安徽宁国刘村二长花岗岩地球化学特征、LA-ICP-MS锆石U-Pb年龄及其地质意义
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本文为安徽省矿产资源潜力评价项目(1212010881616)、安徽省重要金属成矿区带与邻区成矿地质条件对比研究项目(2010-g-14)资助成果。

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    摘要:

    刘村岩体位于浙江安吉和安徽广德两县交界处的皖南地区,该岩体主要为浅红掠带肉红色中细—粗中粒似斑状二长花岗岩,岩体沿由寒武系地层组成的背斜轴部侵入。刘村二长花岗岩为具高钾、富碱、Mg#小等特征的准铝质—过铝质A型花岗岩。稀土元素的球粒陨石标准化曲线右倾斜明显、铕谷较深。微量元素原始地幔标准化蛛网图见明显的Ti、Sr谷,曲线整体右倾,岩体整体亏损HFSE,富集LILE。主、微量元素的地球化学特征研究均表明,形成刘村二长花岗岩的岩浆源于岩石圈地幔,并受到地壳物质的混染,岩体岩浆演化过程中发生有磷灰石、角闪石、辉石、榍石等矿物的结晶分异作用。通过LA-ICP-MS锆石U-Pb法确定刘村二长花岗岩年龄为( 132.84±0.57) Ma,表明该岩体形成于早白垩世,为皖南地区燕山期第二期岩浆活动的产物。刘村二长花岗岩形成于晚侏罗世—早白垩世中国东部构造活化和构造机制由挤压开始向拉张转折的转换阶段。该区金化探异常明显,是寻找金、银、钨(钼)多金属矿的有利地段。

    Abstract:

    The Liucun intrusion locates in the south of Anhui province where is the junction of Anji county in Zhejiang and Guangde county in Anhui. Main constitution of the intrusion is the fine-coarse porphyritic monzogranite with colour of light to pinkish red. The intrusion invaded from the anticlinal axis composed of Cambrian strata. Liucun monzogranite is the approach-aluminous to peraluminous A-type granite with the features of high-potassium, alkali-rich and low-Mg#. The rare earth element chondrite-normalized distribution pattern leans to the right obviously, and has deep europium valley. The spider diagram of the primitive mantle-normalized trace element curves have obviously negative Ti and Sr anomalies leaning to right. Overall,the intrusion has low HFSE and high LILE. Characteristics of major and trace element indicate that the magma formed the Liucun monzogranite came from lithospheric mantle and contaminated by continent crust. The process of magmatic evolution had occurred crystallization and differentiation of the minerals of apatite, hornblende, pyroxene, titanite and so on. Liucun monzogranite was dated to be 132.84±0.57 Ma by LA-ICP-MS zircon U-Pb method, which belongs to early Cretaceous. It is the second stage magmatic movement of Yanshanian in southern Anhui province. Liucun monzogranite formed at the transfering period of the structure activation and tectonic mechanism converting from compression to extension in late Jurassic to early Cretaceous。This area is favourable for prospecting gold, silver, tungsten-molybdenum polymetallic deposits because of its obvious geochemical gold anomalies.

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陈芳,王登红,杜建国,许卫,胡海风,王克友,余有林,汤金来.2014.安徽宁国刘村二长花岗岩地球化学特征、LA-ICP-MS锆石U-Pb年龄及其地质意义[J].地质学报,88(5):869-882.
CHEN Fang), ), ), ),,WANG Denghong, DU Jianguo, XU Wei, HU Haifeng, WANG Keyou, YU Youlin, TANG Jinlai.2014. Geochemical Characteristics and LA-ICP-MS Zircon U-Pb Geochronology of the Liucun Monzogranite in Ningguo, Anhui Province and Their Geological Significance[J]. Acta Geologica Sinica,88(5):869-882.

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  • 收稿日期:2013-07-11
  • 最后修改日期:2013-09-03
  • 录用日期:2013-09-09
  • 在线发布日期: 2014-05-13