摘要
宝音图花岗岩基位于华北地台北缘西段,针对其中牙马图岩体、罕乌拉岩体及布格道苏绍崩岩体等的岩石地球化学研究与年代学测定,结果表明岩体时代分别为261Ma±1.3 Ma,220.9 Ma±0.3 Ma和204.9 Ma±5.9 Ma,系晚二叠世—晚三叠世侵入岩体,其岩石类型主要为黑云母花岗闪长岩、斑状黑云母花岗岩和二云母花岗岩,其中晚二叠世花岗闪长岩Na2O/K2O平均值为2.06,A/CNK为0.96~1.15,平均值为1.03,里特曼指数（σ）平均值为1.9,总体属过铝质钙碱性岩;晚三叠世花岗岩Na2O/K2O平均值为0.82,A/CNK为0.92~1.16,平均值为1.03,里特曼指数（σ）为2.18,属过铝质钙碱性岩。岩石化学构造环境分析表明,晚二叠世—晚三叠世早期岩浆活动是俯冲造山过程中形成的具有岛弧性质的闪长岩类和花岗岩类,而晚三叠世晚期岩浆作用是与之有关的造山晚期陆缘花岗岩类。
Based on the new data from some recent studies,the granitic batholith in Buyant area in the western part of northern margin of North China platform is composed of 4 granitic intrusive bodies of the Late Permian and the Late Triassic Period,with the emplacement age of 261 Ma±1.3 Ma,220.9 Ma±0.3 Ma and 204.9 Ma±5.9 Ma respectively.The intrusive rocks consist of biotite granodiorite,porphyritic biotite granite and two-mica granite.Late Permian biotite granodiorite is characterized by mean Na2O/K2O ratio of 2.06,mean A /CNK contents of 1.03 and mean σ contents of 1.9,belonging to calc-alkaline series.The Late Triassic granite has an average Na2O/K2O ratio of 0.82,mean A /CNK contents of 1.03 and mean σ contents of 2.18,belonging to calc-alkaline series.Petrochemical plots for diagnosing tectonic environments of rocks indicated that the Late Permian biotite granodiorite and the Late Triassic biotite granite were a series of island arc dioritoid and granitoid formed in the process of subduction.However,the Late Triassic two-mica granite was post-orogenic continental granitoid.
出处
《矿物岩石》
CAS
CSCD
北大核心
2011年第1期49-55,共7页
Mineralogy and Petrology
基金
中国地质调查局内蒙古自治区地质勘查招标项目(2005-(2-13)-KD71)
关键词
花岗岩
岩石化学特征
构造环境
宝音图
granite
petrochemical characteristics
tectonic environments
Buyant area
