Dizhi lixue xuebao (Feb 2022)
On research methodology for deformation history of tectonic lithofacies in sedimentary basin and their application
Abstract
The coupling pattern between the deformation history of tectonic lithofacies and the sequence of ore (reservoir)-forming in the basin remain as an unsettled scientific issue, for (non-) metals, uranium, coal, oil and gas resources being hosted in the same sedimentary basin. On the basis of tectonic lithofacies mapping and tectonic lithofacies deformation history study, the deformation history of tectonic lithofacies can be classified into six stages: pre-basin formation, basin formation, basin inversion, basin deformation, basin-in magmatic superimposition, and basin supergene. The main results are as follows. Firstly, patterns and combination of snygenetic structure in the basin can be delineated by innovative approach of tectonic lithofacies mapping. The tectonic lithofacies mapping of 12 lithofacies series of cryptovolcanic rock intrusion, volcanic cyptoexplosion-intrusion and volcanic explosion-eruption in the volcanic area helps to delineate the central parts of volcanic edifice, diagenesis and mineralization of volcanic hydrothermal fluid, and sedimentation of volcanic hydrothermal vent. Secondly, the transitional tectofacies zone of basin-mountain-plateau is a tectonic lithofacies zone for fluid migration and storage on a large scale, and also a favorable tectonic lithofacies belt for (non-) metals-uranium-coal-oil and gas resources hosted in the same basin. Foreland basin, intermountain basin, and hinterland basin have different styles of deformation tectonics. The study of tectonic lithofacies and mapping contributes to understand the paleo-geothermal reservoir, the series of reservoir-forming and ore-forming events for the hydrocarbon generation and migration derived from the coal-measure metal-bearing source rocks, etc. Thirdly, basin-in crust-source magma, combination of crust-mantle derived magma, and mantle-derived magma had formed their corresponding magmatic superimposing tectonics and magmatic superimposing diagenetic lithofacies system, respectively. Four coupling structures of magma-tectonics-lithology-hydrothermal fluid existed in the asymmetry dome-shaped complex fold formed by magmatic hunch-up. On the one hand, tourmaline-rich plume tectonics produced by the diagenesis and ore-forming of basin-in magmatic reconstruction-superimposing were typified by hunch-up and rotated fault-fold zone, series of tourmaline alteration facies. On the other hand, CO2-rich plume tectonics produced by basin-in magmatic reworking was characterized by thermal-derived faults, vertical zoning of Fe-Mn-carbonate minerals, and they intergrowth with vertical zoning of siderite skarn, skarnized marble, Fe-Mn carbonate minerals hosted in marble, and marbleization crystalline limestone in sequence.
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