Affiliation:
1. National Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi China
2. Xinjiang Laboratory of Mineral Resources and Digital Geology Urumqi China
3. Innovation Academy for Earth Science CAS Beijing China
4. College of Earth and Planetary Sciences University of Chinese Academy of Sciences Beijing China
5. State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China
6. Institute of Geology Chinese Academy of Geological Sciences Beijing China
Abstract
AbstractThe Devonian tectonic setting is still controversial in the Proto‒Tethyan North Qilian belt. The Hexi Corridor of the North Qilian belt occupies a key position in constraining the tectonic evolution of the Proto‒Tethyan Ocean and the growth of the Asian continent. Turbidites, as an important component of the Jiayuguan mélange in the Hexi Corridor, consist of conglomerate, pebbly sandstone, sandstone, siltstone, calcareous mudstone, and chert that feature typical Bouma sequences of Ba, Bc, Bcd, Babc and/or Bab. They are strongly deformed into NW‒trending folds with NE‒ and SW‒inclined thrust faults. Detrital zircon U‒Pb dating results demonstrate that these sediments successively young to the southwest with maximum depositional ages (MDA) ranging from 560 Ma to 411 Ma, indicating that the youngest block was deposited after 411 Ma. Petrological, geochemical and detrital zircon U‒Pb age data indicate the sedimentary rocks provenanced from weak weathering, recycling, and multiple mixing sources, and that the dominant source was the Andean‒type Alxa arc. Together with the published data, we suggest that double‒sided subduction of the North Qilian Ocean (Proto‒Tethyan Ocean) occurred between the North Qilian arc and the Andean‒type Alxa arc during the early Devonian.
Publisher
American Geophysical Union (AGU)