甘肃省龙首山成矿带中段钠长岩脉地质特征及其与铀矿化关系研究  

Geological Features of Albitite Veins and Their Relationship with Uranium Mineralization in the Middle Longshou Mountains of Gansu Province

作　　者：赵如意[1,2] 姜常义[1] 陈旭 王刚 陈云杰 聂利 

机构地区：[1]长安大学,陕西西安710051 [2]核工业二O三研究所,陕西咸阳712000

出　　处：《地质与勘探》2015年第6期1069-1078,共10页Geology and Exploration

基　　金：中国核工业地质局项目(编号:201349;201571);中国地质调查局项目(编号:12120114014901)

摘　　要：钠长岩脉是甘肃省龙首山成矿带中段常见的晚期脉体，与钠交代型铀矿化的关系十分密切。文章在野外调研、钻孔查证、放射性物探测量的基础上，深入研究钠长岩脉的岩石学、地球化学、同位素年代学和稳定同位素特征研究，并探讨其与钠交代型铀矿化之间的关系。钠长岩脉侵位于加里东中期，其LA-ICP-MS锆石u—Ph年龄为442．9±5．7Ma；具有中硅（61．48％-67．14％）、富铝（14．98％～17．59％）、高钠（9．76～％～10．59％）、贫钾（0．08％～0．30％）、低钛（0．11％-0．44％）、低磷（0．02％-0．16％）的特征；N-MORB标准化微量元素蛛网图显示钠长岩脉相对富集大离子亲石元素（LILE）Rb和Ba，不相容元素Th和u显著富集，高场强元素（HFSE）Nb和Ta相对亏损、sr和．ri显著亏损；球粒陨石标准化稀土元素配分曲线图呈碱性花岗岩类的“海鸥”型。综合研究表明，钠长质岩浆是钠质含铀热液的孪生有效载体，钠长岩脉本身即是钠交代型铀矿有利的赋矿岩石，二者具有同源、等时、共体的特征，作为龙首山成矿带中段钠交代型铀矿的找矿标志，进而指导深部找矿和矿床外围盲矿体预测。Albitite veins are common late-period veins in the middle I,ongshou Mountains of Gansu Province, which have a very clnse relationship with sodic metasnmatism type uranium. This paper presents a detailed study oil petrology, geochemical, isotope chronology and stable isotope of albitite veins and discussion on the relationsbip between albitite veins and sodic metasomatism type uranium, based on field surveys, drilling verification and radi- oactive geophysical measurement. Tbese albitite veins intruded during middle Caledonian, with LA-1CP-MS zirc.on U-Pb age 442.9±5.7Ma. They are characterized by intermediate silicon（ 6h 48% - 67. 14% ） , rich alumina（ 14.98% - 17.59% ） , high sodium （ 9.76 - %- 10.59% ） , depleted pntassium （ 0.08% -0. 30% ） , and low titanium （ 0.11% - 0.44% ） anti phosphorus （ 0.02% - 0. 16% ）. They exhibit mewliked chondritenormalized REE patterns as alkali granites. In these re.ins, LILE Rb and Ba are, relative bigh, incompatible elements Th and U are remarkably high, while HSFE Nb and Ta are relatively depleted, Sr and Ti are depleted considerably. The comprehensive research indicates that the alhitic magama is twins effective carrier nf sodic U bearing hydratherm, albitie veins is tavorable host rock for sodic metasomatism type uranium, both of which are isogenesis, contemporary and coenosarcus. We can attempt to use them as the indicator far searching for sodic metasomatism type uranium in the middle Longshou Mountains, for guiding prospetting at depth and for hrecasting buried ore bodies outside the deposit.

关 键 词：钠交代 铀矿 钠长岩脉龙首山 甘肃省 

分 类 号：P618.51[天文地球—矿床学]