In situ U-Pb dating and trace elements of magmatic rutile from Mujicun Cu-Mo deposit,North China Craton:Insights into porphyry mineralization  

作　　者：Fan Yang Jing-wen Mao Wei-dong Ren Jia-run Tu Gilby Jepson Si-yuan Meng Zhi-min Wang 

机构地区：[1]MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China [2]Key Laboratory of Mineral Resources in Western China(Gansu Province),School of Earth Sciences,Lanzhou University,Lanzhou 730000,China [3]Tianjin Center,China Geological Survey,Tianjin 300170,China [4]Department of Geosciences,University of Arizona,Tucson AZ85721,USA [5]Hebei Geological Engineering Exploration Institute,Baoding 071051,China

出　　处：《China Geology》2024年第4期730-746,共17页中国地质（英文）

基　　金：jointly supported by the National Natural Science Foundation of China(42202077;42103025);the Opening Foundation of MNR Key Laboratory of Metallogeny and Mineral Assessment(ZS2209;ZS2106);the Opening Foundation of Key Laboratory of Mineral Resources in Western China(Gansu Province)(MRWCGS-2021-01);the Natural Science Foundation of Gansu Province(22JR5RA440);the Fundamental Research Funds for the Central Universities(LZUJBKY-2022-42);the Guiding Special Funds of“Double First-Class(First-Class University&First-Class Disciplines)”(561119201)of Lanzhou University,China。

摘　　要：Porphyry Cu(Mo-Au)deposit is one of the most important types of copper deposit and usually formed under magmatic arc-related settings,whilst the Mujicun porphyry Cu-Mo deposit in North China Craton uncommonly generated within intra-continental settings.Although previous studies have focused on the age,origin and ore genesis of the Mujicun deposit,the ore-forming age,magma source and tectonic evolution remain controversial.Here,this study targeted rutile(TiO_(2))in the ore-hosting diorite porphyry from the Mujicun Cu-Mo deposit to conduct in situ U-Pb dating and trace element composition studies,with major views to determine the timing and magma evolution and to provide new insights into porphyry Cu-Mo metallogeny.Rutile trace element data show flat-like REE patterns characterized by relatively enrichment LREEs and depleted HREEs,which could be identified as magmatic rutile.Rutile U-Pb dating yields lower intercept ages of 139.3–138.4 Ma,interpreted as post magmatic cooling timing below about 500℃,which are consistent or slightly postdate with the published zircon U-Pb ages of diorite porphyry(144.1–141.7 Ma)and skarn(146.2 Ma;139.9 Ma)as well as the molybdenite Re-Os ages of molybdenum ores(144.8–140.0 Ma).Given that the overlap between the closure temperature of rutile U-Pb system and ore-forming temperature of the Mujicun deposit,this study suggests that the ore-forming ages of the Mujicun deposit can be constrained at 139.3–138.4 Ma,with temporal links to the late large-scale granitic magmatism at 138–126 Ma in the Taihang Orogen.Based on the Mg and Al contents in rutile,the magma of ore-hosting diorite porphyry was suggested to be derived from crust-mantle mixing components.In conjunction with previous studies in Taihang Orogen,this study proposes that the far-field effect and the rollback of the subducting Paleo-Pacific slab triggered lithospheric extension,asthenosphere upwelling,crust-mantle interaction and thermo-mechanical erosion,which jointly facilitated the formation of dioritic magmas dur

关 键 词：Rutile U-Pb geochronology Rutile geochemistry Intra-continental porphyry mineralization Paleo-Pacific slab subduction Tectonic evolution Magma source Ore-forming age Mujicun Cu-Mo deposit Mineral exploration engineering North China Craton 

分 类 号：P618.41[天文地球—矿床学] P618.65[天文地球—地质学]