PLANT MATERIAL IN TERTIARY SEDIMENTS
Adriána Pénzesová, Ľudmila Illášová
Department of Zoology and Anthropology, Faculty of Natural Sciences, Constantine the Philosopher University,
Nábrežie mládeže 91, 949 74 Nitra, Slovakia
Gemological Institute, Faculty of Natural Sciences, Constantine the Philosopher University, Nábrežie mládeže
91, 949 74 Nitra, Slovakia
Corresponding author: [email protected]
Abstract
The object of the study is silicified wood found in Tertiary sediments which have arisen over a long geological
period by complex processes that led to their preservation to these days. The aim of this study is to identify the
original plant component which naturally occurred in Tertiary period in the territory of Slovakia.
Key words: wood opals, petrified wood, silicification, petrification.
1 Introduction
Geological processes that formed the Earth from its bebinning, left some records in rocks
and minerals. Some of these rocks preserved information about the environments in which
organisms developed and lived together with their remains (Palmer et al., 2009).
In Neogene violent natural processes occured in the territory of today's Slovakia where
volcanic activitz plazed an important role.
Approximately 16,5 – 11 millions of years B.C. one of the biggest stratovolcanos
developed – štiavnica – which dominated in the territory of today's Central Slovakia. Periods
of intensive volcanic activity alternated with periods of temporary volcanic calms,in which
processes of destruction and demolition dominated. Vegetable matter was devastated during
volcanic activity, considerable part of plant material burned, only a small part was preserved
in fossil forms (wood opals and ventilated tree caves).
Petrification is a general term concerning fossilization, transformation of living organisms
to fossils, or processes leading to preservation of paced organisms in the form of hard rocks
(Pokorný et al., 1992; Petránek, 1993).
Fossilization processes occur by acting of silica solutions, this process is known as
silicification, or opalisation – formation of wood opals. Silicification occurs when interacting
silica with plant remains and its transgression through them (Mesiarkinová et al., 2009).
Volcanic explosions were accompanied by heavy rainfalls which caused entrainment and
leaching of wood-mass pieces (limbs, branches, roots, trunks) together with tuff material.
These were later overlaid and silicificated by the influence of solutions penetration, mainly by
silica to the cells of plants. This process gave rise to the formation of different variants of
wood opals.
The aim of this study is to identify the original plant components which occured in Tertiary
in our territory.
2 Material and Methods
This study we can divide into two parts – field and laboratory research. The field study
includes visiting areas which had to meet our established criteria, collection of quality
material and analysis of the surrounding sediment.
Laboratory research is focused on the processing gained plant materials. A part of the
petrified wood samples will be used in its original condition for grinding and a piece of
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material will be used for X-ray analysis. Grinding and polishing itself will be moved to a
specialised workstation.
For the microskopic study of silicified plant materials we will need cuts in three basic
sections: transverse, radial and tangential. These cuts are described sequentially and
systematically determined by using optical microscopy (PPL – plain polarised light). Surface
morphology of silicified woods will be studied by scanning electron microscopy (SEM).
Systematic identification and subsequent classification of samples into paleobotanic
taxonomic system will be based on well-preserved anatomical structures and features.
The results of X-ray analysis will help us to identify the degree of silicification which
reflects the temperature and pressure conditions.
After this stage, the work will focus on synthesis and interpretation of results.
3 Results and discussion
The study is under processing. The research is still ongoing and further action will be
determined on the basis of initial results. However, the results should involve: a systematic
classification of the samples, macroscopic and microscopic description and the results of Xray analysis.
Fig. 1 Wood opal from Veľký Ďur (Pénzesová, 2012).
4 Conclusion
Mass extinction at the end of the Cretaceous (Mesozoic) had less dramatic impact on plant
life than on the other organisms. Most plants survived and continued to diversify.
A new and important element in the development of forest vegetation was formed by
flowering trees. In this geological period warm climate with high rainfall dominated which
led to the development of rain forests not only in the equatorial zone. At the height of warm
climate in Eocene (Paleogene) tropical vegetation dominated, trees grew even close to the
North Pole. On the other hand, during the transition of Paleogene and Neogene a dramatic
cooling began which led to the dicline of thermophilus plant species in the tropics and
subtropics. There si an emergence of new types of habitats.
During the Neogene the diversity and significance of many types of flowering plants
increased, especially those typical of open habitats. Changing climate conditions during this
period resulted in further propagation of species of almost all groups of terrestrial plants
(Taylor et al., 2009).
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This suggests that during the Tertiary flora not only in Slovakia, but world-wide came over
a huge evolutionary influenced by climate-geographical changes. These changes are due to
volcanic activity deposited in the form of wood opals. We are able not only identify but also
reconstruct the vegetation occuring in our country through varios methods of analysis by
using wood residues. This is the objective of the study.
5 References
Mesiarkinová, M. et al. Mineralogické štúdium silicifikovaných driev pri Častkovciach
v Malých Karpatoch. In Mineralia Slovacca. ISSN 0369-2086, 2009, no. 41, p. 503-510.
Palmer, D. et al. 2010. Predhistória. Bratislava: Ikar, 2010. 512p. ISBN 978-80-551-2268-7
Petránek, J. 1993. Malá encyklopedie geologie. České Budejovice: JIH, 1993. 246p. ISBN 80900351-2-4
Pokorný, V. et al. 1992. Všeobecná paleontologie. Praha: Karolinum, 1992. 296p. ISBN 807066-585-8
Taylor, N. T. et al. 2009. Paleobotany. The biology and evolution of fossil plants. New York:
Elservier, 2009. 1230p. ISBN 978-0-12-373972-8
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