甘肃红石泉伟晶状白岗岩岩相学和岩石地球化学  

Petrography and Petrogeochemistry of Pegmatoidal Alaskite in Hongshiquan,Gansu

作　　者：杨春四 张树明[1,2] 许迅[1] 秦雨[1] 阮小语 彭瑞强 

机构地区：[1]东华理工大学省部共建核资源与环境国家重点实验室培育基地,内蒙包头014000 [2]东华理工大学放射性地质与勘探技术国防重点学科实验室,南昌330013 [3]中国核工业地质局208大队,内蒙包头014000

出　　处：《地质科技情报》2017年第3期82-91,共10页Geological Science and Technology Information

基　　金：国家自然科学基金项目(41172079)

摘　　要：伟晶状白岗岩是红石泉铀矿床的含矿主岩,主要由钾长石、石英以及斜长石、黑云母、白云母组成,副矿物为黄铁矿和锆石。具有富硅(w(SiO_2)平均72.36%)、高碱(w(Na_2O+K_2O)平均8.75%),相对富钾贫钠(w(K_2O/Na_2O)平均2.67),低铁(w(TFe_2O_3)平均2.75%)、镁(w(MgO)平均0.70%)、钙(w(CaO)平均0.74%),弱过铝的特点,属于弱过铝高钾钙碱性系列岩石,具有S型花岗岩特征。微量元素Rb、Th、U、La、Ce、Nd、Zr、Hf等元素相对富集,Ba、Sr、Ti、P等元素相对亏损,具有明显的U、Th富集,Eu负异常。轻稀土元素相对富集,较重稀土元素分馏明显,球粒陨石标准化分布型式图总体略显右倾。结合该区的构造-岩浆演化特点,认为伟晶状白岗岩形成于中高温低压的后碰撞构造环境。Pegmatoidal alaskite is a hosting rock of Hongshiquan uranium deposit, containing primary min- erals k-feldspar, quartz, plagioelase, biotite and muscovite, and accessary minerals, pyrite and zircon. The characteristics of alaskite is its enriched silicon （SiO2 =72.36%）, and alkali （NazO＋K2O=8.75 %）, relatively rich in potassium but depleted in Na（K2O/Na2O=2.67）, iron（TFe2O3 =2.75%）, magnesium （MgO=0.70%）, and caleium（CaO=0.74%）, with weak peraluminous. It belongs to the weak aluminum high potassium talc alkaline series rocks, showing the characteristics of S type granite. The trace elements are relatively rich in Rb, Th, U, La, Ce, Nd, Zr, Hf and other elements, and depleted in Sr, Ba, Ti, P and other elements, with obvious U and Th enrichment, and Eu negative anomaly. Rare earth elements are relatively enriched light REE, and LREE fractionation of heavy REE are significant, chondrite stand- ard of distribution pattern diagram slightly tilted to right on the whole. The characteristics of tectonic- magmatic evolution of the area shows the pegmatoidal alaskite is formed in post eollisional tectonic envi- ronment of middle-high temperature and low pressure.

关 键 词：伟晶状白岗岩 岩石地球化学 岩相学 红石泉 甘肃 

分 类 号：P588.12[天文地球—岩石学]