Zircon U-Pb Dating Of The Yingqian Granodiorite Of The South Jiangxi And Its Relations To Mineralization

Granites of different geological periods are widely distributed in Nanling area.From Jinning period to Himalayan period,granite-related mineral deposits are also found all over the area.In the long evolution history of the Nanling area,the Yanshanian period is a particularly important period.The crust activity in the Nanling area of the Yanshan period is extremely active,and a large number of ore-bearing intrusions have been concentrated.In the early period of Yanshan,Nanling was in the state of“local tension-cracking”after orogeny.At this time,frequent magmatism created a series of high-kcala-alkaline intrusions and accompanying Copper-Lead-Zinc Polymetallic Ore,Yingqian Intrusion is one of them.The Yingqian intrusion is located in Shangyou County in the south of Jiangxi Province.It is a Compound massif of Yanshanian magmatism.The main lithology is granodiorite and its mafic enclaves,and a small part of fine-grained granite is exposed.The predecessors have carried out some research work for Yingqian,but the diagenetic age of the intrusion and,main intrusion granodiorite and the metallogenic relationship lack systematic discussion,in the Chong-Yu-You quartz Vein Type Tungsten Polymetallic Deposits In the area,the research work of silver-lead-zinc ore is relatively weak.Based on the work of the predecessors,this paper makes accurate zircon U-Pb chronology tests on the granodiorite with close relationship between the Yingqian intrusion and mineralization,in the meantime,it makes systematic intrusion geochemistry and Sr-Nd isotope studies of the mafic enclaves and their host intrusions and fine-grained granites.From the perspectives of geochronology,petrological mineralogy and intrusion geochemistry,the origin of the Yingqian intrusion and its relationship with mineralization and tectonic evolution are discussed.Combined with the geochronological and petrochemical characteristics of the Yanshanian tungsten-forming,tin-forming and copper-lead-zinc-forming typical intrusion in Nanling,the preferentiality of the intrusion of different metallogenesis preferentiality have summarized.The zircon LA-ICP-MS results show that the granodiorite age is 166.0-173.3Ma,and it can be confirmed that the Yingqian intrusion was formed in the early Yanshanian period and belongs to the Middle Jurassic.Geochemical characteristics show that granodiorite and fine-grained granite are metaluminous-weak peraluminous high-K calc-alkaline series,which can be classified into I-type granites.Among the trace element compositions,Ba,Nb,Sr,P and Ti showed significant losses,while Rb,U,La,Nd and Sm were relatively enriched.Characteristics of LREE enrichment,HREE loss,Eu amormaly is not obvious,the value of intrusion I_sr is 0.70792⁰.70796,?_Sr?t?value is51.3⁷7.5Ma,?_Nd?t?value is-6.41^-3.38,The model age of two-stage Nd(T_2DM)is1229¹471Ma.The comprehensive study shows that the Yingqian intrusion was formed in the tectonic setting of the extension-thinning of the early Yanshanian lithosphere,and the mid-Pacific plate subducted the Huaxia plate along the northwest direction,causing the basaltic magma to underplat the lower crustal melting and mixing some of the mantle source to form intrusion of Yingqian.The comprehensive study on the ore-bearing intrusion of the Yanshanian tungsten-forming,tin-forming and lcopper-lead-zinc-forming in the Nanling area shows that the tungsten-bearing granite body is the most common in the early Yanshan,mainly near the Chenzhou-Linwu fault zone or distributed on the east side.The intrusion association is mostly two mica granites and?Tourmaline-bearing Intrusion?garnet muscovite granites.The dark minerals have low content of biotite,a few horn blende are present,and tourmaline is commonly found.Xenolith from the country intrusions is commonly found in intrusions,and low content of mafic microgranular enclaves;The Ore-forming Granites are most common in the late Yanshanian,mainly near the Chenzhou-Linwu fault zone or distributed on the west side.The intrusion genetic types can be classified into aluminous A-type and H-types.The intrusion types is more common with Monzonitic-orthoclase Granites and alkali feldspar granite,granodiorite and adamellite,the degree of differentiation is relatively high,two types of intrusion genetic types,all of which have the participation of mantle-derived material;The petrogenic age of copper-lead-zinc-forming granite body in the Nanling area is concentrated in the Yanshanian period,and mainly in the early Yanshanian,mainly near the Chenzhou-Linwu fault zone distribution.The intrusion genetic types is divided into I-type granites,and the intrusion association is granodiorite.The low content of dark minerals,Biotite and Amphibole is more common,the dark enclaves of the intrusion is relatively small,its diameter is small,the degree of differentiation is low,and there is participation of a small crust material in the diagenesis processThrough comparative study on metallogenic preferences of different Mesozoic metallogenic granitoids in Nanling area,it is found that the geological and geochemical characteristics of Yingqian rock are consistent with those of the regional copper-lead-zinc deposit.Combined with the discovered deposits?points?related to rock mass around Yingqian rock,especially in Jiaoli and Jingziao silver-lead-zinc-tungsten deposits,which have been put into production at present,it can be determined.The mineralization of Yingqian intrusion is obviously preferentiality,and the mineralization is more inclined to skarn type Ag-Cu-Pb-Zn deposit.