摘要
以东准噶尔北塔山一带泥盆纪火山岩为研究对象,通过岩石地球化学分析,获得安山岩及玄武岩样品SiO_2含量47.26%~68.03%,Al_2O_3含量14.61%~20.08%。Na_2O含量1.01%~4.39%,K_2O含量0.26%~3.02%,Na_2O/K_2O为0.55~10.50。酸性火山岩SiO_2含量67.55%~70.46%,Al_2O_3含量13.7%~14.92%。Na_2O含量2.93%~3.53%,K_2O含量3.06%~3.34%,Na_2O/K_2O为0.96~1.06。所有样品里特曼指数0.32~4.08。稀土元素总量44.91×10^(-6)~247.98×10^(-6),轻稀土略富集((La/Yb)N=1.83~5.76),δEu=0.74~1.13。大离子亲石元素(Sr,K,Rb,Ba)富集,Ta,Nb亏损强烈,绝大部分样品Nb含量小于11×10^(-6),K*(2KN/(TaN+LaN)、Sr*(2SrN/(CeN+NdN))多大于1,显示消减带火山岩特征。结合区域构造演化,认为北塔山一带泥盆纪火山岩形成于卡拉麦里小洋盆的洋壳向北俯冲过程中的岛弧环境。
The article focuses on the Devonian volcanic rocks,including basalt,andesite,dacite and so on,and being located at the Beitashan area of the Eastern Junggar.By analyzing the rock samples,basalt and andesite have SiO2 ranging from 47.26%～68.03%,Al2O3 ranging from 14.61%～20.08%,Na2O ranging from 2.93%～3.53%,K2O ranging from 0.26%～3.02%,Na2O/K2O=0.55～10.50,and dacite samples have SiO2 ranging from 67.55%～70.46%,Al2O3 ranging from 13.7%～14.92%,Na2O ranging from 2.93%～3.53%,K2O ranging from 3.06%～3.34%,Na2O/K2O=0.96～1.06.For all the samples,Rittmann Indexσ=0.32～4.08,ΣREE=44.91×10-6～247.98×10-6,LREE enrichment,(La/Yb)N=1.83～5.76,δEu=0.74～1.13.The volcanic rocks are enriched LILE(Sr,K,Rb,Ba),and intense Ta、Nb depletion.Nb content of the most samples is less than 11ppm.The value of K*and Sr*are greater than 1.The geochemical characteristics of the trace element of the volcanic rocks are similar to island arc volcanic rocks.In additional,according to the age of the ophiolite in the Kalamaili area,and the regional tectonic’s evolution of the East Junggar,it could be conclouded that the volcanic rocks of Devonian borned in a island arc environment,which caused by northward subduction of the Paleozoic Kalamaili oceanic crust.
作者
肖鸿
李科
王璐
Xiao Hong;Li Ke;Wang Lu(No.1 Geological Team of Xinjiang Bureau of Geology and Mineral Resource,Changji,Xinjiang,831100,China)
出处
《新疆地质》
CAS
CSCD
2017年第3期267-272,共6页
Xinjiang Geology
基金
新疆阿尔泰成矿带地质矿产调查评价项目<新疆东准噶尔地区1:5万L46E018003
L46E018004
L46E018005
L46E018006
L46E018007
L46E018008六幅区调>(1212011120511)研究成果
关键词
东准噶尔
泥盆纪火山岩
地球化学
构造意义
Devonian volcanic rocks
Geochemistry
Tectonic significance
Eastern Junggar
