The Ore Genesis And Ore-searching Prospects Of Copper Deposit In Datongchang, Huili County, Sichuan Province

The Datongchang copper deposit in Huili County, is one of the most importantmedium-sized copper deposit in Sichuan Province，which is the typical representativeof glutenite type copper deposit. It located the western margin of Yangtze plate，andalso the southwest side of the Huili Mesozoic rift basins in the eastern edge of Sichuanand Yunnan north-south tectonic zone the middle of the Kang-Dian axis. On the basisofprevious studies and combining the existing data，this article summarizes the genesisof Datongchang copper deposit and evaluates the ore-searching prospects in this basinby the study of regional geological background and geological features. It analysis thecontaining ore lithology，ore fabric，geochemical exploration，key ore-controllingfactors and forming material source of the Datongchang copper deposit.The Datongchang copper deposit exist in the Xiaoba group strata of lateCretaceous in the Mesozoic. Its ore lithology main contains sandstone andconglomerate and its orebody outputs as layered and bedded，which gradientconformable contact with wall rock and shows apparent stratabound characteristics.The ore minerals in this area mainly is barrels of sulphides and secondary copper oxide.It can be find that ore and wall rock has the same mineral composition andgeochemical characteristics by analyzing the mineral composition and Geochemicalexploration of ore and wall rock in Datongchang copper deposit. Ore and wall rock hasthe same material sources or close genetic relationship because the content andcharacteristic parametersofconstant element，trace elements and rare earth elements isbasically the same in Datongchang copper deposit. It can be knowed that themineralization mainly happens in partial restore the environment and there is rare earthelements such as migration bythe analysis of indicative elements and parameters oftheenvironment. At the same time，the feature of sulfur isotopes and lead isotopes in this deposit shows the mineralization occurs mainly in the transformation ofpost-diagenetic. The analysis of the source area into the minerals directly from theore-bearing rock series shows that the remote source of ore for the high basin aroundthe copper magmatic rocks and old strata, the Mosuoying to the north west side of thebasin granite body and the west side of Longzhou Hill basalt body as the main source.The Datongchang copper deposit orebodies in the north-south Qingwajia anticlineeast wing of rock production like gently inclined lot or rock convergence slowed by thesteep parts of the sandstone, conglomerate. Holding ore body to the river side beachgravel with impurity-based little, sorting good and high permeability characteristics.The mineralization is mainly affected by the control of groundwater rich in salts on theone hand, due to the presence of paste rock, groundwater, copper in the form ofcomplexes with migration with groundwater dissolved in water; the other hand, thewater table near the oxide reduction zone is actually a conducive copper geochemicalbarrier reduction precipitation with copper complex forms of existence with thegroundwater to migrate to more conducive to slow groundwater directional flow ofgood permeability of the rock slow tilt parts, namely, in this barrier band is reduced tocopper sulfide precipitation down gradually to the formation of copper ore bodies.The comprehensive studies have shown that the Datongchang copper deposit is adeposition–the transformation of the causes of sandy conglomerate-type copperdeposit which is controlled by groundwater. Its metallogenic model can roughly bedivide into four stage，which is source of ore formation stage，copper activationmigration stage，the sand body storage of ore in place the stage and enrichment andmineralization stage. This study shows that the analysis of prospecting perspective ofthe exact location in the Huili Mesozoic rift basins should consider the influence byspatial location, direction of groundwater flow, nature of the ore reserve body, attitudeof rocks and other factor.