摘要
东昆仑金水口二级电站附近的加里东期花岗岩包括堇青石二长花岗岩和黑云花岗闪长岩。两类花岗岩具有相似的主元素特征:较高CaO、FeOT、MgO含量,低Na2O,K2O,DI>88,A/CNK>1.1,刚玉分子C>1.2;有区别的稀土元素特征:δEu分别为0.41～1.01,0.81～2.51,(La/Yb)N分别为3.18～4.74,4.18～18.56;相同的Nd-Sr同位素组成:εN(dt)为-9.0～-12.8,87Sr/86Sr为0.7205～0.7570。两类花岗岩均为典型的S型过铝花岗岩。其Nd模式年龄为1.7～2.1Ga,表明金水口花岗岩可能为柴达木地块元古宙基底部分熔融的产物。金水口花岗岩的微量元素特征暗示其形成于岛弧环境。
Caledonian granites nearby the Second Power Dam of Jinshuikou in East Kunlun consist of cordierite granite and biotite granodiorite. The two types of granite have similar characteristics in major elements:higher contents in CaO,FeOT and MgO,low contents in Na2O and K2O,and DI>88,A/CNK>1.1,C>1.2. The rare element characteristics are different:δEu from 0.41 to 1.01 and from 0.81 to 2.51 respectively,(La/Yb)N from 3.18 to 4.74 and from 4.18 to 18.56 respectively,while Nd-Sr isotopic composition are same:εNd(t)(9.0～-12.8)and 87Sr/86Sr(0.720 533～0.756 953)respectively. The two types of granite are S-type strongly peraluminous granite with pattern age of Nd from 1.7 to 2.1 Ga,which is consistent with the pattern age of Qaidam terran,It shows that the granite may be formed by the partial melting of the Proterozoic basement of Qaidam terran. The geochemical characteristics of the Jinshuikou granites imply that they were formed in the island-arc environment.
出处
《世界地质》
CAS
CSCD
2005年第2期123-128,共6页
World Geology
基金
中国地质调查局资助项目(200113900070)
教育部科学技术研究重点项目(02087)
