Petrogenesis and Magmatic Evolution of Highly Fractionated Granite and Their Constraints on Sn- (Li-Rb-Nb-Ta) Mineralization in the Weilasituo Deposit, Inner Mongolia, Southern Great Xing'an Range, China
Zhang Tianfu
Guo Shuo
Xin Houtian
Zhang Yun
He Peng
Liu Wengang
Zhang Kuo
Liu Chuanbao
Wang Kexiang
Zhang Chao
Abstract：In recent years, great breakthroughs have been made in the deep Sn-Li prospecting in the Weilasituo area of the southern of Great Xingan Range.However, the genesis and evolution of deep hidden rock mass closely related to the mineralization has not been studied in depth.In this paper, this cancealed granite was selected as example for a detailed geochronological, geochemical and Sr-Nd-Hf isotopic composition study in order to elucidate their petrogenesis.LA-ICP-MS U-Pb zircon age for Weilasituo pluton was 130.7±0.5Ma (MSWD=0.53) , indicating that it was generated in Early Cretaceous.Chemically, Weilasituo granite is metaluminous- (weakly) peraluminous (A/CNK concentrated in the range of 1.02-1.08) , which shows high contents of silica, alkalis and natrium, low abundances of calcium, magnesium, iron and extremely low P2O5 (<0.01％) , with high Rb/Sr, Nb/Ta and low Zr/Hf ratios.They are also enriched in Cs, Rb, Th, U, Nb, Ta, Li, F and depleted in Ba, Sr, Ti, REE elements with low LREE/HREE ratios and obviously negative Eu abnormality (δEu=0.02-0.15) .Zircon saturation temperatures (691-727℃) and Zr+Nb+Ce+Y contents of Weilasituo pluton are less than those of the low-limit values of the A-type granite.Integrated geological and geochemical data suggest that the pluton was highly fractionated I-type granite.The granite has positiveεNd (t) (+1.10-+3.75) and relatively highεHf (t) (+4.2-+8.7) and young two-stage Nd and Hf model ages (T (Nd) CDM=607-829Ma;T (Hf) CDM=627-914Ma) , suggesting that the rock was dominantly derived from the partial melting of a juvenile lower crust with a mass of mantle magma mixed into the crust, followed by fractional crystallization during magma ascent.The Sn- (rare-metal) mineralization of the pluton was controlled jointly both by high fractionation of the magma and fluid-melt interaction during the late stage.A complete magmatic-hydrothermal system was revealed by the Sn- (rare-metal) mineralization granite with the surrounding vein ore bodies.
Keywords：highly fractionated I-type granitesouthern of Great Xing'an RangeWeilasituo depositzircon U-Pb datingNd-Hf isotopesrare metalgeochemistry
Publication Date：2019-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：20( 248-267 )