| Yamansunan?YN?Indosinian granite pluton consists of YN number?number of pluton and YN number?of pluton.Zircon LA-MC-ICP-MS U-Pb dating results show that the crystallization age of?and?are 243±6Ma and 217±12M a.Geochemically,YB number?of pluton is characterized by high silicon?SiO2=75.83%75.83%?and alkali?Na2O+K2O=8.54%8.61%?,low titanium,calcium and magnesium,which attributes to peraluminous granite rock?A/CNK=1.031.05?and high K calc-alkaline granite;The pluton is also rich in Rb,K,Th,U,Zr,Ta and Hf,and depleted Sr,Ba,Eu,P,Ti and Nb;?REE is relatively low,and LREE and HREE fractions are not obvious,the Eu??Eu=0.080.10?is strongly negative anomalies.YB number?of pluton is characterized by high silicon?SiO2=75.58%75.58%?and alkali?Na2O+K2O=8.36%8.68%?,low titanium,calcium and magnesium,which attributes to peraluminous granite rock?A/C NK=0.040.05?and high K calc-alkaline granite;The pluton is also rich in Rb,K,Th,U,Zr,Ta and Hf,and depleted Sr,Ba,Eu,P,Ti and Nb;?REE is relatively low,and LREE and HREE fractions are not obvious,the Eu??Eu=0.160.25?is strongly negative anomalies.The?pluton of value is lower than the?pluton in?HREE.The geochemistry characteristics of the two rocks are similar,and they show the characteristics of the Highly fractionated I-type granite.Zircon in-situ Hf isotopic composition analysis yields the?Hf?t?and tDM2values of the YB number?pluton varying-1.3+5.9 and 8911351Ma,and the ?Hf?t?and tDM2values of the YN number?pluton varying+2.1+6.5 and 8351113Ma.Based on geochemical and Hf isotopic characteristics and the regional tectonic evolution,the study indicates that the YN pluton resulted from mantle magma underpalting induced partial melting of the Meso-neoproterozoic new-born crust.and it subjected to high degree of fractionation.Combining previous research this paper suggests the geodynamic background of the rock mass of YN may be a continuation of the post-collision phase of hercynian. |
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