Genesis Relationship Between Two Types Of Mineralization In Yinkeng Ore Field,Southern Jiangxi Province,Nanling Region

Yinkeng ore field,which is located in conjunction of Nanling and Wuyi Mountains metallogenic belts,possesses not only W-polymetallic deposits-related to biotite granite,but also Au-Ag-Pb-Zn-Cu-Mn deposits-related to granodiorite.The two types of deposits,occurring independently,are closely located and nearly formed simultaneously.On the base of detailed geological survey,logging of scientific drilling,microscope mineral identification,diagenetic dating and geochemistry,some achievements have been obtained.(1)According to spatial distribution and mineralized metallogenic mechanisms,polymetallic deposits in the Yinkeng ore field can be classified as two types:W-polymetallic deposits represented by Huamei'ao W deposit,Yanqian W deposit and Shihoushan Fe-W deposit,and Cu-Pb-Zn-Au-Ag-polymetallic deposits represented by Niuxingba-Liumukeng Au-Ag-Pb-Zn-Cu deposit,Laohutou-Qiaozikeng Pb-Zn(-Ag-Au)deposit and Yingnao Mn-Ag-Pb-Zn deposit.(2)W-polymetallic and Cu-Pb-Zn-Au-Ag-polymetallic deposits,occurring nearly in the same tectonic location simultaneously,are related to granite and granodiorite,respectively.The two types of mineralization-magmatite display characteristcs of Nanling and Wuyi Moutains metalogenic belts,and belong to two metallogenic series separately.Accompanying occurring of them was resulted from superposition of two metallogenic series in conjunction area of different metallogenic belts.(3)Aiming at exploring deep magmatic activity and metallogenic mechanism of conjunction area of metallogenic belts,the Nanling Scientific Drilling Project(ab.as NLSD-1)was carried out,and the hole was drilled in Niuxingba-Liumukeng mining area.The drilling project,with footage of 2967.83 meters,was started at June 25,2011 and accomplished at July 22,2013.Nappe structure(No.F1),which controlled occurrences of intrusions and ore bodies,was uncovered at depth of 1373.71m.Pyroclastic rocks of Kuli Formation of the Qingbaikou System lies above the thrusting nappe structure F1,while marine-terrogenous facies sediments of Leping-Chetou-Xiaojiangbian(Chihsia)Formation of the Permian System below.Four types of magmatic dykes was exposed,with ages of 381.0±3.1Ma for rhyolite,150.9±0.5Ma?152.1±1.0Ma for granite porphyry,160.3±0.8Ma?162.5±2.4Ma for granodiorite porphyry,101.3±0.8Ma and 161.0±4.1Ma for gabbrodiorite porphyry.Meanwhile hundreds of lead-zinc-gold-silver-copper mineralization zones and some tungsten-bismuth-uranium mineralization were exposed.(4)Ore-forming regularity of Yinkeng ore field has been established on the base of geological,geochronological and geochemical research on deposits,intrusions,strata in Yinkeng ore field.NNE trending Yingtan-Dingnan fault zone and nappe structures controlled strata,magma activity and mineralization.Occurrences of Cu-Pb-Zn-Au-Ag-polymetallic deposits were controlled by nappe structure F1 and its secondary fractures,while W-polymetallic deposits depended on fractures resulted from magma intrusion.Peculiar tectonic setting,intersection of Nanling and Wuyi Mountains metallogenic belts,possesses linear faults deep into mantle and latticed ones deep into crust simultaneously.Different tectonic mechanism results in two independent metallogenic series of granite-W-polymetallic mineralization and granodiorite-Au-Ag-Cu-Pb-Zn mineralization in Yanshanian Period.(5)On the base of study of ore-forming regularity,metallogenic mode of Yinkeng ore field has been established.Deep nappe structure,contact zone between concealed intrusion and strata,Yanshanian Gaoshanjiao granodiorite intrusion and Jingbishan-Zhangshu'ao cryptoexplosive breccia are proposed as potential prospecting targets.