东昆仑造山带拆沉作用的数值模拟  

Numerical simulation of delamination in the east Kunlun orogenic belt

作　　者：詹华明[1] 罗照华[2] 林舸[3] 

机构地区：[1]天津华北地质勘查局地质研究所,天津100370 [2]中国地质大学(北京),北京100083 [3]中国科学院边缘海地质重点实验室,广州地球化学研究所,广州510640

出　　处：《地质找矿论丛》2016年第1期77-86,共10页Contributions to Geology and Mineral Resources Research

基　　金：国家重点基础研究发展规划项目(编号:2002CB412601);中国科学院边缘海地质重点实验室项目(编号:MSGLCAS0405-8)联合资助

摘　　要：在构建东昆仑造山带晚古生代—早中生代地质-物理模型的基础上,利用FLAC软件模拟了幔源岩浆底侵后形成的榴辉岩岩石圈拆沉作用及动力学机制,结果表明,东昆仑造山带在幔源岩浆底侵后确实发生过岩石圈拆沉作用,昆北、昆中、昆南地区的拆沉量差异较大,并形成以橄榄岩、榴辉岩和中酸性麻粒岩为源区的岩浆活动;柴达木地区未发生拆沉作用,而是下沉,同时在高密度层(榴辉岩)的顶部存在较多的断裂。文章探讨了拆沉作用与大规模岩浆活动、盆地形成、C型埃达克岩的关系,认为镁铁质岩石的特殊性质是导致拆沉作用发生的直接动力,岩石圈拆沉之后的深部约束受拆沉的量及范围控制;论证了东昆仑造山带的岩石圈拆沉作用触发了柴达木盆地的形成,并形成一系列热液矿床。Based on the Late Paleozoic-early Mesozoic Geological-physical model building of the East Kunlun orogenic belt software FLAC was used to simulate the delamination of eclogite lithosphere formed after underlay of mantle derived magma and the dynamic mechanism.The results show that the lithospheric delamination did happen after the mantle derived magma underplating with varied delamination in the north,central and south of Kunlun areas and magmatic activities in the peridotite,eclogite and intermediate-acidic granulite areas.No delamination occurs in Qaidam region,only sink,and many fractures at top of the high density layer（eclogite）.This paper discussed the relation of delamination to large scale magmatic activities and formation of basin and the C type adakite.We consider that the special nature of the mafic rocks is the direct force leading to the delamination.The deep constraint of the lithosphere is controlled by the amount and range of the delamination.It is proved that the lithosphere delamination of the east Kunlun orogenic belt triggered the formation of the Qaidam Basin and a series of hydrothermal deposits.

关 键 词：东昆仑造山带 拆沉作用 数值模拟 岩浆活动 

分 类 号：P542.5[天文地球—构造地质学]