古地磁与酒西盆地南缘推覆体

酒西盆地南缘晚古生代以来发育的典型冲断—褶皱推覆体隶属于北祁连构造带,自泥盆纪开始,它就拚接于华北板块边缘,成为其一部分,它所经历的构造变迁史是与华北板块紧密相连的,但与塔里木板块却是在二叠纪以后才联合到一起,联合部位在阿尔金断裂带。在伴随华北板块主体一同北向“漂移”的运动中,经历了3次较强烈运动阶段:(1)泥盆纪～石炭纪期间;(2)二叠纪～三叠纪期间;(3)第三纪～第四纪。并有过两个运动和缓时期:石炭纪～二叠纪期间和三叠纪～白垩纪。 推覆体多期推覆作用的发生对酒西盆地基底形态、范围、沉积物类型、有机质演化条件等均具有明显控制作用,进而给油气赋存亦带来极大影响。

PALEOMAGNETISM AND THE SOUTH NAPPE OF JIUXI BASIN GANSU

The typical thrust-fold nappe,occured by the south boundary of Jiuxi Basin since the late Palaeozoic , belongs to the North Qilian Structural Belt. Based on the paleomagnetic researchs and the comparisons with the paleomagnetic data from North China,Ordos and Tarim regions,it is shown that the thrust-fold nappe connected with the southwest margine of North China Plate and became a part of the plate about the beginning of the Devonian Period. The tectonic development of the thrust-fold nappe is close contacted with North China Plate,and it is also shown that the nappe had connected with Tarim Plate a-long Altun Deep Fracture from the end of Permian Period. Further studied results revealed that the thrust-fold nappe had undergone three violent movements during its"drifting" to north with North China Plate: (l)The Denonian-Carboniferous Period; (2)The Permian-Triassic Period; (3)The Tertiary-Quaternary Period. And it had had two stable periods The Carboniferous-Permian Period and The Triassic-Cretaceous Period. Many times napping of the thrust-fold nappe has been deeply controlling the basement shape and range of the Basin, the type of deposits and the condition for the evolution of organic materials in Jiuxi Basin,and it influences the hosting of oil and gas in Jiuxi Basin and the nappe.