Jiandingshan and Heiliangzi anticlines in the Qaidam Basin, northern Tibetan Plateau are investigated to depict the intracontinental deformation pattern. Based on remote sensing images and seismic profiles, the structural patterns and kinematic characteristics of the surface faults and underground structures of the Jiandingshan-Heiliangzi anticlines are interpreted and analyzed. Remote sensing images show that most surface faults of the Jiandingshan anticline change from NW-SE striking transpressional to N-S striking normal faults to the southeast, while most surface faults of the Heiliangzi anticline are NNE striking sinistral transtensional faults. Seismic profiles show that the Jiandingshan-Heiliangzi anticlines are composed of upper thrust detachment fault systems and lower basementinvolved positive flower structures. In addition, it is inferred that the decoupling between shallow and deep structures of the Jiandingshan and Heiliangzi anticlines is influenced by the gypsum-salt layers in Lulehe Formation. Considering the fault map, kinematic features, and along-strike variations of the surface faults and basement-involved faults, the Jiandingshan-Heiliangzi anticlines are treated as dextral transpressional structures. It is inferred that the interior of the Qaidam Basin has experienced differential eastward extrusion during its continuous shortening induced by the convergence of the Indian and Eurasian continents, leading to a series of transpressional anticlines in the basin.

Qaidam Basin, remote sensing and image interpretation, seismic profile, dextral transpressional structure, strike-slip movement, salt structure

选取青藏高原北部柴达木盆地内尖顶山和黑梁子背斜作为研究对象, 基于遥感影像和地震剖面, 解释并分析该背斜构造带的地表次级断裂以及地下构造的变形样式与运动特征。遥感影像显示, 尖顶山背斜的大部分地表次级断裂从北西走向的压扭断裂向东南方向过渡为南北走向的正断层, 而黑梁子背斜的地表次级断裂为北北东走向的左行张扭断层。地震剖面显示, 尖顶山和黑梁子背斜由上部逆冲滑脱断裂和下部基底正花状构造组成, 深层与浅层的变形解耦主要受新生界下部路乐河组的膏盐层影响。结合地表次级断裂和地下基底断裂的平面展布样式、运动特征以及沿走向的变化, 认为尖顶山和黑梁子背斜为右行压扭构造, 推测在印度板块与欧亚大陆汇聚的背景下, 柴达木盆地内部在持续缩短变形的过程中发生向东的差异性挤出, 从而形成一系列压扭性质的背斜构造。