首页|Mantle contributions to granitoids associated with Sn mineralization:Geochemical and isotopic evidence from the giant Dachang deposit,South China

Mantle contributions to granitoids associated with Sn mineralization:Geochemical and isotopic evidence from the giant Dachang deposit,South China

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Major Sn deposits are commonly linked to crust-derived and highly evolved granites,with magma gener-ation aided by mantle heating.However,whether and how the mantle components contribute to Sn poly-metallic mineralization remains unclear.In this study,in combination with a compilation of equivalent data in the region,we provide new constraints on this issue based on detailed investigations on the pet-rogenesis and metallogenic significance of granitoids including the causative batholith and later granodi-orite porphyry dike in the giant Dachang Sn deposit from South China.The former has zircon U-Pb ages of 93-91 Ma and belongs to highly evolved S-type biotite granite,which experienced fractionation of mas-sive feldspar.The latter shows zircon U-Pb ages of 90 Ma and displays I-type granite features.The bath-olith was mainly derived from the dehydration melting of biotite in the metasedimentary sources,as revealed by the relatively low whole-rock Pb contents(＜30 ppm)and high Ba/Pb ratios(2.71-17.1)and initial T(ti-zr)of 790 ℃.Compared with the adjacent crust-derived S-type granites(-24.8--5.1)and 1-type granites(-11.0 to-5.2),the Dachang S-type biotite granites present higher zircon eHf(t)values(-9.1 to-2.1).Furthermore,the low magmatic zircon 618O values(6.2 ‰)and higher apatite LREE(3277-4114 ppm)and Sr(1137-1357 ppm)contents than of arc-type basic rocks were discerned.These characteristics jointly hint the contributions of mantle components.The higher initial T(ti-zr)(＞850 ℃),whole-rock Mg#(52 to 58),apatite εNd(t)(-9.2 to-6.5)and zircon EHf(t)(-7.6 to 2.5)values but lower zircon δ18O values(6.33 to 8.30 ‰)of the later granodiorite porphyry dike than those of the batholith also suggest that mantle material was involved in the generation of the dikes,which is evident by the variational features of zircon and apatite trace elements.In addition,at the zircon Hf＜12000 ppm and Eu/Eu*＞0.05,the higher zircon △FMQ values(mostly from-1.8 to 2.0)and H2O contents(100-1100 ppm)of the Dachang granitoids than the pure crust-derived S-type granites(△FMQ=mostly from-3.7 to-1.5;H2O＜100 ppm)imply that mantle materials involved are relatively rich in water and oxidized.These suggest that the addition of mantle components is conducive to the extraction of Sn from metased-imentary sources,and moderately facilitates the increase of oxygen fugacity which still maintains the incompatibility of Sn in magmas with △FMQ＜2.Also,the involvement of mantle components upgrades the H2O contents in S-type magmas,favoring the migration of ore-forming elements from magmas to hydrothermal fluids.The sediment-derived causative granites displayed higher εHf(t)and εNd(t)values with greater Sn tonnages of their associated world-class Sn polymetallic deposits,supporting the opinion that the contributions of mantle components play an important role in the generation of giant Sn deposits.

Highly evolved S-type biotite graniteI-type granodiorite porphyry dikeCrust-mantle mixingMantle contributionsDachang Sn mineralization

Tingyi Wang、Qihai Shu、Xiaoping Xia、Chao Li、Yanning Wang、Jiahao Chen、Xiang Sun、M.Santosh、Qingfei Wang

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State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China

Frontiers Science Center for Deep-time Digital Earth,China University of Geosciences(Beijing),Beijing 100083,China

State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China

National Research Center for Geoanalysis,Chinese Academy of Geological Sciences,Beijing 100037,China

Department of Earth Science,University of Adelaide,Adelaide,South Australia 5005,Australia

State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China

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国家自然科学基金Key Project of the Resource Exploration Bureau in Guangxi ProvinceKey Project of the Resource Exploration Bureau in Guangxi ProvinceKey Project of the Department of Natural Resources in Guangxi ProvinceKey Project of the Department of Natural Resources in Guangxi Province111 Plan under the Ministry of Education and the State Administration of Foreign Experts Affairs,ChinaScience and Technology Leading Talents Team Funds for the Central Universities for the Frontiers Science Center for Deeptime中央高校基本科研业务费专项

92162215201822201918201967320201111B070112652023001

2024

10.1016/j.gsf.2023.101718

地学前缘(英文版)
中国地质大学（北京） 北京大学

地学前缘(英文版)

CSTPCD
影响因子：0.576
ISSN：1674-9871
年,卷(期)：2024.15(1)
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