江西上饶龙门高岭石-叶蜡石矿的矿物组成及稳定同位素特征

在野外地质工作、镜下观察的基础上,采用电子探针、X射线粉晶衍射、氢氧稳定同位素测试等方法对江西上饶龙门高岭石-叶蜡石矿床矿石进行了分析。其主要组成矿物为高岭石族矿物、叶蜡石和石英,其次有少量的绢云母、黄铁矿和赤铁矿等。矿石中高岭石族矿物Hinckley指数为0.33～0.94,整体属于较无序高岭石,叶蜡石有2M型和1Tc型两种多型,以2M型为主。矿石的δ18O值为4.5‰～6.6‰,δD值为-71.7‰～-98.5‰。综合分析认为该矿床为晶屑玻屑凝灰岩受热液蚀变而成,其成矿热液主要来自大气降水,成矿温度为75℃～300℃,压力<1kb。

Mineral Components and Stable Isotope Compositions of the Longmen Kaolinite-pyrophyllite Deposit in Shangrao, Jiangxi Province

Based on field survey and microscope observations,the authors selected representative samples of the ores from the Longmen kaolinite–pyrophyllite deposit in Shangrao of Jiangxi Province to analyze mineral compositions by such means as electron microprobe analysis,X-ray powder diffraction and hydrogen and oxygen isotope analysis.The ores mainly consist of kaolin-group minerals(kaolinite,dickite),pyrophyllite and quartz with minor sericite,pyrite and hematite.Kaolin-group minerals are mainly relatively-disordered kaolinite with the Hinckley index varying between 0.33 and 0.94,and most of the pyrophyllites belong to 2M type.Theδ1 8O andδD values of the ores range from 4.5‰to 6.6‰and from-71.7‰to-98.5‰respectively.It is suggested that the ore deposit was formed by replacement of tuff by hydrothermal fluids,which mainly came from the meteoric water. The formation temperature of the ore deposit was 75℃～300℃ and the ore-forming pressure was less than 1 kb.