摘要
石家金矿床位于胶东金矿集区的蓬莱-栖霞金矿带北段,矿区广泛出露的早白垩世镁铁质-长英质脉岩与金矿体空间关系密切。脉岩岩石类型多样,主要包括煌斑岩、辉绿岩和花岗斑岩。各类脉岩的岩石地球化学特征研究表明,煌斑岩与辉绿岩具有低Si、低Fe和高Mg的特征,富集轻稀土和大离子亲石元素(如Ba、Sr、Pb),亏损高场强元素(如Nb、Ta、Zr、Hf、Ti),起源于富集岩石圈地幔的部分熔融,与岛弧火山岩类似。花岗斑岩具有高Si、高K、高Al的特点,富集轻稀土和大离子亲石元素(Th、U、Rb、Ba、Pb),亏损高场强元素(Ta、Nb、Ti、Zr、Hf),属高钾钙碱性系列过铝质岩石,是在软流圈上涌、幔源岩浆底侵背景下由杂砂岩部分熔融所形成的。虽然有学者认为这些脉岩可以作为有效的找矿标志,但年代学研究显示脉岩与金矿化无直接的成因联系。
The Shijia gold deposit is situated in the north of the Penglai-Qixia gold belt in the Jiaodong Peninsula.Different types of early Cretaceous mafic-felsic dykes,mainly including lamprophyre,diabase,and granite porphyry dykes,are closed associated with gold mineralization in space at Shijia.Based on the study of geochemical characteristics of vein rocks,it is concluded that lamprophyre and diabase dykes are characterized by low contents of SiO_(2),TFe_(2)O_(3) and high MgO,they are enriched in light rare earth elements(LREEs)and large ion lithophile elements(LILEs;Such as Ba,Sr,and Pb),but depleted in high field strength elements(HFSEs;Such as Nb,Ta,Zr,Hf,and Ti).It is considered that lamprophyre and diabase dykes with arc-like trace element patterns are originated from partial melting of the enriched lithospheric mantle.Granite porphyry dykes are pera-luminous,high potassium calc-alkaline rocks which are characterized by high concentrations of SiO_(2),K_(2)O and Al_(2)O_(3),with enrichment in LREEs and LILEs(Th,U,Rb,Ba,and Pb)and depletion in HFSEs(Ta,Nb,Ti,Zr,and Hf).They were formed by partial melting of greywacks under the background of asthenosphere upwelling and mantle-derived magma underplating.Although some researchers suggest that these dykes can be used as ef-fective ore prospecting indicators,chronological studies show that there is no direct genetic relationship be-tween the dykes and gold mineralization.
作者
石启慧
章永梅
顾雪祥
冯李强
王佳琳
张英帅
SHI Qihui;ZHANG Yongmei;GU Xuexiang;FENG Liqiang;WANG Jialin;ZHANG Yingshuai(School of Earth Science and Resources,China University of Geosciences(Beijing),Beijing 100083,China;State Key Laboratory of Geological Process and Mineral Resources,China University of Geosciences(Beijing),Beijing 100083,China;Command Center of Natural Resources Comprehensive Survey,CGS,Beijing 100055)
出处
《西北地质》
CAS
CSCD
北大核心
2023年第1期99-116,共18页
Northwestern Geology
基金
国家自然科学基金重点项目“新疆西天山北缘晚古生代斑岩-矽卡岩型铜钼铁多金属成矿与岩浆-热液作用过程”(42130804)资助。
