Geological Characteristics and Metallogenic Model of Dewulu Skarn-type Copper Deposits in West Qinling, Gansu Province

The Dewulu skarn-type copper deposit is located in western Qinling of south Shangdan Suture, Gansu Province. The intrusion of Dewulu ismainly granodiorite. The impulsive intrusion of the comagmatic magma formed granodiorite porphyry and micro-crystal quartz diorite, the later metalliferous magmatic hydrothermal filled and replaced the wall rock and formed skarnization marble and diopside-garnet skarn. The main industrial orebody occurs in the skarn. Mineralization concentrated in the complex zone that intercalated by intrusive dykes. The ore shoot occurs in the cove of the intrusion or the extending area of the apophyse. During the Indosinian movement in Middle-Late Triassic, deep earth crust melted and became magma, containing abundant mineral resources. Research results show that magma of deep crust melts carried abundant metallogenic materials to replace the wall rock and make the ore mineral precipitate in the condensation and diagenetic process, forming skarn-typeand hydrothermal-type mixed copper deposit. Areaswith early Yanshanian granodiorite, granite diorite porphyry(vein), quartz diorite porphyrite and diopside-garnet skarn, skarnization marble, area containing malachite, azurite, ferritization, and other oxidized minerals, accompanied by area with magnetic anomaly, secondary halo of copper and low resistivity, are favorable prospecting places. Thus, the Longdegang-Meiwuxinsi district is considered to be a favorable area for ore prospecting.More exploration and research work should be conducted there.