Earth Science Frontiers ›› 2023, Vol. 30 ›› Issue (3): 262-281.DOI: 10.13745/j.esf.sf.2022.12.20

• Special Section on The India-Eurasia Collision and Its Long-Range Effect (Part 7) • Previous Articles     Next Articles

Tectonic evolution and Cenozoic deformation history of the Qilian orogen

WU Chen1(), CHEN Xuanhua2, DING Lin1   

  1. 1. State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences,Beijing 100101, China
    2. SinoProbe Center, Chinese Academy of Geological Sciences and China Geological Survey, Beijing 100037, China
  • Received:2022-12-04 Revised:2022-12-13 Online:2023-05-25 Published:2023-04-27

Abstract:

The Qilian orogen—formed along the northern margin of the eastern Tethys as results of pre-Cenozoic multi-phase subduction, continental collision and punctuated orogeny involving the North China craton and the Qaidam paleocontinent—develops widespread ophiolitic mélange belts and (ultra-) high pressure metamorphic and arc igneous rocks. The present Qilian Mountains, a key tectonic zone undergoing plateau uplift/expansion along the northern margin of the Tibetan Plateau, with complex intracontinental deformation and deep structures, records the histories of tectonic deformation and basin-mountain evolution during different stages of plateau growth in the Cenozoic. This paper, on the basis of comprehensive analysis of regional geological data, discusses the nature of Proterozoic metamorphic basement, paleo-oceanic evolution during the Neoproterozoic-Paleozoic, and Mesozoic-Cenozoic structural deformation, and explores the tectonic evolution of the Qilian orogen and the intracontinental deformation history of the Qilian Mountains. The Early-Neoproterozoic and Early-Paleozoic arcs represent respectively subduction-collision events took place in the Paleo-Qilian and (South/North) Qilian oceans. Basement structure beneath the North China craton suggests that the Qilian ocean is not the ocean separating the Gondwana and Laurasia continents, but rather a relatively small embayed sea along the southern margin of the Laurasia continent. The northeastern margin of the Tibetan Plateau experienced two-stage tectonic deformation and basin-mountain evolution in the Cenozoic, while transition from Early-Cenozoic thrust activity to joint action of strike-slip/thrust faults occurred in the Miocene, where, with rapid uplift of the Eastern Kunlun Range, a large Paleogene basin split into two basins—the current Qaidam Basin and the Hoh Xil Basin. Since the Middle-Late Miocene the tectonic framework along the margin has been mainly controlled by the development and clockwise rotation/lateral growth of two large near-parallel transpressional tectonic systems, of Eastern Kunlun and Haiyuan. The growth process and development mechanism of the large-scale strike-slip fault system in the Qilian orogen is a central issue of research on intracontinental deformation and requires in-depth quantitative examination.

Key words: Tibetan Plateau, Qilian orogen, tectonic evolution, structural deformation, plateau growth, basin-mountain evolution

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