由伊利石结晶度研究桂西右江地区区域极低级变质作用  

VERY LOW-GRADE REGIONAL METAMORPHISM IN THE YOUJIANG REGION, WESTERN GUANGXI, USING ILLITE CRYSTALLINITY

作　　者：燕守勋[1] 王志刚[1] 黄永权 

机构地区：[1]中国科学院遥感应用研究所,北京100101 [2]广西壮族自治区凌云县经济贸易局,凌云533100

出　　处：《地质科学》2003年第1期107-113,共7页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目 (批准号 :4 0 0 72 0 92 )。

摘　　要：运用伊利石结晶度K櫣ｂｌｅｒ指数将桂西右江地区下三叠统罗楼群和中三叠统百逢组下段划归为浅层变质带 (K .IΔ2θ°为 0 2 2～ 0 2 5 ) ;将中三叠统百逢组上段和河口组划归为近变质带 ,中三叠统百逢组上段为高级近变质带 (K .IΔ2θ°为 0 2 6～ 0 33) ;中三叠统上部河口组为低级近变质带 (K .IΔ2θ°为 0 38～ 0 40 ) ,不排除局部为成岩带的可能。地层柱自下向上 ,伊利石结晶度K櫣ｂｌｅｒ指数由小变大 ,变质程度由高变低 ,而且 ,变质作用级别与岩层在地层柱中位置协调以及变质带边界与地层界线趋于一致 ,证明为区域埋藏极低级变质作用。凌云明山金矿区剖面矿体和百逢组各层段伊利石结晶度K櫣ｂｌｅｒ指数为 0 42～ 0 5 0 ,属成岩带 ,且没有明显时空变化规律。The clay mineralogical composition and illite cyrstallinity were measured,with the samples from the Lizhou-Hekou section in Tianlin county and the Mingshan gold ore deposit in Lingyun county, and with D/max-2500 apparatus and the XRD measuring standard of SY/T 5163 1995. According to the Kübler index of illite crystallinity, the Early Triassic Luolou Group to the Middle Triassic low member of Baifeng Formation belonged to epizone with K.IΔ2θ° being 0.22; the Middle Triassic upper member of the Baifeng Formation and the Hekou Formation belonged to anchizone, among them the former as high anchizone with K.IΔ2θ° being 0.26～0.33, and the Hekou Formation as low anchizone with K.IΔ2θ° being 0.38～0.40. Additionally, it was possible that there was a diagenitic zone in the upper strata. It could be deduced that very low-grade regional burying metamorphism happened in the Lizhou-Hekou region, because the metamorphic grade was concordant with the location of the rocks, and the metamorphic grade boundary line was nearly same as the strata boundary line in the strata column. The Kübler index of illite crystallinity in the Mingshan gold ore deposit were 0.42～0.52 which belonged to diagenitic zone, and with no concordant with strata, which showed the characters of the gold metallogenitic hydrothermal alteration illite during the Yanshanian cycle after the regional burial metamorphism.

关 键 词：变质作用 伊利石 结晶度 Kuebler指数 XRD测量 广西 岩层 中三叠统 

分 类 号：P578.94[天文地球—矿物学]