Science & Research | Geology

Regional geology of sedimentary formations

RNDr. Lilian Švábenická, CSc.
Head of the Department

Regional geology of Lower Paleozoic sedimentary formations

During the past few years, Lower Paleozoic research has concentrated on detailed studies of the the development of the Prague Basin's Silurian and Lower Devonian facies, systematic studies of the Bivalvia and Cephalopoda (including their paleocommunities), and the correlation of Bohemian Silurian and Lower Devonian with other North Gondwana regions. The study of the Wenlock migration of nautiloid cephalopods to the Prague Basin was completed in 2004. The protection and conservation of important geological sites in the Lower Paleozoic of Bohemia is also of high importance.

Mapping and studies of Upper Paleozoic

Geological mapping has improved our knowledge of the structure and distribution of Carboniferous and Permian sediments in the Plzeò and Kladno-Rakovník basins and of the Krkonoše Piedmont Basin. Stratigraphic and paleontological investigations are currently being carried out in order to help correlate the Permian horizons in the northern part of the Boskovice Graben as well as the palaeobotanical evaluation of the plants from the tuffaceous horizons of the Central and Western Carboniferous. The Permian Trutnov Formation in the Intrasudetic Basis have also been studied by means of facial analysis, also heavy mineral association.

Paleobotany and palynology: Cuticles of cordaites and seed-ferns were investigated as part of grant projects. The projects dealing with the investigation of spores of "in situ" spore-plants entailed an intimate conjunction of paleobotany and palynology. The Archaic group of Progymnosperm plants (Noeggerathia), which became extinct by the Upper Paleozoic, was carefully studied.

The revision of older materials in the archives of the CGS, such as boles, cones and fronds of the species Noeggerathia foliosa, enabled the reconstruction of an image of an entire plant with its cuticles and primitive stomas. Other spore-plants, such as seed-ferns and club-mosses, were also studied.

Research in the Upper Cretaceous sequences Cretaceous sediments

forms the most extensive pre-Quaternary platform cover of the Bohemian Massif.

Bohemian Cretaceous Basin contains the largest sources of groundwater and some important mineral deposits, such as uranium, sand for glass making and foundries, building materials (lime, gravel, sand) and decorative stones. Regional geology and geological mapping: One of the main objectives of our Cretaceous research is systematic regional geological investigation and mapping at different scales.  Publications about the Bohemian Cretaceous Basin and the Police Basin present some of the main outcomes of these studies. Current geological mapping activity has given us an updated view of the stratigraphy and tectonic structure of the Cretaceous in Northern and Eastern Bohemia and Moravia.

In the years 2002–2004 the specialists of the Department of Sedimentary Formations participated in the project „Stratigraphic architecture of Cenomanian strata of the Bohemian Cretaceous Basin: relationship of depositional system and reactivation of basement fault zones coordinated by the Geophysical Institute of the AS CR.

Biostratigraphy and paleontology: A general paleobotanical investigation of the Bohemian Cenomanian was undertaken. The past five years have also been dedicated to the study of Cretaceous bivalves, foraminifers and calcareous nannoplankton.

Micropaleontological and biostratigraphic research

The investigation of calcareous nannofossils was successfully applied to biostratigraphy during geological mapping and in large-scale joint projects with the International Correlation Programme, a bilateral cooperation with the Academy of Sciences of the Czech Republic. This research covered the following areas:

• Bohemian Cretaceous Basin: Attention was given to the Braarudosphaera-bloom during the Turonian which can be explained by an increased input of terrigenous material and/or a complete sea-level standstill.
• Outer Western Carpathians: The joint occurrence of  high-  and low-latitude nannofossil taxa was found in the Cretaceous flysch. The degree of influence of the "boreal" province fluctuated during geological time and was affected by paleogeographic conditions. This phenomenon was used for the paleogeographic reconstructions of the N Tethys Sea.
• The Upper Cretaceous nannofossil assemblages from the Eastern Alps, Western Carpathians and Northern Europe were compared and the conclusions were published jointly with our Austrian colleagues.
• The K/T boundary was identified in the distal flysch sediments of the Raèa Unit, Magura Group of nappes.
• Carpathian Foredeep: studies were carried out especially in the Lower/Middle Miocene boundary sediments.

Tertiary Research

Besides the geological mapping and research of Tertiary volcanic and sedimentary rocks the issues of Tertiary fluvial relics and Carboniferous sedimentary basins were solved – comprising the history of sedimentary basins and relics, paleogeography with source areas, petrology of rocks, stratigraphy, paleontology and palynology, tectonic history. Many old deep drills and geophysicals data were used for constructing of the basin relief.

Quaternary Research

Our Quaternary geologists have participated in the construction of more than 50 geological and thematic maps the explanatory notes of which contain significant stratigraphic, biostratigraphic, paleobotanical and malacozoological conclusions. Geological mapping in the scale 1:25,000 has started to cover the last large Quaternary accumulation region in the  Bohemian Massif is the middle course of the Labe River and connect the well known areas of the eastern Polabí and the Vltava-Labe confluence near Mìlník. The re-assessment of the stratigraphic clasification and incidental correlation with Central Europe is the main scientific goal of the project.

Palynological investigation of organic sediments in the currently compiled geological maps  helps with stratigraphic classification of Quaternary deposits as well as with determination of past environments. Recent investigations concern the palynology of the lacustrine and oxbow sediments of the Morava (March) River. Important Quaternary outcrops, new exposures of flood deposits, and landslide areas were documented and evaluated.

The assessment of valuable objects from the Paleolithic up to the Middle Ages was accomplished with cooperation of archeologists. The investigation of Quaternary sediments in Europe, Asia and Latin America was also carried out on an international scale. Some Quaternary localities were carefully documented and presented to the authorities for official protection measures.