Вопрос о трансгрессивных и регрессивных явлениях при накоплении осадков вступил в новую фазу. Это произошло благодаря изучению угленосных формаций с учетом цикличности их строения. В литологических работах по Кузнецкому, Карагандинскому и другим бассейнам, а особенно по Донецкому, выяснилось значение осадочных циклов, состоящих из регрессивных и трансгрессивных частей. В дальнейшем было установлено, что регрессия не повторяет в обратном порядке пород и фаций трансгрессивной части цикла. Она характеризуется рядом фаций с особыми признаками, если даже они развиваются на тех же глубинах и тех же расстояниях от берега, что и трансгрессивные фации. Соответственные признаки пород также несут на себе черты отличий, которые все более и более выявляются.
Вопрос о предпосылках углеобразования нуждается в периодическом пересмотре вследствие непрерывного прогресса в различных областях геологической науки и критической проверки многих ее положений на основе диалектического мировоззрения и исторического сопоставления. Многое в угольной геологии, что было постоянным и застывшим в положениях западно-европейских руководств и казалось незыблемым и, что было выведено из изучения среднекарбоновых каменных углей на практике оказалось неполным, односторонним и неправильным в приложении к угленакоплению более молодых угленосных эпох. При рассмотрении всего многообразия угольных бассейнов различного возраста бросается в глаза прежде всего непостоянство обстановки, благоприятствующей угленакоплению из периода в период. Представление об одних каких-то стандартных оптимальных условиях и необходимых предпосылках углеобразования должно быть отброшено и заменено представлением о необратимом развитии этих предпосылок во времени и пространстве.
Для специалистов угольной геологии краевые прогибы приобрели особый интерес после того, как стала несомненной связь этих структур с угленосностью. Установление этой связи было затруднено тем, что одни авторы причисляли краевые прогибы к платформам, другие — к. геосинклиналям и, наконец, третьи, не без некоторого основания, зачисляли их в новую, особую (третью) категорию, равноценную геосинклинали и платформе, называя ее переходной областью. Необходимо было разъяснить этот сложный, чисто тектонический вопрос, заключающий целый ряд противоречий и недоразумений, вызванных отчасти неточностью определений и разграничений различных понятий. Настоящая статья отнюдь не претендует на внесение каких-нибудь новых тектонических представлений или положений. Она имеет целью подвергнуть анализу существующие представления о краевых прогибах с историко-геологических и логических позиций. В стремлении разобраться в вопросе о положении и развитии краевых прогибов автор старается не упустить из виду проверку отвлеченных рассуждений связью с угленосностью и практикой. В статье ставится ряд элементарных вопросов перед тектонистами в надежде, что они выскажут свою окончательную точку зрения и доведут до конца те мысли, которые .были высказаны только предварительно.
При вычерчивании детальных геологических карт со штриховой и притом сложной легендой возникает обыкновенно затруднение в подборе условных обозначений, обеспечивающих резкое выделение отдельных геологических горизонтов. Часто даже в ответственных изданиях можно встретить неудачные так называемые «слепые карты». Это снижает качество оформления книги и мешает ясному восприятию иллюстраций. Подбор наиболее удачных условных обозначений до известной степени всегда остается делом искусства и опыта составителей и чертежников карт. Но в этом вопросе может помочь и знание некоторых основных простейших положений, позволяющих избежать по крайней мере элементарных ошибок при вычерчивании карт. В настоящей статье намечается ряд общих принципов комбинирования условных обозначений, которые нужно не упускать из виду в интересах наибольшей наглядности карт. Штриховые обозначения можно расположить в ряд с возрастающей или убывающей густотой темной окраски. Для этого целесообразно использовать сочетание двух, трех или четырех указанных выше способов контрастирования — различия в толщине, расстоянии и направлении между линиями (или значками). Наибольший эффект создается при использовании всех четырех различий, в частности соседства черного и белого цветов. Комбинировать эти различия надо так, чтобы каждое новое прибавление в данном обозначении действовало в одном направлении. Применение пунктиров и фигурных значков подчиняется тем же закономерностям, т. е. в них нужно также комбинировать различия в направлении, расстоянии и толщине или жирности значков.
The issues of genetic classification and typification of coal basins are of great fundamental and practical importance. The value of such a classification will depend on the significance of the principles underlying it, on its applicability in practice and on the possibility of making a more or less complete forecast based on it. Since the appearance of G. A. Ivanov's classification of coal basins, it can be considered established that the geotectonic principle is the first and most essential for genetic subdivisions into large groups. Fifteen years after the appearance of this classification, the study of geotectonic structures now allows us to make a more detailed subdivision based on the same geotectonic principle. However, this does not exclude the possibility and necessity of having other classifications of coal basins for different purposes, based on completely different criteria. For example, basins have long been divided into parallic and limnic based on the ratio of coal-bearing sediments to the proximity of the sea. This is, so to speak, a paleogeographic division. From the point of view of exploration and study, it is important to subdivide coal basins into open, semi-closed and completely closed based on the development and preservation of the rocks covering the coal-bearing strata. For the needs of geophysical work, they can be classified by the nature of tectonic forms, i.e. by the type of dislocations, as P. I. Stepanov does. Basins can be divided into brown coal and hard coal by the quality of coal, and by age into carboniferous, Permian, Jurassic, Tertiary, etc.
"In the petrographic study of coals, one has to deal with a number of concepts and terms that change their meaning over time as science develops. Therefore, at each stage of the development of coal petrography, as in any other scientific field, there is a need to revise the terminology used, clarify concepts, and establish a connection between different groups of terms. Among the current issues of coal petrography that require clarification, one of the first is the issue of macro- and microstructure and their relationship. Then comes the issue of the relationship between structure and texture, which is sometimes understood in different ways. Next comes the issue of the material composition of coals and its relationship with structure and other factors. Finally, the most difficult problem arises in linking genetic concepts with structure and texture. To do this, it is necessary to consider these issues comprehensively, in their relationship and in development, since structural differences and material changes can be considered at different stages of the development of coal matter (brown coal - anthracite).
The problem of metamorphism and transformation of coal matter is very complex. It involves questions of chemical transformation of organic matter in nature, on the surface of the earth's interior, questions of physical changes in coal matter under different conditions, questions of the impact of geological agents (temperature, pressure, mineralizers) and a number of others. Therefore, scientists of different specialties approach these questions somewhat differently and, based on different premises, often come to opposite conclusions. At the same time, sometimes what is only a hypothesis is presented as facts, and ignorance of factual material from a neighboring field of science sometimes leads to the denial of well-known facts and conclusions of this science on this issue. That is why the problem of coal metamorphism still remains unsolved. All these difficulties could be overcome if a comprehensive work on this problem was set up, which would include the joint development of all controversial issues by scientists of different specialties.
At present, it can already be considered sufficiently clear that coal-bearing strata represent unique geological polyfacial formations, appearing in the history of the earth under certain conditions. In a number of characteristic features, they differ sharply from other equally typical formations, for example, flysch, molasse, salt-bearing, etc. However, the conditions of formation, as well as the very nature of coal-bearing deposits, do not remain constant for all geological periods, but, on the contrary, reveal changes and development. This development for large segments of geological history reveals its progressive nature, although it experiences periodic fluctuations and deviations, reflecting in this sense the general course of development of the earth. The present work sets as its task, by analyzing a wide range of material, to reveal the features of coal-bearing sediments, as a certain type of deposits, and to illuminate the patterns of their accumulation; and on the basis of the latter, to outline specific methods of study, arising precisely from their characteristic features, not inherent in many other complexes of deposits.
The issue of coal provinces is of great practical importance. It is closely related to forecasts in the search for new or closed coal deposits and the prediction of possible qualities of coal in unexplored areas. Therefore, not only coal geology is interested in establishing coal provinces, but also prospecting and exploration and the coal industry. This issue can only be correctly resolved as a result of a deep comparative study of coal basins and the generalization of individual coal occurrences into a single whole. However, it cannot be separated from the discussion of the volume and larger and smaller subdivisions than a province. The next, smaller, unit of subdivision is a coal basin. A province consists of several basins and isolated deposits. The basin itself is divided into a number of regions and deposits. The boundaries of these concepts are quite clear. The issue of larger units of the coal hierarchy is much less developed. Academician P. I. Stepanov introduced the concept of coal accumulation belts into science. By coal accumulation belt he means that “...area of the earth’s surface within which, during a certain geological period, the most abundant accumulation of coal deposits and coal masses occurred.
Currently, in the Kuznetsk basin, the boundary of productive (Erunakovskaya, Balakhonskaya) and unproductive formations and subformations is considered to be the last or first layer of working thickness (more than 0.70 m). However, recently a lot of data has accumulated that contradicts this assumption. The paleontological division will not coincide with the industrial one. A more objective criterion could be a quantitative, i.e. statistical, approach to various lithological features. Based on the idea of the cyclic structure of coal-bearing strata and knowing the differences between the typical cycles of the Ilyinskaya and Erunakovskaya subformations, primarily in scale, we made an attempt to statistically test changes in the average and maximum thickness of cycles in a specific section. Statistical, i.e. quantitative, analysis of a number of lithological characteristics (mainly thickness) reveals the possibility of establishing a sharp and fundamental boundary corresponding to a sharp change in the average amplitude of cycles. Other features of the cycles are closely and genetically related to this change, for example, the thickness of the basal sandstones of the continental facies, the thickness of coal seams, and therefore a sharp increase in the number of working seams, i.e. purely practical consequences. This allows us to recognize that it is more rational to draw the boundary of two subformations, Ilyinskaya and Yerunakovskaya, on the basis of the cyclicity of about 41 layers, which has a number of advantages (see article).
The geological and historical features of coal-bearing strata undoubtedly depend on the previous development of the face of the earth and on the nature of the movements at the corresponding time. In other words, they are a function of geotectonic and paleogeographic conditions. The multiple appearance of alluvial fans and proluvial, river-washed pebbles is especially characteristic only of the Lower Jurassic coal accumulation period in the USSR. The establishment of a special type of coal accumulation in the Lower Jurassic period in the Hercynian mountain country of Western Siberia, Kazakhstan and Central Asia is of great fundamental importance.
The study of stratification in a group of rocks of organic (more correctly, mixed) origin, such as solid caustobiolites, showed a certain similiarity of its origin with the stratification of plastic rocks. The stratification of coals has specific features that are characteristic only of fossil fuels. They are associated with a significant reduction in material and volume and compaction during humification and coalification from fresh peat to anthracite, which can be estimated at about 5-7 times. The horizontal orientation of plant remains is partly related to this very phenomenon. Stratification, its nature, origin and degree of identification are closely related to the conditions of origin of the coals themselves and can provide significant material for deciphering coals.
Observations of the forms and character of cross-bedding gave me reason to ask myself whether they could serve as a criterion for recognizing the genesis of this sequence. The purpose of this work is: 1) to arouse interest and outline a program for detailed and careful observations of the very peculiar phenomena of cross-bedding; 2) indicate an approach to their interpretation (given the current state of our knowledge) and 3) applying these general considerations to the observed specific cases, raise the question of the possible clarification of the genesis of the coal-bearing strata of the Moscow basin and continental deposits in general by studying the nature of the bedding."
