北祁连宁缠河地区花岗岩地球化学特征

Geochemical Characteristics of Granite in Ningchanhe Area,North Qilian

通过北祁连宁缠河地区花岗岩微量元素和稀土元素等特征的研究,探讨了宁缠河地区花岗岩均属轻稀土富集型,稀土配分曲线为右倾型,属地壳经不同程度的部分熔融形成的花岗岩。微量元素标准化分配型式均表现为强不相容元素(K、Rb、Ba、Th)富集,中等不相容元素选择性富集(Ce、Nb)及弱不相容元素(Ta、Yb)亏损,并探讨其形成的构造环境分别为清阳河序列反映出火山弧花岗岩的特征,宁缠河序列各单元反映出造山带花岗岩的特征。

By researching on the characteristics of trance elements and REE of granite in Ningchanhe area of northern Qilian orogenic zone,we find that granite of Ningchanhe area enrich LREE and REE partition curve is right type,it belongs to the granite formed by different degrees of partial melting of crust.The standardization distribution patterns of trace elements show that incompatible elements（K,Rb,Ba,Th） enrichment,medium incompatible elements（Ce,Nb） selective enrichment,while compatible elements（Ta,Yb） assuming a depletion trend.Besides,the tectonic setting in which such granite characteristics occurs may include the feature of volcanic arc granite reflected by the Qingyang sequence and the orogenic one by every unit of the Ningchanhe sequence.