新疆及周边古地磁研究与构造演化

新疆古地磁研究始于1979年,20年来通过对塔里木、准噶尔、昆仑山等地区的古地磁研究,获得了古生代—新生代塔里木板块、准噶尔板块和青藏板块古地磁极移曲线和古纬度资料。震旦纪以前塔里木板块尚未形成,晚震旦世在赤道附近各地块才联合成塔里木板块的主体部分。后经历了两次快速北移,一次快速南移。准噶尔板块早古生代为一个独立的微板块,在晚古生代与哈萨克斯坦板块联合成一体,组成了哈萨克斯坦-准噶尔板块;塔里木板块震旦纪时还属冈瓦纳大陆的一个组成部分,早古生代逐渐脱离了冈瓦纳大陆,快速向北漂移,晚古生代早期与准噶尔板块首次在东部碰撞,成为劳亚大陆南缘的一个增生体。将介于劳亚大陆和冈瓦纳大陆之间的古陆体,称之谓华夏古陆群。晚古生代末—中生代早期,华夏古陆群先后增生到劳亚大陆南缘;早古生代早期古特提斯洋尚未形成,诸地块处于冈瓦纳大陆范围内,位于南半球的赤道附近。在中-晚志留世,这些地(板)块才快速向北漂移,由于洋扩张,形成了古特提斯洋,构成了三大陆块群夹两个大洋的古地理格局;二叠纪是特提斯构造演化关键时期,晚侏罗-早白垩世昆仑地块与柴达木地块和塔里木地块发生碰撞,联合成一体。早侏罗世早期柴达木地块等与塔里木地块发生碰撞联合,造成了古特提斯洋消亡。早侏罗世中期,开

PALEOMAGNETIC STUDY AND TECTONIC EVOLUTION OF XINJIANG AND ITS NEIGHBORING REGIONS

Based on the paleomagnetic study of Tarim,Junggar and Kunlun Mountains region,the paleomagnetic polar wandering path amd paleolatitude data of Tarim,Junggar and Qinghai Tibet plates from Paleozoic to Cenozoic have been obtained.The Tarim plate was not formed until Sinian,since it was preliminary formed in Late Sinian,it has undergone twice rapid northward shifting and once rapid southward shifting.The Junggar plate remained a single microplate in Early Paleozoic,it combined with Kazakhistan plate in Late Paleozoic and formed the Kazakhistan Junggar plate.Tarim plate still was one part of Gondwanaland before Sinian,it graduately separated from Gondwana in Early Paleozoic and shifted northward rapidly,It first collided with Junggar plate in the early stage of Late Paleozoic and became a accretionary wedge of Southern Laurasia.The blocks located between Laurasia and Gondwana were called Cathaysia group.From the end of Late Paleozoic to early of Mesozoic,the blocks combined with Laurasia at the south margin.The Paleo Tethys was not formed until the early stage of Early Paleozoic,the blocks distributed in the range of Gondwanaland and located at the equator of south hemispher.In Middle late Silurian,these blocks began to shift northward rapidly,the ocean was enlarged and formed the Paleo Tethys.Which formed a framwork of three lands with two oceans between.Permian was an important stage for the evolution of Tethys tectonics,from Late Jurassic to Early Cretaceous,the Kunlun terrane,Chaidamu block and Tarim block collided and formed one block,the collision between Tarim and Chaidamu at the early stage of Early Jurassic made the Paleo Tethys extinct.The new Tethys was created in the middle stage of Early Jurassic.In the middle stage of Late Cretaceous,Himalaya Indian block moved northward quickly,which narrowed the new Tethys and wiped it out at the late stage of Tertiary,the evolutional history of Tethys tectonic domain was ended.The paleogeography of Paleozoic,Mesozoic and Cenozoic of China can be reconstructed based on the paleomagnetic data.At the early stage of Late Paleozoic,the Paleo Asian Ocean,paleo Atlantic and paleo Tethys were formed by sea floor spreading,the main plates were also formed at the same time.Since China is located in one of the main convergent regions of plates,it made the tectonics of China very complex.The present researchers have realized that the plates can not be divided by one simple line.There is a very complex tectonics between the plates.The sutures of plales have the chronzone feature.