Bibliography: pages 110-117. / To the east of Pofadder in Bushmanland, N.W. Cape, an area of some 3600 km² has been geologically mapped. Emphasis has been placed on the role of shearing in the deformation history of the area. The study area occurs within the Namaqualand Metamorphic Complex and consists of gneisses, schists and quartzites. These rocks are overlain to the south by the Dwyka Formation of the Karoo Sequence. The rocks of the Namaqualand Metamorphic Complex have undergone polyphase deformation and have been mapped according to their fabric and composition. The Bushmanland Group consists of supracrustal rocks and the following lithologies have been mapped: quartzite (granular and glassy varieties), muscovite-quartz schist, calc-silicate gneiss, quartzo-feldspathic rocks (quartzo-feldspathic gneiss, leucogneiss and leptite), para-amphibolite gneiss and pelitic gneiss. Pre-tectonic intrusive rocks consist of the Nouzees Gabbronorite Suite, a mafic granulite, amphibolite and alkali-feldspar granitic gneisses. Syn to post-tectonic intrusive rocks include a granodiorite-tonalite suite, diorite, pegmatite and vein quartz. Dolerite is post-tectonic, most likely of Karoo age and occurs as sills and remnant hillocks. Non-diamondiferous kirnberlite pipes occur in the west and their emplacement appears to have been structurally controlled, being situated along the Nouzees shear zone.

South Africa lies within an intraplate setting, characterised by sparse, scattered, low-magnitude seismicity not easily correlated with known neotectonic features. Recent seismicity has repeatedly been shown to result from the reactivation of pre-existing geological structures, typically large faults or shear zones, which are preferentially-aligned to the contemporary stress field. Expanding the catalogue of stress data for the region is therefore vital to better understand the regional stress field pattern and aid in identifying potentially seismogenic structures. In these intraplate regions, reliable high-quality indicators of maximum horizontal compressive stress (SHmax) are difficult to obtain in the absence of earthquake-derived focal mechanism solutions (so called "beach balls"). In South Africa however, extensive hydrocarbon exploration drilling in the Mesozoic offshore provide an opportunity to utilise the borehole breakout technique to derive quality SHmax orientation data. In collaboration with the World Stress Map Project (WSM), and utilising borehole logs provided by the Petroleum Agency South Africa (PASA), training and software was provided to review, analyse and visualise borehole breakouts observed in 4-arm calliper logs from exploration areas in the Outeniqua and Orange basins. Digital music software can limit the forms of music we create by using interfaces that directly copy those of the analogue instruments that came before. In this study we report on a new multi-touch interface that affords a completely new form of drum sequencing. Based on ideas from Avant-guard music and embodied interaction, a technology probe was created and then evaluated by a wide range of users. We found that for users with no musical training, and for users with a large amount of musical training, the software did allow them to be more creative. However, users with limited training on existing sequencing software found the new interface challenging.

Bibliography: pages 54-59. / The incorporation of nitrogen in living cells gives rise to cycling between atmospheric, inorganic and organic forms of nitrogen. Nitrogen cycling is largely controlled by microbial respiration and metabolism. In aquatic systems, N-cycling occurs dominantly in sediments. Removal of nitrogen from aquatic sediments occurs through the successive Ntransformation processes of mineralisation (organic N -> NH4+), nitrification (NH4+ -> NO3-) and denitrification (NO3- -> N2). Denitrification, mineralisation and also immobilisation of inorganic N (NO3-, NH4+ ) to organic N occur under reducing conditions. Build-up of the nitrate (NO3- ) concentration in groundwater is a widely-recognised phenomenon. Groundwater nitrate may contribute significantly to the N input to aquatic bodies that receive groundwater flow. The Verlorenvlei coastal lake on the arid south-west coast of South Africa is an important ecological habitat and also a valuable agricultural water resource. Analyses conducted in this study indicate that the groundwater, which flows towards the lake, has a significantly higher NO3- concentration than the lake water. The difference in NO3- concentration is due to: 1. Dilution of groundwater by a larger quantity of low-nitrate water in the lake, and/or, 2. Removal of nitrate from groundwater through microbial processes in the lake sediments. Insufficient information is available concerning the magnitude of groundwater flow into the lake to investigate the importance of option 1. Experiments were conducted on two lake sediments (high organic content and low organic content) to determine the relevance of option 2. Sediment subsamples were incubated under reducing conditions and amended with 25mg/l and 100mg/l NaNO3-N solutions with and without the addition of 40mg/l glucose and with and without irradiation. After 10 days incubation, a period chosen to simulate the residence time of groundwater in the sediments, the added NO3- had all been removed through denitrification or immobilised as organic N. The exact removal pathway could not be determined. The high organic content sediment was found to remove nitrate more efficiently. It was concluded that the decrease in nitrate concentration as high-nitrate groundwater flows into the Verlorenvlei lake can probably be ascribed to denitrification or immobilisation processes under reducing conditions in the sediment lining of the lake.

The reworking of granulites by amphibolite- to granulite-facies metamorphism can complicate the interpretation of their geological history because the event that reached higher peak P-T conditions will either completely overprint earlier peak assemblages or prevent the formation of new 'peak' minerals. The extent of reworking in granulites is controlled by three main factors, namely: (1) the pressures and temperatures reached in earlier and later metamorphic events, (2) the extent of deformation during subsequent events, and (3) the amount of fluid influx into the system during subsequent metamorphic events. Extensive reworking will occur if the peak temperature of the later event exceeds that of the earlier event, but if it does not, reworking will be less pervasive, and restricted to areas of deformation and/or fluid influx. The Salknappen nunatak in central-Eastern H.U. Sverdrupfjella, Antarctica forms a part of the highgrade Maud Belt that was formed by a granulite facies Grenvillian orogeny and was variably overprinted by high-grade metamorphism (eclogite to amphibolite facies) during the PanAfrican orogeny. The degree of reworking during the Pan-African has been a contentious issue for some time, with early workers assigning the metamorphic peak to the Grenvillian, whereas others assigned it to the Pan-African. Mineral assemblages and textures preserved in metapelitic and metamafic rocks preserve evidence of only one prograde to retrograde metamorphic cycle with peak mineral assemblages that are characteristic of granulites. Sillimanite in metapelitic rocks forms pseudomorphs after kyanite whereas garnet breakdown microstructures and in both metapelitic and metamafic rocks formed as a result of near-isothermal decompression. Garnet and hornblende display retrograde zoning profiles whereas retrograde cummingtonite, hornblende, plagioclase and ilmenite in metamafic rocks moderately constrain retrograde conditions. Pseudosection modelling with THERMOCALC on peak mineral assemblages from metapelitic and metamafic samples collected at Salknappen provides a robust peak P-T estimate (M1) of 760 – 790 ºC at 8.5 – 10 kbar. Phase diagram modelling of more subtle retrograde assemblages constrain retrograde metamorphic conditions (M2) to between ~550 – 750 °C and ~2 – 5 kbar. Both M1 and M2 likely occurred during the Grenvillian in a single orogenic cycle along a clockwise metamorphic path, where peak metamorphism was followed by near-isothermal decompression of ~5 kbar. Recrystallised quartz in melt leucosomes confirms that retrogression (M2) occurred after peak metamorphism. M2 was followed by the intrusion of megacrystic leucogranite dykes that most likely formed during the Pan-African in response to iii melt migration as a result of melting deeper in the crust. These dykes and earlier gneisses were intruded by the Dalmation granites at c. 470 Ma, at which point the Salknappen nunatak was at crustal conditions approximating the brittle-ductile transition. The study area in central-Eastern H.U. Sverdrupfjella preserves the peak and retrograde metamorphic assemblages from the Grenvillian orogeny and does not display evidence of reworking by a later granulite facies event. Salknappen does not display evidence of reworking during the Pan-African because peak metamorphism did not exceed peak temperatures attained during the Grenvillian orogeny and also did not form discrete, localised deformation zones with a significant influx of fluid during the Pan-African orogeny. This study presents a case where the effects of mid-crustal reworking by a high-grade metamorphic event are not shown due to the lack of rehydration, pervasive deformation and an elevated residuum solidus as a result of higher peak temperatures in an earlier granulite facies metamorphic event. When working with polymetamorphic terranes that have been subjected to more than one granulite facies orogenic cycle, the interpretation of the geological history of such an area should be done with caution and P-T estimates should be done with methods that are less affected by the long retrograde histories.

Bibliography: leaves 108-114. / Although the status of the Knysna Estuary is considered to be in an acceptable environmental condition, pressures of development and tourism in the area are likely to cause substantial deterioration. Investigating the microfossil assemblages in the Knysna Estuary is imperative, since foraminifera serve as essential ecological indicators, and can be used to monitor the health of the ecosystem during development, as they are extremely sensitive to any environmental changes. The Knysna Estuary is well suited for investigating microfossil assemblages, since it has the richest fauna of the larger benthic invertebrates of any of the South African estuaries and it is open to the sea throughout the year.

Bibliography: pages 157-167. / The Ventersdorp Contact Reef (VCR) is an auriferous conglomerate which unconformably overlies the rocks of the Witwatersrand Supergroup. It acted as a palaeo-aquifer and is capped by relatively impermeable metabasalts of the Ventersdorp Supergroup. Three post-depositional alteration events, which form an alteration halo in the footwall and hangjngwall rocks around the VCR, can be recognised. The first of these alteration events is attributed to regional metamorphism and is identified by the formation of pyrophyllite in the footwall quartzites and a lower green schist facies mineral assemblage in the hangingwall metabasalts. The second and third alteration events are interpreted as metasomatic fluid in filtration events which were focused along the VCR horizon. The second alteration event involved K⁺metasomatism which affected the footwall and hanging wall rocks up to a distance of several metres away from the VCR The third alteration event, during which the muscovite was partially replaced, was associated with the formation of chlorite in and immediately around the VCR-Chlorite thermometry suggests a temperature of 307 ± 14°C for this event. The close mineralogical association of gold with chlorite, secondary pyrite and secondary quartz in the VCR is interpreted to indicate that gold remobilisation was associated with the chlorite forming alteration event. The inhomogeneity found in gold particles within a hydrothermal quartz vein indicates a sharp drop in temperature after gold precipitation, suggesting a very short period of hydrothermal fluid infiltration.

Bibliography: leaves 80-95.

This study is aimed at developing a workflow for quantitative seismic interpretation. The workflow generated probability maps of various facies and pore-fluid by combining seismic attributes and wireline log data through rock physics relationships and supervised statistical classification. The workflow was developed mainly for hydrocarbon exploration, but could be used for other purposes, provided the target is seismically detectible. Any prior regional geological knowledge is built into the workflow, by extending the training date appropriately. The workflow aims to maximize the extraction of quantitative geological parameters from data that are most commonly acquired for hydrocarbon exploration, namely seismic and wireline log data. The workflow is presented using 3D seismic data from the Bredasdorp Basin offshore South Africa's south-coast. Wireline log data from the E-BX1 borehole are also used in the study, as well as regional geological interpretations. The study focused on the siliciclastic Aptian "13B" sequence, which was encountered at a depth of 2500 m below sea level at borehole E-BX1. Two massive 13B sandstone units were encountered at E-BX1. The lower unit is 50 m, and the upper 20 m thick. Both are water wet. The results of this study suggest that there are two oil accumulations at the 13X level around E-BX1. This is indicated by the high probability predicted for oil-bearing sandstone in these two areas.

Includes bibliographical references. / South Africa is considered a stable continental region where earthquakes from a tectonic source are usually of small to moderate magnitude. In September 1969 a local magnitude (ML) 6.3 sinistral strike-slip earthquake occurred near the towns of Ceres and Tulbagh in the Western Cape, South Africa. This is still the largest earthquake in instrumental history in South Africa. During 2012, a temporary seismic array of 15 surface stations was deployed for a 3 month period in the aftershock zone of the 1969 Ceres earthquake. A total of 168 microseismic events could be located within the boundaries of the array, roughly 30 km x 40 km. Travel times of these events were used for coupled hypocenter-velocity inversion to produce a one dimensional velocity model with station corrections. The hypocenters of recorded events were relocated using the velocity model and local magnitude was empirically derived for all 168 events. P- and S-wave velocity ranges from 4.9 km/s to 6.4 km/s and 2.8 km/s to 4.7 km/s, respectively, from the surface down to 12 km depth. The magnitude of the microseisms ranges from -2.2 < ML < 1.6 with a magnitude of completeness of Mc -1.5, and follow a Gutenberg-Richter distribution with a b -value of 0.9. The microseismic events occurred down to a depth of 15 km within a sub-vertical fault zone roughly 4 km wide, striking SE-NW and passing below the towns of Ceres and Tulbagh. Seismic events appear to occur in two clusters ranging from 0 to 5 km and 8 to 12 km depth, respectively, separated by a 4 km along-strike discontinuity in seismic activity. There is good agreement between the orientations of the strike of the surface trace of the 1969 aftershock plane and the strike of the surface trace of the microseismic plane. Microseismic activity is attributed to the reactivation in basement structures of either the Malmesbury Group, or the Namaqua Natal Metamorphic complex from far field stress transfer from the Southwest Indian Ridge. It is proposed, albeit on speculation, that the presence of microseismic activity along the vertically oriented fault zone could be the manifestation of an incipient plate boundary formation.

Trace fossils in the form of large (~11 cm diameter and up to 2 m in length) burrows were studied at three localities in the Early Triassic Katberg Formation in the south-eastern and central parts of the main Karoo Basin, Eastern Cape, South Africa. The most interesting site, Hobbs Hill, northwest of Cathcart (Eastern Cape) has numerous burrows, contains an exceptionally well exposed sedimentary succession and bone beds. This site is also the type locality for the holotype of the parareptile Kitchingnathus untabeni (BP/1/1187). The aims of this dissertation are to: 1) reconstruct the local paleoenvironments of the burrow localities; 2) determine the purpose of the burrows; 3) identify the possible burrow makers based on the sedimentology and burrow morphology and 4) attempt to use photogrammetry and low-cost hardware to produce 3D digital burrows for improved descriptions. Insights into the survival strategies and behaviours of organisms during the P/T extinction recovery period are explored. Detailed analysis is mainly done on observations from the Hobbs Hill site; the results and interpretations are important for and compatible with the entire Katberg Formation. The interactions between the physical (sedimentary) and biological (animal behaviour) processes are important in ichnology and paleoenvironmental reconstruction. The analyses have therefore been undertaken through a multidisciplinary approach based on ichnological, sedimentological, petrographical, stratigraphic and paleontological evidence, gathered both in the field and laboratory.