Provenance analysis of detrital monazite, zircon and Cr‐spinel in the northern Tibetan Plateau: Implications for the Paleozoic tectonothermal history of the Altyn Tagh and Qimen Tagh Ranges

Abstract

Sediment provenance studies have proven to be an effective method to extract the sediment provenance and tectonic process information recorded by detrital minerals. In this contribution, we conducted detrital monazite and zircon U‐Pb geochronology and detrital Cr‐spinel major element chemistry analyses on samples from the Qaidam Basin to reconstruct the spatial and temporal evolution of the Altyn Tagh Range and the Qimen Tagh Range in the northern Tibetan Plateau. Based on the significant variation in [Th/U]N, [Gd/Lu]N and [Eu/Eu*]N and the U‐Pb ages of the monazite and zircon, the South Altyn Tagh subduction‐collision belt and the North Qimen Tagh Range were, respectively, the main provenances of the Ganchaigou section and the Dongchaishan‐Weitai section in the Qaidam Basin in the Cenozoic. Paleozoic peak metamorphism, retrograde granulite‐facies metamorphism and amphibolite‐facies metamorphism in the South Altyn Tagh subduction‐collision belt were well recorded by the detrital monazite. In comparison, the detrital zircon is a better indicator of igneous events than detrital monazite. Synthesizing the detrital monazite, zircon and Cr‐spinel data, we concluded that the South Altyn Tagh Ocean and Qimen Tagh Ocean existed in the early Paleozoic and that the Altyn Tagh terrane and Qimen Tagh terrane experienced different Paleozoic tectonothermal histories. The collision between the Qaidam terrane and the Azhong terrane occurred at ca. 500 Ma. The Middle Ordovician was the key period of transformation from the collision‐induced compressional environment to an extensional environment in the area of the South Altyn Tagh Range. In the early Paleozoic, the Qimen Tagh area was characterized by the subduction of oceanic crust.

Mesozoic-Cenozoic evolution of the Eastern Kunlun Range, central Tibet, and implications for basin evolution during the Indo-Asian collision

“…These sources were replaced by uplifting and/or advancing thrust belts that define the modern northwestern and southern topographic boundaries of Qaidam basin (Yin et al, 2002(Yin et al, , 2008bQian et al, 2018). Thus, the character of Qaidam basin sediments changed in concert with the evolution of the basin margins, with exposure of Precambrian basement rocks in Altyn Tagh Range uplifts and unroofing of voluminous igneous rocks in the Eastern Kunlun Range driving compositions toward a more mixed provenance (Zhu et al, 2018). The Eocene zircon ages were reported in early Miocene sample of , which is possibly be derived from the Cenozoic volcanic rocks exposed on the northern margin of the Qiangtang terrane (Jolivet et al, 2003;Ding et al, 2007).…”

“…2.5 Ga populations are also probably from the Quanji Massif in the northern Qaidam basin (e.g., Lu, 2002;Lu et al, 2006;Gong et al, 2012;X.J. Yu et al, 2017c;Chen et al, 2013;Li et al, 2018;Zhu et al, 2018). One sample was collected from an outcrop located along the southern margin of Qaidam basin in which rare trough cross-stratification gives a mean paleocurrent direction of 358° (McRivette et al, 2019).…”