Magmatic history of the northeastern Tibetan Plateau

Abstract

[1] The northeastern margin of the Tibetan Plateau is underlain by the Qaidam and Qilian terranes, which consist primarily of mid-Proterozoic through lower Paleozoic oceanic and arc-type assemblages that have been accreted to the southern margin of the Tarim/SinoKorean craton. Most previous models suggest that these assemblages formed along a northeast dipping subduction system constructed along the margin of the Tarim/SinoKorean craton during early Paleozoic time. The main components are interpreted to have formed either as an archipelago of volcanic arcs and back arc basins, or as a broad expanse of accretionary complexes. Our geochronologic data support a model, suggested by Sobel and Arnaud [1999], in which the Qaidam and Qilian terranes are separated from the Tarim/Sino-Korean craton by a mid-Paleozoic suture that closed along a southwest dipping subduction zone. The basement to these terranes consists of oceanic assemblages that were amalgamated into a coherent crustal fragment prior to emplacement of $920-930 Ma granitoids. Early Paleozoic arc-type magmatism occurred between $480 and $425 Ma, apparently sweeping southwestward across much of the Qilian and Qaidam terranes. Accretion-related magmatism along the inboard margin of the Qilian terrane occurred between $423 Ma and $406 Ma. Following Silurian-Devonian accretion, the region has experienced late Paleozoic and Mesozoic uplift and erosion and has been severely overprinted by Tertiary thrusting, uplift, and strike-slip motion along the Altyn Tagh fault. Correlation of geologic features and magmatic histories between the Altun Shan and the Nan Shan suggests that the eastern Altyn Tagh fault has a total left-lateral offset of $375 km.

Garnet effect on Nd-Hf isotope decoupling: Evidence from the Jinfosi batholith, Northern Tibetan Plateau

“…The Mohe gneiss within the NQ-UHPM is the oldest sampled crystalline basement in the QOB, dated at ~ 2.5 Ga , and the inherited zircons with ages >2.6 Ga confirm the existence of an Archean basement in the region (Huang et al, 2015;. Different models have been proposed to explain the tectonic evolution in the whole QOB (Xu et al, 1994;Yin and Harrison, 2000;Yang et al, 2002;Gehrels et al, 2003Gehrels et al, , 2011Song et al, 2006Song et al, , 2013Song et al, , 2014Wu et al, 2006Wu et al, , 2010Xu Z. Q, 2006;Xiao et al, 2009;Huang et al, 2015). The…”

Silurian high-pressure granulites from Central Qiangtang, Tibet: Constraints on early Paleozoic collision along the northeastern margin of Gondwana

“…(1) A north-facing arc, which is interpreted to have brought the Nan Shan-Qilian Shan-Altun Shan terrane juxtaposed with the southern margin of the Tarim craton (Yin and Nie, 1996;Sobel and Arnaud, 1999;Gehrels et al, 2003aGehrels et al, , 2003b (Fig. 10a).…”

From Subduction to Collision in the Northern Tibetan Plateau: Evidence from the Early Silurian Clastic Rocks, Northwestern China

“…The late Paleoproterozoic to Neoproterozoic detritalzircon grains in the analyzed samples were probably derived from the Central Qilian Block, where Mesoproterozoic-Neoproterozoic granitic intrusions and metamorphosed sedimentary rocks with late Paleoproterozoic to Neoproterozoic detrital zircons constitute the major part of the basement ( fig. 9e, 9f; Guo et al 2000;Wan et al 2001;Gehrels et al 2003aGehrels et al , 2003bTung et al 2007a;Wang et al 2007;Xu et al 2007;Yong et al 2008a;Xue et al 2009). Cambrian-Ordovician zircon grains, in addition to Precambrian detritus, occur in the Lujiaogou Formation of the Sunan area in the Sunan Subprovince ) and in the Late Ordovician sediments of Xiehao area in the Jingyuan Subprovince (Xu et al 2010; fig.…”

“…In e and f, ARC p island-arc basalt; CFB p continental flood basalt; LIP p large igneous province; MORB p mid-ocean ridge basalt; OIB p ocean-island basalt; SSZ p suprasubduction zone. (BGMRQP 1991;Xia et al 1995Xia et al , 2003Zhang et al 1997;Mao et al 1999Mao et al , 2000Wang et al 2005a;Chen 2007;Yu et al 2010), 1.1-0.8 Ga (2) for the Central Qilian Block (Guo et al 2000;Wan et al 2000Wan et al , 2001Gehrels et al 2003b;Tung et al 2007a;Wang et al 2007;Xu et al 2007;Yong et al 2008a;Xue et al 2009), and 2.1-1.7 and 2.6-2.4 Ga (3 and 4, respectively) for the North China Craton (Krö ner et al 1988;Wan et al 2003;Darby and Gehrels 2006;Tung et al 2007b;Li et al 2008). Taylor and McLennan (1985).…”

“…Potential ophiolitic source rocks within the North Qilian Belt are represented by the Jiugequan, Dachadaban, and Yushigou-Dongcaohe ophiolites, which were emplaced during the Cambrian to Early-Middle Ordovician within/between the back (Xu et al 2010); e, Central Qilian Block granitic intrusions (Guo et al 2000;Wan et al 2000Wan et al , 2001Gehrels et al 2003b;Tung et al 2007a;Wang et al 2007;Xu et al 2007;Yong et al 2008a;Xue et al 2009); f, metasedimentary basement of the Central Qilian Block (Gehrels et al 2003a;Tung et al 2007a;Xu et al 2007); g, detrital zircons from the basement of the North China Craton (Krö ner et al 1988;Wan et al 2003;Darby and Gehrels 2006;Tung et al 2007b;Li et al 2008 (Xia et al 2003) and the high-Crcontent rocks of the Dachadaban ophiolite (Chen et al 1995;Zhang et al 1998b). The average value of Shuiquan samples, representing the continent provenances ), was calculated with Dachadaban ophioliteprovenance average value to generate two-end-member mixing lines, accounting for the high Cr/Th and Cr/V ratios of some samples from the Lujiaogou Formation.…”