阿尔金-祁连山接合部重力场特征及其构造变形
Probe into Structural Deoformation in the Joint Part between Altun and Qilian Mountains Based on Gravitational Characteristcs
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摘要: 根据阿尔金、祁连山接合部新近完成的6幅1:20万区域重力调查资料,在区内划分出4处不同重力场特征和构造变形。北东东向密集重力梯级带反映出阿尔金断裂带为左行走滑兼有逆冲,阿尔金左行走滑断裂带夹持重力高和重力低,反映了其为隆起与坳陷组成的断裂构造带。扭、压、张3种构造变形应力场效应共存,以扭应力为主,在不同地段兼有压、张性。祁连山造山带西段呈北西西向弧形重力高、重力低相间分布,反映了挤压推覆、逆冲叠置、盆山耦合的构造格局,反映出祁连造山带内挤压型盆山偶合的对应关系。据估算,香毛山、大雪山两重力梯级带侏罗纪至今,最小位移量为分别为140km、120km。敦煌盆地、苏海盆地重力场疏缓开阔,具有变形相对较弱的稳定地块特征。
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关键词:
- 重力场特征 /
- 阿尔金-祁连山接合部 /
- 构造变形 /
- 左行走滑断裂 /
- 挤压逆冲推覆构造
Abstract: In the joint part between Altun and Qilian mountains,four kinds of gravitational fields and its related structural deformation were marked out based on 6 newly completed 1:200000 grvitational map The dense NEE gravitational step zone implies the Altun fault zone,which is characterized by left strike-slip with an obduction feature,is a fault zone composed of swell and sagreflected by higher gravitation and lower gravitation together with which shear,compression and tensional stress fields coexist but principally shows shear;in addition,compression and tension also can be seenhere and there.In the west section of Qilian orogenic belt,the higher gravitation as well as lower gravitation stret chin alternant arcs show it selfa tectonic pattern of nappe-extrusion,obduction-superimposition,and basin-mountain coupling,and are related to basin-mountain coupling.It is estimated that the minimum displacements of Xiangm aoshan and Daxueshan are respectively 140km and 120km.The gentle and widegravitational fields of Dunhuang basin and Suhai basin imply their weaker deformations. -
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