| Guishan is located in the eastern part of Tongling ore district,tectonically belonging to the northern margin of the Yangtze plate,the transition zone of the Fanchang depressionand Tongling uplift in the middlel of depression of the Lower Yangtze plate.In recent years,Yaojialing super-large zinc-gold polymetallic deposit and a number of small-medium sized deposits,such as Zhujiachong copper deposit,Guihuachong copper deposit,Guishan copper polymetallic deposit,have been found in the surrounding area of Guishan.The achievement of geological prospecting in many years,show that the ore-forming geological conditions of Guishan is well,and great prospecting potentia in the deep area.This study combine with geophysical technology(gravity and magnetic anomaly information)and geological research,take the analysis of the 1:50000 gravity and magnetic anomaly information as a guide,analysis of regional ore background conditions,and geological interpretation of high-precision gravity and magnetic(1:10000)anomalous characteristics in key areas,analysis of typical ore deposits,summarize the metallogenic regularity,and mineralization prediction in the deepth area of Guishan.According to the regional gravity and magnetic data with the scale of 1:50000 in the Guishan area,using “gravity and magnetic data processing and three-dimensional inversion platform” to process the data and get various gravity-magnetic anomalies maps.In combination with the regional geological background and the characteristics of gravity and magnetic anomalies,the locations of Tongling uplift,Fanchang basin and Xuannan depression were identified,and determined the approximate location of Daigongshan anticline,Kedoushan anticline,Guiji syncline and the distribution of Shatanjiao rock mass,Daijiahui rock mass,Shizixing rock mass,Qingshan-Xiniushan rock mass and the caldera of Kedoushan.The geological structure of Guishan was initially constructed.Based on the geological interpretation of regional gravity and magnetic characteristics,this study selected the key areas from Guishan to carry out 1:10000 high-precision gravity and magnetic measurements,which was about 10 square kilometres,and used “gravity and magnetic data processing and three-dimensional inversion platform” to process the data.Through the geological interpretation of the high-precision gravity and magnetic anomalies,three folds and five faults were determined,six rock mass were determined,which was Qingshan rock mass,Guishan rock mass,and Xiniushan rock mass.The Qingshan rock mass had the characteristics of low-medium magnetic and low density,Guishan rock mass was medium magnetic and low density,Xiniushan rock mass was high magnetic and low density.The ore-controlling formation,which is the limestones and marbles of Carboniferous to Triassic,have the features of low magnetism or no magnetism and high density.By analysis the distribution of anomaly characteristics,it is believed that the eastern side of the Qingshan rock mass,the west side of the Guishan rock mass and on both sides of the Xiniushan rock mass were the potential space for deep-seated mineralization.Based on the study of regional geochemical fields,geochemical anomalies were closely related to the distribution of medium-acidic intrusive rocks.The rock mass relatively rich in copper,gold and other metallogenic elements,the highest content of ore-forming elements is near the contact zone between rock mass and surrounding rock,especially skarn.It shows that the contact zone between rock mass and surrounding rock is a favorable part of mineralization.Geochemical analysis from typical deposit show that diagenetic age of the intermediate-acidic intrusive rock mass associated with metallogenesis in the Guishan area was 141.3±3.6Ma,and the metallogenic age was 1136.9±2.2~143.7±2.7Ma.The ore-forming material is mainly derived from magma.Comprehensive analysis of the above research results,it was considered that the complicated tectonic setting was a prerequisite for diagenesis and mineralization;high-precision gravity and magnetic anomalies were the tracers of mineralization prediction;medium-acidic intrusive rock mass was an important ore-forming source rock;the development of fault structure provided an important channel for the migration of magmatic and ore-bearing hydrothermal fluids;the carbonatestrata of Carboniferous to Triassic not only to be an ideal space for containment and a passable structure,but also provided some material sources for mineralization;the contact zone between intermediate-acid intrusive of Yanshanian and surrounding rock of carbonate rock,and the altered rock mass was the key part of the deep prospecting;skarnization,pyritization,carbonation,marbleization,sericitization and other alterations were important indicators for prospecting.According to the comprehensive analysis of the conditions of metallogenic geological,geophysical information and geochemistry information in Guishan,summing up the elements of multi-information coupled metallogenic prediction in this area,and established a prediction model.Based on this model,Xiniushan metallogenic prospect,Gejiacun metallogenic prospect and Qingshan metallogenic prospect have been delineated in Guishan,it provides guidance for the future prospecting work in Guishan area. |
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