X-Ray Radiography Analysis of Massive Sandstone and a Discussion on Their Genetic Mechanism
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摘要: 沉积岩中的层理构造大多是在沉积时的物理作用下产生的,因此提供了有关地质作用、沉积环境和古地理方面的大量信息。在大部分岩石中,层理构造的细节可以通过各沉积层间的颜色、结构、成分或胶结物的变化而显示出来。然而,在许多沉积物中用肉眼看不出结构、成分与胶结物等的明显变化,以致岩石在表面上看来是无构造和均质的,通常称其为“块状层理”(massive bedding)或“均质层理”(homogeneous bedding)。这种现象在野外露头和岩心中都经常遇到。Abstract: The term "massive sandstone" in this paper is designated to deseribe those sandstones which show no visible internal structures. X-ray radiography has provided to be a new method for the study of massive sandstones. Some of the massive sandstones show different kinds of stratification on X-ray exposures, but some of them remain structureless and homogeneous even under the radiation of X-ray. The former can be produced by vertical or lateral accretion and may be called "pseudomas-sive"; the latter are mainly formed by gravity flow and may be called "true massive". In the present paper, the principle and process of this method have been briefly introduced, and the genetic mechanisms of the two types of massive sandstones have been discussed in rather detail, exemplified by the Dainan Formation of northern Jiangsu, China. Finally, according to the associated sequences of sedimentary structures, several kinds of depositional environments which account for the formation of massive sandstones are recognized. The result of the study indicates that this method is of practical significance for identifying the sedimentary environments of reservoir rocks and for guiding hydrocarbon exploration.
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[1] Hamblin, W.K.,1962,X-ray radiography in the study of structures in homogeneous sediments,Jour,Sed,Pet,V.32 P201-210. [2] Middlton,G.V.and Hampton,M.A,1976,Subaqueous sediment transport and deposition by sediment gravity flows,In:Marine sediment transportand environmental management, (Ed, by Stanley, D.J. and Swift,D. J. P.),P.197-218. [3] Walker,R.G.,1975,Generalized facies models for resedimented conglomerates of turbidite association,Bull.Geol.Soc.Am v.,86,P.737-748. [4] 布拉特等,1978,沉积岩成因(中译本),P.85,科学出版社. [5] 赖内克等,1979,陆源碎屑沉积环境(中译本),石油工业出版社.
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