摘要
河南祁雨沟金矿位于秦岭造山带最北部,属典型的角砾岩筒型成矿系统。矿区16号角砾岩筒下伏斑岩体锆石的ε_(Hf)(t)值为-10.50~-14.43,Hf模式年龄为2.57~2.93Ga,表明花岗斑岩主要来源于古老下地壳的部分熔融。锆石LA-ICPMS U-Pb年龄为134.1±2.3Ma,与7号角砾岩筒中的辉钼矿Re-Os等时线年龄135.6±5.6Ma一致。这些年龄数据与熊耳山地区燕山期花岗岩体的侵位年龄基本相同,共同指示其形成于地壳缩短增厚之后的伸展减薄过程。熊耳地体的地壳缩短增厚缘于同碰撞时期沿马超营断裂带的A型俯冲作用,而A型俯冲导致了包括祁雨沟金矿系统、燕山期花岗岩类和脉状造山型矿床在内的熊耳矿集区的形成。
The Qiyugou gold system in Henan Province is hosted in breccia pipes in the Xiong'er terrane of the northernmost Qinling Orogen, and is consequently of typical breccia pipe-type deposits in genetic classification. Zircon grains from the granite porphyry underlying the No. 16 breccia pipe yield epsilon(Hf)(t) values of -10.50 similar to -14.43 and Hf model ages of 2.57 similar to 2.93Ga, indicating that they originated from partial melting of an ancient crust. The granite porphyry is dated to be 134.1 +/- 2.3Ma by LA-ICPMS zircon U-Pb method, which is in accordance to the Re-Os isochron age of 135.6 +/- 5.6Ma of the molybdenite flakes from the No. 7 breccia pipe. These ages are also consistent with zircon U-Pb ages of the other granites in the Xiong'er terrane, and holistically suggesting that the Qiyugou breccia-pipes emplaced during Early Cretaceous crustal extension-and-thinning following a crust shortening-and-thickening which was caused by the syn-collisional northward A-type subduction along the Machaoying fault. The A-type subduction led to the formation of the Xiong'er Au-dominated ore-province including the Qiyugou Au system, Yanshanian granites and orogenic-type lode deposits.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第2期374-384,共11页
Acta Petrologica Sinica
基金
本文得到国家973计划项目(2006CB403500)
河南省科技攻关项目(豫财招标采购(2006)26407号)
国家自然科学基金项目(40730421,40872067,40425006)资助