Проведена ревизия возраста поверхностей выравнивания Австралии. Устанавливается полная аналогия в количестве и возрасте поверхностей выравнивания Австралии, Европы и Азии. Эта общность объясняется связью формирования поверхностей выравнивания с глобальными экстатическими трансгрессиями океанов.
Предлагается оригинальная общая многоступенчатая классификация литокриогенных процессов и явлений и новые классификации отдельных их типов. Применена новая методика построения классификационных схем.
Характеризуются особенности рельефа Центральных Кодр и основные этапы его развития. Особая роль в формировании облика современного рельефа Кодр принадлежит оползневым образованиям и прежде всего крупным эрозионно-оползневым циркам в верховьях балок-гыртопам. Детально рассмотрены морфология гыртопов и ее связь с геологическим строением Корр. На основе комплексного палеогеоморфологического и палеогеографического анализа выделены три этапа новейшего развития рельефа Молдавских Корр. Этап наиболее интенсивного и массового развития оползневых явлений связывается с эпохой похолодания и перигляциальных условий в Кодрах, соответствующей последнему оледенению, а современная активизация оползней - с антропогенным влиянием.
Геоморфология и народное хозяйство
На примере Иппата-Мерекского рудно-россыпного оловоносного района, расположенного в горном узле на стыке Буреинского и Дуссе-Альиньского хребтов, рассмотрены важнейшие черты развития расчлененного среднегорного рельефа, определившие условия вскрытия рудных проявлений, нашедшие отражение в размещении и составе россыпей. Выделены главные направления специализированного геоморфологического анализа в изучении системы коренной источник россыпь.
Предложена комплексная оценка эффективности детальных структурно-геоморфологических исследований с целью прогноза буроугольных залежей (на примере Белорусского Полесья). Эффективность этих исследований оценивается следующими критериями: 1) совпадением выявленных структур с крупномасштабными геолого-геофизическими данными, 2) затратами времени на проведение исследований и получение окончательных результатов, 3) стоимостью детальных структурно-геоморфологических исследований.
Научные сообщения
Two large and complicated morphostructural areas can be recognized both at the shelf .and at the land within the zone of contact between the Black Sea basin and the North-Western Caucasus: Tamar and Novorossiysk areas. The areas differed from each other in morphostructures characteristics, direction and rate of neotectonic movements throughout the Neotectonic stage. Morphostructural analysis allowed to distinguish within the areas morphostructural regions and individual morphostructures differing in neotectonic movements intensity. The most pronounced features of the areas' topography were formed during last (Neogene-Quaternary) stage, characterized with considerable sinking of the basin along fault lines and its enlargement on account of middle masses of the Alpine geosyncline.
The role of the bedrock topography in the distribution of the Pleistocene deposits within the range of the insular heights is analyzed, the age of Haanja and Otepaa bedrock elevations being defined. Conclusion is drawn that the tectonic movements were not of great importance in the formation of the insular heights and the latter were formed on the bedrock cores between glacier lobes which differed in the rate of ice flow. Thus the bedrock topography was of primary significance, it predetermined debris accumulation both at its proximal and distal slopes under the moving glacier.
The author calculated thickness of average layer removed by erosion per year on the basis of solid discharge data; the thickness appeared to be more at middle` mountains of Calcareous Daghestan than at high mountains of Schistous Daghestan. It is accounted for by deep valleys and intensive weathering at Calcareous Daghestan. Considering the results the author thinks it possible that the direct correlation of erosion intensity with height (postulated by A. Penck) can be in some cases essentially disturbed.
A geomorphological scheme of the shelf of the North-East Black Sea has been compiled, showing submarine terraces, «marginal bar» or system of bars and the shelf's edge. Analysis of the present-day abrasion processes allows concluding that the terraces are regularly formed at depths less than 20 meters and more than 60 to 70 meters. A simple mathematical model of shelf evolution is introduced.
The author argues the necessity to take into account a correction for the World Ocean level change when total neotectonic movement amplitudes are calculated or neotectonic maps are compiled. The correction (when used on the scale of the whole planet) is shown to increase considerably the areas submerged during the neotectonic stage, which confirm the well-known hypothesis of progressive contraction of the Earth.
Geomorphic processes change the surface topography, and the changes themselves induce decrease or increase in the processes intensity. Thus the auto-regulation of the forming relief is manifested through the intricate interaction. Stage of erosion can be defined by the character of real surface, using a dissection index which can be easily' calculated from topographic maps.
The Vagai valley cuts three basin terraces of different age. There are II local fluvial terraces within lower reaches of the valley (150 km long) which are associated with the three basin terraces levels and the Irtysh River terraces. The valley is proved to consist of three section differing in age, their limits are basin shorelines 110 and 75-80 meters high, corresponding to two transgressions maxima. The floodplains are also of different age. The terraces are considered to be eustatic. Their typical features are association with a certain basin terrace, local extent, relative lowering upstream to the first terrace level, each terrace disappears approximately at the height of the upper limit of the next (higher) basin terrace.
The author describes the mechanism of expiration (glacial erosion) at the sea floor by Shelf glaciers, the latters differing in mass budget (Ross glacier freezes and melts at its base, McMurdo glacier actively freezes at the base). The expiration rate is calculated to be not less than 1 cm per year at loose sediments and 1,0 to 1,5 mm per year at rock floor. Typical features of expiration topography are stated, which has been formed by shelf glaciers and emerged due to tectonic uplift of the Transantarctic Mountains (sub-horizontal expiration terraces, crossing flatbottomed valleys, now situated above mountain glaciers surface). A classification is developed of loose deposits- formed by shelf glaciers.
A detailed structural-geomorphological analysis of coastal plains and shelf at East; Arctic sector of the USSR allows to distinguish four group of structures, including: archdome uplifts inherited from late erogenous stage, structures due to differentiated down-warping of the shelf; block structures at the zone of shear stress; rift structures. The delineated system of circumpolar faults shows similarity of submerged and emerged parts of the arctic margin of the continent, the system itself being a structure of planetary rank. Its special features and contacts with more ancient continental structures indicate that besides the shelf down-warping lateral shear movements were of importance.
Into the group of rock solifluctional forms the author includes stone steps, garlands, tongues and some transitional forms. The structure, distribution, conditions and mechanism of evolution of the forms are described. A single genetic sequence is -shown: stone polygons-stone steps and garlands-stone tongues--turf-covered solifluction tongues.
Рецензии
Эрозия почв и русловые процессы (географические аспекты проблемы): рецензия на сборники «Эрозия почв и русловые процессы» (научный редактор Н. И. Маккавеев), Изд-во МГУ, вып. І, 1970, вып. 2, 1972, вып. 3, 1973, вып. 4, 1974, вып. 5, 1976, вып. 6, 1978, вып. 7, 1979.
Юбилеи
18 августа 1980 года исполняется 60 лет со дня рождения и почти 40 лет производственной, педагогической и научной деятельности Александра Петровича Рождественского, доктора геолого-минералогических наук, профессора, заведующего Лабораторией геоморфологии и новейшей тектоники Института геологии Башкирского филиала Академии наук СССР.
ISSN 2949-1797 (Online)