magnets orientation and structural characteristics. But the formation and evolution of these thrust belts are related with distribution of faults. All faults are divided into two group, one group has thrust characteristic and its orientation is east-west or nearly north-east, it controls south-north distribution of folds, as a result, alternate appearances of uplift and depression in northern periphery of Tarim Basin, the other has strike-slip characteristic and its orientation is north-west, it controls east-west structural pattern, as a result, western structural deformation characteristics are different form eastern. The two group faults systems were formed in the condition of south-east compressed tectonic stress, result of research indicates that Himalayan epoch tectonic stress field made great influence on northern periphery of Tarim Basin.Apatite fission tracks of the samples from Talike, Shawabuqi and Bashibulake in southern Tianshan area, were measured and analyzed. Using the measurement data of whole Tianshan area, four uplifting epochs, which are 135～145Ma(latest Jurassic); 75～40Ma(latest Cretaceous-latest Eocene); 25～10Ma(Miocene); 4.0Ma～0(latest Pliocene-now), were founded in southern Tianshan aera, and thermal uplifting history were simulated in these three areas, we calculate uplifting speed of each epoch from the simulated map, find that Shawabuqi area has highest uplifting speed of 889.7～991.4m/Ma.Shawabuqi area entered into the evolution stage of Neotectonic activity in late Pliocene. Vertical uplift is main structural pattern in this area, because of existence of basement thrust fault.
　　Therefore, the uranium deposit suffered from being uplifted, eroded and Epigenetic reworked by shallow water; on the other hand, the southern uplifting mountain of uranium deposit, which make the uranium bodies free of further erosion, is benefit http://www.chinamagnets.biz for conservation of uranium bodies.Northern periphery of Tarim Basin enter into evolution stage of rift basin in Jurassic, coal-bearing coarse clastic rocks formation, which is benefit for interlayer oxidation zone sandstone type uranium mineralization, were deposited in Shawabuqi area. Based on analysis of cycles and facies of sedimentation, the Tiemiersu formation are divided into two lithology sects, and four lithology sub-sects. Uranium mineralization formed in sand bodies of braid delta facies in upper sect of this formation. Steep shapes of ore bodies show plank type, layer type and lentoid type. The most part of uranium element are absorbed, and the coffinite is primary uranium mineral, there are little isomorphism uranium.High content of Toc and S were measured in bearing ore sand bodies, they have positive correlation. The contents variety of Fe element in the different stone show that the uranium bodies undergone eluviation, variety of Cd, Mo and Re elements on drill show the distribution characteristic of rare elements in model interlayer oxidation zone sandstone type uranium mineralization.Using the REE distribution patterns of the rocks and thermal history simulation of granite uplift in Shawabuqi area, we find that the early Permian lava clastic rocks not only provide sediment, but also provide uranium element for Jurassic series with lower Cambrian.bedded chert.Main uranium ore-formation age of 39.0Ma is measured by "U-Pb" Dating Method. We find that, Jurassic benefit series were tilted by the great fault of Tianshan frontier, Paleo-climate turned to be dry and hot from warm and wet, early Permian lava clastic rocks and lower Cambrian. http://www.chinamagnets.biz   bedded chert, which have high uranium content, had uplifted already, uranium ore-formation occurred in Eocene, by the influence of all above factors.At last, according to analysis of tectonic evolution of Tianshan and uranium ore-formation, the author propose the tectonic-uranium ore-formation model of Shawabuqi area.