Geological-geochemical Characteristics Of Xiahaoping-Dianfang Gold Deposit, Songxian County, Henan Province

The Xiahaoping-Dianfang gold field is located in Songxian County, HenanProvince, in administrative divisions and in the south margin of North China Platform inregional geological tectonic units. The tectonomagmatic activities were intense and theendogenic metallogenic conditions are superior in the study area. The MiddleProterozoic Xiong’er group Jidanping Fm (Pt2xj) intermediate-acidic extrusive rockoutcrops and the major ore-controlling structure is NWW-trending Shaowayao fracture.In order to survey the potential of resources in deep, adapt the demand of minesustainable development and solve the problems of Xiahaoping gold mine that isdeposit genesis, metallogenic model, material source of metallogenesis, metallogenicepoch, ore source in deep and prospecting potential etc. and through field survey,polished and thin sections identification, testing-analysis of rock, ore, monomineral,major element, trace element, rare earth element and isotope, the study gained manyachievements as follows:Volcanic rocks in this area mainly are calc-alkalic dacites with the same sourceregions. The crustal contamination has a slightly effect to the rocks during the magmaticevolution. The trace elements have the same characteristics as continental crust andacidic rock. The previously named “volcanic breccia” has the same source as“cryptoexplosive breccia”, both of whom are all cryptoexplosive breccia.The Heyu granite body belongs to crust-mantle mixed type. The cryptoexplosivebreccia, granite dyke and Heyu granite body are all negative Eu and negative Tbanomalies, which have a higher degree of correlation. In addition, they have the similardiagenetic environment and succession relations. The Pb isotope mainly is enriched inthe surrounding of orogenic belt or crust craton. The data points of Pb isotope centralize,which shows the componential source of the rock is single. The REE distribution patternof pyrite shows the rock is derived from mantle. The mineralization has a close relationwith granite.The sulfophile elements Pb, Cd, Bi, Ag, Cu, As, Zn etc. are highly enriched in thecourse of mineralization. The metallogenesis operates under the reduction environmentof sulfur enrichment. With the increasing of the buried depth of orebody and the weaking of the intensity of silicified action, the values of δEu gradually increase in oresand the gold grade reduces, which means the gold mineralization has a close relationwith silication.The deposit types are subvolcanic hydrothermal deposit and altered tectonite typedeposit. The vein orebody of subvolcanic hydrothermal deposit has the vertical zoningpattern followed by Au, Pb (Ag), Mo, from top to bottom. According to the pattern, thestudy deduces that there is the high-temperature subvolcanic hydrothermal Mo depositunder the vein orebody of intermediate-temperature combination. The top of K2orebodyhas been eroded. The depth of the main body of gold deposit is about550-600m. TheAg-Pb orebody still extends to some extent in the deep and the K13orebody does more.The∑REE values of orebodies or mineralized bodies in F40fracture zone arefrom466.65×10-6to739.37×10-6and the average is593×10-6, which is2-3times morethan that of surrounding rock or other types of orebody. Especially, the LREE is morehighly enriched, which means the hydrothermal activity is intense and themetallogenesis has a close relation to intrusive rock, especially granodiorite. Comparedwith the deposit of cryptoexplosive breccia type, galena lode and fluorite lode, themetallogenesis of F40fracture alteration zone may have gone through multistage andlong transformation and the enrichment of hydrotherm, so the metallogenesis is moreintense.Rb-Sr isotope testing showed the metallogenic time is129±45Ma in study areawhich means the metallogenic time of Xiahaoping-Dianfang gold deposit is lateYanshannian period.According to the study, the vertical zoning sequence of deposit geochemistry wasestablished that is Mo-Au-Cu-As-W-Ag-Pb-Sb-Bi.The mineralization prospect of goldand its associated metals in deep was predicted.