黑龙江翠宏山铁多金属矿区岩体锆石U-Pb年龄、Hf同位素特征及其地质意义  

Characteristics of Hf Isotopes and Zircon U-Pb Ages of Granites in the Cuihongshan Iron Polymetallic Deposit,Heilongjiang and Their Geologic Implications

作　　者：陈贤[1] 刘家军[1] 张琪彬[1] 杨增海[1] 杨隆勃[1] 吴杰[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,地质过程与矿产资源国家重点实验室,北京100083

出　　处：《矿物岩石地球化学通报》2014年第5期636-644,680,共10页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金项目(40973035);中国地质调查局地质矿产调查评价专项(1212011085471)

摘　　要：黑龙江翠宏山铁多金属矿床位于小兴安岭 张广才岭成矿带北部.该成矿带上分布有大量对成矿起制约作用的岩浆岩体.前人有关矿区成岩、成矿时代的认识差异较大,且缺乏对矿区岩体成因的研究.为了解这些岩体的成岩时代、岩体成因、区域构造背景及其与成矿的关系,本文对其开展了锆石U-Pb年代学和Hf同位素研究.3个花岗岩类样品的锆石LA-ICP-MS U-Pb年代学和Hf同位素分析结果显示,黑云母花岗岩、花岗斑岩和碱长花岗岩的形成年龄分别为496±1.5 Ma、193±1 Ma和173 ±1 Ma;黑云母花岗岩的εHf（t）值和tDM2分别为-4.7～0.0和1463～1764 Ma,花岗斑岩及碱长花岗岩的εHf（t）值和tDM2值分别为0.2～10.1和781～1184 Ma.结合前人的年代学数据,推断矿区至少存在4期岩浆活动,其中二长花岗岩与成矿关系最密切.研究结果也表明松嫩地块在中新元古代时期曾发生过两次重要的地壳增生事件.LA-ICP-MS zircon U-Pb dating and Hf isotopic composition analysis are reported for three granites collected from the Cuihongshan deposit,Heilongjiang,to constrain their formation age,petrogenesis,and the relationship between regional tectonic setting and the ore deposit.The LA-ICP-MS zircon U-Pb ages of biotite granite,granite porphyry and alkali feldspar granite from the mining area were obtained as 496 ±1.5Ma,193 ±1Ma and 173 ±1 Ma,respectively.Combined with the previous zircon U-Pb age of 199 ±3.1Ma for the monzonitic granite and the molybdenite Re-Os isochron age of 198.9 ±3.7Ma,it is suggested that there were at least four events of magmatic intrusion and monzonitic granite are the most closely related with the ore deposit.According to zircon Hf isotope analyses,the εHf（t） values and the Hf modal ages of the biotite granite are from-4.7 to 0.0 and from 1463 Ma to 1764 Ma,respectively,which suggest that the magma source would mainly derive from Mesoproterozoic crustal materials.Both the granite porphyry and the alkali feldspar granite mainly have εHf（t） values from 0.2 to 10.1 and Hf modal ages from 781Ma to 1184 Ma,indicating that their sources derived from the depleted mantle and the crust of the Songnen Block was extracted from the mantle two times during the Meso-Neoproterozoic.Combined with previous published data of Nd-Hf isotopes,it is concluded that crust growth of the Songnen Block mainly occurred in the Meso-Neoproterozoic,which is consistent with that of the Eergu＇Na block but older than that of the Xing＇an Block （Neo-Proterozoic and Phanerozoic）,indicating these blocks have different evolution history.

关 键 词：黑龙江 锆石U-PB年龄 HF同位素 岩石成因 

分 类 号：P597.3[天文地球—地球化学] P618.2[天文地球—地质学]