Abstract
Cenozoic intracontinental tectonics of central Asia are dominated by reactivation of older structures and initiation of new structures in response to the far-field effects of collision between India and Asia. Similarly, the Mesozoic was a time of tectonic amalgamation along the southern margin of Asia, and geologic evidence suggests corresponding intracontinental deformation in localities as diverse as the Tarim basin and southern Mongolia. However, the extent to which Mesozoic intracontinental deformation was comparable in style and distribution to that of the Cenozoic is not well understood. Newly characterized Mesozoic rocks in the northeast Qaidam basin provide evidence for rejuvenation of the Qilian Shan in response to accretionary tectonics on the southern margin of Asia. Jurassic and Cretaceous strata were deposited in an entirely nonmarine intracontinental foreland basin system that developed southwest of, and was subsequently involved in, the south Qilian Shan fold and thrust belt. Paleocurrent indicator measurements and provenance analysis indicate derivation of siliciclastic detritus from the Qilian Shan. Facies analysis, geohistory analysis, and structural relationships provide evidence that Jurassic and Cretaceous rocks currently exposed along the northeast margin of Qaidam were deposited in proximal foreland basin and thrust wedge-top (piggyback basin) positions. This evidence extends an already documented series of linked Mesozoic foreland basins from the China-Kazakstan border into central China along the Tian Shan, Bei Shan, and Qilian Shan, and suggests that Mesozoic intracontinental deformation may have more closely resembled current structural patterns than previously recognized. Sedimentary evidence for a Cretaceous paleorain shadow south of the Qilian Shan, with humid lacustrine facies north of the range, and semiarid fluvial and overbank facies south of the range, provides evidence for sustained uplift of the mountain belt into the late Mesozoic.