The Geological Condition Of Ore-Forming And Direction Of Exploration Study For Jingushan Au-Deposit In Yanbian Ar Ea, Jilin Province

Jingushan Au deposit is located southwestwardly about 8km to Kaishan town of Longjin city, Jilin Province. And its physical position is E: 129°40′00″~129°44′00″, N: 42°36′00″~42°40′00″, while its transmeritional length is 6km, south-north width is 5.5 km, and its area is about 33km2. There are some geography teams,institutes worked there continuously since 1965. Some ore bands and ore bodies were discovered with profounded work. The deposit will be great ore-searching foreground due to more than 10 tons estimate gold reserved there.Tectonically, the deposit is located on the paleosuture zone between the Xingkai Block and the Pohai Block, the conjunct area between E-W tectonic zone controlled by continental margin active belt of Paleo-Asian Ocean and N-E tectonic zone controlled by continental margin active belt of the western Pacific Ocean. Such tectonic setting will be propitious to forming ore.The host rocks of Jingushan deposit is a set of the metamorphic rock series of Permian Kedao formation. The metamorphic grade of the rocks is low greenschist facies, and the metamorphic assemblage is sericite + chlorite + quartz + albite, the main rock type are metavolcanic lava, metapyroclastic rock, matavoclaniclastic sedimentary rocks, metapyroclastic turbidite, metaintrusive rock, phyllite and mylonite. The original rock is mainly neutral-acidic metavolcanic- metapyroclastic sedimentary rocks. Kedao Formation is the source bed of Jingushan deposit because the ore bodies have not special preference on host rocks, and the contents of Au,As,Sb in host rock are universally higher than those in the crust average and the regional strata average, indicating their close genetic relations, Kedao formation is the source bed of Jingushan deposit.Jingushan deposit's Au mineralization has a close relationship with basic-ultrabasic rock of Variscan orogemy later period. The ore bodies of the deposit mostly found around the contact belt of rock mass and Kedao formation. The rock mass is the product of tectono-magmatic active. The main rock type include harzburgite,gabbro,diabase. The contents of Au,As,Cr,Ni,Co,Mo,Cu,Pb,Zn in basic-ultrabasic rock are higher than those in the crust Clarke, indicate that basic-ultrabasic rock provide Au,As ore-forming material for Jingushan gold deposit.The deposit is controlled by Jingushan anticline structure and ductile shear deformation and metamorphism belt. Jingushan anticline is a typical Ramsay dome-basin superposed fold, its main strike is N-S, later EW fold superposed on it, made its axial trace curviplanar buckling, stick out to the west, assume as a dome. Small scale folds are often seen in Jingushan acticline. Because of the interlayer-gliding of anticline fold, in high stress area and frail layer grow ductile shear deformation and metamorphism belt, the types of mylonite are mylonization rock, initialmylonite,mylonite and ultramylonite. The higher rocks mylonization grade and the better ore-bearing. The ore bodies in the deposit are mostly preserved in anticline plunging crown in ductile shear deformation and metamorphism belt. And its attitude are the same as ductile shear belt's or intersected it with a small angle. The ore bodies are usually vein, lensoid, lenticular shaped with apparent branching and merging pinching and swelling. The main ore minerals include pyrite arsenopyrite, then are chalcopyrite sphalerite galena native gold electrum and so on. the tectures of ores are featured by hypidiomorphic granular texture metasomatic relict texture crush texture erosion texture. The structure of ores include brecciated structure vein structure disseminated structure and massive structure. Wallrock alteration is in ductile shear belt and its round area, including silicification,sericitization, carbonatization,chloritization,pyritization,alunitization and so on.The tensile act of Miaoling Aulacogen of Permian, the area was in semienclosed neritic hydrologic basin, volcano outbreak was induced by aulacogen, accompanied by some...