Metallogenic Condition And Prospecting Model Of Explosive Breccia Type Molybdenum Copper Gold Deposit In Tai Ping Ling Volcanic Rock Zone

The study area is south margin of Jiamusi Terrain, bordered by the Dunmi faultedzone, which metallogenetic division belongs to Palaeo-Asian metallogenic domain, Jilinand Heilongjiang metallogenic provinces and Tai Ping Ling metallogenic belt. Thisregion is one of gold and polymetallic metallogenic prospecting areas related to avolcano-magmatic activity during late Jurassic and the early stage in eastern Jilin andHeilongjiang provinces.The aim of this paper is to analyze the cause of acid subvolcanic rock closely relatedto crypto-explosive breccia pipe in Tai Ping Ling volcanic rock zone and thecharacteristic and classification of breccia pipe in study area. In condition, based onore-forming age, volcanic and sub-volcanic rock, physicochemical property and genesisof this deposit, it aims to study the geological characteristics of crypto-explosive brecciatype deposit. Thought spot investigation in typical deposit, this paper generalizes theore-control regularity, prospecting indications and information from geophysics,geochemistry and remote sensing in study area so as to build prospecting model andprovide important evidence for future prospecting in the area.According to the petrochemical characteristics, subvolcanic rocks in this areabelongs to metaluminous to peraluminous and calc-alkaline series.Geochemicalcharacteristics and regional tectonic evolution background indicate that the rocks formedin island arc（active continental margin）type from compressive orogenic environment topost-orogenic extension environment. Based on some specific characteristics of brecciatype deposit, it can be divided into two groups：breccia pipe related to intermediate rock and breccia pipe related to acid rock. It is found that crypto-explosive breccia pipe ofintermediate rocks interrelates to Au and it of acid rocks interrelates to Cu, Mopolymetallic mineralization.The granodiorite porphyry of copper-molybdenum deposit in Jin Chang Gou hasbeen tested by U-Pb method and its weighted mean age is114.08±0.82Ma. Combinedwith other associated data, metallogenic epoch of the same type deposits baselyconcentrates on96.9-118.9Ma. Isotopic and trace elements data show that the majormetallogenetic matters originated from crust-mantle contamination. Hydrothermal oreforming solution mainly comes from magmatic water mixed by atmospheric water. Theresult from fluid inclusion examination indicates that the ore-forming temperature isabout60-550℃and ore-forming depth is0.6-2.5km. The Cu-Mo-Au deposit in JinChang Gou can be regarded as crypto-explosive breccia pipe related to acid rocks. JinChang gold deposit is crypto-explosive breccia pipe related to intermediate rocks.The main ore control factors of crypto-explosive breccia deposit in Tai Ping Lingvolcanic rock zone are multiphase tectonic activities and acid magmatic activities duringYanshannian period, which multiphase tectonic activities are dominant and acidmagmatic activities are decisive. The geological-geochemical characters andmetallogenetic specialization of hypabyssal-ultrahypabyssal and sub-volcanic intrusiverocks have a close relationship with Au, Cu poly-metallic metallogenesis, which are theimportant prospecting marks. The intersection part of faults dominate spatial distributionof eruption centers and sub-volcanic hypabyssal rock. Huangsongqun Gr low grademetamorphic rocks are main surrounding rock of the deposits, two-mica quartz shist,which contact zone with intermediate-acid rocks can be taken as prospecting criteria.Alteration assemblages of pipe are mainly silicification-pyritized-sericitization andsericitization-kaolinization based, and potassic alteration, carbonatation, chloritization.Stream sediment survey of1:50000-1:100000indicates that the composite anomalyof Cu, Pb, Zn, Mo, Au, Ag, and As is significant prospective area for gold polymetallicdeposits. There is a corresponding relationship between soil geochemical anomaly andcrypto-explosive breccia pipe. Geochemical anomaly of front elements like Cu, Mo, Au, Ag arranged in circles. Gravimetric and aeromagnetic methods are important fordelineation intermediate-acid rocks related to crypto-explosive breccia pipe.Mineralization in breccia pipe or where the ore bodies might be present shows lowresistance high polarization. The upper part of the ore body appears combined profilingorthogonal point. The varying characteristics of ρs section isoline corresponds to tiltedcharacter of the pipe. Crypto-explosive breccia vein are distributed in the edge of largecircular structure, intersect places of large circular structure and small one, the structurewhich formed as "φ" by fracture and circular structure. In all, through an integratedapproach of "geological-geophysical-geochemical-remote sensing", prospecting modelcan be built for crypto-explosive breccia pipe with orebody.