Dizhi lixue xuebao (Aug 2021)
Mesozoic tectonic deformation and its rock/ore-control mechanism in the important metallogenic belts in South China
Abstract
Since the Mesozoic, the convergence of the Tethys ocean plate and the Paleo-Pacific plate on the South China block has resulted in the multi-sequence tectonic deformation as well as the multi-stage magmatic and metallogenic events, and has formed many important polymetallic metallogenic belts in South China. In this context, mineralization stages, distribution of ore bodies and metallogenic mechanisms of typical skarn deposits in metallogenic areas were sorted out. And then the mineralization processes and genetic mechanisms of typical deposits are completed using the sequence of tectonic deformation and its rock/ore-control regularity. A structural deformation analysis was made on the southwestern Fe polymetallic metallogenic belt, the northeastern Jiangxi Taqian-fuchun W-Cu metallogenic belt and the Laojunshan W-Sn ore concentration area to set up three relatively complete periods of deformation sequence during the Indosinian period, the middle-late Jurassic and the Cretaceous, combined with previous research results; however, the three deformation sequences differ in duration of tectonics, structural property, scale and strength, and deformation style. The analysis of rock-control by tectonics together with the existing isotope chronology data both revealed that the magmatic or metamorphic thermal events were consistent with the deformation sequence occurred in each mineralization zone, and then the multi-stage magmatic events related to the Makeng-type Fe polymetallic deposit, the Zhuxi W-Cu deposit and the Nanyangtian W deposit were clarified using the corresponding laws between deformation sequence and magmatic stage. On this basis, we identified the multi-stage mineralization events and supposed that multi-stage superposition occurred in the mineralization process of all three typical deposits. From the point of view of structural control over the emplacement mechanism of the ore deposit, this paper analyzed the mechanism of the decentralized polymorphic orebody of the Makeng-type deposit, the vertical large-span mineralization and deep giant orebody of the Zhuxi deposit, and the stratiform-vein superposition orebody of the Nanyangtian deposit, which are controlled by the folding detachment of the ore-bearing strata, the large-scale thrust duplex and the two-stage tectonic compounding respectively. The dynamic background of tectonic deformation and magmatic mineralization in the important metallogenic belts of South China at different stages were discussed.
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