地质通报2024，Vol.43Issue(5)：726-742,17.DOI:10.12097/gbc.2022.08.022
蒙古国东北部脑明特铜矿床成矿岩体年龄、Hf同位素、地球化学特征及其对成矿构造背景的约束
Geochronology,Hf isotope,geochemical characteristics of the metallogenic rock mass in Nomint copper deposit,Northeastern Mongolia,and its constraint on metallogenic tectonic setting
摘要
Abstract
The Nomint medium-scale copper deposit,located in the central part of the Mongolia-Okhotsk suture zone,is the largest known copper deposit in the northeastern part of Mongolia.To explore the relationship between the rock mass and mineralization,this paper conducts zircon U-Pb chronology,trace element,and Hf isotopic geochemical research on the ore-forming rock mass of this deposit,based on mineralogical studies.The results show that the biotite granodiorite yielded zircon U-Pb ages of 166.3±2.3 Ma and 162.6±1.6 Ma,respectively,representing the products of the late Middle Jurassic magmatism;In the geochemical composition,the metallogenic rock mass are SiO2(62.81%～66.03%)>56%,Al2O3(15.01%～15.77%)>15%,MgO(2.06%～2.72%)<3%,K2O/Na2O<1,trace elements are relatively enriched in LREE and relatively deficient in HREE.Eu anomaly was not obvious and Y(10.67×10-6～14.05×10-6,<18×10-6)and Yb(1.20×10-6～1.65×10-6,<1.9×10-6)were poor,and Sr enrichment(547.6×10-6～661.8×10-6,greater than 400×10-6).It indicates that the metallogenic rock mass has the geochemical characteristics of Adakite rock.In the meanwhile,the metallogenic rock mass has relatively high Mg#,Cr and Ni contents,which is similar to Adakite formed from melting of crust under subsidence.In terms of Hf isotopic composition,the pluton has a low εHf(t)value(0.3～4.3)and a Mesoproterozoic model age(TDM2=1183～937 Ma),suggesting that some Mesoproterozoic basement rock components were mixed during the magmatic rise.The comprehensive research indicates that the metallogenic rock magma of the deposit originated from partial melting of the lower crustal delamination,formed in an intracontinental extensional environment following the closure of the Mongolia-Okhotsk Ocean in the late Middle Jurassic.关键词
脑明特铜矿床/锆石U-Pb测年/地球化学/埃达克岩/蒙古-鄂霍茨克洋Key words
Nomint copper deposit/zircon U-Pb dating/geochemistry/adakite/Mongol-Okhotsk Ocean分类
天文与地球科学引用本文复制引用
吴涛涛,陈聪,王庆双,姚远,周永恒,柴璐,鲍庆中..蒙古国东北部脑明特铜矿床成矿岩体年龄、Hf同位素、地球化学特征及其对成矿构造背景的约束[J].地质通报,2024,43(5):726-742,17.基金项目
中国地质调查局项目《东北亚和欧洲国际合作地质调查》(编号:DD20230130)、《中蒙俄毗邻区大型铀、铜资源基地评价》(编号:DD20190438) （编号:DD20230130）
