Characteristics And Their Geological Significance Of Paleoproterozoic Granite In Jinchuan, Gansu Province

Jinchuan is one of the most impostant bases of nonferrous metal and noble metal in China and, Jinchuan Cu-Ni sulfide (platinum-containing) deposit is one of well-known super-large magmatic cu-ni sulphide deposits all over the world. Paleoproterozoic granite is the preddmonant country rock around the Cu-Ni sulfide (platinum-containing) deposit.In this paper, Jinchuan paleoproterozoic granite was studied by petrography, mineralogy and geochemistry, etc, and we find out the petrography and geo chemistry characteristics of paleoproterozoic granite and, the forming environment was analyzed.Understandings below were obtained in this research:1. Jinchuan granite body consists of adamellite and granite, which is metaluminous and alkali.2. Granitoid mainly in study area consists of amphibole, biotite, plagioclase, potassic and quartz. Among them, most of potassic is orthoclase and, main plagioclase is albite, minority is oligoclase.3. In study area, REE appear to LREE enrichment, and trace elements content was higher than those in primitive mantle, and incompatible elements enriched. It can be thicked that, the structural environment of granite body is post-collisional.4. Jinchuan granite was determined using the zircon U Pb method to have an age of 2233±15.16Ma, MSWD=0.90.5. Compared the elements abundance distribute of granitoid, lithochemistry, the characteristics of elements ratios, trace elements and Pb isotope of the tectonic area of north China and south China, we find that Jinchuan is more close to north china landmass, so it can be assigned to tectonic region of north china.