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

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：SiO₂含量为49.15%～52.96%、Na₂O+K₂O含量为2.71%～5.07%、CaO含量为7.07%～10.40%、Al₂O₃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.

PETROGRAPHY AND IDENTIFICATION OF THE ATYPICAL OPHITIC DIABASES IN EASTERN CENTRAL ASIAN OROGENIC BELT

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 SiO₂ (49.15%-52.96%), Na₂O+K₂O (2.71%-5.07%), CaO (7.07%-10.40%), Al₂O₃ (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.