丹霞地貌砂岩的微观化学风化作用电子探针研究  

STUDY BY EPMA ON MICROCOSMIC CHEMICAL WEATHERING TO SANDSTONE IN DANXIA LANDFORM

作　　者：郭国林[1] 郭福生[1] 刘晓东[1] 严兆彬[1] 杨志[1] 

机构地区：[1]东华理工学院核资源与环境教育部重点实验室,江西抚州344000

出　　处：《中国岩溶》2006年第2期172-176,共5页Carsologica Sinica

基　　金：教育部重点科技项目(批准号:204081);东华理工学院院长基金项目(批准号:DHY0406);核资源与环境教育部重点实验室开放基金项目(040804)

摘　　要：利用偏光显微镜观察、电子探针分析等手段对江西龙虎山丹霞地貌崖壁砂岩的微观化学风化作用的发展过程进行了研究,重点观测黑云母蛭石化以及长石黏土化过程中矿物组分的变化,进而探讨丹霞地貌砂岩的微观化学风化作用机理。在微观化学风化下,强风化层胶结物中的方解石迅速分解流失,从而导致黑云母大量发生蛭石化和铁的氧化物在矿物边部富集;长石则大量发生黏土化而使高岭石、石英等矿物富集。研究表明丹霞地貌砂岩在微观化学风化作用下矿物分解以及新矿物的形成都破坏原来岩石中的力学平衡,因而风化作用在宏观上表现为岩面片状剥离和重力崩塌,据此推断更大尺度的风化作用可能与岩石中矿物的微观化学风化作用存在着密切联系,是微观化学风化作用长期累积后在宏观上的综合表现。The microcosmic chemical weathering process to sandstone on the cliff wall of Longhushan mountain, a Danxia landform, in Jiangxi province is studied by means of petrographic microscope and EPMA etc in the paper. And in order to explore the mechanism of microcosmic chemical weathering to sandstone of Danxia landform, the study focuses on the change of mineral compositions such as vermiculite of biotite and argillation of feldspar. Calcites in weakly weathered layer cement decomposed and are washed away quickly under microcosmic chemical weathering condition, which resulted in mass vermiculite of biltite and is characterized by enrichment of ferriferous oxide in margin of minerals grains; in strong-weathered layers, mass argillation of feldspar are marked by enrichments of minerals such as kaolinite and quartz. The study indicates that as for sandstone of Danxia landform, both decomposition of old minerals and formation of new minerals destruct the mechanical equilibrium of original rocks, thus the weathering appeared as scar exfoliate and gravitational landfall, judging by this, lager scale of weathering may have close relationship with microcosmic chemical weathering of minerals in rocks and is the macroscopic comprehensive representation of microcosmic chemical weathering after long-term cumulation.

关 键 词：电子探针 微观风化 丹霞地貌 砂岩 

分 类 号：P575.1[天文地球—矿物学]