Structural-Magmatic Evolution And Prospecting Direction Of Longxianggai Pluton In Dachang Ore Field, Guangxi

The Dachang tin polymetallic ore field is located on the southwestern edge of the Jiangnan paleo-uplift,the northeast side of the Youjiang Basin,is an important non-ferrous metal base in China.This article is based on a comprehensive analysis of previous research data and achievements of the region.Through the study of regional geology,deposit geology,magmatic rock evolution,rock control ore structure and geochemical characteristics of the study area.Determined the evolutionary stage of magmatic rocks and the ore-controlling ore-controlling structure,explored the metallogenic model of the deposit and proposed direction for prospecting.Mainly obtained the following results:1.Magmatic rock features:through the study of underground magmatic rocks in the mining area,the period of magmatic rock intrusion was ascertained:speckled granite-biotite granite-quartz porphyry.The zircon U-Pb ages of the biotite granites,quartz porphyries and granites are 92.48±0.71Ma(MSWD=0.14),88.88±0.92 Ma(MSWD=2.4)and 91.39 ±0.77 Ma(MSWD=2.0).The age of diagenetic granite for the late Yanshanian age,consistent with the large-scale metallogenic times throughout South China.2.Through the field geological surveys,identified the major rock-controlling ore-controlling structures in the mining area:rock intrusion and contact zone construction system.Mainly includes the annular fracture structure formed on the top of rock mass due to condensation shrinkage;Crumpling structure formed by magmatic baking;Oblique sliding zone formed by the upper arch of rock mass;The SN-inclined anticline or flexure formed by the magmatic uplift.3.According to metallogenic geological conditions and ore control laws summarized as follows:the ore-bearing strata are mainly Devonian.Magma hydrothermal fluids provide minerals.Ore-forming fluids rise along high-angle fractures,and skamization occurs on both sides of the fine strip marble.Bottom skarnization forms a stratified ore body.The metallogenic model is deep contribution,vertical migration along the fault,lateral Alteration and Mineralization.4.Prospecting direction:consider the Lamo mining area is in an oblique east wing,the formation of the stratiform emplacement of the rock body is a stratiform and veined ore body formed by intrusion from the southwest to the northeast.Then there may be magmatic rocks invaded from southeast to northwest in the oblique west wing.In this way,a layered ore body similar to that in the Lamo Mining Area can be formed.