Göttingen, Universiẗat, Diss., 1999. / Dateiformat: zip, Dateien im PDF-Format.

M.Sc. / The Mamatwan mine is situated at the most southern end of the world’s largest landbased resource of manganese, the Kalahari manganese field. The mine is operated by South African Manganese Corporation Limited (SAMANCOR) and is the largest open pit manganese mine in the world. The sedimentary manganese ore bed is interbedded with iron-formation of the Hotazel Formation of the Early Paleoproterozoic Voëlwater Subgroup of the Transvaal Supergroup. The open pit Mamatwan mine has a proven economic ore reserve of between 300 and 400Mt and produces 1.2Mt of manganese ore annually, of which 0.5Mt of ore is beneficiated and shipped through the harbour at Port Elizabeth. The remaining ore is railed to ferro-alloy plants at Meyerton and Newcastle. Carbonate-rich manganese lutite mined at the Mamatwan Mine is widely known as Mamatwan-type ore. It has a manganese content ranging from 30 – 38%. Only a small portion (15m of a total thickness of 49m) of the ore bed, containing an average of 38% Mn, is being mined and processed at present. The larger portion of the ore bed is not utilized. This study focuses on the physical and chemical characteristics of the ore bed in more detail in order to make suggestions on how to a) reduce waste by upgrading the upper parts of the lower manganese ore bed, or b) to improve the current recovery from the present economic zone. A second part of this study pays special attention to the lithostratigraphy of the lower manganese ore bed. The focus is on the paragenetic sequence and the diagenetic evolution of the braunite lutite that constitutes the manganese ore. The Mamatwan-type ore can be described as diagenetic to very low-grade metamorphic carbonate-bearing braunite manganolutite. Based on geochemical and mineralogical data, the lower manganese ore body was previously subdivided into eleven lithogically distinct zones. Based on detailed diamond drill core logging and with the aid of geochemical and physical data of two selected drill cores, an additional thirteen subzones were identified in this study. These new subzones were found to be consistent across the entire study area, located to the west and north of the present Mamatwan open pit. The paragenetic sequence recognised in the ore of the lower manganese ore bed can be subdivided into four stages, namely: (a) sedimentation, which is represented by fine lamination and the presence of fine-grained “dusty hematite”. (b) early diagenesis as represented by micritic carbonate matrix and possibly braunite, (c) late diagenesis or low-grade metamorphism are represented by coarse grained hausmannite, specularitic hematite, partridgeite and Mn-calcite, and supergene alteration that occurs immdediately below the contact of the ore bed to the unconformably overlying Tertiary Kalahari Formation. This supergene altered zone is marked by the presence of Mn4+ oxides such as cryptomelane, manjiroite, romanechite and pyrolusite, in addition to barite. The results obtained in this study permit definition of two sedimentary cycles within the manganese ore bed at the Mamatwan mine. Both cycles are defined by a carbonate-rich finely laminated zone at the base, overlain by a central manganese-rich economic zone, capped by manganese lutite that is enriched in carbonate ovoids. The two manganeserich zones are known as the M (lower) and X (upper) zone, and are characterized by the replacement of carbonate ovoids by hausmannite. The two Mn-rich zones are chemically and physically almost identical, with the M zone 7.5m thick and the X zone 5.5m thick. However, in the present mining configuration only the M zone is being mined. The most important result arising from the present study is the recommendation to restructure the future mining operation in order to mine not only the M zone, but also the X zone.

The Kalahari Group sediments cover vast portions of the Archean Kaapvaal and Congo cratons that are considered highly prospective for economic kimberlites. In southern Africa, the term Kalahari refers to a structural basin, a group of Cretaceous to recent terrestrial continental sediments and an ill-defined desert, all of which have been grouped together as the Mega Kalahari by Thomas and Shaw (1993). The Mega Kalahari grouping includes sediments stretching from South Africa in the south to the Democratic Republic of Congo in the north, and from eastern Namibia to western Zimbabwe. This sand sea, at 2.5 million km², is the largest on earth and presents significant obstacles and challenges to the kimberlite explorationist attempting to locate bedrock-hosted diamondiferous kimberlite bodies. The Mega Kalahari sediments represent an ancient depositional environment with a complex history in which the stratigraphy and age of the deposits are not particularly well constrained or understood. Low fossil content, limited exposure, poor differentiation of the dominant surficial Kalahari Sand and a limited comprehension of an extensive duricrust suite has delayed the understanding of the sedimentological and environmental history of the basin. This sequence of sediments has accumulated and evolved through fluvio-deltaic, aeolian and groundwater processes, with characteristics due to primary deposition and subsequent modification being difficult to distinguish. Deposition in the Kalahari Basin has been subject to tectonic influences, changes in drainage directions and source areas of sediments, river capture and numerous large and small climatic fluctuations both in the basin and surrounding areas. It bears the imprint of recurring cycles during which the same sediments were reworked, sometimes by different agencies, all of which exacerbate attempts to correlate sedimentary units across the sequence. The Mega Kalahari is a series of contiguous Phanerozoic sedimentary basins situated within the African Superswell. The Superswell has dominated the gross geomorphology of southern Africa and contributed significantly to the present character of the Mega Kalahari and the evolution of the drainage systems. Overall, the tectonic framework established in southern Africa by the division of Gondwanaland led to the creation of a dual drainage system, with the hingeline acting as a watershed between a coastally-orientated exoreic system and an endoreic system draining into the interior. Deposition of sediments started in the late Cretaceous. Neo-tectonic activity expressed in the rifting in central Botswana, further influenced sedimentation rates and exerted a strong control over paleo-drainage directions. This revIew presents the complexities of the Kalahari cover sequence. The most Important geomorphological and sedimentary factors to be considered when designing and implementing kimberlite exploration programs within the Mega Kalahari environment are outlined and discussed. New data from exploration drilling programs are presented on the thickness of the Kalahari within portions of northern Namibia, western Zambia and Botswana. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

Diss.--Mainz, 2004. / Bibliogr. p. 301-363.

Road ecology is becoming an increasingly important aspect of conservation biology. Carcasses lying on the road often confront visitors travelling to the Kgalagadi Transfrontier Park between Upington and the Twee Rivieren Rest Camp. This study investigated the species killed, the factors contributing to their deaths, and suggested solutions to curtail these mortalities. Twelve surveys to record mammal and bird road mortalities were conducted on the R360 main road between Upington and Twee Rivieren (261 km) from January to September 2007. One hundred and eighty four carcasses were recorded from 22 species, and the most common taxa killed were the bat-eared fox (n = 47) and spotted eagle owl (n = 10). The road mortality rate on the R360 road was very high, 5.44 mammals and 1.14 birds per 100 km. Birds were predominantly killed in summer. Notably more nocturnal mammals were killed than diurnal and ‘indistinct’ species. A mammal hotspot was identified along the 91 km of road that traversed the Gordonia duneveld. Since the nine roadside traffic warning signs erected on the R360 road had no measurable impact on road mortalities, it is recommend that three rumble strip sections with accompanying signage be erected in the hotspot to slow down vehicles and curtail mortalities.

Diss. Uppsala : Uppsala universitet, 2006.

Frankfurt (Main), Univ., Diss., 2004. / Computerdatei im Fernzugriff.

Würzburg, Univ., Diss., 2001. / Computerdatei im Fernzugriff: 18,4 MB (das Oeffnen des Links kann einige Minuten dauern).

Würzburg, Univ., Diss., 2001. / Computerdatei im Fernzugriff: 18,4 MB (das Oeffnen des Links kann einige Minuten dauern).

Frankfurt (Main), Universiẗat, Diss., 2004.