NEW PhD. DISSERTATION TOPICS

 

The Institute of Earth Sciences of the Slovak Academy of Sciences offers new dissertation PhD topics for the academic year 2021/2022. The doctoral program is organized in cooperation with the Faculty of Natural Sciences, Comenius University in Bratislava for the following disciplines: applied geophysics, mineralogy, sedimentology and paleontology. For more information applicants are advised to contact directly the PhD advisors via email.

 

APPLIED GEOPHYSICS

 

Forming mechanism of intense geomagnetic disturbances

PhD Advisor:  Mgr. Fridrich Valach, PhD.

email: ks.ga1632833282moeg@1632833282hcird1632833282irf1632833282

The dissertation will focus on gaining new knowledge about the geomagnetic activity, which is an important part of space weather. Topicality of the issue is determined by dependency of modern society on sensitive technological systems in space and on the ground, threatened by the manifestations of space weather. The up-to-day findings suggest that the two main causes of the increased geomagnetic activity are coronal mass ejections (CME) and co-rotating interaction regions (CIR), which are the major disturbances of the solar wind in interplanetary space. Comprehensive sources of information on outer space exist, e.g. the SOHO / LASCO CME Catalog. The interaction of CMEs and CIRs with the Earth's magnetosphere cause intensification of the complicated current system around the planet. Recent studies have indicated that the present understanding of the crucial role of the ring current may be partly incorrect for the most intense magnetic disturbances that occur in magnetic mid-latitudes. It also appears that the course of the geomagnetic activity caused by the CME or the CIR may be different. For studying the geomagnetic activity, time series of geomagnetic indices (K, Kp, Dst, AE etc.) are available. These indices measure the contribution of the different current systems to disturbances of the geomagnetic field. Available is also a large number of registered magnetograms, e.g. the database of INTERMAGNET. The aim of the dissertation thesis is the analysis of the available observed data in order to gain deeper understanding of the generation mechanism of intense geomagnetic disturbances, especially the geomagnetic storms. Expected benefits include new knowledge that might be useful for an improvement on the predictions of the geomagnetic activity.

 

Intensification of precipitation forming processes in the atmosphere in their spatial variability in the Western Carpathians mountain range

PhD Advisor:   Mgr. Milan Onderka, PhD.

email: ks.ab1632833282vas@a1632833282kredn1632833282o.nal1632833282im1632833282

Warmer climate should theoretically lead to more precipitation extremes due to increasing atmospheric water vapor content. The main reason for this trend is considered to be the higher content of water vapor in the atmosphere, which is increasing due to the increase in the temperature of the atmosphere and the surface of the oceans. This fact is also physically consistent with the theory describing the dynamic processes associated with moisture flows in the atmosphere and the genesis of atmospheric precipitation. Physical reasoning based on the Clausius-Clapeyron equation shows that warming the atmosphere by 1 ° C leads to an increase in water vapor content in the atmosphere by up to 7%, which not only increases the likelihood of extremely high total precipitation, but also contributes to more dynamic precipitation processes. The relationship of extreme precipitation with temperature has been shown to be more complicated depending on local climatic conditions, humidity, and orography. Global simulations of climate models confirm this trend when they assume a global 1% reduction in the duration of extreme precipitation per degree of warming. In the Netherlands, extreme rainfall lasting less than an hour increased as would be expected from the Clausius-Clapeyron relationship. Similar results have been reported by other authors in Switzerland, Germany, the United Kingdom, Australia and North America. A close relationship between extreme precipitation and dew point temperature has been identified. Dew point temperature in India has proven to be a suitable supplementary variable in non-stationary precipitation models. The relationship between air temperature and possibly also dew point temperature and precipitation extremes must therefore be assessed at the local/regional scales (within the Western Carpathians mountain range). The key objective of the PhD project is to investigate and analyze selected characteristics of rainfall and its extremes with respect to air temperature, humidity and dew point temperature.  In particular, the task of the PhD student will quantify the effects of rising air temperature and humidity on extremality of atmopsheric precipitaion at selected sites in the Western Carpathian mountainrange using ground-thruth data and ECMWF re-analysis data.

 

Geoelectrical modeling of the contact zone between the Inner and Outer Carpathians

PhD Advisor:   RNDr. Ján Vozár, PhD.

email: ks.ab1632833282vas@o1632833282vajfo1632833282eg1632833282

Co-advisor: RNDr. V. Bezák, CSc.

The interpretation of the crustal structure of the Western Carpathians based on magnetotelluric data and their multi-dimensional modeling by direct and inverse algorithms using the theoretical solution of the electromagnetic response of the conductive environment. The modeling of magnetotelluric data will be carried out using new analytical programs to determine the geoelectric properties of the structures in the studied area and to identify the main geological interfaces. The resulting geoelectric models will be used for integrated modeling with other geophysical parameters based on gravimetric (density), magnetic (magnetization), seismic (velocities) and thermal (thermal conductivity and sources) data. Based on the models, it will interpret the spatial position and structure of the basic deep crustal tectonic units and identify significant deep fault zones. All geophysical information will be compared with current theories on the geological and tectonic structure of the Inner and Outer Carpathians. Published interpretations can serve as a model for further interpretations of similar crustal geophysical parameters anomalies. The work requires basic physical and mathematical knowledge of electromagnetic theory and the programming languages.

 

 

SEDIMENTOLOGY

 

Upper Cretaceous red-bed formations of the Western Carpathians: microbiostratigraphy, redefinition and paleoenvironmental sedimentary conditions

PhD Advisor:   doc. RNDr. Ján Soták, DrSc.

email: ks.bb1632833282vas@k1632833282atos1632833282

Western Carpathians represent a type area of the Upper Cretaceous red-bed sediments, which were introduced already by Dionýz Štúr under name of the Púchov Marls in 1860.  The Púchov beds, as frequently used informal lithostratigraphic units of red pelagic marls within the Tethyan domain, need a revision of historical stratotypes and study of additional  neostratotypes in the Pieniny Klippen belt, Podmanín unit, Brezová Group, etc. Current research of the Púchov beds raised with their appurtenance to facies of the Cretaceous oceanic red-beds (CORB), which are in first importance of the paleoenvironmental study of oxic and anoxic events occurred in the Late Cretaceous oceanic basins. Therefore, the aim of the PhD study will be intended not only in redefinition of the Upper Cretaceous red-bed formations (Púchov beds, Gbelany beds, Košariská marlstones, Kysuca beds, Jaworki beds, Malinowa beds, etc.), but also in analysis of depositional environments of these red-beds considering of planktonic bioproductivity, foraminiferal benthic associations (DWAF), paleobathymetry, oxygen concentration, isotope paleothermometry, etc.

 

Depositional systems of continenal environments and shelf margins of the Central Carpathian Paleogene Basin

PhD Advisor:   doc. RNDr. Ján Soták, DrSc.

email: ks.bb1632833282vas@k1632833282atos1632833282

The subject of the dissertation is intended in analysis of clastic sedimentary formations on the continental margins of the Central Carpathian Paleogene Basin (CKPB). Research will focus on pre-transgressive sediments of Vajsková Conglomerates, Braväcovo Beds and the Borové Formation, which represent sediments of debris tali, alluvial fans, braided streams, fluvial environments, fan deltas, lacustrine and pedogenic carbonates, lateritic residues and plant remains. The study will also be processed in sedimentary sequences with the transition of continental to shallow water environments and shelfal sediments on the continental slope marginc (intrabasinal and in the Veporic land). The shallowing of the CKPB at the end of the Oligocene led to the deposition of lacustrine sediments, sandy bars and coarse-grained deltas in Hron Valley, Rajec and Horná Nitra Depressions, etc. Therefore, the dissertation will include a study of regressive formations of the CKPB containing a mollusc-rich sands and correlation of the Carpathian fauna with Oligocene mollusc fauna of the Paratethys (Solenovian), analysis of clays, weathered residues and resistant heavy minerals from eroded substrates of the Central Carpathians and their correlation with “Augenstein” formations of the Alps. The result will be an interpretation of synrift subsidence, tectonic inversion, paleogeography, depositional systems and physiogeography of the continental margins of the CKPB.

 

 Carbonate ramps of basal formation of the Central-Carpathian Paleogene Basin: microfacies, sedimentology and biostratigraphy of the nummulite limestones

PhD Advisor:   doc. RNDr. Ján Soták, DrSc.

email: ks.bb1632833282vas@k1632833282atos1632833282

Initial phase of marine flooding in the Central-Carpathian Paleogene Basin led to accomodation of carbonate ramp. Depositional environments of these ramps were enriched by nummulitic shells, which accumulations are known as so-called “nummulite banks“. Lagunar environments were more suitable for adaptation of alveolinids.  Deeper facies of carbonate ramp are developed as allodapic limestones  or even calciturbidites s prevalence of large foraminifers like Discocyclina and Heterostegina. The aim of the thesis will be interpretation of depositional architecture of carbonate ramp, microfacial description of foramol, rhodalgal and other types of limestones, analysis of progradational and aggradational sequences and cycles depending on eustatic sea-level changes, improvement of stratigraphy based on SBZ zonation of large foraminifers  (Serra-Kiel et al. 1998), counting of the ratio between micro- and macrospherical tests of nummulites and another taphonomical properties of nummulitic limestones.

 

 

PALEONTOLOGY

 

Evolution of planktonic foraminifera since the Cretaceous/Tertiary mass extinction and their gradual recovery in the Paleogene formations of the Western Carpathians

PhD Advisor:   doc. RNDr. Ján Soták, DrSc.

email: ks.bb1632833282vas@k1632833282atos1632833282

Upper Cretaceous microfauna provided a richness and species diversity of planktonic foraminifera. Biotic crisis at the Cretaceous/Tertiary boundary affected the planktonic foraminifera by impoverishing their assemblages, reduction of foraminiferal species, dwarfing of test size and preferences of oportunistic forms. Subsequent foraminiferal assemblages proceeded by their recovery, morphogenesis of a new taxons, specialization with regard to temperature and nutrient demands, appearance of exucursion species, enhanced biodiversity and diversity, etc. The aim of the PhD thesis will be intended in analysis of the stratigraphic sections from the Upper Cretaceous and Paleogene formations of the Western Carpathians with respect to critical time in the evolution of planktonic foraminifera.

 

Morphogenesis of clavate and digitate planktonic foraminifera in anoxic environments of the Cretaceous and Paleogene basins of the Western Carpathians   

PhD Advisor:   doc. RNDr. Ján Soták, DrSc.

email: ks.bb1632833282vas@k1632833282atos1632833282

Foraminiferal communities are sensitive to deficiency of oxygen in sedimentary basins. Under anoxic water, they develop various adaptations of the tests, which would allow them to survive in the upper layers of the water column. Such morphogenesis of planktonic foraminifers reveals a tendency to evolve a clavate and digitate species. The Cretaceous species of digitate foraminifer comprise of  Clavihedbergella, Leupoldina, Schackoina, etc. Similar morphotypes also appear during the Paleogene like  Clavigerinella, Hantkenina, Protentella and Bolliela species. The aim of the dissertation will be a morphological analysis of species of clavate and digitate foraminifers, the study of their biometric parameters, structures and taxonomic classification. Occurrences of these atypical species will be documented from Hauterivian, Aptian, Cenomanian - Turonian, Middle Eocene and Oligocene formations, and analyzed in a complex assessement of the systematics and paleoecology of the foraminiferal microfauna of the these formations (Pseudothurmannian, Koňhora, Wronine, Hulina,  Malinowa, Domaniža and Žilina, Menilite). The study of clavate and digitate species is intended to identify events of global anoxia and basinal semi-isolation in the Western Carpathians (Selli, Bonarelli, Eocene  "red-beds", Tard, Maykop, etc.)

 

Trends in paleoecological change in the Tatra Mts alpine and sub-alpine areas during the last 5000 years detected by diatom associations

PhD advisor: Dr. Radovan Kyška Pipík, PhD.

email: ks.bb1632833282vas@k1632833282ipip1632833282

Long-term natural changes in the high mountain environment of the Tatra Mts. reflect changes in humidity and temperature, which were also reflected in the oscillation of climatic zones and the frequency of debris flow events. With rise of civilisation, the human activity modified the mountain environment to man needs by changing of the plant community and introducing of the new animals. The combination of all these factors affected the hydrological and chemical regime of the limnic environment, of which diatoms are a very sensitive indicator. The aim of the doctoral thesis will be a high-resolution analysis of diatom communities and quantification of ecological changes in pre-industrial sediments of selected Tatra Mts. lakes.