一种新的闪石共存对——铁闪石与铁韭闪石对  

A NEW PAIR OF COEXISTING AMPHIBOLES: THE GRUNERITE AND FERROPARGASITE PAIR

作　　者：丁阳[1] 薛纪越[1] 罗谷风[1] 

机构地区：[1]南京大学地球科学系

出　　处：《地质论评》1997年第4期415-419,共5页Geological Review

摘　　要：新近在我国山西省娄烦县尖山铁矿的角闪片岩中发现一种取向连生的镁铁质闪石与钙质闪石共存对。电子探针分析确定它们分别为铁门石K_(0.001)(Na_(0.027)Ca_(0.073)Mn_(0.031)Fe_(1.801)^(2+)_(1.932)(Fe_(2.948)^(2+)Mg_(1.964)Ti_(0.002)Al_(0.087))_5Si_(8.069)O_(22.10)(OH)_2与铁韭闪石(K_(0.135)Na_(0.461))_(0.596)(Na_(0.088)Ca_(1.853)Mn_(0.005)Fe_(0.072)^(2+))_2(Mn_(0.005)Fe_(2.789)^(2+)Mg_(0.875)Ti_(0.021)Fe_(0.499)^(3+)Al_(0.812))_5(Si_(6.103)Al_(1.897))_8O_(22.00)(OH)_2。共存的两种闪石以共轴取向联生的形式共同组成一个“单晶”,两者间的边界在化学和光学上都是突变的。对比前人所发现的镁铁质闪石与钙质闪石的共存情况,本次所发现的新的共存闪石对,具有更低的镁铁比值和更大的不混溶间隙。A new coexisting amphibole pair was recently found in Jianshan iron deposit Leufan of Shanxi Province, China. Electron microprobe analysis shows that the coexisting pair is composed of grunerite K0.001(Na0.027Ca0.073Mn0.031Fe1.8012+ )1.932 (Fe2.9482+Mg1.964Ti0.002 A10.087)5Si8.069O22.10 (OH)2 and ferropargasite (K0.135Na0.0461)0.596 (Na0.088Ca1.853Mn0.005Fe0.0722+)2 (Mn0.005Fe2+2.789Mg0.875Ti0.021 Fe0.4993+Al0.812)5(Si6.103Al1.897)8O22.00(OH)2. The two kinds of amphiboles occur in amphibole schist not only as separate phenocrysts but also combine to form ' single- crystal' phenocrysts in the form of topotactic integrowths with the common c- and b-axes. The boundary between the topotactic grunerite and ferropargasite is optically and chemically sharp. In comparison with the coexisting magsioferruginous amphibole and calcareous amphibole pair discovered by predecessors, the newly discovered pair has lower Mg/Fe ratios and wider miscilibility gaps.

关 键 词：闪石共存对 铁闪石 铁韭闪石 角闪石 

分 类 号：P578.955[天文地球—矿物学]