Triassic tectonics and mineral systems in the Qinling Orogen, central China

Abstract

The Qinling Orogen in central China preserves the records of a complex geological and tectonic history, and also carries abundant mineral resources. Previous investigations on the Qinling Orogen have identified that the final transition from the Palaeo‐Tethys Ocean to a continental orogen occurred in the Triassic, although the timing of the oceanic closure and the tectonic affinity of the Triassic Qinling belt have been poorly constrained. In this contribution, we compile the palaeomagnetic data and geological evidence related to sedimentation, magmatism and mineral systems. The palaeomagnetic data show that the Palaeo‐Tethys Ocean in the Qinling Orogen gradually closed westward during the Triassic, terminating in the beginning of the Jurassic. Triassic strata are widely developed in the Qinling Orogen and conformably overlie the Permian strata. They are composed of carbonates and siliciclastic rocks that were strongly deformed and weakly metamorphosed during the Late Triassic to Late Jurassic. The Triassic magmatic rocks are dominated by I‐type granitoids, with subordinate S‐type and alkaline granites and minor carbonatite dykes, with a clear northward transition in lithology and geochemical features from the Mian‐Lue Suture. Different types of Triassic mineral systems have been reported from this region, including sedimentary‐hosted epizonogenic hydrothermal Hg–Sb, Pb–Zn ± Ag, Au deposits, metamorphic hydrothermal lodes of Au, Ag–Pb–Zn, Mo–Au and Mo, magmatic hydrothermal systems including porphyry Mo, breccia pipe Au, and carbonatite‐hosted Mo deposits. We infer that the Triassic Qinling Orogen witnessed synchronous oceanic plate subduction in the west and continental linkage in the east, with a transition from oceanic basin to continental orogen through gradual subduction‐related consumption of the oceanic plate. The Palaeo‐Tethys Ocean closed in a westward scissor‐like fashion in the Triassic and continental collision and extensive crustal shortening in the Jurassic, following which post‐collisional extension occurred in the Early Cretaceous. Copyright © 2014 John Wiley & Sons, Ltd.

Isotope and fluid inclusion geochemistry and genesis of the Qiangma gold deposit, Xiaoqinling gold field, Qinling Orogen, China

“…1A, B; Chen et al, 2009bDong et al, 2011;Li et al, 2011aLi et al, , 2014Chen and Santosh, 2014). The Qinling Orogen incorporates four distinct tectonic units, namely from north to south, the Huaxiong Block representing the reactivated southern margin of the North China Craton, the Northern Qinling accretionary belt, Southern Qinling Orogenic belt, and the Songpan foreland fold-thrust belt along the northern margin of the Yangtze Craton, with the San-Bao, Luanchuan, Shang-Dan, Mian-Lue and Longmenshan faults defining the boundaries ( Fig.…”

“…During this collision, large-scale fluid circulation, granitic magmatism and metallogenesis took place in the Qinling Orogen. As an example, in the Xiaoqinling gold field voluminous granitic rocks and all the gold deposits were formed in the period of Late Jurassic −Early Cretaceous (Yanshanian Orogeny) (Chen and Fu, 1992;Chen and Santosh, 2014;Chen et al, 2007aChen et al, , 2009aMao et al, 2002), but the gold deposits show no direct spatial relationship with Yanshanian intrusions (Fig. 1) (Jiang et al, 2009).…”

Isotope (S–Sr–Nd–Pb) constraints on the genesis of the ca. 850 Ma Tumen Mo–F deposit in the Qinling Orogen, China

“…The geological and geochemical characteristics of the deposit are similar to those of magmatic hydrothermal Mo systems both in the Qinling-Dabie Orogen, and in other parts of the world (Chen and Santosh, 2014;Zhang and Li, 2014;Wu et al, 2014). Examples of Mesozoic magmatic hydrothermal Mo systems include Yuchiling (Li et al, 2012b), Nannihu (Yang et al, 2012), Shangfanggou (Yang et al, 2013a), Jinduicheng (Zhu et al, 2010), Tangjiaping (Chen and Wang, 2011), Yaochong , Qian'echong (Yang et al, 2013b;Mi et al, 2015), and Shapinggou (Ni et al, 2015).…”

“…The CCO evolved from when the interaction between the northernmost part of the Paleo-Tethys Ocean was sandwiched between the colliding North China and Yangtze cratons during the Mesozoic ( Fig. 1; Zhang et al, 2001;Chen et al, 2009;Chen and Santosh, 2014;Dong et al, 2011;Zheng et al, 2013;Li et al, 2015;Wu and Zheng, 2013;Diwu et al, 2014).…”

“…The Qinling Orogen is composed of four tectonic units which, from north to south, are: (1) the Huaxiong Block representing the activated southern margin of the NCC; (2) the North Qinling accretion belt; (3) the South Qinling fold belt; and (4) foreland fold-thrust belts along the northern margin of the Yangtze Craton (such as the Songpan fold belt; Chen and Santosh, 2014 Chen and Santosh, 2014).…”