Ore-forming Mechanism Of The Jilongshan Au Skarn Deposit In Southeastern Hubei

Jilongshan skarn Au deposit is located in the Southeast Hubei province,Ore host strata is the Daye Formation of the Triassic,Folds and faultsare important ore control structures;Intrusions formed during the intense magmatism of the Mesozoic,granodiorite porphyry and the mineralization has genetic relationship;Gold ore bodies on a certain scale occur in the contact zone between the granodiorite porphyry and ore host strata.A detailed study has been carried out on the skarn deposit,with a focus on an analysis of skarn evolution and ore genesis so as to set up a mode of Au skarn mineralization.The following are major achievements obtained in this dissertation.1.The Re-Os isochronal age is 149.5 ± 1.2 Ma of theJilongshan Au skarnDeposit forming Late Jurassic,the product emplaced by acidic magma and hydrothermal belonging to the late stage of Yanshan.Ore-forming materials is the crust-mantle mixed type,having the characteristics of magmatic origin.2.Jilongshan rock diagenetic age of 151 ± 1 Ma,the rock mass is fromed by rising and emplaced with lava composed of crust and mantle,formed in the period of the main ore-bearing rocks in the Southeastern Hubei,consistent with magmatic activities partition and evolution trend in Southeastern Hubei.3.Jilongshan granodiorite porphyry has the characteristics of moderate enrichment of silicon,aluminum and total alkali content;trace element is rich in large ion lithophile elements Sr and compatible elements Cr,Co,Ni,V and loss of Nb,Ta,La,Ti,P,Y,Yb;rare earth elements is rich in light rare earth elements,no obvious negative Eu anomalies and negative Ce anomalies.Preliminary studies show,Jilongshan ore-bearing rock is peraluminous high-k calc-alkaline type I-granodiorite porphyryand,a part of magmatic activity-rock events in the southeastern Hubei lithospheric extensional geodynamic background.4.The skarn mineralogy character reveal the garnet belongs to the calcium aluminum-calcium iron series,pyroxene diopside,the calcium iron garnet-diopside symbiotic gold-rich skarn combination is formed at high oxygen fugacity and relatively low in acidity condition,with copper,gold metallogenetic specialization;Along with the fluid evolution,skarn and ores have close relation in space and origin;Combination of mining development in a porphyry orebody,Jilongshan Gold deposit may have unified porphyry-skarn mineralization system,deep with great prospecting potential.