大兴安岭北段岔路口和大黑山斑岩型钼矿床硫、铅同位素特征  

Sulfur and lead isotopic characteristics of Chalukou and Daheishan porphyry Mo deposits in northern segment of Da Hinggan Mountains

作　　者：胡新露[1] 姚书振[1] 何谋春[1,2] 丁振举[1] 刘明 崔玉宝[1] 沈军[1] 

机构地区：[1]中国地质大学资源学院,湖北武汉430074 [2]中国地质大学地质过程与矿产资源国家重点实验室,湖北武汉430074 [3]黑龙江省有色金属地质勘查研究总院,黑龙江哈尔滨150000

出　　处：《矿床地质》2014年第4期776-784,共9页Mineral Deposits

基　　金：大兴安岭北段典型矿床剖析及成矿模式专题研究项目(编号:SDK2010_25);黑龙江省"斑岩体系"成矿模式及找矿方向研究项目(编号:201211008)联合资助

摘　　要：岔路口和大黑山钼矿床位于大兴安岭北段,是近年来新发现的2个斑岩型钼矿床.文章通过对这2个矿床的硫、铅同位素的研究,探讨了成矿物质来源.岔路口矿区硫化物的δ34S值为1.8‰～2.9‰,平均2.4‰;大黑山矿区硫化物的δ34S值变化于0.4‰～2.3‰,平均1.53‰,均显示出典型的岩浆硫特征.岔路口矿区硫化物的206Pb/204Pb、207Pb/204Pb和208Pb/204Pb值分别变化于18.311～18.356、15.536～15.573和38.115～38.229,大黑山矿区硫化物的206Pb/204Pb、207 Pb/204Pb和208Pb/204Pb值则分别变化于18.341～18.719、15.529～15.637和38.033～38.363.铅同位素进一步指示铅的来源与燕山期岩浆作用有关.在铅同位素构造模式图中,矿石铅主要投点于地幔演化线和造山带演化线之间,表明铅来自于壳幔物质的混合.大兴安岭北段在晚侏罗世受古太平洋板块俯冲的影响,发生了强烈的壳、幔相互作用并产生了大量含钼岩浆,为该区斑岩型钼矿床的形成奠定了基础.The Chalukou deposit and the Daheishan deposit are two newly discovered porphyry Mo deposits in the northern segment of the Da Hinggan Mountains. This paper reports the sulfur and lead isotopes of these two deposits, with the purpose of constraining the source of the ore-forming materials. The results suggest that the 834S values of the Chalukou and Daheishan deposits vary from 1.8%0 to 2.9%0 （2.4% on average） and from 0.4% to 2.3% （1.53% on average）, respectively, suggesting typical magmatic sulfur. The sulfides in the Chalukou deposit have ^206 pb/^204 Pb, 207 pb/^204 Pb and 208 pb/204 Pb ratios of 18.311-18.356, 15.536 - 15.573 and 38.115-38.229, respectively, while the sulfides in the Daheishan deposit have ^206pb/^204pb, ^207Tpb/^204pb and ^208pb/^204pb ratios of 18. 341 -- 18. 719, 15. 529 -- 15. 637 and 38. 033 -- 38. 363, respectively. The lead isotope characteristics additionally indicate that the origin of the Pb was related to the Yanshanian magmatism. In the tectonic discriminant diagram of lead isotopes, most of the samples fall in the transition zone between the mantle lead evolution line and the orogen lead evolution line, suggesting that the lead was mainly derived from mixture of crust-mantle materials. The northern segment of the Da Hinggan Mountains experienced the subduction of the Paleo-Pacific Plate, accompanied by intense crust-mantle interactions, thus resulting in the generation of abun- dant Mo-bearing magma, which laid a good foundation for the formation of the porphyry Mo deposits in this area.

关 键 词：地球化学 硫同位素 铅同位素 岔路口 大黑山 斑岩型钼矿床 大兴安岭 

分 类 号：P618.67[天文地球—矿床学] P597.2[天文地球—地质学]