【作者】 李明立；

【导师】 张德会； 卢欣祥；

【作者基本信息】 中国地质大学（北京） ， 地球化学， 2009， 博士

【摘要】 河南省大别山地区位于大别山造山带西段北麓,区内构造演化历史复杂,岩浆活动频繁,其中中生代燕山期侵入岩最为发育。在燕山期侵入岩中,中酸性小岩体数量众多,与钼等多金属矿化关系密切。大别山地区中生代中酸性小岩体主要沿北西西向深大断裂分布,受北西西向与北北东向断裂联合控制。小岩体多呈岩株或脉状产出,出露面积多数在1km2以下;岩性主要为花岗斑岩、似斑状花岗岩、二长花岗岩,少量为石英闪长岩及闪长岩等;岩石化学成份以高硅、富碱、多钾、贫镁、少钙为特征,属高钾钙碱性系列或钾玄岩系列。中酸性岩浆主要来源于下地壳的部分熔融,并上升至地壳浅部侵位,属深源浅成型花岗岩类。中酸性小岩体与钼多金属矿床具有密切的空间和成因联系。钼多金属矿床主要赋存于小岩体内或其周围区域;小岩体成矿元素丰度高,是钼多金属矿的成矿母岩。大别山地区钼多金属矿床成因类型主要有斑岩型、矽卡岩型、脉型和角砾岩筒型,它们具有相似的成矿环境和成矿作用过程,可厘定为一个统一的斑岩型钼多金属成矿系统。矿石硫同位素、铅同位素、辉钼矿Re的含量及稀土元素特征等资料显示,大别山钼多金属矿床成矿物质可能主要来源于下地壳。测定母山斑岩型钼矿床和陡坡钼矿化点的辉钼矿Re-Os同位素模式年龄分别为155.7±5.1Ma和140.5±8.2Ma,结合前人测定的同位素年龄资料,认为大别山钼多金属矿床成矿年龄可分为两期:早期成矿年龄为155.7±5.1 Ma～140.5±8.2 Ma,晚期成矿年龄为(122.1±2.4)～(113.1±7.9) Ma,但晚期成矿规模大,为主成矿期。成矿时代从整体上要晚于东秦岭华北克拉通南缘的斑岩型钼成矿带。成岩成矿时代表明,晚侏罗至早白垩纪区域构造体制由挤压向伸展的转换和其后伸展体制下岩石圈大规模减薄拆沉是大别山地区中生代中酸性岩浆活动和钼多金属成矿作用的地球动力学背景。大别山钼多金属矿床形成后主要受区域隆升和风化剥蚀作用的改造,但整体上矿床保存较好,区内找矿潜力较大。更多还原

【Abstract】 Dabieshan area of Henan province located in the northern foot of Western Dabie orogenic belt, the structural evolution and magma intrusions are complicated at this region, especially of theYanshanian intrusive rocks. There are many intermediate-acid small intrusive bodies among Yanshanian intrusive rocks and they are usually closed related to Molybdenum-polymetallic mineralization.Mesozoic intermediate-acid small intrusive bodies of Dabieshan area mainly distributed along deep-seated faults and controlled by groups of faults with orientations of NWW and NNE. Most of small intrusive bodies are stocks or dikes, and each of the dimension is less than 1km2 ; they are mostly granite-porphyry、porphyritic-granite、monzogranite,a small amouts of them are quartz diorite or diorite; the chemical characters are high content of SiO2、K2O and low content of Mg and CaO, on the SiO2-K2O diagram all the samples fall in the field of high-K calc-alkalic series and shoshonite series. The magma of small intrusive bodies come from partial melting of lower crustal, and intruded in shallow crustal, they belonged to deep-hypabyssal Granites.Small intrusive bodies are closely related with the molybdenum-polymetallic deposits in space and genesis. Most molybdenum-polymetallic deposits situated in or around small intrusive bodies; small intrusive bodies which had high abundance of ore-forming elements are source rocks of metallogenesis. The main types of molybdenum-polymetallic deposits in Dabieshan area include porphyry-type Mo deposits, skarn deposit, vein-type deposits and breccia pipe-type deposits, they had the similar ore-forming environments and metallogenetic processes, they can be defined as a unitized porphyry-type molybdenum-polymetallic metallogenic system.Characters of S istopic compositions, Pb istopic compositions, contents of Re in molybdenite and characters of REE reveals that ore-forming materials of molybdenum-polymetallic deposits in Dabieshan area came from lower crustal.Re-Os model ages of molybdenite at Mushan porphyry-type Mo deposit and Doupo Mo ore spot are 155.7±5.1Ma and 140.5±8.2Ma, respectively. Combined with others isotopic ages, it’s considered that the metallogenetic ages of molybdenum-polymetallic deposits can be devided into two groups: the earlier group is 155.7±5.1 Ma～140.5±8.2 Ma and later 122.1±2.4～113.1±7.9 Ma, and the metallogenetic scale of the later group is larger, so it’s the main metallizing stage. The metallogenetic age is later than it is in Eastern Qinling porphyry-type Mo metallogenic belt.Rock-and ore-forming ages reveal that the geodynamicas setting of magma activities and molybdenum-polymetallic metallogenesis was transition of the regional structural stress field from compressional to extensional and large scale lithospheric delamination at late Jurassic to early Cretaceous.Molybdenum-polymetallic deposits in Dabie mountain are reformed by uplift of weathering, but mainly preserved well, this area is potential for ore prospecting.更多还原