摘要
托克逊县干沟一带出露有早古生代蛇绿混杂岩和志留纪前陆盆地沉积。其时空配置表明,新疆中天山北缘早古生代大洋在奥陶纪曾发生大规模的向北消减,志留纪因前陆和岛弧的碰撞而形成前陆盆地,充填序列揭示了碰撞造山作用过程。对碎屑岩中陆源锆石同位素测年表明其最新物源的年龄不小于461Ma。而侵入该前陆盆地碎屑岩的花岗闪长岩中火成锆石的同位素测年数据为(386.1±4.1)Ma,限定了前陆盆地的上限。前陆盆地的终结标志着碰撞造山作用的结束。
Early Paleozoic ophiolitic melange and sedimentary sequence of Silurian foreland basin are exposed at Gangou of Tokxun, Xinjiang. Their time-space distribution shows a large-scale northward subduction of Early Paleozoic ocean along the northern margin of the Middle Tianshan mountains. Foreland basin formed by collision between foreland and island arc during the Silurian. Filling sequences of the foreland basin indicate a collisional erogenic process. Isotopic dating for terrigenous zircon from clastic rocks in the foreland basin shows that the latest material source of the foreland basin is younger than 461 Ma. But isotopic dating for igneous zircon from granodiorite intruding the clastic rocks of the foreland basin gives an age of 386.1±4.1Ma., which defines the upper limit of the foreland basin. The end of the sedimentation of the foreland basin indicates completion of the collisional orogeny.
出处
《新疆地质》
CAS
CSCD
2002年第4期326-330,共5页
Xinjiang Geology
基金
中国地质调查局国土资源大调查项目(0499210196)资助
关键词
新疆
天山
干沟
志留纪
蛇绿混杂岩
前陆盆地
Xinjiang
northern margin of the Tianshan mountains
Gangou
Silurian
ophiolitic m61ange
foreland basin
