广东丹霞山红色岩层中白斑成因的矿物学研究  

Mineralogy study on the origin of white spots in the red strataof Danxia Mountain,Guangdong

作　　者：杨志军 都衡恒 罗曦 张珂 何旺 刘逸 毛梦嫒 YANG Zhijun;DU Hengheng;LUO Xi;ZHANG Ke;HE Wang;LIU Yi;MAO Mengyuan(School of Earth Sciences and Engineering,Sun Yat-sen University,Zhuhai 519082,Guangdong,China)

机构地区：[1]中山大学地球科学与工程学院,广东珠海519082

出　　处：《矿产与地质》2022年第1期129-137,共9页Mineral Resources and Geology

基　　金：广东省自然科学基金(批准号:2021A515011472);技术服务项目“韶关市丹霞山管理委员会委托项目”(编号:HT-99982020-0040);广东国家公园建设专项资金(编号:2021GJGY026)共同资助。

摘　　要：采取光学显微镜、XRD、FTIR、Raman光谱等研究方法对广东丹霞山红色岩层中的白斑进行矿物学研究,旨在为白斑的成因模型构建奠定基础。研究结果表明:丹霞山红色砂岩中的白斑区域的主要矿物组成与红色砂岩相似,主要为石英、长石等造岩矿物,但出现了与还原环境相关的黄铁矿等矿物及未出现明显的赤铁矿、针铁矿等含Fe^(3+)矿物;白斑区域含有一定量的与sp^(3)杂化C—H键、O—N—O相关等相关的有机质组分及(或)C—H相关大分子组构体,它们对红色退变成白色可能起到相当的影响;富含有机质、H_(2)S、H_(2)O及CO_(2)等的气态物质沿砂岩中的矿物间空隙上升,形成大小不一的近椭球形区域,并在微生物及富含有机质、H_(2)S、H_(2)O及CO_(2)等的气态物质及(或)C—H相关大分子组构体作用下,造就还原环境,进而致使近椭球形区域中的红色含铁物质中的Fe^(3+)被还原及(或)被流体带走,从而使红色退变成白色形成白斑。The mineralogy of the white spot in the red strata of Danxia Mountain in Guangdong is studied by optical microscopy,XRD,FTIR,Raman spectroscopy and other research methods,in order to lay a foundation for the construction of the genetic model of the white spot.The research result shows that the main mineral composition of the white spot area is similar to that of the red sandstone of Danxia Mountain,mainly quartz,feldspar and other rock forming minerals,but there are pyrite and other minerals related to the reduction environment,and there are not obvious Fe^(3+)containing minerals such as hematite and goethite.The white spot area contains a certain amount of organic matter and/or macromolecular fabrics related to sp3hybridized C—H bond,O—N—O,etc.,which may play a considerable role for the rock from the red to white.Gaseous material rich in organic matter and H_(2)S,H_(2)O,CO_(2)along the gap between the mineral grain in the sandstone,forming a nearly spherical area in different sizes.Under the combination action of microorganisms with gaseous material rich in organic matter,H_(2)S,H_(2)O and CO_(2)and(or)C—H related macromolecular assemblies,a reducing environment is created,which in turn causes the Fe^(3+)of the red iron-containing material in the nearly ellipsoid area to be reduced and(or)taken away by the fluid,thus making the red fade to white.So white spots form.

关 键 词：丹霞地貌 白斑 成因 XRD 振动光谱 

分 类 号：P571[天文地球—矿物学]