Water-Flux Melting of Amphibolite in Paleozoic Leucogranite from the North Qinling,Central China:Implication for Post Collisional Setting  

作　　者：Jiangbo Wang Tong Li Yan Zhang Weihong Li 

机构地区：[1]State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China [2]Research Institute No.203,CNNC、Xianyang 712000,China

出　　处：《Journal of Earth Science》2020年第5期867-874,共8页地球科学学刊（英文版）

基　　金：the Project of the Youth Science and Technology New Star in Shaanxi Province(No.2017KJXX-94);the National Natural Science Foundation of China(Nos.41102037,41421002);the Project of Investigation and Evaluation of Uranium Resources(No.DD2016013623);the National Excellent Doctoral Dissertation of China(No.201324)。

摘　　要：Paleozoic granites can provide important insights of crustal differentiation and collision process of the North Qinling terrane. The Dafanggou leucogranites that intruded in the Qinling Complex is a Paleozoic granite with zircon U-Pb age of 404±6.4 Ma(MSWD=0.13, n=9). The leucogranites display moderate SiO2(68.4 wt.% to 71.7 wt.%) content and high Na2O/K2O(1.07 to 2.74) and Sr/Y(42 to 65) ratios, and low A/CNK(1.04 to 1.08) and Rb/Sr(0.09 to 0.16) ratios. Combined with negative ε(Nd)(t)(-10.4) and ε(Hf)(t)(-9.35 to-0.25) values and ancient TDM2 ages(1.2 to 1.7 Ga), suggesting the leucogranite are derived from ancient amphibolitic crust in the Qinling Group. In addition, the absence of coeval mafic igneous rocks or mafic enclaves occurred in the Dafanggou pluton and the low T(Zrn)(~700 ℃) of leucogranites preclude that the leucogranites derived from high temperature dehydration melting of amphibolite. Thus, we propose that the occurrence of the Dafanggou leucogranite indicates that water-flux melting of middle-lower crust in postcollision setting may be a potential model for the genesis of granites in collisional orogenic belt.

关 键 词：LEUCOGRANITE North Qinling Late Paleozoic crustal differentiation zircon Lu-Hf isotope 

分 类 号：P534.4[天文地球—古生物学与地层学] P588.245[天文地球—地质学] P597.3