SEISMOLOGY AND GEOLOGY ›› 1980, Vol. 2 ›› Issue (3): 1-9.

• Brief Report •     Next Articles

A DISCUSSION ON THE EXOTIC BLOCK ON NORTHERN SLOPE OF THE HIMALAYAS AND THEIR ORIGIN

Zheng Xilan   

  1. Institute of Geology, Aoademia Sinica
  • Received:1979-11-30 Online:1980-09-03 Published:2009-11-25

喜马拉雅山北坡的外来岩块及其成因的讨论

郑锡澜   

  1. 中国科学院地质研究所

Abstract: The exotic blocks on northern slope of the Himalayas described in present paper are the relics of rock blocks transported in a long distance in the process of subduction and collision. Genetically, they are distinguished from both klippe and nappe as well as from melanges and olistostromes because they are not the result of mixing with allochthonous rocks. The characteristics of exotic blocks on northern slope of the Himalayas are presented as follows:1. They distribute on the southern side of Yarlun-Zangbo Jiang suture, in a narrow longitudinal belt on the northern border of the Indian plate.2. These blocks are composed mainly of Permian brittle limestones.3. Their gentle occurrence and the overturning of drag folds to wards the south indicate that these exotic blocks were transported from the north.4. The source of these exotic blocks is quite different because, faunistically, they reflect different sedimentary environments. Basing on the characters of faunal assemblage and lithologic correlation, the origin of these exotic blocks may be distinguished into three types: the subduction, the obduction and the compression. They are all formed by the northward subduction of the Indian plate down the Eurasian plate and the collision between them.

摘要: 本文所描述的外来岩块是指在板块俯冲、碰撞的作用下,经过远距离的搬运残留下来的岩石块体。喜马拉雅山北坡外来岩块的主要特点是:多数由二叠纪厚层石灰岩组成,出露于雅鲁藏布缝合线附近和由北往南的运动性质。根据岩性、古生物的特征,它的成因可分为三种类型:俯冲型、仰冲型和挤压型。它们是在印度板块向北移动同欧亚板块俯冲、碰撞过程中,产生下部(印度板块)向北,上部(欧亚板块)往南的一对水平空间力偶的作用而形成的。