青海省天峻县木里煤田聚乎更矿区构造轮廓和地层格架

Structure and stratigraphy of the Juhugeng coal district at Muli,Tianjun County,Qinghai Province

木里煤田聚乎更矿区是全球陆上中纬度、高海拔冻土带天然气水合物的发现地,也是当前青藏高原地质研究的热点地区之一。依据近年来的煤炭地质勘查资料,对聚乎更矿区的构造轮廓、含煤地层、沉积相和聚煤作用进行深入分析,认为聚乎更矿区位于祁连坳褶带西段,受大通山北缘和托莱山南缘对冲断裂组的制约,构造线总体方向为北西-南东向,构造轮廓表现为南北2个向斜,其中北向斜的煤炭赋存条件优于南向斜。聚乎更矿区含煤地层为中侏罗统木里组和江仓组,主要可采煤层赋存于木里组上段,聚煤作用主要发生于木里组沉积期的辫状河淤浅之后发育的泥炭沼泽和湖泊、水下三角洲淤浅而发育的泥炭沼泽。

Since gas hydrates were found in the permafrost of the Juhugeng ore district （JHG） in the Mull coalfield of Qinghai Province, the JHG has become one of the hot spot areas in the Tibetan Plateau. This paper has investigated the geological structure, coal-bearing stratigraphy and depositional facies of the Jurassic coal measures in the JHG area. The JHG area is structurally located in the western section of the Qilian depression-folding zone. Controlled by the thrusting faults along the northern margin of the Datong- shan and the southern margin of the Tuolaishan, the structures in the JHG area extend from northwest to southeast, and find expression in two synchnes, i.e., northern syncline and southern syncline. Coal resources are preferentially preserved in the northern syncline. Coals were formed in the Middle Jurassic Muli Formation and fiangcang Formation, and the regionally minable coals are preserved in the Upper Member of the Muli Formation. Coal accumulations mainly occur in the swamp environment developed in the abandoned braided river system and in the swamp environment developed by shallowing of the lacustrine and subaqueous delta.