摘要
新疆西准噶尔构造带分布着大量的中酸性侵入体,其岩石成因和侵位期次对于认识该构造带的岩浆演化具有十分重要的意义。本次研究在详细的野外地质调查基础上,针对西准噶尔南部克孜勒巴斯套岩体8个样品进行地球化学特征分析。结果表明,克孜勒巴斯套岩体出露面积约7km^2,岩性主要为碱长花岗岩。其形成时代为306.4 Ma±3.7Ma,属晚石炭世晚期。岩石主量元素具有高硅(w(SiO_2)=74.30%～77.18%)、富碱且相对富钠(w(Na_2O+K_2O)=7.38%～8.73%,Na_2O/K_2O=0.97～1.39)、贫钙镁(w(CaO)=0.22%～0.48%;w(MgO)=0.19%～0.44%)、相对富铝(w(Al_2O_3)=11.93%～13.42%)的特征,明显富集Rb,K等大离子亲石元素及Zr,Hf等高场强元素,亏损Ba,Sr,P,Eu,Ti等元素,具有较高的TFeO/MgO(5.88～9.07),Zr+Nb+Ce+Y(372.4×10^(-6)～482.7×10^(-6))值及锆石饱和温度(860℃～890℃),属于碱性准铝质-弱过铝质A型花岗岩,为低压高温氧化条件年轻下地壳物质部分熔融的产物。结合区域构造背景和前人研究成果,认为西准噶尔南部地区在晚石炭世晚期仍处于俯冲体制,可能与晚石炭世洋脊俯冲作用有关。
There are large numbers of intermediate to acid intrusions distributed along the tecto -no - magmatic belt of western Junggar , Xinjiang.It is of great significance on the understanding ofthe magmatic evolution of this tectono - magmatic belt through their petrogenesis and emplacementperiods.Detailed field geological survey has made it available for the study of petrogeochemistry(eight samples ) of Kezilebasitao granite.It shows that Kezilebasitao granite is mainly composedof alkali feldspar granite and covers an outcrop area of 7km2 ,with an age of 306.4Ma±3.7Ma ,representing that the formation time of the alkali feldspar granite is late Late Carboniferous.Ma-jor elements of the rock indicate that these alkali feldspar granites are characterized by high Si( w (SiO2 ) =74.30%~77.18% ), enrichment of alkali and relatively enrichment of Na ( w ( Na2O+K2O ) =7.38%~8.73% , Na2O/K2O=0.97~1.39 ), low Ca and Mg ( w ( CaO ) =0.22%~0.48% ;w ( MgO ) =0.19%~0.44% ) and relatively enrichment of Al ( w ( Al2O3 ) =11.93%~13.42% );The trace elements of the rock are rich in Rb , K and other large ion lithophile elements ( LILE )and high field strength elements ( HFSE ) Zr , Hf , and poor in Ba , Sr , P , Eu , Ti , with high TFeO /MgO ratios ( 5.88~9.07 ) and Zr+Nb+Ce+Y contents ( 372.4×10^-6 ~482.7×10^-6 )and highzircon saturation temperatures ( 860℃~890℃ ), characteristic of alkaline metaluminous to weak -ly peraluminous series A - type granite , which was originated from the partial melting of juvenilelower crust under high temperature and low pressure conditions.It is considered that the south -west Junggar region was still in a subduction - dominated setting in the late Carboniferous , and it isrelated to the oceanic ridge subduction in late Carboniferous period.
作者
支倩
李永军
王冉
段丰浩
苏文博
ZHI Qian;LI Yongjun;WANG Ran;DUAN Fenghao;SU Wenbo(School of Earth Science and Resources , Chang′an University , Xi′an 710054, China;KeyLaboratory for the Study ofFocused Magmatism and Giant Ore Deposits , MLR , Xi′an 710054, China;College ofEarth Science , University ofChinese Academy ofSciences , Beijing 100049, China)
出处
《矿物岩石》
CAS
CSCD
北大核心
2018年第4期21-29,共9页
Mineralogy and Petrology
基金
国家自然科学基金(41402044
41273033
41303027)
国家重点研发计划专项(2018YFC0604000)
新疆两权中央留成专项资金项目(Y14-5-LQ06)
