Trzeciorzędowe skały piroklastyczne Roztocza i Wzniesień Urzędowskich
Abstract
Badania petrograficzne, mineralogiczne i chemiczne pozwoliły na szczegółową charakterystyę skał piroklastycznych z zachowanymi replikami fragmentów roślinnych. Skały te występują luźno na powierzchni terenu w formie nieregularnych, lekko obtoczonych głazików i głazów spotykanych na północnym skłonie Roztocza oraz w obrębie Wzniesień Urzędowskich. Występują one poza obszarami, gdzie zostały stwierdzone nagromadzenia skamieniałych pni drzew. Skały te mają skład kwaśnego, popiołowego, krystaloklastycznego tufu ryolitowego. Obecność tych skał autorzy wiążą z okresem petryfikacji skrzemieniałych drzew Roztocza Południowego, tworzeniem się bentonitów w obrębie południowego obrzeżenia Gór Świętokrzyskich oraz z poziomami tufów na przedgórzu Karpat, związanych stratygraficznie z górnym miocenem (karpat–sarmat).
TERTIARY PYROCLASTIC ROCKS OF THE ROZTOCZE AREA AND URZĘDOWSKIE ELEVATIONS (SE POLAND)
Summary
Petrographic, mineralogical and chemical characteristics of pyroclastic rocks with the floral fragment replicas that occur on the northern slope of the Roztocze area and within the Urzędowskie Elevations on the ground surface forming irregular, slightly rounded shingles and boulders were carried out. The pyroclas tic rocks occur beyond the areas where the fossilified stock-lode of the trees have been discovered. These rocks have acid, ashy, crystalloclastic, rhyolitic tuff composition. Their principal components are the crystalloclasts of quartz having a stiletto shapes, corrosive sinuates and another evidences of magmatic resorption. In the quartz the volcanic glass inclusions are found. The groundmass is composed of acid, mostly devitrified and cryptocrystalline at places volcanic ash. The accesory minerals, such as zircon, tourmaline, rutile and brookite commonly occur. The presence of these rocks on the Roztocze and the Urzędowskie Elevations area the authors connect with the following geological events: 1) formation of bentonites within southern border of Holly Mts., 2) occurrence of tuff horizons on the Carpathian foreland related to the Upper Miocene (Karpatian-Sarmatian) and 3) petrification of siliceous trees of the Southern Roztocze. The lack of these rocks in the exposures in situ alike as fossilified stock-lode of trees preclude the exact determination of their stratigraphic position and the conditions of their petrification.
TERTIARY PYROCLASTIC ROCKS OF THE ROZTOCZE AREA AND URZĘDOWSKIE ELEVATIONS (SE POLAND)
Summary
Petrographic, mineralogical and chemical characteristics of pyroclastic rocks with the floral fragment replicas that occur on the northern slope of the Roztocze area and within the Urzędowskie Elevations on the ground surface forming irregular, slightly rounded shingles and boulders were carried out. The pyroclas tic rocks occur beyond the areas where the fossilified stock-lode of the trees have been discovered. These rocks have acid, ashy, crystalloclastic, rhyolitic tuff composition. Their principal components are the crystalloclasts of quartz having a stiletto shapes, corrosive sinuates and another evidences of magmatic resorption. In the quartz the volcanic glass inclusions are found. The groundmass is composed of acid, mostly devitrified and cryptocrystalline at places volcanic ash. The accesory minerals, such as zircon, tourmaline, rutile and brookite commonly occur. The presence of these rocks on the Roztocze and the Urzędowskie Elevations area the authors connect with the following geological events: 1) formation of bentonites within southern border of Holly Mts., 2) occurrence of tuff horizons on the Carpathian foreland related to the Upper Miocene (Karpatian-Sarmatian) and 3) petrification of siliceous trees of the Southern Roztocze. The lack of these rocks in the exposures in situ alike as fossilified stock-lode of trees preclude the exact determination of their stratigraphic position and the conditions of their petrification.