Browsing by Subject "Botswana"

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Cyfrowy model deltowej asocjacji facjalnej na przykładzie grup Ecca i Beaufort (nadgrupa Karoo) w południowo-zachodniej części Botswany, Afryka południowa
(Data obrony: 2011-07-26) Radwański, Lechosław
Wydział Geologii, Geofizyki i Ochrony Środowiska
The objective of this thesis was to create a digital 3D model representing the deltaic facies of the Karoo Supergroup (Carboniferous-Jurrasic) in the south-western part of Botswana. It is the first work of this kind. Creating the model was done with the use of the Petrel software application owned by the Schlumberger Company. The input data consisted of a series of cores obtained from drilling operations conducted in south-west Botswana. As a result a simple model of the Karoo Ecca-Beaufort succession has been created. The boreholes intersected only the uppermost part of the underlying complex of glaciogenic Karoo sediments known as the Dwyka group and did not reach the basement rocks. Due to the small number of boreholes and their disadvantageous locations only a simple model, which gives general insight in to the structure of the Ecca and Beaufort units, could have been created. However, the results enabled to show the general time–space relations and lateral thickness changes of the distinguished lithostratigraphic divisions. These relations reveal the main subsidence zones, their changes and links between subsidence and the facies variability of the sediments. The facies variations were controlled by the evolution of the main supply system and depositional zones within the delta. The detrital material was derived from the north (beyond the research area) and was transported towards the south. During the early phase of the Ecca sedimentation main zones of deposition were defined by the topography of the marine basin. The basin bottom was covered with glaciogenic sediments (the Dwyka Group) in which two major depressions were interpreted – most likely glacial valleys. They are located in the northern part of the area and extended from north to south. During the main phase of the delta development, proximal coarse grained sediments of delta channels and sandy lobes were filling up these depressions causing local subsidence, most likely by loading into thick complex of glaciogenic mudstones and siltstones. Between delta channels, interchannel sediments were deposited in delta-top lakes and swamps. The last sedimentation phase resulted in a vast deposit of fine-grained material (Beaufort Group) – muds and silts of lacustrine origin with minor fluvial fine-grained sands.
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Konstrukcja Mapy geologicznej 1:5 000, wraz ze szczegółowymi profilami litostratygraficznymi oraz przekrojami, wschodniej części obszaru wzgórz Tsodilo (pn-zach. Botswana) w oparciu o dokumentację archiwalną i dane literaturowe
(Data obrony: 2016-01-28) Prędki, Konrad
Wydział Geologii, Geofizyki i Ochrony Środowiska
Celem pracy jest konstrukcja mapy geologicznej wzgórz Tsodilo Hills wraz ze szczegółowymi profilami litostratygraficznymi oraz przekrojami. Praca sprowadzała się do digitalizacji archiwalnych map i szkiców z formy papierowej na cyfrową. Do konstrukcji mapy posłużono się programem ArcGis for Desktop 10.3, natomiast przekroje i profile zostały wykonane w programie CorelDRAW. Do wykonania opisów litologii wzgórz Tsodilo Hills potrzebne były przetłumaczenia dostępnych publikacji z języka angielskiego na język polski, które zostały wykonane przez autora. Finalnym produktem projektu mają być: wysokiej jakości mapa geologiczna w formacie cyfrowym, przekrój w formacie cyfrowym, profil litostratygraficzny w formacie cyfrowym oraz opis litologii. Wszystkie produkty finalne zostały dodatkowo wydrukowane w odpowiednim formacie i z zachowaniem skali i dodane jako załączniki. Figury zawarte w tekście mają charakter poglądowy i mają na celu ukazanie treści załączników.
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, Andrzej
The 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.