作　　者： ; ; ; ; ; ;

机构地区： 中国科学院广州地球化学研究所

出　　处： 《大地构造与成矿学》 2009年第2期259-269,共11页

摘　　要： 东秦岭钼矿带是中国最主要的钼矿带,钼矿呈近东西向展布。钼矿以斑岩型为主,从南到北,钼矿带钼矿大体有斑岩Cu-Mo矿、斑岩Mo矿、斑岩Au-Mo矿分带的趋势,与从俯冲带到克拉通边缘斑岩Cu矿、斑岩Cu-Mo矿、斑岩Mo矿依次发育的分带现象相似,表明钼矿的形成与扬子地块向华北地块俯冲有关。根据钼矿Re-Os年龄资料统计钼矿分为～220Ma、～140Ma和～110Ma三期,其成矿动力学背景分别为碰撞造山、碰撞造山后伸展和中国东部岩石圈减薄。钼矿流体包裹体均一温度介于83℃～424℃;平衡盐度介于0.61%～42.5%。流体包裹体水的δD介于-100‰～-40‰,δ18OH2O介于-4.3‰～8.7‰;且从成矿早期到晚期流体包裹体水的δD和δ18OH2O分别变小,表明钼矿的成矿流体主要来源于岩浆,后期有大气水的加入。东秦岭钼矿的铅同位素为206Pb/204Pb=17.12～17.89、207Pb/204Pb=15.23～15.70、208Pb/204Pb=37.57～39.10,与区域下地壳铅同位素一致;小斑岩体的Sri=0.705～0.714,δ18O=7.2‰～12.1‰,与I型花岗岩的锶、氧同位素相一致,表明钼矿的成矿物质主要来源于下地壳。东秦岭钼矿带的钼资源总量占中国钼资源的51%以上,美国克莱马克斯-亨德森钼矿带(Climax and Hender-son)的钼资源总量占美国钼矿资源的42%以上,美国和中国的钼资源在世界上的排名分别为第一和第二位,两钼矿带是世界钼资源高度集中的两个区域。克莱马克斯-亨德森钼矿带位于美国中西部、美洲克拉通西缘;钼矿主要形成于33～18Ma,稍晚于拉腊米(Laramide,75～54Ma)陆内造山运动;钼矿形成于碰撞造山后伸展环境。东秦岭与克莱马克斯两钼矿带相比:1)两钼矿带都位于克拉通边缘;2)两钼矿带的钼矿化都形成于陆内碰撞造山之后的伸展环境,与成矿有关的岩体都为花岗斑岩小岩体;3)两钼矿带钼矿的辉钼矿平均丰度分别为0.073%～0.140%和0.171%～0.264%,东秦岭钼矿的丰� The eastern Qinling molybdenum belt is the main molybdenum metallogenic regions in China, which is located in the southern margin of North China Craton. Molybdenum deposits generally occur in nearly E-W direction along the tectonic lineation, most of which occur as porphyry-type deposits. There is a trend of porphyry Cu-Mo, Mo and Au-Mo deposit zoning from south to north, similar to the mineralization zoning of porphyry Cu, Cu-Mo and Mo in subduction zone. It indicates that the molybdenum mineralization was correlated with the northward subduction of the Yangtze Block beneath the North China Block. According to Re-Os chronology data of molybdenite from Mo deposits in the eastern Qinling, three episodes of molybdenum mineralization are recognized： - 220 Ma, - 140 Ma and - 110 Ma. The formation time for Mo deposits are corresponding to those of intra-continental collision, post-collision extension and rift extension, respectively. Homogenization temperatures of fluid inclusion in Mo deposits range from - 83 ℃ to 424℃ and salinities from 0.6l % to 42.5 % （ NaCl equivalent）. Oxygen （δ^18 OH2O = -4.3 - 8.7‰） and hydrogen （δD = -100 -40‰） isotope data on fluid water of hydrothermal minerals indicate a dominant derivation from magmatic fluid and post-magmatic meteoric water （e. g. post-mineralization alteration）. The features of Mo mineralization and alteration of wall rocks indicate that the Mo mineralization may have been enriched by fluid differentiation from the small granite porphyry hosts. The lead isotopic compositions （^206 pb/ ^204pb = 17.12 - 17.89, ^207pb/^204pb = 15.23 - 15.70 and ^208pb/^204pb = 37.57 - 39.10） of Mo deposits are identical with that of lower continental crust, while strontium （ Sr1 = 0. 705 - 0. 714） and oxygen （ δ^18 O = 7.2‰- 12.1‰） isotopic eompositions of granite porphyry are akin to that of I-type granites. So, the above results of Mo deposits and small granite porphyry stocks indicate a derivation of lower continental crust for Mo deposits.

关 键 词： 东秦岭 钼矿 克莱马克斯 亨德森 花岗斑岩 斑岩矿床

领　　域： [天文地球] [天文地球]