中亚造山带东部非典型辉绿结构辉绿岩的岩相学特征及鉴定
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摘要
在中亚造山带东部构造带中发现角闪变质辉绿岩,岩相学特征表明具非典型辉绿结构,显示变余辉绿结构及变余嵌晶含长结构.主要矿物为斜长石及角闪石,次要矿物为单斜辉石和阳起石.全岩岩石化学分析结果:SiO_2含量为49.15%～52.96%、Na_2O+K_2O含量为2.71%～5.07%、CaO含量为7.07%～10.40%、Al_2O_3含量为14.77%～17.31%、TFe0含量为8.80%～12.27%、MgO含量为6.45%～9.57%;在火山岩TAS分类图落入玄武岩区,属于基性岩范围;说明研究区具有非典型辉绿结构的岩石命名为角闪变质辉绿岩的正确性.角闪变质辉绿岩经历了退变质作用:基性斜长石(拉长石)退变质为中性斜长石(中长石),进一步退变质为钠长石或钠更长石;单斜辉石退变质为角闪石,角闪石退变质为阳起石.
Hornblende metamorphic diabase is found in the eastern tectonic zone of Central Asian Orogenic Belt. Its petrographical features present atypical ophitic texture,as blastodiabasic texture and blastophitic poikilitic texture,with major minerals of plagioclase and hornblende and minor clinopyroxene and actinolite. The whole rock petrochemical analysis results show that the chemical compositions in the samples include SiO_2(49.15%-52.96%),Na_2O+K_2O(2.71%-5.07%),CaO(7.07%-10.40%),Al_2O_3(14.77%-17.31%),TFeO(8.80%-12.27%),and MgO(6.45%-9.57%). The data fall into the basalt area in the volcanic rock TAS classification diagram,belonging to basic rock,which confirms the naming of the hornblende metamorphic diabase with atypical ophitic texture. The hornblende metamorphic diabase underwent retrometamorphism with the basic plagioclase(labradorite) turned to intermediate plagioclase(andesine) and further to albite or sodium oligoclase,while the clinopyroxene is metamorphosed to hornblende,and then to actinolite.
Hornblende metamorphic diabase is found in the eastern tectonic zone of Central Asian Orogenic Belt. Its petrographical features present atypical ophitic texture,as blastodiabasic texture and blastophitic poikilitic texture,with major minerals of plagioclase and hornblende and minor clinopyroxene and actinolite. The whole rock petrochemical analysis results show that the chemical compositions in the samples include SiO_2(49.15%-52.96%),Na_2O+K_2O(2.71%-5.07%),CaO(7.07%-10.40%),Al_2O_3(14.77%-17.31%),TFeO(8.80%-12.27%),and MgO(6.45%-9.57%). The data fall into the basalt area in the volcanic rock TAS classification diagram,belonging to basic rock,which confirms the naming of the hornblende metamorphic diabase with atypical ophitic texture. The hornblende metamorphic diabase underwent retrometamorphism with the basic plagioclase(labradorite) turned to intermediate plagioclase(andesine) and further to albite or sodium oligoclase,while the clinopyroxene is metamorphosed to hornblende,and then to actinolite.
引文
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(2)付俊彧,等.大兴安岭成矿带北段基础地质综合研究成果报告. 2013.
[2]李锦轶,曲军峰,张进,等.中国北方造山区显生宙地质历史重建与成矿地质背景研究进展[J].地质通报,2013,32(2/3):207-219.
[3]潘桂棠,肖庆辉,陆松年,等.中国大地构造单元划分[J].中国地质,2009,36(1):1-28.
[4]刘训,李廷栋,耿树芳,等.中国大地构造区划及若干问题[J].地质通报,2012,31(7):1024-1034.
[5]孙德有,吴福元,李惠民,等.小兴安岭西北部造山后A型花岗岩的时代及与索伦山-贺根山-扎赉特碰撞拼合带东延的关系[J].科学通报,2000,45(20):2217-2222.
[6]付俊彧,汪岩,那福超,等.内蒙古哈达阳镁铁-超镁铁质岩锆石UPb年代学及地球化学特征:对嫩江-黑河地区晚泥盆世俯冲背景的制约[J].中国地质,2015,42(6):1740-1753.
[7]白文吉,杨经绥,胡旭峰,等.内蒙古贺根山蛇绿岩岩石成因和地壳增生的地球化学制约[J].岩石学报,1995,11(Sl):112-124.
[8]包志伟,陈森煌,张桢堂.内蒙古贺根山地区蛇绿岩稀土元素和SmNd同位素研究[J].地球化学,1994,23(4):339-349.
[9]赵春荆,彭玉鲸,党增欣,等.吉黑东部构造格架及地壳演化[M].沈阳:辽宁大学出版社,1996:2-36.
[10]孙德有,吴福元,高山,等.吉林中部晚三叠世和早侏罗世两期铝质A型花岗岩的厘定及对吉黑东部构造格局的制约[J].地学前缘,2005,12(2):263-275.
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[15]陈曼云,金巍,郑常青.变质岩鉴定手册[M].北京:地质出版社,2009:83-105.
(1)付俊彧,等.东北基础地质综合调查与片区总结成果报告. 2016.
(2)付俊彧,等.大兴安岭成矿带北段基础地质综合研究成果报告. 2013.