Mineral Chemistry,Trace Elements,Isotopic Analysis and Zircon U-Pb Dating in the Hesar Pluton,Northern UDMA,Iran:Implications for Pre-Collisional Magma Mixing  

作　　者：Kazem KAZEMI Soroush MODABBERI Parisa GHARIBNEJAD XIAO Yilin Fatemeh SARJOUGHIAN Ali KANANIAN 

机构地区：[1]School of Geology,College of Science,University of Tehran,Tehran,Iran [2]Research Centre for Mineral Resources,Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China [3]National Key Laboratory of Ecological Security and Resource Utilization in Arid Areas,Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China [4]Department of Geochemistry and Environmental Sciences,School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China [5]Department of Earth and Sciences,Faculty of Sciences,University of Kurdistan,Sanandaj,Iran [6]Department of Science Education,Farhangian University,Tehran,Iran

出　　处：《Acta Geologica Sinica(English Edition)》2024年第3期657-678,共22页地质学报（英文版）

基　　金：supported by the Iran National Science Foundation(INSF)(Grant No.98012578);projects from the National Natural Science Foundation of China(Grant Nos.41473033,41673031)。

摘　　要：The Hesar pluton in the northern Urumieh-Dokhtar magmatic arc hosts numerous mafic-microgranular enclaves(MMEs).Whole rock geochemistry,mineral chemistry,zircon U-Pb and Sr-Nd isotopes were measured.It is suggested that the rocks are metaluminous(A/CNK=1.32-1.45),subduction-related I-type calc-alkaline gabbro to diorite with similar mineral assemblages and geochemical signatures.The host rocks yielded an U-Pb crystallization age of 37.3±0.4 Ma for gabbro-diorite.MMEs have relatively low SiO_(2) contents(52.9-56.6 wt%)and high Mg^(#)(49.8-58.7),probably reflecting a mantle-derived origin.Chondrite-and mantle-normalized trace element patterns are characterized by LREE and LILE enrichment,HREE and HFSE depletion with slight negative Eu anomalies(Eu/Eu^(*)=0.86-1.03).The host rocks yield(^(87)Sr/^(86)Sr)_(i) ratios of 0.70492-0.70510,positive ε_(Nd)(t)values of+1.55-+2.06 and T_(DM2)of 707-736 Ma,which is consistent with the associated mafic microgranular enclaves((^(87)Sr/^(86)Sr)_(i)=0.705014,ε_(Nd)(t)=+1.75,T_(DM2)=729 Ma).All data suggest magma-mixing for enclave and host rock formation,showing a complete equilibration between mixed-mafic and felsic magmas,followed by rapid diffusion.The T_(DM1)(Nd)and T_(DM2)(Nd)model ages and U-Pb dating indicate that the host pluton was produced by partial melting of the lower continental crust and subsequent mixing with injected lithospheric mantlederived magmas in a pre-collisional setting of Arabian-Eurasian plates.Clinopyroxene composition indicates a crystallization temperature of~1000℃ and a depth of~9 km.

关 键 词：ENCLAVE magma mixing zircon U-Pb dating Urumieh-Dokhtar magmatic arc 

分 类 号：P597.3[天文地球—地球化学]