283 research outputs found
Structural analysis of the northern Tongbai Metamorphic Terranes, Central China: implications for Paleozoic accretionary process on the southern margin of the North China Craton
No full textAbstract not availableXin Liu, Sanzhong Li, Yanhui Suo, Xiaochun Liu, Liming Dai, M. Santos
Cretaceous source to sink system reconstruction of northeastern Asian continental margin: Insight from integrated detrital geochronology in NE China
No full textDeep structures and surface boundaries among Proto-Tethyan micro-blocks: Constraints from seismic tomography and aeromagnetic anomalies in the Central China orogen
No full textAbstract not availableWenjun Sun, Sanzhong Li, Xin Liu, M. Santosh, Shujuan Zhao, Lingli Guo, Huahua Cao, Shan Yu, Liming Dai, Yong Zhan
SHRIMP U–Pb zircon dating of a metagabbro and eclogites from western Dabieshan (Hong'an Block), China, and its tectonic implications
No full textThe Tongbai HP metamorphic terrane: Constraints on the architecture and subduction/exhumation of the Tongbai-Dabie-Sulu HP/UHP metamorphic belt
No full textPetrogenesis of Eocene mineralized porphyry in Bijiashan, eastern margin of Tibet Plateau: Constraints from geochronology, geochemistry and Hf isotopes
No full textThe Ailaoshan-Jinshajiang porphyry belt located in the Sanjiang area of eastern Tibetan Plateau is one of the major polymetallic metallogenic belts in China. However, the nature and genesis of magmatic intrusions associated with the porphyry copper mineralization in this belt remain contentious. Here we focus on the Bijiashan Deposit, one of the large-scale porphyry copper deposits in this area, to gain insights on the host rock, petrogenetic mechanism, tectonic setting based on geochemistry, zircon U–Pb geochronology and Lu–Hf isotopic compositions. Zircon U–Pb dating of the ore-hosting porphyry yielded an age of 35.6 ± 0.2 Ma. The major elements of the porphyry show wide range in SiO₂ (58.33–70%), high K₂O (2.83–8.85%) and Na₂O + K₂O (mostly>8%), and moderate range in A/CNK (0.56–1.17). Our data suggest that the porphyry belongs to high-Kcalc-alkaline-alkaline and metaluminous-peraluminous series. The trace elements are characterized by enrichment in K, Rb, Ba, La and Nd, but depletion in Ta, Nb, P and Ti, and enrichment in LREE but depletion in HREE with LREE/HREE of 9.78–20.10. The main intrusion associated with mineralization corresponds to alkali-richA-type granitoid, with high TFeO (0.49–3.4%), low Na₂O/K₂O (0.23–1.62), and high 1000*Ga/Al (2.17–2.64 except 1.57), and right-declinedREE patterns. However, some of the geochemical features also are consitent with the typical characteristics of C-adakite rocks, including high contents of Al₂O₃ (13.49–16.12%) and Sr (>400 ppm), lower MgO (mostly <3%), depleted Y (<18 ppm) and Yb (<1.9 ppm), and slightly negative Eu anomalies (δEu = 0.83). The zircon εHf (t) values show a wide range from negative to positive (−13.65 to 2.60) with TDMC varying from 947 Ma to 1982 Ma, suggesting that the Eocene porphyries were derived from the partial melting of the lower crustal materials, together with the addition of mantle source materials. Combined with the regional geological evolution, our study suggests that the ore-hosting porphyry formed under a setting of post-collisional crustal extension. Following the collision between the Indian and Eurasian plates, the stress relaxation resulted in extension and magma emplacement along major faults and the copper polymetallic mineralization formed along the Chenghai-Binchuan Fault.Zhou Jie, Li Sanzhong, Wang Genhou, M. Santosh, Zhang Li, Yu Shengyao, Liu Yiming, Li Xiya
Dynamics of exhumation and deformation of HP-UHP orogens in double subduction-collision systems: Numerical modeling and implications for the Western Dabie Orogen
No full textThe dynamics of formation and exhumation of high-pressure (HP) and ultra-high pressure (UHP) metamorphic orogens in double subduction-collision zones remain enigmatic. Here we employ two-dimensional thermo-mechanical numerical models to gain insights on the exhumation of HP-UHP metamorphic rocks, as well as their deformation during the collision of a micro-continent with pro- and retro-continental margins along two subduction zones. A three-stage collisional process with different convergence velocities is tested. In the initial collisional stage, a fold-and-thrust belt and locally rootless superimposed folds are developed in the micro-continent and subduction channel, respectively. In the second (exhumation) stage of HP-UHP rocks, a faster convergence model results in upwelling of the asthenosphere, which further leads to a detachment between the crust and lithospheric mantle of the micro-continent. A slower convergence model results in rapid exhumation of HP-UHP rocks along the north subduction channel and a typical piggy-back thrusting structure in the micro-continent. A non-convergence model produces a slab tear-off, leading to the rebound of residual lithosphere of the micro-continent. In the third and final stage, a series of back and ramp thrusts are formed in the micro-continent with the pro-continent re-subducted. Based on an analogy of our numerical results with the Western Dabie Orogen (WDO), we suggest that: (1) slab tear-off results in a rebound of residual lithosphere, which controls the two-stage syn-collisional exhumation process of HP-UHP rocks in the WDO; and (2) in contrast to the single subduction-collision system, the exhumation range of the partially molten rocks with lower viscosity and density is restricted to a specific region of the micro-continent by the Mianlue and Shangdan subduction zones, which generated the complex deformation features in the WDO.Liming Dai, Sanzhong Li, Zhong-Hai Li, Ian Somerville, Yanhui Suo, Xiaochun Liu, Taras Gerya, M. Santos
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