SOME ASPECTS OF POLISH-UKRAINIAN GEOLOGICAL AND GEOMORPHOLOGICAL RESEARCHES OF WESTERN VOLYN-PODILLIA DURING THE POLISH INVASION

The proposed article is based on an analysis of publications on field observations published in the then Polish and Ukrainian periodicals, collections of materials from scientific forums at various levels, works collections of individual Polish and foreign scientific institutes, etc. The purpose of the article was an attempt to analyze and generalize the research results of the study area in the field of Quaternary geology and geomorphology. It should also be noted that publications from the listed sections of physical geography are encountered quite sporadically and in significantly smaller numbers than articles on purely geological disciplines such as mineralogy, petrography, lithology, tectonics, etc. The study of geological and geomorphological objects and processes was carried out on the territory of Western Volyn-Podillia, which at that time was a part of the Polish-Lithuanian Commonwealth. The works mainly concerned the study of the stratigraphy of anthropogenic sediments distributed in the Podillia loess and loess soils, continental glaciations and related glacial and fluvial-glacial deposits, surface and underground karst, etc. It was established that significant in volume and depth of generalization of works on the geological and geomorphological structure the region features at that time was not. The studies that were carried out were not systematic, they were often carried out on the researchers initiative and without adequate funding, with localization mainly in the territory with open at that time deposits of certain minerals types. Analysis of publications can be stated as follows: the study of Quaternary deposits of the region and loess in particular was carried out with extensive use of laboratory studies, paleontological method, chemical, particle size distribution mineralogical and petrographic analyzes, the method of separation of loess minerals in heavy liquids, paleontological and archaeological observations, etc., were progressive at that time. It should be noted that individual reports on the determination of the age of the Quaternary strata were poorly synchronized with each other and a reliable generally accepted scale for the division of these deposits in this period was not agreed. During this period, factually substantiated schemes of geomorphological zoning of both the Podillia region as a whole and its individual components were proposed. Regular relationships of the relief features of the region with the lithogenic base, neotectonic movements, glacial and fluvial-glacial processes are traced. Significant progress is noted in the study of stratigraphy, lithology of local loess strata, problematic issues of their genesis are discussed. Among the few works on the study of the loess cover of Volyn-Podillia, the work of Yu. Polianskyi and Yu. Tokarskyi attracts attention first of all. The works on the study of loess are important due to: a) their almost ubiquitous distribution in the described territories; b) value for stratigraphic subdivision of the Pleistocene; c) controversial genesis; d) widespread use for the production of bricks and tiles. Work on the study of surface and underground forms of the Podillia karst has spread. Systematic mapping of individual underground cavities begins which gave impetus to their use in the future as objects of tourism. The largest number of works is devoted to the problems of studying the relief and modern physical and geographical processes in the interwar period. At the same time, along with purely descriptive publications, works appear where conclusions are based on the use of cartographic materials, which allowed researchers to identify significant patterns in the morphological features of the region. In the period under study, numerous publications by soil scientists also appeared, in which Quaternary sediments are considered as parent rocks on which soils were formed, the dependence of the type of soil on the lithology of the underlying rocks is established. In general, the works of Polish and Ukrainian researchers in the characterized period laid a reliable foundation for modern ideas about the geological and geomorphological features of the region. Keywords: geomorphological studies, Quaternary deposits, glacial deposits, stratigraphy, morphology, loess deposits.

Neoproterozoic Deposits of the Bashkir Mega-Anticlinorium (Southern Urals): State of the Art in Regional Stratigraphy

—This paper presents an alternative variant of stratigraphic subdivision of the upper Riphean–Vendian deposits (approximately corresponding to the Neoproterozoic Erathem of the International Chronostratigraphic Chart (ICC)) of the Bashkir Mega-Anticlinorium (BMA), based on the modern concepts of changes in the biosphere, atmosphere, and hydrosphere (and, accordingly, in the climate and the course of sedimentary processes) in the period ~1000–540 Ma, with regard to the results of recent studies and the proposals for improving the Russian General Stratigraphic Scale (GSS) of the Precambrian. The strict necessity of subdividing chronostratigraphic and lithostratigraphic units is shown. The presented data give grounds to regard the Zil’merdak Formation as a Group and assign three of its lower formations to the Middle Riphean (Yurmatinian). It is shown that the period of accumulation of the Karatau Group (comprising the Katav, Inzer, Min’yar, and Uk formations) was significantly shorter than the duration of the Late Riphean (Karatavian). Special attention is focused on the age of the Uk Formation (analysis of the existing data made it possible to refine its stratigraphic position): It formed, most likely, in the period 780–740 Ma. A high uncertainty of the stratigraphic position of the overlying geologic bodies is demonstrated. The Bakeevo, Tolparovo, Suirovo, and Kurgashla formations must be regarded as part of the Terminal Riphean (Arshinian). The Arsha Group, comprising the Bainas, Makhmutovo, Igonino, and Shum formations in the Tirlyan trough and represented by the Krivaya Luka Formation in the Krivaya Luka syncline, should not be totally assigned to the Terminal Riphean. It is proposed to exclude the Bakeevo Formation and the Tolparovo–Suirovo sequence from the Asha Group, because these deposits are, most likely, a modification of the Arsha Group located on the western flank of the BMA. The Uryuk Formation is probably of pre-Vendian age. The current contradictory data on the stratigraphy of the supra-Uryuk unit of the Asha Group are interpreted. The ages of the geologic bodies composing the Group and its stratigraphic interval still call for a thorough study.

Overturned Eocene – Lower Pliocene alluvial stratum on the southern coast of Lake Baikal and its neotectonic significance

The study is focused on a section of sediments exposed on the right bank of Mishikha River, Russia. These sediments have a wide range of ages, from the Eocene to the Lower Pliocene. The stratigraphic subdivision of the section is based on the lithogeochemical data and X-ray phase analysis of the mineral compositions. The particle-size analysis shows the alluvial origin of the deposits. Their ages are constrained by spore-pollen spectra in three palynozones: I – Eocene – Oligocene, II – Early – Middle Miocene (subzone a – Tsuga, Picea in the lower part, and Quercus, Taxodiaceae, Momipites, Carya in the upper part; subzone b – Fagus, Quercus, Tsuga), and III – the Late Miocene – beginning of the Pliocene (subzone ν – Ulmus, Juglans, Carya; subzone g – Carya, Alnus). The section shows a combination of normal and overturned sedimentary layers. The tectonic displacement of the block with its flip was accompanied by the entry into contact of the unlithified Pliocene sediments with a rigid bed and the development of a landslide. The lower age limit of deformations is constrained from the youngest (beginning of the Pliocene) spore and pollen spectrum extracted from deformed layers. It is suggested that the overturned layers result from strike-slip deformations of the sediments at the beginning of the late orogenic stage of the Baikal rift development. The regional correlations of the sedimentary strata give grounds to conclude that the Mishikha section is characteristic of alluvial sedimentation that dominated at the eastern end of the Tankhoi tectonic step (Mishikha-Klyuevka paleovalley), in contrast to the Tankhoi block in the central part of the step, wherein a thick Lower Miocene stratum of swampy-oxbow sediments accumulated. The stratons of the Mishikha section correlate with sedimentary units detected by drilling in the Selenga delta at the central part of the South Baikal basin.

Campanian biostratigraphy and paleoenvironments, a case study from the Central Srednogorie Zone, Central Bulgaria

<p>The Central Srednogorie Zone of Bulgaria represents a chain of strike-slip and pull-apart basins, part of the of the peri-Tethyan arc/back-arc basin system. The Upper Cretaceous volcano-sedimentary sequence in the western part of the Central Srednogorie Zone, forms two strips, spanning the Turonian-Maastrichtian interval. This succession is represented by basal siliciclastic sediments, an interval with magmatic rocks followed by volcanoclastic and epiclastic deposits, covered by white, red, grey limestones, with fast transition to sandy low-density turbidites. One of the most representative and continuous sedimentary record in the Panagyurishte strip is exposed east of the Petrich village (Petrich section).  </p><p>The base of the Petrich section is composed of the rocks from the so-called lower epiclastic unit (Coniacian-Santonian), followed by grey, pink to variegated limestones of the Mirkovo Formation (Santonian-Campanian). The middle and upper part of the section consists of muddy-sandy turbidites of the Chugovitsa Formation (Campanian-Maastrichtian). The lower part of this formation, the Voden Member, composed of grey thin bedded marls with rare sandstones beds, has yielded a comparatively rich macro- and microfossil record. Upwards, thin to medium bedded sandstones and marls are in alternation, with documented mudstone dominated intervals.  </p><p>The present study of the Petrich section is focused on integrated biostratigraphical analysis, based on three important fossil groups for the Campanian – inoceramid bivalves, nannofossils and dinoflagellate cysts. The study in progress creates a comprehensive calibrated dataset, in which the nannofossil and dinoflagellate cyst ranges and inoceramid occurrences, provide valuable markers for age assessment and stratigraphic subdivision of the Campanian. The presence of the nannofossil <em>Ceratolithus aculeus</em> marks a middle to late Campanian age, followed by a typical late Campanian assemblage including <em>Broinsonia parca parca</em>, <em>Reinhardtites levis</em> and rare <em>Eiffellithus eximius</em>. A high diversity dinocyst association is identified and ranges of key Campanian species as <em>Corradinisphaeridium horridum</em>, <em>Raetiaedinium truncigerum</em>, <em>Palaeohystrichophora infusorioides</em> and <em>Cannosphaeropsis utinensis</em> provided valuable markers for the stratigraphic subdivision of the Campanian. Typical middle Campanian “<em>Inoceramus</em>” <em>ellipticus</em> and “<em>Inoceramus</em>” <em>agdjakendsis</em> were documented from the Voden Member. The paleoenvironmental analysis, based on dinocyst assemblages and palynofacies data, suggests stable open-marine depositional environment and oligotrophic conditions, with normal marine productivity and nutrient availability during the Campanian in the basin.</p><p>Acknowledgements. The study is part of the Bilateral Bulgarian-Austrian collaboration within project KP-06-Austria/9.</p>

Eustatic, Climatic, and Oceanographic Influences on Geomorphology and Architecture of Isolated Carbonate Platforms: Miocene, Northwest Shelf, Australia

The Miocene represents an interval of marked global change, and this evolution is reflected in carbonate platforms from this epoch. Seismic stratigraphic characterization of high-resolution (ca 60 Hz) 3D seismic data from the Browse Basin, offshore Australia, reveals a middle to upper Miocene three-part seismic stratigraphic subdivision. Each unit consists of several seismic sequence sets and their component sequences. Seismic stratal geometries and seismic facies define a prograding shelf (Langhian and older), a barrier-reef complex with scattered platforms (upper Langhian–early Tortonian), and aggrading and prograding isolated platforms (early Tortonian–Messinian). The data permit description and interpretation of high-fidelity stratigraphic details of the initiation, expansion, termination, and geomorphology of over 100 platforms in this interval. The results reveal that the isolated platforms initiated following the Middle Miocene Climatic Optimum. The succession includes major seismic stratigraphic boundaries and overall patterns of platform growth and demise that correspond roughly with periods of pronounced eustatic change associated with initiation of eastern Antarctic ice sheets. Although invoking a eustatic control for coarse trends may be tempting, mismatch between the numbers and ages of sequences, as well as the variable stacking patterns among contemporaneous platforms regionally, precludes such an interpretation; conversely, some globally recognized eustatic changes do not have a pronounced manifestation in this area. Thus, it appears that the eustatic signal combined with dynamic physical regional processes such as waves, currents, and variable subsidence creates the complex architecture and geomorphology of platforms. These results illustrate how global changes can interact with local controls to create diverse patterns of birth, growth, and demise of carbonate platforms and drive local stratal heterogeneity.

Inoceramid bivalve and dinoflagellate cyst integrated biostratigraphy of the topmost Campanian–Maastrichtian in a part of the Western Fore-Balkan Mountains, northwest Bulgaria

We present the inoceramid and dinoflagellate cyst record from the topmost Campanian–Maastrichtian strata of three key sections of the Western Fore-Balkan Mountains, northwest Bulgaria. The following inoceramid zones were recognized: “Inoceramus” redbirdensis Zone, Endocostea typica Zone, Trochoceramus radiosus Zone and “Inoceramus” ianjonaensis Zone. The Campanian/Maastrichtian boundary was tentatively drawn slightly below the first occurrence of Endocostea typica. The uppermost inoceramid assemblage was confined to the lower part of the upper Maastrichtian. Dinoflagellate cyst ranges, as well as the first and the last occurrence events of dinocysts, provided valuable markers for the stratigraphic subdivision of the Maastrichtian. The first occurrence of Microdinium carpentierae was documented in proximity to the Campanian/Maastrichtian boundary. The Cerodinium diebelii Zone was recognized with a stratigraphical range from the lower Maastrichtian to the lower upper Maastrichtian. The last occurrence of Alterbidinium acutulum was recorded in the lower Maastrichtian and used as aid for tracing the lower/upper Maastrichtian substage boundary. The marked domination of delicate chorate dinocysts in all sections and the encountered low P/G ratio values are indicative of stable low-energy depositional environment and oligotrophic conditions, with normal marine productivity and nutrient availability in the basin during the Maastrichtian.

Correlation of upper Miocene–Pliocene Lake Pannon deposits across the Drava Basin, Croatia and Hungary

Upper Miocene to Pliocene (Pannonian) sediments of the Pannonian Basin System accumulated in the brackish Lake Pannon and the fluvial feeder systems, between 11.6-2.6 Ma. Their stratigraphic subdivision has been problematic for a long time due to the laterally prograding architecture of the basin fill and the historically independently evolving stratigraphic schemes of the neighbouring countries. We correlated the lithostratigraphic units of the Lake Pannon deposits between Hungary and Croatia in the Drava Basin, using lithological, sedimentological and palaeontological data from boreholes and outcrops, and seismic correlation. The Croatica and Medvedski breg formations in Croatia correspond to the Endrőd Fm. in Hungary, comprising shallow to deep water, open lacustrine, calcareous to argillaceous marls. The Andraševec fm. in Croatia corresponds to the Szolnok and Algyő Fms. in Hungary, consisting of sandstones and siltstones of turbidite systems and of clay marls deposited on the shelf-break slope. The Nova Gradiška fm. in Croatia is an equivalent of the Újfalu Fm. in Hungary, built up of a variety of lithologies, including sand, silt, clay and huminitic clay, deposited in deltaic environments. The Pluska fm. in Croatia corresponds to the Zagyva Fm. in Hungary, consisting of variegated clays, silts, sands and lignites, deposited in alluvial and fluvial environments. Coarse-grained (sand, gravel) basal layers are assigned to the Kálla and Békés Fms. and the Sveti Matej member of the Croatica fm. Coarse-grained intercalations within the deep-water marls belong to the Dorozsma Member of the Endrőd Fm. in Hungary, and to the Bačun member of the Medvedski breg fm. in Croatia. Sediment transport and lateral accretion of the shelf edge in the Drava Basin took place from the N, NW, and W, to the S, SE, and E, respectively. According to the biostratigraphic and chronostratigraphic analyses, the oldest shelf-break slopes in the Mura Basin are more than 8 Ma old, whereas the youngest ones in the southeasternmost part of the Drava Basin may be Pliocene in age (younger than 5.3 Ma). Thus, the 180 km long and at least 700 m deep Drava Basin was transformed into a fluvial plain during the last 3.5 million years of the Miocene.