Geometric and Kinematic Analysis of the Jiandingshan-Heiliangzi Anticlines,NW Qaidam Basin
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 basement-involved 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.
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