琼河坝矿集区花岗岩体的Sr-Nd,Pb同位素特征及地质意义  

ISOTOPIC CHARACTERISTICS OF Sr-Nd AND Pb OF GRANITE AND ITS GEOLOGICAL SIGNIFICANCE IN THE QIONGHEBA ORE CONCENTRATION AREA

作　　者：王得权[1,2] 刘建朝[1] 程建新 彭素霞 张海东[1] 郑利宏[1] 王瑞美[1] 

机构地区：[1]长安大学,陕西西安710054 [2]新疆工程学院,新疆乌鲁木齐830000 [3]西安地质调查中心,陕西西安710054

出　　处：《矿物岩石》2014年第1期70-77,共8页Mineralogy and Petrology

基　　金：阿尔泰-准噶尔北缘成矿带地质矿产调查研究(1212011120519);国家自然基金(41040020);中央高校基金(CHD2011ZY005)

摘　　要：琼河坝地区在志留纪一泥盆纪频繁的岩浆活动与成矿关系密切。矿集区中花岗岩∑REE含量23．16×10-6～110．24×10-6，平均值68．19×10-6，总体上稀土含量较低。（La／Yb）N一3．23～10．97平均值为5．74，显示轻、重稀土分馏不明显，且轻稀土元素较重稀土元素富集。蒙西、琼河坝、和尔赛三个花岗岩体Sr-Nd、Pb同位素值很近，表明琼河坝花岗岩具有相近的成因。（87Sr／86Sr）、值为0．70401～0．70442，平均值为0．70419；（148Nd／144Nd），值为0．512300～0．512478，平均值为0．512415；（208Pb／204Pb），值17．600～17．910，平均值为17．738，（207Pb／204Pb），值为15．410～15．547，平均值为15．459，（206Pb／204Pb）．值为37．250～38．019平均值为37．534。表现出壳幔混染的特征。εsr（t）值为一0．3～7．8，eNd（ε）值为2．9～7．2，为较小的正值，表现出洋壳的特征。花岗岩Al2O3，sr，Y，Yb和3Eu的特征与埃达克岩相近，可能为俯冲洋壳熔融的产物。因此该地区众多铜矿点的出现，应该与埃达克岩有关。In Qiongheba ore concentration area,frequently magmatic activity was closely associ- ated with mineralization In Silurian-Devonian Periods. Geochemical analysis revealed that the con- tent of EREE ranged from 23.16X10-6 to 110. 24X10-6 with average value of 68.19）〈 10-6 and the content of rare earth elements was low ranging from 3.23 to 10.97 with average value of 5.74. Light and heavy rare earths fractionation was not obvious and light rare earth elements were more than heavy rare earth elements. The isotopic values of Sr, Nd and Pb for Mengxi,Qiongheba and Heersai granites were very close,indicating that these granites were similar in origin. Mean- while, （87 Sr/86 Sr）i value was 0. 704 01 0. 704 42 （average 0. 704 19）, （20 pbFo4 Pb）i 17. 600 17. 910（average I7. 738）, （2TPbF4pb）i 15. 41015. 547 （15. 459）, and （26Pb/2Apb）,37. 250 38. 019（average 37. 534）. eSr（t） value was ranging from --0. 3 to 7.8,eNd（t） value from 2.9 to 7.2,and eNd （t） value was a small positive number, showing characteristics of oceanic crust. A12 03, Sr, Y, Yb and 5Eu were similar to adakites,implying that the granites were originated from the melting of oceanic crust. Therefore, the cooper mineralization in the area was related to the adakites rock.

关 键 词：琼河坝矿集区 稀土元素 Sr-Nd Pb同位素 埃达克岩 

分 类 号：P597.3[天文地球—地球化学]