Discriminating characters of ore-forming intrusions in the super-large Chalukou porphyry Mo deposit,NE China

作     者：Peixin Duan Cui Liu Xuanxue Mo Jinfu Deng Jinhua Qin Yu Zhang Shipan Tian 

作者机构：School of Earth Sciences and ResourcesChina University of GeosciencesBeijing 100083China Heilongjiang Institute of Geological SurveyHarbin 150036China Heilongjiang Province Institute of Regional Geology SurveyHarbin 150080China 

出 版 物：《Geoscience Frontiers》 (地学前缘（英文版）)

年 卷 期：2018年第9卷第5期

页      面：1417-1431页

核心收录：

学科分类：07[理学] 

基　　金：funded by the projects of China Geological Survey (Grant Nos. DD20160123 (DD-16-049  D1522)  12120114020901  1212011220928 and 1212011121075) 

主　　题：Greater Hinggan Range Chalukou porphyry Mo deposit Geochronology Ore-forming intrusions Mongolia-Okhotsk ocean 

摘      要：The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain *** we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum *** U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce^(4+)/Ce^(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area.