ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00202.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThis paper presents the main trends in epigenetic research in the U.S.S.R. in the last years:1Study of epigenetic zonality in thick series of sedimentary rocks of various ages and tectonic regions, (zones of unaltered clay matrix, of altered clay matrix, of quartzitic structures and hydromica‐chloritic cement, and of prick‐like structures and phyllite‐like schists).2Principles of stadial analysis and mineral indicators of different epigenetic stages (clay minerals, organic matter, zeolites, feldspars, sulfides).3Facies of regional epigenesis connecting the main petrographic families of unaltered terrigenic rocks (quartz sandstones with kaolinitic matrix and the same composition of associated clays, acidic arkoses with hydromicaceous clays, lithoclastic sands with several matrix components and associated clays, and volcanogenic greywackes) with “related” facies of regional metamorphism.4Some practical aspects of epigenesis are:for petroleum geology: maximum depth of burial according to porosity, interruption of quartz, feldspar, sphene, epidote, carbonate, biotite, and clay mineral epigenesis by oil migration; andfor ore geology: (a) initial epigenesis: ore impregnation (e.g., volkonskoite in wood remains) due to intrastratal solution of heavy minerals and leaching of rock fragments; (b) deep epigenesis: e.g., galena impregnations due to release of trace elements during dissolution of rock forming minerals e.g., feldspars; and (c) metagenesis: “Alpine” veins across and along bedding, filled, e.g., wit

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00203.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe paper describes a method for determining the time of formation of oil and gas accumulations on the basis of the number of epigenetic minerals contained in granular reservoir rocks. The beginning of the accumulation is established by comparing the epigenesis stage in the oil‐ or gas‐bearing crest areas of the trap with the water‐bearing part of the reservoir at different depths of the geological section. This takes into account that the epigenetic processes tend to intensify with depth and to slow down after the rocks become filled with hydrocarbons.The time of accumulation completion is found by comparing the degree of epigenetic alteration of the oil‐ and gas‐bearing reservoirs with the water‐bearing reservoirs occurring at the oil (gas)‐water interface in the trap. The greater the differences, the older is the age of the pool completion. Lack of a difference indicates a youthful pool completion.In this paper, the ratio of detrital to authigenic titanium minerals, the quantity of regenerated quartz grains, and the pelitization of feldspars have been used.The application of this method is exemplified by oil deposits occurring in the productive Valangien and Hauterive beds (Lower Cretaceous) of the Ust‐Balyk and Megion fields of

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00204.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYOne of the productive horizons (17th) of north Sakhalin has been studied. The areas within and beyond oil and gas pools, near the top and at the flanks of structures were compared with areas where the horizon under study was waterbearing. The rocks were least transformed by secondary processes within oil accumulations, where a sudden increase was observed in the content of feldspars and accessory minerals (epidote, ilmenite and sphene) which had not undergone intrastratal solution. Inside gas pools, however, no deceleration of epigenesis has been observed. This points to a more recent (post‐Pliocene) accumulation of gas, whereas the first oil migration in these Miocene strata occurred in the Upper Pliocene, according to the hampered epigenesi

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00205.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe paper presents the dynamics of the structural change of kaolinite and its polymorphous (polytype) modifications at different stages of sedimentary rock formation.Sedimentogenesisis characterized by a gradual disordering of structure of triclinic kaolinite, the degree of disorder produced being proportional to the intensity and duration of the influence of the hydrodynamic medium.Epigenesis(deep) is connected with gradual transformation of kaolinite into dickite through the stage of mixed‐layer growths inheriting the structure of twin rotations of disordered kaolinite from the sedimentogenesis stage.Inmetagenesisfilling of fissures with dickite or nacrite takes place. The former is peculiar to the general thermodynamic medium of deep epigenesis/metagen‐esis, whereas nacrite is an indicator of intense stress and seems to be due to transformation of dick

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00206.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYRelationships between crystal chemistry and genetic conditions are presented for a series of dioctahedral micaceous minerals. Using a ferruginicity index, three groups of micaceous minerals are distinguished: Al‐micas, Fe‐illites, and glauconites. The degree of Al‐for‐Si substitution in the tetrahedral sheets of micaceous minerals depends on their thermodynamic genetic conditions. If pressure and temperature increase, the Al‐IV content increases and the octahedral sheet is “cleaned” from divalent cations. This process is accompanied by structural alteration with a polytype sequence 1Md‐1M‐2M1. Tetrahedral and octahedral charges are the same for micaceous minerals formed at the surface (sedimentogenesis/diagenesis) and are independent of the iron content. For most illites of sedimentary rocks an authigenic or

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00207.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYExperimental studies on saturation of montmorillonite with potassium showed that sorption of potassium tends to produce a regular alternation of the interlayer regions.The sorptive nature of the potassium fixation by montmorillonite appears to form the basis of the epigenetic formation of rectorite.

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00208.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYIn the course of deep weathering of a biotite gneiss, biotite is transformed into mixed‐layer biotite‐vermiculite hydrobiotite. Later biotite‐vermiculite is transformed into biotite‐chlorite under the action of hydrothermal solutions at the stage of epi

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00209.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYPrecision measurements of the densities and the optical constants of authigenic low‐temperature orthoclases, albites, muscovites and quartz, and comparisons with those of their high‐temperature counterparts of identical or similar composition proved that the authigenic orthoclase and muscovite have significantly lower densities than the high‐temperature modifications.For quartz and albite density differences are not established.The optical constants of the low‐temperature minerals (except for quartz) likewise possess specific properties, manifested in the orientation of the optical indicatrix and the values of the a

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00210.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe texture of carbonate cement in clastic rocks reflects the conditions of: (1) free pore crystallization; or (2) recrystallization under elevated temperatures and pressures. Fibrous carbonate cement may be formed as a result of preferential adsorption of clay particles or colloids in the direction perpendicular to c. Cryptocrystalline carbonate cement is formed in sandstones if the ratio carbonate/ argillaceous matter in less than 5 (for montmorillonite) or less than 3–4 (for illite), especially if it is near 2–1.The maximum amounts of isomorphic admixtures of Mg and Fe in calcite cement (see Fig.2) can be used for temperature reconstructions of the epigenetical environment.In deep‐buried rocks which are almost closed systems, migration rates are lower than diffusion rates and microenvironments of detrital grain corrosion may exist adjacent to those of precipitation of the same mi

ISSN:0037-0746    

DOI:10.1111/j.1365-3091.1970.tb00211.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY