摘要
本文对冀东迁安麻粒岩及有关岩石中的辉石进行了研究,结果表明:辉石的含铁度明显受寄主岩石化学成分的制约,寄主岩石的〈FeO〉/MgO和〈FeO〉=(Fe_2O_3×0.8999+FeO)值愈高,辉石的含铁度也愈高;共存辉石对的Fe^(2+)—Mg分配系数(K_D)不仅受结晶温压条件控制,同时也受辉石其它成分的影响。但Ca—Mg—Fe三角图解等资料研究表明:共存的二辉石对是平衡结晶的产物,其K_D平均值也符合张儒媛等统计的变质辉石平均值为1.85的规律。通过二辉石温度计计算和矿物共主组合等资料的分析,得出辉石形成的温度为869±60℃、压力为5×10~8—9×10~8Pa。本区与铁矿体成过渡关系的辉石岩全铁含量与工业铁矿大致相等,铁矿的成因与其有着非常密切的关系。
Pyroxene from granulite and related rocks in Qianan County has beenstudied in this paper, and the results show that iron content of pyroxene isobviously governed by chemical composition of host rocks: the higher the(FeO)/MgO and (FeO)=(Fe_2O_3 × 0.8999 + FeO) values of host rocks, thehigher the iron content of pyroxene. The Fe^2+ -Mg distribution coefficient(K_D) of clinopyroxene-orthopyroxene pair is not only controlled by tempe-rature-pressure conditions of crystallization but also affected by other compo-nend of pyroxene. Nevertheless, the Ca-Mg-Fe triangular diagram indicatesthat the coexisting clinopyroxene and orthopyroxene are products of equi-librium crystallization with their average K_D value in accord with the lawadvanced by Zhang Ruyuan et al. that the average K_D value of metamorphicpyroxene is 1.85.The calculation with the clinopyroxene-orthopyroxene thermometer and ananalysis of data on mineral association show that the temperature and pres-sure for the formation of pyroxene are 869±60℃ and 5×10~8--9×10~8 Parespectively. T_Fe content of pyroxenite that shows gradual contact with the iron orebody is approximately equal to that of economic iron ore. Tron ore is gene-tically closely related to pyroxenite.
出处
《岩石矿物学杂志》
CAS
CSCD
1992年第1期83-91,共9页
Acta Petrologica et Mineralogica
关键词
含铁
变质岩
辉石
铁矿
成因
Qianan of east Hebei
Qianxi Group
Ferriferous metamorphic rocks
pyroxene
iron ore
