西藏高原古地磁及大陆漂移

关于欧亚板块与印度洋扳块的交接地带,根据我们在青藏科学考察中,采集了雅鲁藏布江两侧大量的定向标本:帕里的上新世沉积岩,林周和比如的晚白垩世到古新世的红砂岩,札木的花岗闪长岩,定日白垩纪灰岩,晚侏罗纪的拉萨灰岩和江孜扳岩,土隆三迭纪砂岩,进行了古地磁研究,其结果表明:印度河上游-雅鲁藏布江的北侧属于欧亚板块,南侧属于印度洋板块。 根据古纬度的变化表明:印度洋板块向北漂移,自白垩纪以来,其年平均速率不超过5.5厘米。

PALAEOMAGNETIC OBSERVATION IN XIZANG AND CONTINENTAL DRIFT

Up to now opinions differ on the location of the contact zone between the Eurasian plate and the Indian plate. Some scientists assert that it is at the southern foot of the Himalaya mountain and others assert that it is at the zone of the upper Indus River to the Yarlung Zangbo River valley. Someone even suggests that it is at Pang-kog Co. To resolve this question, we have collected a large number of oriented rock samples from the both sides of Yarlung Zangbo River during the scientific expedition in Qinghai-Xizang Plateau. Palaeomagnetic studies were made on the Pliocene sediments in Pagri; Paleocene and Late Cretaceous red sandstone in Lhiinzhub and Biru, Grano-diorite in Zhamo （K-Ar age 76.3M.Y）, Cretaceous limestone in Tingri; Late Jurassic limestone in Lhasa; Jurassic slate in Gyangz（?）; Triassic sandstone in Tulung.The results indicate that the northern side of the upper Indus River and the Yarlung Zangbo River belong to the Eurasian plate, while the southern side belongs to the Indian plate.According to the palaeolatitude variations, the Indian plate drifted towards the north. Since Cretaceous it has been moving with an averege speed of less than 5.5 cm/yr.