陕西省洛南县熊耳群细碧岩中杏仁体特征及其成因探讨  

An Approach to Characteristics and Genesis of Amygdaloid Bodies in Spilite of the Xiong’er Group,Luonan,Shaanxi

作　　者：康琴琴 张文硕 刘新会 KANG Qin-qin;ZHANG Wen-shuo;LIU Xin-hui(Geoanalysis Center,Shaanxi Geological Survey,Xi’an 710054;-The Fifth Geological Party,CAPF,Xi’an 710054)

机构地区：[1]陕西省地质调查实验中心,西安710054 [2]原武警黄金第五支队,西安710054

出　　处：《四川地质学报》2022年第1期17-23,35,共8页Acta Geologica Sichuan

摘　　要：华北板块南缘陕西境内熊耳群火山岩为细碧岩,岩石中杏仁体发育。通过野外地质调研、室内显微镜观测,研究得出细碧岩主要由斜长石和辉石的交代蚀变矿物组成。杏仁体由石英、钠长石、绿泥石、绿帘石、方解石、阳起石、黑云母、绿鳞石、钙沸石等充填气孔形成,有6种矿物组合:Qzt+Cal;Qzt+Chl;Qzt+Bit;Ep+Act;Qzt+Ep;Qzt+Ab,与细碧岩中的交代蚀变矿物组合基本一致。杏仁体具有环带结构,研究认为其形成先后次序为Bt/Act(平行气孔壁切面方向生长)→Qtz1/Chl1/Ep1(垂直气孔壁生)→Qtz2/Ep2/Act/Chl2(静态重结晶形成)→Qtz3/Chl3(动态重结晶形成)→Cal。即由气孔壁向内依次为钾化→钠化→硅化(2期)→青磐岩化(绿泥石-绿帘石-阳起石)→碳酸盐化。杏仁体一般呈椭圆状、圆状等,部分压扁拉长,分布比较均匀,具假流动构造。研究认为杏仁体为交代蚀变流体充填形成。为区域岩石学研究及铁矿勘查提供依据。Spilite of the Xiong’er Group in Shaanxi Province on the southern margin of the North China plate is characterized by development of amygdaloidal structure.The amygdaloid bodies consist of quartz,albite,chlorite,epidote,calcite,actinolite,biotite,celadonite and scolecite.The amygdaloid bodies are rounded and oval-shaped and characterized by zonal texture and pseudo-flow structure.The order of the development of the zonation is biotite-actinolite(parallel to the pore wall),quartz1-chlorite1-epidote1(perpendicular to the pore wall),quartz2-epidote2-actinolite-chlorite2(static recrystallized),quartz3-chlorite3(dynamic recrystallized)and calcite.They are products of potassic alteration,soda alteration,silicification,propylitic alteration(chlorite-epidote-actinolite)and carbonatization,respectively.

关 键 词：熊耳群 细碧岩 杏仁体 交代蚀变 形成机制 

分 类 号：P583[天文地球—岩石学]