内蒙古中部红格尔地区二叠纪A型花岗岩锆石U-Pb年代学、地球化学及岩石成因
发布时间：2019-02-13 01:46
【摘要】：内蒙古中部红格尔地区碱长花岗岩是白音乌拉-东乌旗A型花岗岩带的重要组成部分,其LA-ICP-MS锆石U-Pb年龄为286~294 Ma,表明其形成时代为早二叠世。岩石富硅(SiO_2=75.13%~80.17%)、富碱(Na_2O+K_2O=7.33%~9.11%)、富铁(TFe_2O_3=1.01%~2.31%)、贫镁(MgO=0.09%~0.27%)和贫钙(CaO=0.12%~0.52%)。微量元素中大离子亲石元素(LILE)Rb、Th、K和Pb明显富集,Sr、Ba强烈亏损;高场强元素(HFSE)Nb、Ti、La和Ce亏损明显,Zr、Hf相对富集。岩体稀土总量较低且变化大(∑REE=33~165μg/g),轻重稀土分异程度低且轻稀土弱富集,具明显的Eu负异常(δEu=0.06~0.13),稀土元素分布模式表现为较平缓、轻微右倾的海鸥型分布型式。εNd(t)为正值(+1.08~+3.18),tDM2变化于805~965 Ma之间;有较高的放射成因铅,(~(206)Pb/~(204)Pb)i为18.710~19.280,(207Pb/204Pb)i为15.557~15.597,(~(208)Pb/~(204)Pb)i为37.887~38.330。岩石学、主元素和微量元素地球化学特征显示红格尔地区碱长花岗岩属于铝质A型花岗岩,其形成于碰撞后伸展构造背景,是后碰撞俯冲板片断离诱发中下地壳镁铁质岩石部分熔融的产物。红格尔地区A型花岗岩的发育可能反映了内蒙古中部古亚洲洋在二叠纪前已经闭合。
[Abstract]:Alkali-feldspar granites are an important part of the Baiyinwula-Donwuqi A-type granite belt in central Inner Mongolia. Its LA-ICP-MS zircon U-Pb age of 2860.294 Ma, indicates that it was formed at an early Permian age. The rocks are rich in silicon (SiO_2=75.13%~80.17%), alkali-rich (Na_2O K _ 2O-7.33%), and rich in iron (TFe_2O_3=1.01%~2.31%), Poor magnesium (MgO=0.09%~0.27%) and poor calcium (CaO=0.12%~0.52%). The large ion lithophile elements (LILE) Rb,Th,K and Pb) and the high field strength elements (HFSE) Nb,Ti,La and Ce) were obviously enriched in microelements, and the Sr,Ba was strongly depleted, while the Zr,Hf was relatively enriched in high field strength elements (HFSE) Nb,Ti,La and Ce). The total amount of rare earth in rock mass is low and large (鈭，
本文编号：2421045
[Abstract]:Alkali-feldspar granites are an important part of the Baiyinwula-Donwuqi A-type granite belt in central Inner Mongolia. Its LA-ICP-MS zircon U-Pb age of 2860.294 Ma, indicates that it was formed at an early Permian age. The rocks are rich in silicon (SiO_2=75.13%~80.17%), alkali-rich (Na_2O K _ 2O-7.33%), and rich in iron (TFe_2O_3=1.01%~2.31%), Poor magnesium (MgO=0.09%~0.27%) and poor calcium (CaO=0.12%~0.52%). The large ion lithophile elements (LILE) Rb,Th,K and Pb) and the high field strength elements (HFSE) Nb,Ti,La and Ce) were obviously enriched in microelements, and the Sr,Ba was strongly depleted, while the Zr,Hf was relatively enriched in high field strength elements (HFSE) Nb,Ti,La and Ce). The total amount of rare earth in rock mass is low and large (鈭，
本文编号：2421045
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