Time filter

Source Type

Twardogóra, Poland

Krajewski K.P.,Instytut Nauk Geologicznych PAN | Gonzhurov N.A.,Polar Marine Geological Research Expedition | Laiba A.A.,Polar Marine Geological Research Expedition | Andrzej T.,Biologii Antarktyki PAN
Polish Polar Research | Year: 2010

The Panorama Point Beds represent a subfacies of the Early to Middle Permian Radok Conglomerate, which is the oldest known sedimentary unit in the Prince Charles Mountains, MacRobertson Land, East Antarctica. This unit records clastic sedimentation in fresh-water depositional system during the early stages of development of the Lambert Graben, a major structural valley surrounded by crystalline highlands in the southern part of Gondwana. It contains common siderite precipitated through early diagenetic processes in the swamp, stagnant water, and stream-flow environments. There are two types of siderite in the Panorama Point Beds: (1) disseminated cement that occurs throughout the sedimentary succession; and (2) concretions that occur at recurrent horizons in fine-grained sediments. The cement is composed of Fe-depleted siderite (less than 90 mol % FeCO3) with an elevated content of magnesium, and trace and rare earth elements. It has negative δ 13CVPDB values (-4.5 to-1.5‰).The concretions are dominated by Fe-rich siderite(morethan 90 mol % FeCO3), with positive δ 13CVPDB values (+1 to +8‰). There are no noticeable differences in the oxygen (δ18OVPDB between-20 and -15‰) and strontium (87Sr/86Sr between 0.7271 and 0.7281) isotopic compositions between the siderite types. The cement and concretions developed in the nearsurface to subsurface environment dominated by suboxic and anoxic methanic degradation of organic matter, respectively. The common presence of siderite in the Panorama Point Beds suggests that fresh-water environments of the Lambert Graben were covered by vegetation, starting from the early history of its development in the Early Permian.

Szulc J.,Jagiellonian University | Racki G.,Instytut Nauk Geologicznych PAN | Racki G.,University of Silesia
Przeglad Geologiczny | Year: 2015

Lithostratigraphic division of the Upper Silesian Keuper continental succession belongs to abandoned matters, even if newly-discovered sites with unique vertebrate faunas highlight an increasing request to more precise designation of their stratigraphic setting. As a result of multidisciplinary grant and with a guide use of new borehole sections, a major lithostratigraphic unit is formally proposed for the middle Keuper (i.e., above the Schilfsandstein; Stuttgart Formation in Stratigraphische Tabelle von Deutschland, 2002), based on previously inaccurately used unit, Grabowa Formation of Bilan (1976). The re-defined Formation of Variegated Mudstones and Carbonates from Grabowa includes Upper Gypsum Beds and Steinmergelkeuper in traditional scheme from Germany (=Weser and Arnstadt Formations), and generally correlates with the Norian stage. Two bone-bearing horizons (Krasiejów and Lisowice) are placed within the unit, which is completely subdivided in three members: Ozimek (mudstone-evaporate), Patoka (marly mudstone-sandstone) and Woźniki (limestone).

New evidence of Eocene preglacial environments has been found on the southern coast of Ezcurra Inlet on King George Island, South Shetland Islands, West Antarctica. Plant remains (trunks, leaves, detritus) and carbonaceous seams and beds occur in sedimentary strata in a 4 km long Cytadela outcrop of the Point Thomas Formation. They are an evidence for the presence and diversity of terrestrial vegetation in the northern Antarctic Peninsula region. The forests were composed mostly of Podocarpaceae-Araucaria-Nothofagus, with an undergrowth of hygrophilous and thermophilous ferns, and grew on volcanic slopes and surrounding lowland areas of King George Island during breaks in volcanic activity. The succession that crops out at Cytadela provides a record of changing climatic conditions from a warm and wet climate with extensive vegetation to a much drier climate with limited vegetation and ubiquitous weathering of volcanic bedrock. The geochemical indices of weathering (CIA, PIA and CIW) have narrow and relatively high value ranges (76-88), suggesting moderate to high chemical weathering under warm and humid climate conditions. The decrease in humidity and the decline in plant life through the succession can be related to the gradually cooling climate preceding development of the Oligocène ice cover across the Antarctic continent.

Zelazniewicz A.,Instytut Nauk Geologicznych PAN | Oberc-Dziedzic T.,Wroclaw University | Fanning C.M.,Australian National University | Protas A.,Poszukiwania Nafty i Gazu | Muszynski A.,Adam Mickiewicz University
Tectonophysics | Year: 2016

The Trans-European Suture Zone (TESZ) links the East and West European Platforms. It is concealed under Meso-Cenozoic cover. Available seismic data show that the lower crustal layer in the TESZ is an attenuated, ~200 km wide, SW margin of Baltica. The attenuation occurred when Rodinia broke-up, which gave rise to evolution of the thinned, thus relatively unstable margin of Baltica. It accommodated accretions during Phanerozoic events. We focus on acid magmatism, specifically granitoid, observed close to the SW border of the TESZ in Poland. This border is defined by the Dolsk Fault Zone (DFZ) and the Kraków-Lubliniec Fault Zone (KLFZ) on which dextral wrenching developed as a result of the Variscan collision between Laurussia and Gondwana. The granitoids at the DFZ and KLFZ were dated at ~300 Ma. In the Variscan foreland that overlaps the TESZ, orogenic thickening continued to ~307-306 Ma, possibly contributed to melting of the thickened upper continental crust (εNd300 = -6.0 to -4.5) and triggered the tectonically controlled magmatism. The wrenching on the TESZ border faults caused tensional openings in the basement, which promoted magmatic centers with extrusions of rhyolites and extensive ignimbrites. The Chrzypsko-Paproć and Małopolska magmatic centers were developed at the DFZ and KLFZ, respectively. The magmatic edifices commenced at ~302 Ma with relatively poorly evolved granites, which carried both suprasubduction and anorogenic signatures, then followed by more evolved volcanic rocks (up to 293 Ma). Their geochemistry and inherited zircons suggest that the felsic magmas were mainly derived from upper crustal rocks, with some mantle additions, which included Sveconorwegian and older Baltican components. The complex TESZ, with Baltica basement in the lower crust, was susceptible to transient effects of mantle upwelling that occurred by the end of the Variscan orogeny and resulted in an episode of the "flare-up" magmatism in the North German-Polish Basin. © 2016 Elsevier B.V.

Zelazniewicz A.,Instytut Nauk Geologicznych PAN | Jastrzcbski M.,Instytut Nauk Geologicznych PAN | Redlinska-Marczynska A.,University Adama Mickiewicza | Szczepanski J.,Wroclaw University
Geologia Sudetica | Year: 2014

During the 2002 meeting of Czech, Polish and Slovak tectonic community in Żelazno, the Sudetes, the Central European Tectonic Studies Group (CETeG) was established. 12 years ago, participants of the meeting made an excursion to the eastern part of the Orlica-Śnieznik Dome (OSD), which was focused on a variety of gneisses with inserts of (U)HP eclogites and various enclaves. The 2014 meeting brought members of the CETeG to the OSD again and an accompanying field excursion was dedicated mainly to evolution of metasedimentary and metavolcanogenic rocks in the region. This paper is a short review of the results of the studies undertaken in the OSD by different research groups in the last 12 years. The review is set against a background of what we knew about the geology of the dome in 2002. A significant progress was made. P-T paths were determined for mica schists and marbles as well as for metarhyolites originated from the continental crust and metabasites derived from the mantle. New light was shed on the origin of various types gneisses in the OSD and their genetic and structural relationships. A plethora of isotopic studies helped to better constrain timing of igneous and metamor-phic events in the Orlica-Śnieznik complex. Ages clustered around 350-340 Ma are repeatedly obtained, yet scarcer older ages up to 390 Ma and their geological significance are open to debate. Tectonic evolution of the dome was revised and new geodynamic concepts were proposed. However the new data has created some new problems and some old problems are still to be resolved in the future.

Discover hidden collaborations