Petrogenesis of the concealed Daqiling intrusion in Guangxi and its tectonic significance: Constraints from geochemistry, zircon U-Pb dating and Nd-Hf isotopic compositions  

作　　者：ZHANG HuaiFeng LU JianJun WANG RuCheng MA DongSheng ZHU JinChu ZHANG RongQing 

机构地区：[1]State Key Laboratory of Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University [2]Uranium Resources Company Limited, China Guangdong Nuclear Power Corporation

出　　处：《Science China Earth Sciences》2014年第8期1723-1740,共18页中国科学（地球科学英文版）

基　　金：supported by National Key Basic Research Program of China (Grant No. 2012CB416702);National Natural Science Foundation of China (Grant No. 41230315);China Geological Survey Program (Grant No. 1212011085407)

摘　　要：The samples from the hidden Daqiling muscovite monzonite granite, which has recently been recognized within the Limu Sn-polymetallic ore field, have been analyzed for zircon U-Pb ages and whole rock geochemical and Nd-Hf isotopic compositions to discuss its genesis, source, and tectonic setting. LA-ICP-MS zircon U-Pb dating indicates that the granite crystallized in the late Indosinian（224.8±1.6 Ma）. The granite is enriched in SiO2 and K2 O and low in CaO and Na2 O. It is strongly peraluminous with the A/CNK values of 1.09–1.20 and 1.4 vol%–2.7 vol% normal corundum. Chondrite-normalized REE patterns show slightly right-dipping shape with strongly negative Eu anomalies（δEu =0.08–0.17）. All samples show enrichment of LILEs（Cs, Rb and K） and HFSEs（U, Pb, Ce and Hf）, but have relatively low contents of Ba, Sr and Ti. The zircon saturation temperatures（Tzr） are from 711 to 740°C, which are slightly lower than the average value of typical S-type granite（764°C）. The granite has negative εNd（t） and εHf（t） values, which change from ？9.1 to ？10.1 with the peak values of ？9.2 to ？9.0 and from ？3.7 to ？12.6 with the peak values of ？6 to ？5, respectively. The C DMT（Nd） and C DMT（Hf） values are 1.74–1.82 Ga with the peak values of 1.73–1.75 Ga and 1.49–2.04 Ga with the peak values of 1.5–1.6 Ga, respectively. These characteristics reveal that the source region of the granite is dominantly late Paleoproterozoic to early Mesoproterozoic crustal materials. Seven inherited magmatic zircons are dated at the age of 248.6±4.3 Ma, which suggests the existence of the early Indosinian granite in Limu area. These zircons have the εHf（t） values of ？6.7– ？2.3, similar to those of the Daqiling granite, implying the involvement of the early Indosinian granite during the formation of the Daqiling granite. Inherited zircon of 945±11 Ma has the εHf（t） and TDM（Hf） values of 8.7 and 1.14 Ga, respectively, compatible with those of the Neoproterozoic aThe samples from the hidden Daqiling muscovite monzonite granite, which has recently been recognized within the Limu Sn-polymetallic ore field, have been analyzed for zircon U-Pb ages and whole rock geochemical and Nd-Hf isotopic compositions to discuss its genesis, source, and tectonic setting. LA-ICP-MS zircon U-Pb dating indicates that the granite crystallized in the late Indosinian(224.8±1.6 Ma). The granite is enriched in SiO2 and K2 O and low in CaO and Na2 O. It is strongly peraluminous with the A/CNK values of 1.09–1.20 and 1.4 vol%–2.7 vol% normal corundum. Chondrite-normalized REE patterns show slightly right-dipping shape with strongly negative Eu anomalies(δEu =0.08–0.17). All samples show enrichment of LILEs(Cs, Rb and K) and HFSEs(U, Pb, Ce and Hf), but have relatively low contents of Ba, Sr and Ti. The zircon saturation temperatures(Tzr) are from 711 to 740℃, which are slightly lower than the average value of typical S-type granite(764℃). The granite has negative εNd(t) and εHf(t) values, which change from -9.1 to -10.1 with the peak values of -9.2 to -9.0 and from -3.7 to -12.6 with the peak values of -6 to -5, respectively. The C DMT(Nd) and C DMT(Hf) values are 1.74–1.82 Ga with the peak values of 1.73–1.75 Ga and 1.49–2.04 Ga with the peak values of 1.5–1.6 Ga, respectively. These characteristics reveal that the source region of the granite is dominantly late Paleoproterozoic to early Mesoproterozoic crustal materials. Seven inherited magmatic zircons are dated at the age of 248.6±4.3 Ma, which suggests the existence of the early Indosinian granite in Limu area. These zircons have the εHf(t) values of -6.7– -2.3, similar to those of the Daqiling granite, implying the involvement of the early Indosinian granite during the formation of the Daqiling granite. Inherited zircon of 945±11 Ma has the εHf(t) and TDM(Hf) values of 8.7 and 1.14 Ga, respectively, compatible with those of the Neoproterozoic arc magmatic rocks in the eastern Jiangnan orogenic belt. Therefore we in

关 键 词：Daqiling concealed granite zircon U-Pb dating Nd-Hf isotopic compositions petrology and geochemistry POST-COLLISION 

分 类 号：P597[天文地球—地球化学] P588.121[天文地球—地质学]