The mapped area, measuring about 400m2, is situated along the southern margin of the Archaean Kaapvaal Craton south of Melmoth in KwaZulu-Natal and comprises greenstones and metasediments forming a narrow, linear E-W trending and dominantly northerly inclined belt flanked to the north and south by various granitoids and granitoid gneisses which have been differentiated for the first time in this study. This belt is here referred to as the ILANGWE GREENSTONE BELT. The lIangwe Belt rocks are grouped into the Umhlathuze Subgroup (a lower metavolcanic suite) and the Nkandla Subgroup (an upper metasedimentary suite). The former consists of: (a) the Sabiza Formation: a lower amphibolite association occurring along the southern margin of the greenstone belt; (b) the Matshansundu Formation: an eastern amphibolite-BIF association; (c) the Olwenjini Formation: an upper or northern amphibolite-banded chert-BIF association. whereas the latter is sub-divided into: (a) the Entembeni Formation: a distinctive phyllite-banded chert-BIF association occurring in the central and the eastern parts of the belt; (b) the Simbagwezi Formation: a phyllite-banded chert-amphibolite association occurring in the western part of the belt, south-east of Nkandla; (c) the Nomangci Formation: a dominantly quartzite and quartz schist formation occurring in the western part of the belt, south-east of Nkandla. The contacts between the six major tectonostratigraphic formations are tectonic. In the eastern sector of the lIangwe Belt, the lowermost metasedimentary formation, the Entembeni Formation, cuts across both the Sabiza and Matshansundu Formations (the lower formations of the Umhlathuze Subgroup) in a major deformed angular unconformity referred to as the Ndloziyana angular unconformity. In the central parts of the belt, the Entembeni Formation structurally overlies the Olwenjini Formation in what seems to be a major local unconformity (disconformity). In the western sector of the belt, the Simbagwezi Formation occurs as a structural wedge between the lower and upper formations of the Umhlathuze Subgroup. That is, it structurally overlies the Sabiza Formation and structurally underlies the Olwenjini Formation. The uppermost metasedimentary unit, the Nomangci Formation occurs as a complex series of finger-like wedges cutting and extending into the Simbagwezi Formation and in each case showing that the Nomangci Formation structurally underlies the Simbagwezi Formation. This structural repetition of lithological units is suggestive of normal dip-slip duplex structures. Palimpsest volcanic features, such as pillow structures and minor ocelli, indicate that many of the amphibolitic rocks represent metavolcanics, possibly transformed oceanic crust. This is also supported by limited major element geochemistry which suggests that the original rocks were ocean tholeiites. Evidence suggests that the talc-tremolite schists and the serpentinitic talc schists represent altered komatiites. The nature of the metasediments (represented by banded metacherts, quartzites and banded iron formations) and their similarity to those of the Barberton, Pietersburg and Nondweni greenstone complexes suggests that they were formed in relatively shallow water environments. The lIangwe magmatism is represented by different types of granitoids and granitoid gneisses and basic-ultrabasic intrusive bodies. Based on similar geochemical and mineralogical characteristics and on regional distribution, mutual associations and contact relationships, these granitoids and granitoid gneisses can be divided into three broad associations, viz: (a) The Amazula Gneiss - Nkwa/ini Mylonitic Gneiss - Nkwalini Quartzofeldspathic Flaser Gneiss Association: a migmatitic paragneiss and mylonitic to flaser gneiss association of older gneisses of Nondweni age occurring in several widely separated areas and intruded by younger granitoids. (b) The early post-Nondweni Granitoids comprising the Nkwalinye Tonalitic Gneiss (a distinctive grey gneiss intrusive into the greenstones and older gneisses) and the Nsengeni Granitoid Suite (an association of three granitoid units of batholithic proportions flanking the greenstone belt and intrusive into the greenstones, older gneisses and Nkwalinye Tonalitic Gneiss). (c) The late post-Nondweni Granitoids comprising the Impisi-Umgabhi Granitoid Suite, a batholithic microcrystic to megacrystic association of five granitoid phases/units occurring to the north and south of the greenstone belt and intrusive into the greenstones, older gneisses and early post-Nondweni granitoids. Limited major element geochemistry suggests that the granitoids and granitoid gneisses are of calc-alkaline origin and are of tonalitic, granodioritic, adamellitic and granitic composition. An igneous derivation from material located possibly at the lower crust or upper mantle is suggested. At least three major episodes of deformation (01, O2 and 03) have been recognized in the greenstones. During 01, a strong penetrative S1 tectonic foliation developed parallel to the So primary layering and bedding. This period was characterized by intense transpositional layering, recumbent and isoclinal intrafolial folding with associated shearing,thrusting and structural repetition of greenstone lithologies. These processes took place in an essentially horizontal, high strain tectonic regime. The first phase of deformation (OG1) in the migmatitic and mylonitic gneisses was also characterized by recumbent and isoclinal intrafolial folding and is remarkably similar to the 01deformational phase in the lIangwe greenstones. Structural features of the first phase of deformation suggest that it was dominated by formation of fold nappes and thrusts and was accompanied by prograde M1 medium-grade middle to upper amphibolite facies metamorphism. During D2 deformation, the subhorizontal D1 structures were refolded by new structures with steeply inclined axial planes. This resulted in the formation of superimposed Type 3 interference folding in the amphibolitic rocks and large-scale, E-W trending, doublyplunging periclinal folds in the metasediments. These periclinal folds have steeply inclined and overturned limbs and are characterized by narrow, closed elliptical outcrop patterns well-defined by extensive banded ironstones and metacherts. The second phase of deformation in the granitoids (DG 2) was characterized by steeply plunging and steeply inclined small-scale tight to isoclinal similar folds. Large-scale folds are not present in the granitoids. Evidence suggests that the second phase of deformation was a major compressional event which resulted in the large-scale upright, flattened flexural folds. It was accompanied by widespread regional greenschist metamorphism and the intrusion of the early postNondweni granitoids. The third phase of deformation produced steeply plunging small-scale folds on the limbs and axial planes of the pre-existing large-scale F2 folds and upright open folds in the granitoid terrain. This episode was characterized by the emplacement of the late postNondweni granitoids (along the D2 greenstone boundary faults) and is associated with two significant events of prograde M3 upper greenschist facies metamorphism and retrograde M3 lower greenschist facies metamorphism. Post-D3 deformation is characterized by late cross-cutting faults and the emplacement of younger basic - ultrabasic bodies. / Thesis (Ph.D.)-University of Natal, 1997.

Heavy mineral deposits along the east coast of South Africa represent the world's largest demonstrated resource of beach placer ilmenite. This mineral occurs as homogeneous, subrounded grains, with chemical compositions close to pure FeTi03• Concentrates contain between 48 and 52 per cent Ti02, with minor impurities of MnO, MgO, and Cr203. Most coastal ilmenites are unaltered or display only incipient alteration, but the entire spectrum of alteration products from ilmenite to rutile or anatase, is observed. Transmission electron microscopy of weathered ilmenites reveals that ilmenite commonly alters to pseudorutile and then to rutile or anatase, as described by Teufer and Temple (1966) and Grey and Reid (1975). Ilmenite may also alter directly to rutile (or anatase) in a single-stage process. In addition, ilmenite altered by high temperature oxidation and hydrothermal processes is found in the deposits. There is good mineralogical evidence that the alteration of ilmenites found in the coastal sediments is best described by a multi stage model, in which some ilmenite grains were altered prior to final deposition. Other common iron-titanium oxides in the deposits include magnetite, rutile and hematite, which may occur as discrete grains or as composite grains of two or more oxides. Ilmenite and magnetite in the coastal sediments are derived from rocks of both the Karoo Igneous Province and the Natal Basement, while rutile is derived solely from the latter. Ilmenites from certain rock groups may be distinguished on the basis of their chemical composition. However, magnetite chemistry is a better indicator of provenance, and magnetites from the above two sources can be clearly distinguished. The petrography of the iron-titanium oxides may be used as a provenance indicator, but may be misleading, as the proportions of the oxide intergrowths change with transport and weathering. Variations in the proportions and chemical compositions of iron-titanium oxides and other heavy minerals within the coastal sediments are caused by provenance, selective sorting during deposition, age of the deposit, weathering, and the recent geological history of the area. A model is proposed in this study which describes the formation of the heavy mineral deposits in relationship to the above influences. / Thesis (Ph.D.)-University of Natal, Durban, 1993.

The Nsuze Group forms the lower, predominantly volcanic succession of the Pongola Supergroup. The 2.9Ga Nsuze Group outcrops in southeastern Mpumalanga, northern KwaZulu-Natal and Swaziland. The volcanic rocks of the Nsuze Group are basalts, basaltic andesites, andesites, dacites and rhyolites preserved as both lava and pyroclastic deposits. The oldest volcanic sequence of the Nsuze Group is the basaltic Wagondrift Formation. The younger Bivane Subgroup represents the main volcanic component of the Nsuze Group. The White River Section represents a complex volcanic history of magma storage, fractionation, and eruption, supplied by a multi-level system of magma chambers. The basaltic and basaltic andesite rocks of the White Mfolozi Inlier represent the steady and non-violent eruption of lavas from related volcanic centres. The Nsuze Group rocks have been metamorphosed by high heat flow burial metamorphism to lower greenschist facies. Geochemically, elements display well-defined fractionation trends, with evident sub-trends within each phase group of samples. These sub-trends are related to the fractionation of key minerals, in particular plagioclase. The REE patterns show that evolution of magma was largely controlled by the fractionation of plagioclase. All REE patterns show LREE enrichment relative to the HREE. The Wagondrift Formation was derived from a more depleted source than the younger Bivane Subgroup volcanic rocks and exhibits a within-plate tectonic signature. The volcanic rocks of the Bivane Subgroup in the White River Section and the White Mfolozi Inlier are geochemically similar. The volcanic rocks of the Bivane Subgroup of both the White River Section and the White Mfolozi Inlier have a subduction zone tectonic signature, in particular a Ta-Nb negative anomaly. Tectonic discrimination diagrams suggest an enriched source related to a continental-arc setting. The geochemistry suggests an eclogitic source for the Nsuze Group volcanic rocks. The formation of eclogite in the mantle requires subduction of basaltic material. Archaean models for subduction-like processes include decoupling of oceanic crust and subsequent underplating of the continental lithosphere, and low-angle subduction which minimises the effect of the mantle wedge. It is possible that a combination of these processes resulted in an enriched eclogitic source for the magmas of the Nsuze Group. / Thesis (M.Sc.)-University of Natal, Durban, 2003.

This study presents the interpretation of Edo-Western and Sparker seismic geophysical data acquired on the northern KwaZulu-Natal upper continental margin by various organisations since 1981. Five seismic sequences are recognised and these are traceable across the entire length of the study area. The oldest is interpreted as a late Cretaceous marine sequence (Sequence A), probably the offshore equivalent of the St. Lucia Formation exposed onshore. This sequence is overlain by a progradational, probable late Tertiary shelf sequence (Sequence B) onlapping in places against the underlying marine sequence. The outer portion of this sequence on the upper continental slope is characterised by complicated reflection termination patterns indicating the possible presence of discreet sequences within this shelf and slope unit. These shelf and slope sediments are overlain by a thin (less than 20m) reworked and eroded Pleistocene shelf unit (Sequence C), itself overlain by linear Pleistocene aeolianites (Sequence D) in places. The youngest sequence observed is the Holocene unconsolidated sediment wedge (Sequence E) on the inner shelf, attaining thicknesses of greater than 20m in places. The various sequences were mapped out and sediment isopach maps were produced (wherever possible) as well as an overall geological subcrop map of the study area. 150 kilometres of shallow penetration Edo Western seismic records acquired off the Sodwana Bay continental shelf were interpreted. Two sediment types are recognised, namely consolidated beach rock/aeolianite and unconsolidated Quaternary shelf sand/bioclastic reef derived sediment. In places, accumulations of bioclastic sediment in subaqueous dune troughs which have been subsequently buried by migrating bedforms manifest themselves on seismic records as dark semi-continuous reflectors beneath the migrating bedform. Close inshore, seismic records show prominent reflectors interpreted as consolidated sediment beneath varying thicknesses of unconsolidated sediment. Close to the shelf break (occurring at approximately -60m), seismic interpretation indicates that thin beach rock developments perch directly upon unconsolidated shelf sand, with the beach rock having been eroded through in places to expose unconsolidated sediment beneath. A sediment thickness map for this area was compiled from the seismic data. The limited penetration of the Pinger system necessitated "greater-than" values being used in many areas. Greatest sediment thicknesses occur in subaqueous dune fields where unconsolidated sediment thickness is at least 11 m. In inshore areas absent of subaqueous dune fields, sediment thicknesses are typically low, varying between 1 and 3m. A prominent submerged dune ridge close inshore limits substantial unconsolidated sediment build-up to landward of this feature. On the seaward side substantial build-up is limited by the action of the Agulhas Current which is actively transporting sediment into the head of submarine canyons which incise the continental shelf at Sodwana Bay. This study shows that on the northern KwaZulu-Natal continental shelf where there is a dearth of unconsolidated Quaternary sediment, the Edo Western seismic system is a useful tool for discerning thin veneers of unconsolidated sediment less than 4m thick. When considering the overall low volumes of unconsolidated sediment present on the shelf, this hitherto unconsidered volume of sediment constitutes an important part of the shelf sediment budget. Submarine landslide features observed on sparker seismic records are described and discussed. Submarine landslides are present which affect a) Sequences A and B, b) Sequence B only and c) Sequence A only, ages of these sediment failures can thus be inferred as being either post- Late Cretaceous or post- Late Tertiary. Offshore Kosi Bay, submarine landslide features affecting Sequence A are buried by unaffected Sequence B sediments, indicating a post- Late Cretaceous to pre- Late Tertiary age of occurrence. Style of failure tends towards mass flow in those submarine landslides in which Sequence B only sediments are affected, while those in which Sequence A is affected exhibit some slide features indicating a greater degree of internal coherency of these sediments compared to Sequence B. Slope stability analysis of a submarine landslide feature offshore St. Lucia Estuary Mouth indicates the failed sediment mass would have been stable under static conditions and that external dynamic forces such as storm waves or seismic activity would have been necessary to induce failure. It is demonstrated that the Zululand earthquake of 1932 would have exceeded the intensity necessary to induce sediment failure and this event should therefore be considered as a possible cause. Seismic evidence of fluvial incision/subaerial exposure at the boundaries between Sequences A and B and C and E are further evidence of lowered sea-levels probably during the Oligocene and Late Pleistocene. The position of the incision into Sequence C relative the present course of the Mkuze River indicates the possibility that this incision could represent the palaeo-outlet of this river. Seismic expression of 3 submarine canyons in the study area indicate that they are currently undergoing active headward erosion, independent of any direct modern fluvial influence. In the case of Ntabende Canyon, a nearby continental shelf incision postulated to be the palaeo-Mkuze outlet indicates that provision of terrigenous material to this portion of the continental shelf could well have accelerated mass wasting processes within the canyon itself. This submarine canyon could therefore have progressed more rapidly to a relatively mature phase of development. Subsurface structure indicates the lack of any post- Late Tertiary fault features beneath the canyons, thus excluding faults active in post- Late Tertiary times as a developmental factor. It is shown that the overall, external morphology of the KwaZulu-Natal upper continental margin is strongly influenced by seismic stratigraphic relationships, with the main influencing factors being outcrop position of the various sequences and depositional angle of sediments of which a sequence is comprised. External morphology has also been greatly modified in places by mass-wasting processes. It is demonstrated also that relating the observed seismic stratigraphy to onshore geological cross sections is problematic due to the distances involved and lack of confident offshore dates for the seismic sequences observed. Seismic relationships observed contribute to an understanding of relative sea-level movements since the Late Cretaceous and the overall geological evolution of the northern KwaZulu-Natal upper continental margin, details of which are discussed. / Thesis (M.Sc.)-University of Natal, Durban, 1998.

At present the Karoo Basin covers approximately 20 000 km2. It is a large intracratonic basin which, from Carboniferous to Jurassic times, was infilled with a succession of sediments ranging from glacial deposits to those deposited in warm, equable conditions. The Beaufort Group forms part of this succession, and was deposited in a terrestrial, river dominated environment. The dominant lithologies exposed in the Estcourt region in the KwaZulu-Natal Midlands belong to the lower and middle Beaufort divided by the PermoTriassic boundary. The Permo-Triassic palaeoenvironment in this region is reconstructed using sedimentary profiles combined with the study of the fossil remains discovered in the area, including plant, body, and trace fossils. The lower Beaufort sediments in this region belong to the Estcourt Formation, and the Middle Beaufort sediments to the Belmont Formation. The Estcourt Formation is dominated by a succession of alternating sandstones, siltstones and mudstones, which are interpreted as representing sediments deposited in a fluvial-floodplain environment, which can be divided into two sub-environments. The first is dominated by sediments that were deposited by meandering rivers on a semi-arid floodplain, and the second sub-environment is represented by those sediments deposited in lacustrine environments. Both of these subenvironments are closely linked and alternate in the rock record indicating many episodes of transgressive-regressive lacustrine episodes. The Estcourt Formation can be closely correlated with the lower Beaufort sediments mapped in other regions of the Karoo Basin, indicating similar climatic and environmental controls throughout the Karoo Basin of southern Africa. The Estcourt Formation also contains a wide variety of body and trace fossils. The PermoTriassic boundary can be traced along the western border of Estcourt by using the distribution pattern of the two mammal-like reptiles Dicynodon and Lystrosaurus. There is evidence of an overlap in the distribution between these to mammal-like reptiles, which together with palaeoflora evidence, indicates that Lystrosaurus evolved during the Late Permian and not Early Triassic as previously thought. The first Triassic sediments are represented in the Estcourt region by a series of maroon shales which can be correlated with the Palingkloof Member. / Thesis (M.Sc.)-University of Natal, 1997.

The upper part of the Revue basin in the Manica District, Mozambique is located in a mountainous area underlain by rocks of the Manica greenstone belt. This greenstone belt has alluvial gold deposits in the Revue river and its tributaries Chua and Zambuzi. Alluvial gold in the Manica District has been mined by local people using artisanal mining methods (panning) and by small scale companies. The recovery process of gold involves washing of the auriferous gravel with large quantities of water and the surface water quality has been impaired in this process. The aim of this dissertation is to assess the impact of alluvial gold mining on surface water quality in the Revue basin. Physical and chemical characteristics of the surface water were determined upstream of, within and downstream of the mining area and in the main tributaries immediately before flowing into the Revue river. Upstream of the mining area the water is clear and the rock types of the Manica greenstone belt are likely to be the only source of metals dissolved in the water. Metal concentrations are generally low except Cd, Mo and Ni but the water in this area meets all World Health Organization (WHO) recommendations for drinking water. In contrast within the mining area there are signs of pollution. The water is cloudy and the highest concentrations of most metals are found in the lower part of this area where mining activity is very intense. Thus, the alluvial gold mining is responsible for elevated metal concentrations and constitutes the major point source of pollution in the Revue basin. Water quality within the mining area has been affected and metals Ba, Pb and Mn have concentrations exceeding the WHO recommended values for drinking water. Downstream of the mining area the impounded water in the Chicamba Dam, which is the source of potable water for Chimoio City, reduces the water flow in the Revue river and sedimentation of suspended sediments occurs, together with associated adsorption and precipitation processes. This result in general improvement of water quality with only Ba and Pb concentrations remaining above the WHO recommended values for drinking water. Increase in concentration of metals AI, Ba, K, Pb and Sr occurring in the Chicamba Dam is likely to be due to input to the dam of water from rivers which cross the Granite-gneiss Complex. Geochemical speciation modelling using MINTEQA2 program suggests that the behaviour of metals Cr, AI, Mn and Fe is controlled by redox and precipitation reactions while the behaviour of As, Cd, Zn, Cu, Ni, Pb, Ba and Ca is controlled by adsorption on the sediment surfaces. Changes in environmental conditions, such as pH and dissolved organic matter (DOM) could result in metals being released back into the water. Modelling the effect of a change in pH and variation in DOM indicate that adsorption and precipitation would decrease with decreasing pH values and with increasing DOM. The chemical form of dissolved metals, the type of interactive processes (absorption and precipitation) and concentration of particulate matter gives the distribution of pollutants while the transport process affect the fate of pollutants in the Revue river water. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

The reduced fresh water input into the St Lucia Estuary combined with the increase of sediment in the St Lucia Lake System has necessitated the implementation of a dredging programme. To ensure the effectiveness of the dredging programme, the behaviour of the sediment under various flow and tidal conditions needs to be determined. To establish how sediment will move, it is necessary to understand the hydrodynamics of the estuary. To achieve this, a hydrodynamic model which can be linked to a sediment transport model needs to be developed. Various existing types of hydrodynamic and sediment transport models are reviewed, to determine their suitability for the above purpose. Results of the analysis indicate that a two-dimensional hydrodynamic model is required. The two-dimensional hydrodynamic model developed is based on the momentum and continuity equations for an unsteady, non-uniform, free-surface flow for an incompressible fluid. The two dimensions are in the horizontal plane and flow is averaged over the depth. The equations are non-linear and are not decoupled, thus a numerical technique was needed to solve them. An Alternating Direction Implicit technique has been used. Boundary conditions in the modelled region were specified as flow velocity at the upstream boundary, and water levels, relative to the Mean Lake Level, at the downstream boundary. Two short simulations using hypothetical data were run on a 80826 IBM compatible. Results of the simulation indicate two areas where irregularities in the model output are a consequence of the use of hypothetical data in defining the boundary conditions. Recommendations for the collection of data in order to improve and calibrate the model are discussed. / Thesis (M.Sc.)-University of Natal, 1993.

Zircon from the zircon concentrate of Richards Bay Minerals was investigated with a view to understanding the morphology and provenance. The obsevations were applied to the reduction of uranium, thorium and other trace elements in the heavy mineral placer deposits. It is evident from differences in morphology, optical characteristics, cathodoluminescence, inclusion types and trace element analyses that the zircon is derived from numerous parent rocks. Rare earth element modelling reveals several possible parent rocks including rhyolites, granites, syenites, pegmatites and carbonatites. Fission track U mapping of individual zircons indicated an enrichment of U in the rims and grain terminations. The U maps were used to devise and test several methods, including abrasion and partial dissolution, to reduce the combined U and Th concentration from 450-563ppm to below 400ppm. The effect of magnetic cleaning, density separation and size classification of the zircon concentrate on the U +Th concentration was found to be negligible. Air abrasion and HF acid dissolution successfully reduced the U +Th concentrations to between 332 and 383ppm. The contribution of trace elements from inclusions, surface pit fillings and coatings, and foreign minerals within the zircon concentrate were evaluated by by scanning electron microscope identification. / Thesis (M.Sc.)-University of Natal, Durban, 1992.

Thesis (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Foreland basins commonly fill with sediment derived from the adjacent fold/thrust belt, providing a relatively simple source-to-basin configuration. However, that is not true for the early southwestern Karoo Basin, since the composition of the Ecca Group sedimentary rocks do not match the composition of the adjacent fold/thrust belt. The southwestern Karoo Basin is bordered to the west and south by the Cape Fold Belt (CFB) and provides the opportunity to study the linkage between its early structural evolution and deposition in the two spatially and temporally distinct Tanqua and Laingsburg depocentres. The CFB was formed when the early Palaeozoic passive continental margin, which formed a large section of the southern edge of Gondwana, evolved into an active convergent margin during the late Palaeozoic. Orogenesis resulted in a northwest-trending Cedarberg branch and an eastwest-trending Swartberg branch. The oroclinal bend between the two branches includes large-scale northeast-trending syntaxis structures, such as the Hex River and Baviaanshoek anticlinoria, which influenced the sedimentation path into the basin. Spectral gamma ray (SGR), mineralogical and geochemical studies of exposed rocks from the Tanqua and Laingsburg depocentres indicate a near uniform provenance for both, dominated by granitic and metamorphic material derived from a provenance seemingly far beyond the CFB. SGR data, combined with lithology, show that regional stratigraphic correlation is possible in the Skoorsteenberg, Kookfontein and Waterford Formations in the Tanqua depocentre. The same is true for the Laingsburg and Fort Brown Formations in the Laingsburg depocentre. There are no major changes in the SGR data set between the successive sandstone or shale units that could imply different origin, and no distinct signals in the SGR pattern of the shale intervals that could potentially correspond to maximum flooding surfaces. The Tanqua and Laingsburg depocentre sandstones are very fine- to lower mediumgrained, tightly packed, poorly to well sorted, and have undergone mechanical compaction and pressure solution. The mineralogical composition and texture of these sandstones suggest that they have undergone high-grade diagenesis to low-grade regional burial metamorphism to the lower greenschist facies (250 ± 50ºC; ~2 kbars). They are mineralogically and geochemically classified as lithic arenites and greywackes, and the Tanqua depocentre sandstones are slightly more mature than the Laingsburg depocentresandstones. REE patterns for the Tanqua and Laingsburg depocentre sandstones are similar, suggesting that both form part of the same evolutionary pattern and that the sediments have one common origin, i.e. a provenance predominantly composed of granitic material. Homogenous εNd-values for all sandstone samples of around –5 at the time of deposition indicate that there is little or no variation in provenance between the Tanqua and Laingsburg depocentre sediments. TCHUR model ages of 0.70 to 0.95 Ga, and TDM model ages of 1.19 to 1.49 Ga, resulted from a mixture of Archaean and Proterozoic material in unknown proportions. The most likely source terrane is thought to be the North Patagonian Massif. The latter show Nd isotopic compositions corresponding to an average εNd-value of -5 at 265 Ma. / AFRIKAANSE OPSOMMING: Voorlandkomme word oor die algemeen gevul met sediment afkomstig van die aanliggende plooigordel, wat lei tot ‘n redelik eenvoudige brongebied-tot-afsettingskom konfigurasie. Dit is egter nie van toepassing vir die vroeë suidwestelike Karookom nie, aangesien die samestelling van die Ecca Groep sedimentêre gesteentes nie ooreenstem met die samestelling van die aanliggende plooigordel nie. Die suidwestelike Karookom word aan die weste en suide begrens deur die Kaapse Plooigordel en bied die geleentheid om die verwantskap tussen die vroeë strukturele evolusie en afsetting in die twee ruimtelik en temporeel afsonderlike Tankwa en Laingsburg subkomme te bestudeer. Die Kaapse Plooigordel het gevorm toe die vroeë Palaeosoïkum kontinentale grens, wat ‘n groot deel van die suidelike grens van Gondwana was, ontwikkel het tot ‘n aktiewe konvergerende grens gedurende die laat Palaeosoïkum. Orogenese het gelei tot die vorming van ‘n noordwes-strekkende Sederberg tak en ‘n ooswes-strekkende Swartberg tak. Die oroklinale buig tussen die twee takke sluit grootskaalse noordoosstrekkende sintaksis strukture in, soos die Hex Rivier en Baviaanshoek antiklinoria, wat die sedimentasie rigtings na die kom beïnvloed het. Spektrale gammastraal (SGR), mineralogiese en geochemiese studies op die dagsome van die Tankwa en Laingsburg subkomme dui ‘n byna identiese brongebied aan vir beide, oorheers deur granitiese en metamorfe materiaal vanaf ‘n brongebied oënskynlik vêr vanaf die Kaapse Plooigordel. SGR data, gekombineer met litologie, dui aan dat dit moontlik is om regionale stratigrafiese korrelasies in the Skoorsteenberg, Kookfontein en Waterford Formasies in die Tankwa subkom te maak. Dieselfde geld vir die Laingsburg en Fort Brown Formasies in die Laingsburg subkom. Daar is geen groot veranderinge, wat ‘n verskil in oorsprong kan aandui, in the SGR datastel tussen die opeenvolgende sandsteen of skalie eenhede nie, en ook geenuitstaande tekens in the SGR patroon van die skalie-intervalle wat moontlik kan ooreenstem met ‘n maksimum vloedingsvlak nie. Die Tankwa en Laingsburg subkom sandsteenlae is baie fyn- tot laervlak mediumkorrelrig, dig gekompakteer, swak tot goed gesorteer, en het meganiese kompaksie en drukoplossing ondergaan. Die mineralogiese samestelling en tekstuur van hierdie sandsteenlae dui daarop dat hulle hoë-graadse diagenese tot lae-graadse regionale begrawingsmetamorfose tot laervlak groenskis fasies (250 ± 50ºC; ~2 kbars) ondergaan het. Hulle word mineralogies en geochemies geklassifiseer as litiese areniete en grouwakke. Die Tankwa subkom sandsteenlae is effens meer volwasse as die Laingsburg subkom sandsteenlae. Die lantanietgroep patroon vir die Tanqua en Laingsburg sandsteenlae is eenders, wat aandui dat beide deel gevorm het van dieselfde evolusionêre ontwikkeling en dat die sedimente een gesamentlike oorsprong gehad het, naamlik ‘n brongebied bestaande hoofsaaklik uit granitiese materiaal. Homogene εNd-waardes van ongeveer –5 by tye van afsetting vir al die sandsteen monsters dui daarop dat daar min of geen verandering in brongebied vir die Tankwa en Laingsburg subkom sedimente was nie. TCHUR model ouderdomme van 0.70 tot 0.95 Ga, en TDM model ouderdomme van 1.19 tot 1.49 Ga, is afkomstig van ‘n mengsel van Argeïese en Proterosoïese materiaal in onbekende hoeveelhede. Die mees waarskynlike brongebied is die Noord Patagoniese Gebergtes. Dit wys Nd isotopiese samestellings wat ooreenstem met ‘n gemiddelde εNd-waarde van –5 by 265 Ma.

MSc / Thesis (MSc (Earth Sciences))—University of Stellenbosch, 2009. / Fan 2, one of five submarine fan systems of the Tanqua fan complex in the south-western Karoo Basin, South Africa, is subdivided into Lower, Middle and Upper units. Here, detailed analysis of the internal architecture and distribution of lithofacies associations of Middle Fan 2 facilitated the 3-D visualisation of the sedimentological and stratigraphical changes towards the pinch-out. Middle Fan 2 is interpreted to be a lower-fan, sand-rich terminal lobe, comprising three sandstone-lobe elements, separated by two siltstone interlobe elements. It is fed by a distributary channel that is hypothetically positioned to the west-southwest of the study area. The sandstone-lobe elements pinch out downdip to the north-east and updip to the southsouthwest in the study area. The consecutive pinch out of lobe elements to the north-east indicates a progradational stacking pattern similar to the entire lobe complex. Palaeocurrent analysis and the interpretation of isopach maps indicate that the transport direction of Middle Fan 2 was in a north-easterly direction. The fringes of the lobe and the distribution of internal elements (channels, amalgamated sheets and sheets) show a finger-like geometry in plan-view, in contrast to simple radial-lobe bodies that are commonly envisaged.