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Deye 1 Well (DY 1 Well) completed in 2013 is the first drilling well that reached the early Paleoproterozoic crystalline basement in the northeastern Qaidam basin. This paper analyzes the drilling core samples from DY 1 Well. Petrology and geochemistry indicate that the drilling core samples belong to high-Na trondhjemite. LA-ICP-MS zircon dating for the drilling core samples yields a weighted mean 207 Pb/ 206 Pb age of 2383.1 ± 6.3 Ma, which is consistent with its upper interception age. Meanwhile, the geochemical characteristics and the deformation degree of high-Na trondhjemite are significantly different from its adjacent gneisses and the Mohe quartz-dioritic rocks in the Quanji Massif. It implies that the basement of the Qaidam basin under thick Cenozoic sediments may be different from its surrounding outcrops, and differential crustal attributes lead to intensely differential Cenozoic vertical motions between basins and mountains. Meanwhile, the widespread familiarity between the Qaidam and Tarim basins implies that the basement of the Qaidam basin may be a part of the Tarim Block during the Precambrian. [ABSTRACT FROM AUTHOR]

Situated along the western termination of the Eastern Kunlun Mountains, the Qimen Tagh Range represents a key area to understand the Cenozoic basin-range interactions between the northeastern Tibetan Plateau and the Qaidam Basin. Within that region, several huge bow-like fault systems such as the Kunbei and Qimen Tagh fault systems accommodate the transpressive deformation but their kinematic evolution is still highly debated. Newly acquired seismic profiles and isopach maps of the Late Eocene sediments strongly suggest that the Kunbei fault system (consisting of the Kunbei, Arlar and Hongliuquan faults) in the southwestern Qadaim Basin was initially a left-lateral strike-slip fault system rather than a thrusting system. Growth strata indicate an Early Miocene onset age for this strike-slip deformation. However, earthquake focal mechanisms show that the present-day tectonic pattern of this fault system is dominated by NE–SW transpression. As for the Qimen Tagh fault system, numerous linear geomorphic features and fault scarps indicate that it was again a strike-slip fault system. Deformed sediments within the Adatan Valley prove that strike-slip motion prevailed during the Pleistocene, yet the present day deformation is marked by NE–SW transpression. Collectively, the Kunbei and Qimen Tagh fault systems were initially left-lateral strike-slip fault systems that formed during Early Miocene and Pleistocene respectively. Colligating with these southward younging left-lateral strike-slip faulting ages and the fact that these convex-northward structures converge to the center segment of active Kunlun fault in the east, we thus considered the Kunbei and Qimen Tagh fault systems as former western segments of the Kunlun fault once located further south in the present-day location of that fault. These faults gradually migrated northward since the Early Miocene while their kinematics changed from left-lateral strike-slip motion to NE–SW transpression. [ABSTRACT FROM AUTHOR]