Geological Characteristics and Metallogenic Environment of the Longweigou Porphyry Copper(tungsten) Deposit,Gansu

The Longweigou porphyry copper(tungsten) deposit,a newly found deposit,lies in the Oulongbuluke uplift belt of the Qilian orogenic belt.The evaluation and research of the Longweigou copper(tungsten) ore deposit will present important guidance and reference for copper exploration in the Qilian Mountain area.The chronology and the geochemistry of the ore-bearing porphyry deposit were studied and the occurrence features of the deposit,the components of gold mineral and the alteration of the wall rock were investigated.Results showed that the formation age of the granodiorite porphyry is 358.7Ma;and that the ore-body,which has occurrences of stratiform or lenticular or vein,occurs mainly in the high potassium alkali series porphyry and is controlled by NS structures;and that chalcopyrite,pyrite,pyrrhotite,and scheelite are main ore minerals,which have veinlet-disseminated and disseminated structures;and that mineralization is characterized by enriching copper,tungsten and gold and depleting molybdenum;and that the mineralization related wall-rock alterations are mainly sericitization and secondly potassium-silicate alteration and silisification;and that the metallogenic epoch is the early Variscan and the deposit was formed in the inner-continental oregenic extension setting.On the basis of the above finds,we believe that the porphyry copper deposit,which formed the intra-continent orogeny of the Qilian area,has excellent prospecting potential.