广东丹霞山红色成因的矿物学研究  

A mineralogical study on the genesis of red color of the Danxia Mountain in Guangdong Province

作　　者：罗曦 杨志军 张珂 王汉雨 都衡恒 何旺 LUO Xi;YANG Zhi-jun;ZHANG Ke;WANG Han-yu;DU Heng-heng;HE Wang(School of Earth Science and Engineering,Sun Yat-sen University,Zhuhai 519080,China)

机构地区：[1]中山大学地球科学与工程学院,广东珠海519080

出　　处：《矿物学报》2021年第6期704-712,共9页Acta Mineralogica Sinica

基　　金：广东省自然科学基金(编号:2021A515011472);横向课题(编号:丹霞山白垩纪地层红色成因研究以及丹霞地貌定义的厘定)。

摘　　要：广东丹霞山作为丹霞地貌的典型代表和命名地,对于其独具特色的红色成因至今仍存在争议,本文利用光学显微镜、X射线粉末衍射以及电子探针微区分析对丹霞山红色地层石英砂岩开展了矿物学研究。结果表明,该石英砂岩中含有的主要矿物为石英、长石和云母等。红色物质主要呈团簇状、串珠状和浸染状3种状态,分布于胶结物和基质中,并在矿物表面形成一层薄膜,使岩石宏观上呈红色。Fe元素是致红色的关键,其来源可能是非晶态的铁氧化物,属于赤铁矿的无定形早期形态或铁络合物的形式。铁镁硅酸岩等母体矿物的继承,以及被地下水机械渗透的碎屑和粘土矿物,都能够为染色提供直接的铁来源。丹霞山的红色是在沉积后改造形成的,地下水的参与促进了长石等矿物的溶解,导致次生孔隙的发育和含铁物质的沉淀。含氧水环境的持续更新有利于溶蚀作用和胶结作用的进行,促使蚀变过程中释放出来的铁和溶液中的铁不断沉淀,导致红色加深,最终形成丹霞山广泛分布的红色地层。对于丹霞山红色成因的研究,有利于为以丹霞山为代表的丹霞地貌红色成因和致色机理研究提供新的科学理论依据。The Danxia Mountain in Guangdong province is the typical representative and named place of the Danxia type landform. The genesis of its distinctive red color is still controversial. In this paper, the polarizing microscope, X-ray Powder Diffraction(XRD) and electron probe microanalysis(EPMA) have been used to carry out a mineralogical study of the red sandstone in the Danxia Mountain. The results show that main minerals of the quartz sandstoneinclude quartz, feldspar, and mica. The red pigment in quartz sandstone is mainly distributed in three states, including clustering, beadlike, and disseminated states, in the cement and matrix of the sandstone. It occurred as a thin film on the surface of minerals, resulting in the appeared red color of the sandstone at macro-scale. Fe is the key factor causing the red color. It could be sourced from non-crystalline iron oxides which belong to the amorphous early state or iron complex state of hematite. The inheritance of parent minerals of ferromagnesian silicates as well as the mechanical penetration of groundwater in debris and clay minerals could provide direct sources of iron for red coloring. The red color of the Danxia Mountain was formed in the reworking process of sediments after sedimentation, as the penetration of groundwater in the sandstone had promoted the dissolution of its feldspar and other minerals, then led to the development of secondary pores and the precipitation of iron-bearing materials. Continuous renewal of the oxygen-containing water environment is conducive to the above dissolution and cementation, which promoted the continuous precipitation of iron released in the rock alteration process or in the mineral dissolution process, then resulted in the deepening of red color, and finally resulted in the formation of widely distributed red beds in the Danxia Mountain. This study on the genesis of red color of the sandstone in the Danxia Mountain is beneficial to provide a new scientific theoretical basis for researches on the genesis of red color and co

关 键 词：红色成因 矿物组成 含Fe物质 丹霞地貌 

分 类 号：P571[天文地球—矿物学] N34[天文地球—地质学]