新疆东准噶尔地区表壳元素地球化学特征及其地质意义  

Element geochemical characteristics of the supra-crust of Eastern Junggar region, Xinjiang and its geological implication

作　　者：汪洋[1,2] 

机构地区：[1]中国科学院广州地球化学研究所 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《北京地质》2005年第2期14-19,共6页Beijing Geology

基　　金：国家自然科学基金项目(编号 40104003;40376013);中国博士后科学基金;中国科学院王宽诚博士后奖励基金;中国科学院南海海洋研究所边缘海地质与古环境开放室基金课题(BYH02A03)联合资助

摘　　要：根据东准噶尔地区1∶20万化探均匀采集的900余个岩石样品的分析结果,基于全样本统计和迭代剔除方法, 得到新疆东准噶尔地区表壳(出露地壳) 的39种元素丰度值; 同时对其中的SiO2、TiO2、Al2O3、TFe2O3、MgO、MnO、CaO、Na2O、K2O、P2O5 10种常量元素, 按氧化物之和为100%进行了归算。东准噶尔地区表壳在化学成份上相当于花岗闪长岩。与全球大陆上地壳元素丰度值相比, 明显富集Na2O、MnO和As、Sb、Ag元素, 略富集SiO2、TiO2、P2O5 和Y, 明显亏损Co、Cr、Mo、Ni、Sn、W等元素, 亏损CaO、K2O、MgO和Be、La、Nb、Pb、Sr、Th、U等元素。从元素比值来看, 东准噶尔地区地区表壳的K/La、K/Th、Nb/La、Th/La、La/As、K/Na比值低于全球大陆上地壳相应元素比值; 而La/Cr比值高于全球大陆上地壳。东准噶尔地区表壳在成分特征上与典型的岛弧造山带上地壳更为接近, 但较后者略为成熟。加里东和海西期造山作用是影响和制约东准噶尔地区表壳的元素地球化学特征的重要地质因素。On the basis of the analysis results of more than 900 rock samples that were colleted evenly during the geochemical exploration of 1∶200 000 scale charts covering Eastern Junggar region, the average abundances of 39 elements were obtained for the supra-crust (exposed crust) of Eastern Junggar region. For calculating the element contents, the total sample statistics and iteration pick-out method were used; meanwhile, the abundances of ten oxides, SiO 2, TiO 2, Al 2O 3, TFe 2O 3, MgO, MnO, CaO, Na 2O, K 2O and P 2O 5, were normalized to 100%. The whole rock chemistry of supra-crust of Eastern Junggar region corresponds to granodiorite composition. In comparison with the average abundances of elements in the upper crust of global continent, the supra-crust of Eastern Junggar region exhibits the significant enrichment of Na 2O, MnO, As, Sb and Ag, and slight enrichment of SiO 2, TiO 2, P 2O 5 and Y; meanwhile, the supra-crust of Eastern Junggar region shows the significant depletion of Co, Cr, Ni, Mo, Sn, W, and the depletion of CaO, K 2O, MgO, and Be, La, Nb, Pb, Sr, Th, U etc. In the view of element ratios, the ratios of K/La, K/Th, Nb/La, Th/La, La/As and K/Na of the supra-crust of Eastern Junggar region are smaller than those of upper crust of global continent, but the ratio of La/Cr is higher. The supra-crust geochemistry of Eastern Junggar region exhibits some identity to the upper crust of typical island arc, but also have more mature characteristics compared with the latter. The orogenesis of Caledonian and Hercynian cycles are the important geological factors determining the geochemical features of supra-crust exposed in Eastern Junggar region.

关 键 词：元素地球化学特征 东准噶尔地区 表壳 地质意义 新疆 SiO2 TiO2 Na2O P2O5 元素比值 Al2O3 花岗闪长岩 上地壳 分析结果 岩石样品 剔除方法 样本统计 常量元素 化学成份 地壳元素 成分特征 地质因素 造山作用 丰度值 MgO 

分 类 号：P618.51[天文地球—矿床学] P588.121[天文地球—地质学]