Study On Geological And Geochemical Characteristics Of Laoyaling Cu Deposit In Tongling, Anhui Province

Abstract:Laoyaling Copper Deposit is a representative stratabound skarn-type one which is situated in south of Anhui province and in the south area of Dabieshan-Sulu orogenic structure, which also situated on the north-central Yangzi Plate that close to south bank of Yangtze River. The detailed study on this deposit gives a clue to understand the theory of metallogeny theory on this type, and provides new evidences for enrichment of the metallogenic theory of skarn deposits and further exploration of skarn depostis.A detailed regional geological, deposits geological, geochemical study has been carried out on the Laoyaling copper deposits, with a focus on an analysis of the origin of ore-forming materials, the ore-controlling factors and the metallogenic mechanism. According to the study of the origin of ore-forming materials, the ore-forming materials are mainly deprived from the magma, and secondly from strata. As the analysis of the ore controlling factors indicates that the formation of Laoyaling deposits in the Tongling area is controlled by the Permian strata and Triassic strata, quartz diorite, the folded structures and the interlayer gliding structure. The strata offers a favorable condition on lithology and provides a small part of the ore-forming materials. Magma offers heat and provides a large part of the ore-forming materials. The decollements which result from structural deformation is the host structure of Laoyaling deposits. Based on the research of geochemistry, Magma, strata and ore belong to one metallogenic system. With the help of coprecipitate, copper builds up after ore fluid enter into the interlayer gliding structure. Based on above data, the ore-forming mechanisms of Laoyaling deposits is summarized. During the Indosinian structural movement, especially folding, interlayer detachments occurred frequently between Permian strata and Triassic strata; During the Yanshan period, regional extension caused massive magma-hydrothermal activities. Postmagmatic hydrothermal solution migrates along the decollement structure in Gufeng Formation, Longtan Formation and Dalong Formation of Permian and in Xiaoliangting Formation of Triassic. With the help of precipitant, copper builds up rapidly, and finally form the Laoyaling deposits.