国家自然科学基金项目（面上项目，重点项目，重大项目）
首次对羌塘盆地中央隆起带两个湖闪长片麻岩体进行系统的年代学与地球化学研究，以便确定其形成时代及成因。研究表明，两个湖闪长片麻岩体由一套闪长岩、辉长闪长岩组成，锆石呈长柱状自型-半自型晶，普遍发育有很窄的振荡生长环带，具有岩浆锆石的特征，三件闪长片麻岩中锆石的LA-ICP-MS U-Pb定年结果分别为（220.48±0.49）Ma、（217.9±0.51）Ma和（219.98±0.49）Ma，平均值为（219.45±0.50 ）Ma，表明岩体的形成时代为晚三叠世卡尼期。岩石的SiO2、MgO和Al2O3含量分别介于55.17-58.61%、1.71-2.74%和20.18-21.43%之间，且以高Mg#值(0.38~0.53)和富Na(Na2O/K2O= 1.17~7.38)为特征；强烈富集轻稀土元素和大离子亲石元素、明显亏损高场强元素，铕无异常或弱负异常，(87Sr/86Sr)t值和εNd(t)值分别变化于0.70868~0.71024和-3.4 ~ -2.8之间，结合铅同位素特征，认为该岩体的岩浆源区应为遭受了强烈的陆壳物质改造的岩石圈地幔。
Geochronology and geochemistry of dioritic gneiss in the Lianggehu region, Qiangtang Basin is examined for the first time so as to determined its age and genesis. Results show that dioritic gneiss is composed of a suite of diorite and gabbro-diorite. Zircon occur as long columnar euhedral and hypidiomorphic crystals with well-developed tight oscillating zonal structure, indicating magmatic origin. LA-ICP-MS U-Pb zircon dating of three pieces of dioritic gneiss samples are (220.48±0.49)Ma、(217.9±0.51)Ma and (219.98±0.49)Ma respectively, with an average value of (219.45±0.50)Ma, indicating that dioritic gneiss was formed at the age of Triassic Carnian. The SiO2, MgO and Al2O3 contents of dioritic gneiss range from 55.17 to 58.61%,1.71 to 2.74% and 20.18 to 21.43% respectively. The dioritic gneiss are characterized by high Mg# value (0.38~0.53) , Na enrichment (Na2O/K2O= 1.17~7.38), strong LREE and LILE enrichment , obvious negative anomalies of HFSE, and no Eu anomaly. The isotopic (87Sr/86Sr)t and εNd(t) values of dioritic gneiss vary in range of 0.70868 to 0.71024 and -3.4 to -2.8 respectively. These characteristics combined with lead isotopic parameter indicate that the magmatic source of dioritic gneiss is derived from lithosphere mantle modified strongly by the continental crust.
李忠雄,谢尚克,何江林,熊松,吴涛,邓奇.2014.羌塘盆地两个湖地区闪长片麻岩锆石LA-ICP-MS U-Pb同位素定年及地球化学特征研究[J].地质学报,88(1):15-24.
lizhongxiong, Xieshangke, Hejianglin, Xiongsong, Wutao, Dengqi.2014. LA-ICP-MS U-Pb zircon dating of dioritic gneiss and its geochemical characteristics in Lianggehu region, Qiangtang basin[J]. Acta Geologica Sinica,88(1):15-24.
