Wendorff, Marek
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Item type:Article, Access status: Open Access , Modelling of distribution and geometry of lithological complexes of the Ecca Group (the Karoo Supergroup) in SW Botswana(Wydawnictwa AGH, 2013) Wendorff, Marek; Radwański, Lechosław; Papiernik, BartoszThe Ecca Group, a subdivision of the Karoo Supergroup (Upper Carboniferous - Lower Jurassic) in SW Botswana is a sequence deposited as marine deltaic bodies considered to have been supplied from a cratonic source elevated north of the basin. The Karoo strata in this region are covered unconformably by sands of the Kalahari Beds (Upper Cretaceous - Recent). Therefore the bedrock outcrops are extremely rare, limited in size and a low number of boreholes drilled in this vast area (ca. 340 x 540 km) provide the only insights into the succession of the Karoo Supergroup. Very long distances between individual boreholes make correlation, interpolation between localities and interpretations of geometry of lithological bodies that would provide clues supporting basin analysis by traditional means problematic. To achieve the first approximation of the space-time relations between lithologically complex Ecca Group lithofacies associations modelling of these sediments using Petrel software was performed. These relations in turn suggest evolutionary trends of the basin during deposition of the Ecca Group strata. The model suggests two main zones of supply indicated by two distinctly different patterns of deltaic lithofacies associations, and their evolution controlled by post-Dwyka palaeotopography and its subsequent modifications by local subsidence in the centre of the depository. Initially rapid southward progradation of relatively fine-grained delta body located in the west of the area was followed by subsidence-induced aggradation interrupted by stages of abandonment and marine transgression. Such variations, emphasised by the presence of sandy clinoforms of the delta lobes separated by basinal »fines«, imply significant interplay between rates of supply and subsidence. On the other hand, the delta formed in the east contains relatively high proportion of coarse-grained sandstone facies overlying prodelta fines as laterally extensive tabular body formed most probably by lateral migration of distributary channels and delta-front mouthbars, and devoid of abandonment stages. Proximal litofacies of the 'western delta' fill the subsiding depocentre and grade distally into synchronously deposited prodelta fines towards the south. By contrast, distal fine-grained prodelta facies fill basin depocentre in the eastern area and are overlain by proximal facies of the 'eastern delta'.Item type:Article, Access status: Open Access , Compositional differences between Besko and Otryt sandstones of the Krosno Beds (Oligocene) in Eastern part of the Silesian Tectonic Unit(Wydawnictwa AGH, 2016) Godlewski, Paweł; Wendorff, Marek; Świąder, AndrzejThe Krosno Formation (Oligocene) in the Silesian Tectonic Unit of the E part of the Polish Outer Carpathians is represented by two lithofacies called the Besko (or Lesko) and the Otryt facies.Item type:Article, Access status: Open Access , Factors controlling a depositional architecture in synorogenic Outer Carpathian basins - an example of Oligocene-age successions from the Fore-Magura Unit, Poland(Wydawnictwa AGH, 2023) Siwek, Piotr; Waśkowska, Anna; Wendorff, MarekItem type:Article, Access status: Open Access , Olistolity w serii śląskiej i ich związek z fazami rozwoju basenu śląskiego(Wydawnictwa AGH, 2009) Cieszkowski, Marek; Golonka, Jan; Krobicki, Michał; Ślączka, Andrzej; Waśkowska, Anna; Wendorff, MarekOlistoliths of various ages, provenance and dimensions are known in all of the higher-rank tectonic units of the Outer Carpathians. Their occurrences at various stratigraphic levels (Late Jurassic - Early Miocene) are related to different stages of development of the flysch basins, from the stage of rifting to post-rifting, through the orogenic phases, and further to the post-orogenic period.Item type:Article, Access status: Open Access , Sedimentary response to tectonic uplift of the Dukla basin margin recorded at Skrzydlna - the Menilite Beds (Oligocene), Outer Carpathians, S Poland(Wydawnictwa AGH, 2018) Siemińska, Aneta; Starzec, Krzysztof; Godlewski, Paweł; Wendorff, MarekThe Menilite Beds (Oligocene of Polish Flysch Carpathians) at Skrzydlna crops out in a structurally complex zone of the Fore-Magura Unit, which is tectonically overridden by Magura Nappe thrust form the S. The exposed sedimentary suite, representing the Dukla Basin, consists of fine-grained, well organised strata deposited in a low-energy, deep marine basin, which are abruptly overlain by poorly organised, coarse sandy conglomerate that forms a Mass Transport Deposit (MTD) complex. The MTD contains large boulders of extrabasinal rocks, massive sandstone beds with intrabasinal mudstone clasts, and slump sheets of sandstones. Above rests a fining- upwards sequence of sandstone beds interlayered with mudstones. The fine-grained facies reappear above to terminate the exposed succession. Erosional contacts and rapid facies changes, both vertical and lateral, are characteristic for the MTD unit. The sandstone-mudstone unit above contains laterally migrating erosional channels filled with massive sandy conglomerate in the lower part. Turbidites of varying density and completeness of internal structures that occur above are accompanied by an association of mixed facies including large-scale dune cross-bedding. Mineralogically, the sandstones are quartz arenites, sub-lithic arenites and wackes. Calcarenite grains – bioclasts, micrite and marl occur in substantial proportions only in the uppermost part of the succession. The point-counting data plotted on Qm-F-Lt diagram are clustered within the recycled fields: quartzose and transitional. Mineralogical maturity of the sandstones has the tendency to decrease from the sub-MTD strata upwards via the MTD unit to the lower part of the sandstone-mudstone complex, then it increases to the youngest sandstone beds with carbonate grains. These tendencies, associated with sedimentary features of the succession, reflect rapid uplift, emergence and progressive erosion of the terrigenous detritus source area, followed by tectonic stabilisation reflected by the appearance of the »carbonate factory«.Item type:Article, Access status: Open Access , Lithological variations of sedimentary succession within a meteorite impact crater: Jwaneng South Structure, Botswana(Wydawnictwa AGH, 2015) Wendorff, Marek; Master, SharadThe Jwaneng South Structure is a meteorite impact crater located in the Kalahari region of Botswana. The structure has the shape of a bowl 1.3 km in diameter and a maximum depth of 275 m in the centre. It was discovered by an airship-mounted full tensor gravity gradiometer and penetrated by nine vertical diamond drillholes. The crater is underlain by the Gaborone Granite (2785 Ma) and basalts of the Karoo Supergroup (182 Ma). The covering aeolian sediments of the Kalahari Group (Late Cretaceous-Recent) completely obscure the structure. A succession of the following lithofacies overlying authigenic <i>in situ</i> brecciated granite was intersected in the boreholes (from base to top): (i) allogenic heterolithic/oligomictic »fallback« and resedimented breccia (ii) sedimentary breccia and conglomerate with sand matrix; (iii) six intervals of carbonate sediments, with traces of evaporites and mudstone interbeds, which are interlayered with (iv) five intervals of sandstone and sedimentary breccia composed of granules, pebbles and cobbles, mostly of granite, embedded in a matrix of well-sorted medium-grained sand; (v) bioturbated, mostly massive sandstone rich in mud matrix (wacke), with locally preserved interbeds of mudstone and cross-bedded sandstone, and abundant root traces; (v) silcrete and calcrete that occur at the top of the succession. This lithological association suggests that deposition within the Jwaneng South meteorite impact crater took place in a playa lake surrounded by steeply-dipping talus piedmont fans. The depositional cycles were controlled by pronounced climatic oscillations. Wet periods are recorded by lithofacies (iii), which reflects intense supply of sand eroded from the Kalahari dune field surrounding the crater and coarse detritus derived from its rim and steep talus below. Dry intervals of high evaporation and fall of the lake level are reflected by lithofacies (iv). During the youngest wet period (v) the lake filled up with alluvia sands interbedded with muds, abundantly vegetated and homogenised by bioturbation. The silcrete and calcrete layer at the top of the succession is the product of pedogenic processes that affected the Kalahari Desert environment. An asymmetry of lateral distribution of the lithofacies (ii)–(iv) and the presence of sedimentary breccia redeposited into the marginal E (and NE) parts of the crater suggest an asymmetry of the crater depression and its coarse clastic rim, which may imply an oblique trajectory of the impactor approaching from the SW.Item type:Article, Access status: Open Access , Department of Environmental Analyses, Geological Mapping and Economic Geology(Wydawnictwa AGH, 2016) Matyszkiewicz, Jacek; Kotarba, Maciej; Krzak, Mariusz; Wendorff, MarekItem type:Article, Access status: Open Access , Pseudo-shallow marine features in deep marine gravity-flow successions: lessons from the Menilite Beds at Skrzydlna (Oligocene, Western Outer Carpathians)(Wydawnictwa AGH, 2023) Wendorff, Marek; Siemińska, AnetaItem type:Article, Access status: Open Access , Lithostratigraphic classification of the Tsodilo Hills Group: a Palaeo- to Mesoproterozoic metasedimentary succession in NW Botswana(Wydawnictwa AGH, 2019) Wendorff, Marek; Świąder, AndrzejThe Tsodilo Hills Group strata exposed in the Tsodilo Hills are an association of meta-arenites, metaconglomerates, quartz-mica schists, sandstone, red siltstone and sedimentary breccia deposited on an open siliciclastic marine shelf between the Late Palaeoproterozic and Late Mesoproterozoic, and outcropping in NW Botswana. The succession is dominated by three micaceous quartzite units interlayered with subordinate lenses and wedges of other rock types. Facies gradients from S to N are expressed by: decreasing content of muscovite at all levels of metasediment organisation from thin wedge-shaped units to thick quartzite complexes, as well as a decrease in pebble content and increase in arenaceous matrix in some metaconglomerate beds, matching regional palaeotransport direction. Well-rounded pebbles of extrabasinal rocks are flat, suggesting redeposition from a beach environment. Lenticular conglomeratic bodies with erosional lower boundaries represent infills of local incisions in the sandy bottom sediments. The abundance of laterally discontinuous lithological units reflects shelf palaeotopography controlled and modified by deposition and migration of large bed forms, ranging from megaripple marks (or submarine dunes) to sand waves. Deposition was influenced by tides and two regressive events. The older regression resulted in a marker unit of tidal mudflat-related red-bed facies: mudstone, siltstone, channel-fill sandstone and sedimentary breccia. The second regression is indicated by a tabular conglomerate marker reflecting increased input of coarse terrigenous material.