【摘要】 养马甸钼矿床位于燕辽钼(铜)成矿带东段的辽西地区。养马甸岩体由似斑状花岗岩、粗粒花岗岩和细粒花岗岩3个不同岩相组成,主要矿物为石英(30%～45%)、钾长石(35%～50%)、斜长石(15%～25%)和少量黑云母(3%～5%)。矿体主要赋存于养马甸岩体的细粒花岗岩中,少部分赋存在紧邻细粒花岗岩的粗粒花岗岩和似斑状花岗岩中。地球化学研究表明,养马甸岩体总体为富硅(w(SiO2)=69.26%～76.44%)、富碱(w(Na2O+K2O)=7.87%～8.81%),贫钙(w(CaO)=0.36%～1.33%)、镁(w(MgO)=0.17%～0.61%)和铁(w(FeOT)=1.47%～3.39%)的钾质(K2O/Na2O=1.05～1.31)—准铝质花岗岩(A/CNK=0.90～1.00)。该岩体总体富集大离子亲石元素(K、Rb、Th和LREE),高场强元素(Nb、Ta、Zr、Hf和HREE)亏损不明显,而中稀土相对亏损,在稀土元素配分图上呈左陡右缓的"V"型。岩石地球化学及矿物演化特征表明,养马甸岩体的不同岩相为同源岩浆经历不同程度分离结晶作用的产物,其母岩浆来源于高压麻粒岩相下地壳物质的部分熔融。成岩与成矿年代学研究表明,似斑状花岗岩的LA-ICP-MS锆石U-Pb年龄为(192.1±1.9)Ma,粗粒花岗岩的LA-ICP-MS锆石U-Pb年龄为(189.5±1.4)Ma,而细粒花岗岩的LA-ICP-MS锆石U-Pb年龄为(189.3±3.3)Ma。结合对已有资料的归纳和分析,认为养马甸斑岩钼矿形成于后造山背景下的陆内伸展环境,含矿岩体及斑岩型钼矿的形成可能与古亚洲洋残留地幔楔在早侏罗世的再活化有关。更多还原

【Abstract】 The Yangmadian Mo deposit is located in western Liaoning province,eastern part of the Yanshan-Liaoning Mo(Cu) metallogenic belt.The Yangmadian granitic pluton associated with the molybdenum mineralization is composed of three main different lithofacies,porphyraceous granite,coarse-grained granite and fine-grained granite.Their major minerals include quartz(30%-45%),K-feldspar(35%-50%),plagioclase(15%-25%) and biotite(3%-5%).Orebodies of the Yangmadian Mo deposit occur mainly in the fine-grained granite,and minor in the coarse-grained granite and porphyraceous granite.Geochemical researches show that the pluton is rich in Si(w(SiO2)=69.26%-76.44%),alkalis(w(Na2O+K2O)=7.87%-8.81%),poor in Ca(w(CaO)=0.36%-1.33%),Mg(w(MgO)=0.17%-0.61%),Fe(w(FeOT)=1.47%-3.39%),potassic(K2O/Na2O=1.05-1.31) and metaluminous(A/CNK=0.90-1.00).The pluton is generally enriched in Large Ion Lithophile Element(LILE,such as K,Rb,Th and LREE),normal in High Field Strong Element(HFSE,such as Nb,Ta,Zr,Hf and HREE),slightly depleted in Medium REE,and displays a "V" shape chondrite-normalized REE patterns with strong negative Eu anomalies(δEu=0.26-0.76).Both evolution characters of the minerals and geochemical characters of the rocks indicate that the Yangmadian pluton were resulted from different degree fractional crystallization of the common parent magma,which derived from the part melting of lower crust materials under high-pressure granulite facies.The isotopic dating indicates that LA-ICP-MS zircon U-Pb ages are(192.1±1.9) Ma,(189.5±1.4) Ma,and(189.3±3.3) Ma for porphyraceous,coarse-grained and fine-grained granite,respectively.Based on comprehensive researches on existing geological data,it can be conclude that petrogeny and metallogeny of the Yangmadian pluton were resulted from the Early Jurassic reactivation of the residual mantle wedge induced by subduction of the Paleo-Asia Ocean in Paleozoic period.更多还原