Abstract:Lead-zinc deposits in Guangxi are fundamentally stratabound and might be genetically grouped into three major types, i.e., sedimentary-transformation type, sedimentary-magmatic hydrothermal superimposition type, and sedimentary-exotic authineomorphic type. The sedimentary- transformation type lead-zinc deposits are confined to the strata from Lower Devonian Sipai Formation to the bottom of Upper Devonian Liujiang Formation and have no apparent connection with intrusive masses; ore bodies are bedded or stratoid in form and ore minerals are mainly sphalerite, galena and pyrite; dolomitization characterizes the major wall rock alteration; ore-forming temperatures range from 100℃ to 300℃； ores have δS34 values from -26.2‰ to +24.2‰ and have most variable lead isotope compositions with the model ages ranging from 96 m.y. to 658 m.y. The sedimentary-magmatic hydrothermal superimposition type lead-zinc deposits are intimately associated with igneous rocks and confined to Middle-Upper Devonian and Middle Ordovician sediments as well; ore bodies are bedded, stratoid and partly vein-like; ore minerals are predominantly cassiterite, marmatite and jamesonite and wall rock alterations are chiefly silicification and skarnization; ores seem to have formed from 200℃ to 400℃; δS34 values of ore are-9 — +9‰ and lead isotope compositions are also extremely variable with the model ages ranging from 73 m.y. to 757 m. y.; the related intrusive masses have ages from 97 m.y. to 107 m.y. While showing no obvious relationship with igneous masses. the lead-zinc deposits of exotic authineomorphic type are closely in connection with structures. Assuming various complicated veinlike aspects, the ore bodies occur inside the faults cutting the strata and are confined to Cambnian sediments; ore minerals are mainly sphalerite and galena, and silicification is characteristic of wall rock alteration; lead isotope compositions also vary in wide limits. The formation of shatabound lead-zinc deposits in Guangxi seems likely to have controlled combinedly by lithology, sedimentary facies, igneous rocks and. structures. Devonian sediments are the major ore-bearing strata where 84 percent of the discovered ore reserves occur. A less amount of such deposits has been found in Cambrian and Ordovician sediments. Ore-controlling sedimentary rocks are principally biogenetic limestone and biogenetic dolomite and less frequently, sandstone-shale: biogenetic limestone dominates the distribution of the sedimentary-magmatic hydrothermal superimposition type lead-zinc deposits, biogenetic dolomite that of the sedimentary-transformation type lead-zinc ones and sandstone-shale that of the exotic authineomorphic type ones. Ore-controlling sedimentary facies are mainly platform marginal facies→confined platform lagoon facies, platform marginal facies→reef-back lagoon facies and tidal flat facies. Igneous activities have provided the sedimentary-magmatic. hydrothermal superimposition type lead-zinc deposits with ore fluids and metallogenic materials, especially tin, thus playing a decisive role in the distribution of ore-forming elements. The effects of structures on ore formation find expression in the fact that structures of different types control diverse types of ore deposits: uplift and SN-trending structural belt govern the sedimentary-magmatic hydrothermal superimposition type lead-zinc deposits, EW-trending structural belt the sedimentary-exotic authirieomorphic type ones, and NW-and NE-trending structural belt the sedimentary-magmatic hydrothermal superimposition type ones. Besides, the surface of unconformity above Cambrian sediments dominates the distribution of the conglomeratic lead-zine deposits of sedimentary-transformation type. Sedimentary- transformation type lead-zinc deposits are distributed in central Guangxi, sedimentary- authineomorphism type ones in southwest Guangxi, and sedimentary-magmatic hydrothermal superimposition type ones in west, east, and southeast Guangxi.
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冯群耀.1984.广西铅锌矿床类型及主要控矿因素和分布规律的探讨[J].矿床地质,3(3):47~56.1984.A Discussion On Lead-Zinc Deposits In Guangxi:Their Genetic Types,The Major Ore-Controlling Elements And Ore Distribution Regularity[J].Mineral Deposits3(3):47~56
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