关键词: 岩浆岩, 地球化学特征, 岩浆起源, 斑岩钼矿床, 北淮阳地区

Abstract:

There are numerous porphyry molybdenum deposits located in the eastern Beihuaiyang area of QinlingDabie metallogenic belt, where the magmatism is closely related to mineralization. This study has investigated the intrusive rocks in the field which are closely related with porphyry molybdenum deposit, by using the method of wholerock major elements, trace elements and isotope geochemistry research, and discussed its petrogenesis. This research shows that the scale of metallogenetic rock body is small, and the lithology is porphyry granite, which is controlled by the fault structure in northeast and northwest. The chemical composition of rocks is characterized by high silicon, and potassium alkali rich, belonged to highK calcalkaineshoshonitic series, metaluminousperaluminous rocks. Trace and rare earth elements have similar characteristics and show features of crustal sources. Sr Nd Pb Hf isotope geochemical characteristics show that those matallogenic granitic magma has the same sources with Dabie Cretaceous granites. They both originated from Dabie granitic gneiss and TTG like magmatic rocks of the north Yangtze Block in the Neoproterozoic, and interfused some ancient crustal materials from palaeoproterozoic Yangtze craton(such as Kongling complex). The lower crust delamination, asthenosphere upwelling and largescale crustal extension happened in the Cretaceous, the northern margin of Yangtze craton crust melted and provided the mainly diagenetic materials. Upwelling of mantle derived magma probably provided heat source with little materials. The igneous rocks associated with Mo Deposits in this region are similar to Eastern Qinling metallogenic belt, which belongs to deephypabyssal granitoids.

Key words: igneous rocks, geochemical characteristics, magma source, porphyry molybdenum deposit, Beihuaiyang region