Characteristics and Geological Significance of the Julin Ringspotted Granite in Southwest Fujian
Julin ringspotted granite belongs to an important part of Hufang complex rock mass.The main lithology is porphyritic biotite syenite granite with longer ring pattern structure.Ring porphyry consists of a potassium feldspar core and a ring edge of a plagioclase(feldspar)outer shell.Si,NK,K are rich and Al,Ca,Mg are poor in the rocks.K、Rb、Th、U、Pb、REE of LIFE elements are rich and Eu、Ba、Nb、Sr are strongly poor.Zr,Th,Ce HFSE elements of are enrichment and P,Ti are obviously missing and Nb,Ta,Y,Hf are relative deficit.The total amount of rare earth elements is high,the light rare earth is enriched,and the Eμ negative anomaly(δEμ=0.09～0.34)is strong,which has the geochemical characteristics of A-type granite.The U-Pb isotopic ages of the two LA-ICPMS zircons are(232.9±1.4)Ma and(226±1.4)Ma,belonging to the Middle Triassic,which are related to the staged extensional and tensile tectonic setting of the Indosinian period in southwest Fujian.
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