"Crystal Past of Rock Silesia" "Magmatism in the Silesian Basin - Has Everything Been Explained?"" KRZYSZTOF SZOPA, ROMAN WŁODYKA University of Silesia in Katowice, Faculty of Earth Sciences, Department of Geochemistry, Mineralogy and Petrography, ul. Będzińska 60, 41-200 Sosnowiec e-mail: krzysztof.szopa@us.edu.pl Apatite crystal morphology. BSE image. Elongation of crystals is up to 0.2 mm Titanite crystal habit. BSE image. Crystal size is 0.12 mm

Description popularizing the research project

It takes just a glance at a map to see how diversified the Earth is. Higher or lower hills of gentle or steep slopes, deep or shallow valleys, precipices, chasms or canyons. In maps, the pattern of forms and shapes is marked with a scale of colours unmistakably unique for each continent. In fact, it is so unique that many of them we perfectly recognize and show their place on a map. Outside atlases, in a real landscape, together with shapes and height, we can see the colour of rocks and their layering. We notice their brittleness or hardness, lustre or lack of it. We are not surprised at all that they had to be sorted, systematized and named with proper nouns like Pogórze Cieszyńskie (Teschen Foothills), and common nouns like... teschenite.
What we see on the surface as geodiversity is a reflection of geological diversity hidden underground. Geological maps drawn for various areas of the world are often more colourful than physical maps and at the same time they are equally unique. Any given area has characteristic mineral composition and age of rocks. They give it unique character, seen on the surface, and they determine vegetation forming there. Newly-described rocks are named just like newly-discovered species of plants and animals, by their discoverers. That is how teschenite, rocks forming the crust near Cieszyn, entered geology literature. In spite of the fact the rocks occur in other places too, the name shows where they were described for the first time over 150 years ago. Today's research focuses on detailed description of their mineral composition, age, conditions which formed them and processes which transformed them into their current form. Thanks to modern equipment at their disposal, geologists know about teschenite much more than 150 years ago. Has it been long enough to uncover all the secrets of rocks which may be even 145 million years old?

Abstract

Scientific group: dr Krzysztof Szopa and dr hab. Roman Włodyka. Initially, all the igneous rocks occurring in the Carpathian flysch in the Cieszyn Silesia area and Moravia, the Czech Republic, were called 'teschenites'. The term describes numerous magmatic rocks, which are mostly products of the alkaline igneous bodies. These rocks reveal a wide spectrum of chemical and mineralogical composition. They are mainly represented by: picrite, dolerite, basalt (pillow lavas) diabase, syenite, lamprophyre. These rocks are predominantly strongly weathered, often only remnants of the primary minerals. All the magmatic rocks from the studied area were de-posited as sills in the Early Cretaceous sediments. Radiometric dating of minerals, including high-precision apatite dating revealed their formation interval to be 128-120 million years ago. The collected samples and obtained preliminary geochemical data by the project's manager, suggest that examined rocks (minerals) in many cases show another age interval, that is ~140-145 million years ago. Moreover, in one case zircon crystals, which are virtually non-existent in this type of rock, were found. It would be the first case in the world, when zircon crystals in ultramafic vulcanite were dated. The aims of this projects are to describe and characterize the secondary processes that have strongly fingerprinted 'teschenites'. Detailed studies, will help explain behaviour of some elements (including REE) during hydrothermal processes. The results can be applied not only to Cretaceous volcanism of the Silesia unit (External Western Carpathians), but also to all Cretaceous primitive alkaline volcanic rocks in the Pieniny Klippen Belt as well as Fatric and Tatric units in the Central Western Carpathians. The obtained results can be also used to determine the genesis of the other Mesozoic alkaline rocks in Europe.

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