矿物岩石地球化学通报
礦物巖石地毬化學通報
광물암석지구화학통보
BULLETIN OF MINERALOGY PETROLOGY AND GEOCHEMISTRY
2009年
4期
349-355
,共7页
吕文%朱诚%彭华%俞锦标%李中轩%张广胜%欧阳杰%周日良%朱光耀%李兰%朱青
呂文%硃誠%彭華%俞錦標%李中軒%張廣勝%歐暘傑%週日良%硃光耀%李蘭%硃青
려문%주성%팽화%유금표%리중헌%장엄성%구양걸%주일량%주광요%리란%주청
江郎山%岩石岩性特征%丹霞地貌
江郎山%巖石巖性特徵%丹霞地貌
강랑산%암석암성특정%단하지모
Jianglang Mountain%lithological characteristics%Danxia landform
岩性特征的量化研究对分析丹霞地貌的成因具重要意义.江郎山岩石岩性标本的X射线荧光光谱分析和偏光显微镜鉴定发现,江郎山方岩组砂岩、砾岩中SiO2含量高达55.5%～75.8%,火山岩碎屑含量高,石英晶屑多已被高温熔蚀,三爿石中多处贯穿有辉绿岩和橄榄玄武岩的岩脉和岩墙,其辉绿-间粒结构和斜长石与暗色矿物的组合,构成了抗风化能力强的岩体,使三爿石得以长期保存.洞穴岩石CaO含量百分比的平均值是崖壁的三倍,且洞穴中岩石的胶结物多为方解石,其含量超过总胶结物的50%以上,使岩石结构的稳定性受到影响,会发生类似石灰岩地区的溶蚀作用,从而导致岩体的破碎和崩塌,有可能形成诸如会仙岩、天宫洞等大型洞穴和凹槽.
巖性特徵的量化研究對分析丹霞地貌的成因具重要意義.江郎山巖石巖性標本的X射線熒光光譜分析和偏光顯微鏡鑒定髮現,江郎山方巖組砂巖、礫巖中SiO2含量高達55.5%～75.8%,火山巖碎屑含量高,石英晶屑多已被高溫鎔蝕,三爿石中多處貫穿有輝綠巖和橄欖玄武巖的巖脈和巖牆,其輝綠-間粒結構和斜長石與暗色礦物的組閤,構成瞭抗風化能力彊的巖體,使三爿石得以長期保存.洞穴巖石CaO含量百分比的平均值是崖壁的三倍,且洞穴中巖石的膠結物多為方解石,其含量超過總膠結物的50%以上,使巖石結構的穩定性受到影響,會髮生類似石灰巖地區的溶蝕作用,從而導緻巖體的破碎和崩塌,有可能形成諸如會仙巖、天宮洞等大型洞穴和凹槽.
암성특정적양화연구대분석단하지모적성인구중요의의.강랑산암석암성표본적X사선형광광보분석화편광현미경감정발현,강랑산방암조사암、력암중SiO2함량고체55.5%～75.8%,화산암쇄설함량고,석영정설다이피고온용식,삼장석중다처관천유휘록암화감람현무암적암맥화암장,기휘록-간립결구화사장석여암색광물적조합,구성료항풍화능력강적암체,사삼장석득이장기보존.동혈암석CaO함량백분비적평균치시애벽적삼배,차동혈중암석적효결물다위방해석,기함량초과총효결물적50%이상,사암석결구적은정성수도영향,회발생유사석회암지구적용식작용,종이도치암체적파쇄화붕탑,유가능형성제여회선암、천궁동등대형동혈화요조.
Quantitive lithological study is significant for analyzing the genesis of Danxia Landform. Polariscope thin section and X-fluorescence spectroscopy analyses results indicates that volcanic gravel and rock clastic are major components of Fangyan Formation (K_1f), and that SiO2 content is commonly as high as 55.7%～75.8%. The volcanic gravels are very hard and highly inert because of their experience of high temperature activities, like quenching course and because of the peculiar dolerite space-grained structure, plagioclase and dark minerals form hard rock body. The average CaO content of stones in caves is about 6.07%, which is three times higher than those of cliffs. Rock cements in caves are mainly calcite, accounting for more than 50%. Carbon dioxide from air dissolved into the infiltrating water to form ions like CO_3~(2-) and HCO_3~- , which can dissolve calcite component and can modify the stability of stone's structure. Thereby, stones crash and dilapidation phenomenon happens. These processes result in some caves like Huixianyan Cave, Tiangongdong Cave, Jingxinshishi Cave and Zhonggudong Cave.
