The eastern portion of the Namaqua-Natal Mobile Belt, the Natal Metamorphic Province is divided into four main tectonostratigraphic units. These units comprise two accreted island arcs: the Mzumbe and Margate Terranes; an imbricately thrust nappe zone consisting of four ophiolitic nappes in a hinterland-dipping duplex; and the highly deformed metavolcaniclastic/metagreywacke Mfongosi Group directly adjacent to the stable northern foreland of the Kaapvaal Craton. Theories of late-tectonic left-lateral movement in the southern island arcs are extrapolated northwards of the southern margin of the Kaapvaal Craton coincident with the Lilani-Matigulu Shear Zone. The relative timing and structural context of vein-hosted mineralization with respect to major recognized tectonic events is resolved in five separate areas, two in the Natal Nappe Zone and three in the Natal Thrust Front. The Madidima Nappe of the Natal Nappe Zone contains several north-northeast- to northeast-trending and northeast- to east-northeast trending quartzofeldspathic veined reefs considered to have formed in a late-tectonic left-lateral shear system (main shear and synthetic shear orientations, respectively). The northeast- to east-northeast-trending reef is duplicated due to infilling of normally-faulted steep structures in the semi-brittle, incremental normal faulting of the banded amphibolite component of the nappe. Later left-lateral movement has reactivated one of these steep structures along the southern margin of a regional F2-folded band of granite-gneiss in that a southwest extension of this structure may be responsible for sub-economic veining for a length of up to 9 km. The extensive flat-lying topography of the Mbongolwane Flats area, in which the reefs are situated, is accounted for by the accelerated weathering of rocks which underwent sustained late-tectonic metamorphism in the epidoteactinolite facies, accompanied by pervasive shearing and block rotation to the south of the southern limb of the regional F2 fold in the granite-gneiss. A large, kilometer-scale, open advective fluid system which provided fluid-mediated exchange between co-existing rocks existed at the time of vein formation. The fluid system was driven by early-tectonic intrusion of a granite gneiss and amphibole-rich granite. Two areas in the Mfongosi River valley, the northern and southern Mfongosi Valley areas, contain typical evidence of deformation at the leading edge of collision in a mobile belt. The southern Mfongosi Valley area, at the confluence of the Mfongosi and Tugela Rivers, contains veining which resulted from pressure solution of the host metavolcaniclastic/metagreywacke. Veining occupies predictable shear and tension fractures formed during the initial deformation of a foreland margin sequence, in addition to occupying those fractures formed by buckling on the layer-scale. The structural context of the northern Mfongosi Valley veining is defined by subsequent deformation and vein fragmentation such that the metavolcaniclastic/metagreywacke was reduced to a melange in which vein segments acted as competent clasts; a large-scale porphyroblast/matrix system. Formation of the Manyane Thrust to the south of the Mfongosi Group interrupted the normal retrograde metamorphism of the remainder of the Tugela Nappe and initiated a "hot iron effect" whereby a short-lived thermal pulse acted at the thrust plane, producing a reversed geothermal gradient in the underlying Mfongosi group. This reversed gradient would have been counteracted by a steepened normal geothermal gradient in the Mfongosi Group caused by overloading of the Natal Thrust Front by the Natal Nappe Zone. These geothermal gradients partly account for the concentration of veining in the areas of the Mfongosi Group which are directly adjacent to the Manyane Thrust, and directly adjacent to the Kaapvaal Craton, in the lower portions of the thrust front Stable isotope studies indicate fractionation between vein and wall rock under a short-lived, mainly rock-buffered, layer-scale fluid-movement system. Also forming part of the Mfongosi Group of the Natal Thrust Front, the Ngubevu area contains an apparently enigmatic distribution of veining accompanied by gold and base metal mineralization. The structural evolution of the Ngubevu area occurred during consistent left-lateral transpression into which has intruded early-tectonic veins, formed by pressure solution and having the same structural format as the early-tectonic veining in the southern Mfongosi Valley area. Subsequent deformation of the system was accompanied by 1900 -trending tension gashes which were continually ptygmatically-folded, sheared and offset to form occasionally mineralized quartzofeldspathic "blows" and along-strike stringers in the epidote- actinolite schist. Where veining cross-cuts narrow calcite - graphite - sericite - quartz - albite - tourmaline ± chlorite schist layers, gold mineralization occurred. The late-tectonic tension gashes, antitaxially filled by quartz and amorphous calcite, cross-cut the entire range of lithologies. The fluid system during vein deposition varied: during infilling of early-tectonic fractures a short-lived fluid-flow system dominated, with the emplacement of re crystallized wallrock occurring in a closed, non-advective regime under the influence of diffusion caused by pressure solution. The fluid system changed to a more open, advective, greater than layer-scale rock-buffered one with a decreasing contribution of material from immediate host rocks. An internal fluid source is implied for the entire period of vein emplacement, derived from structural analyses which indicates negative dilation across the Mfongosi Group in this area and by comparison of vein:wallrock δ180 values which indicate a lack of igneous-derived fluids. The Phoenix Mine, in the central portion of the Tugela Nappe, and the Ayres Reef, hosted in Manyane amphibolite adjacent to the Manyane Thrust, are grouped together on the basis of their cross-cutting nature and timing with respect to metamorphism and deformation of the host rock, and also due to their similarity in isotopic plots. Both vein sets occur in approximately east-west to east-northeast-trending zones which show evidence of late-tectonic left-lateral movement. Phoenix Mine veining occurs in weakly-metamorphosed meta-gabbro/meta-norite of the Tugela Rand Complex. The Manyane amphibolite demonstrates the amphibolite facies of metamorphism due to the short-lived thermal pulse at the Manyane Thrust. Both sets of veining display slickenlines which are indicative of their emplacement prior to the late-tectonic left-lateral movement. The unusually thick quartz veins of both deposits are the results of late- to post-Tugela Rand Complex fluids or the tapping of late-tectonic metamorphic fluid reservoirs. This caused silica metasomatism and redeposition of material in post-thrusting collapse features. A highly channelized, single-pass fluid system is proposed in the absence of intrusion-derived fluids. Whole rock geochemical data allow a distinction to be made between the Natal Thrust Front and the Natal Nappe Zone: the Foremost nappe of the nappe zone consists primarily of N-type mid-ocean ridge basalts/ocean-floor to within-plate basalts which were intruded prior to nappe emplacement by metaluminous orogenic volcanic arc granitiods. The thrust front displays a lateral variation in metabasite/metasediment ratio, with the ratio increasing from east to west in this inlier. In the east, in the Nkandlha area, melanged metagreywackes dominate and there is a marked paucity of associated metabasites. In the central portions of the thrust front, in the vicinity of the Mfongosi area, active continental margin/continental arc magmatogenic greywackes and arkoses are interlayered with calk-alkaline volcanic arc basalts (volcaniclastics). The greywacke geochemistry indicates little to no mafic/ultramafic influences in sediment contribution and the source of sediment is inferred to be the southern portions of the Kaapvaal Craton. The Nkandlha and Mfongosi area Mfongosi Group segments are considered to be in-situ or para-autochthonous. The western-most Ngubevu area predominantly hosts metabasites. The geochemistry of the metabasites indicates that they are N-type mid-ocean ridge basalts/ocean floor basalts from a destructive plate margin setting. The metabasites are interbanded with metapelitic/metacalcsilicate layers produced in a shallow water oxic environment, here inferred as a spatially-restricted shallow, marginal basin. The metabasites in the Ngubevu area are notably similar to those of the Madidima Nappe, indicating a similar provenance and pre-collisional mode of formation. It is proposed that the variation in the Natal Thrust Front was due to a north-east/south-west distribution of lithological proportions or mixing, with greywackes dominating in the northeast (in proximity to the Kaapvaal Craton) and metabasites dominating in the southwest. Left-lateral transpressional movement within the Mfongosi Group of the Natal Thrust Front, and the Natal Nappe Zone, was continuous throughout plate collision and obduction. / Thesis (Ph.D.)-University of Natal, Durban, 2000.

A regional field and geochemical study has allowed the identification of three primary units within the Proterozoic basement of the Valley of a Thousand Hills. The Nagle Dam Formation incorporates several chemically distinct orthogneiss series, characterised by limited intragroup fractionation, and derived from discrete sources. Intrusive into the gneisses are the megacrystic A-type granites of the Mgeni batholith, comprising the biotite granites of the Ximba Suite; the hornblende granites and charnockite of the Mlahlanja Suite; and the medium grained leucogranite of the Nqwadolo Suite. Petrogenetic modelling indicates that these are predominately cumulates. A general model for the A-type granites suggests that they were derived through variable MASH processes on an original within plate type basalt. Enclaves within the Mgeni batholith form a distinct series, the Valley Trust Formation, comprising a nongenetic orthogneiss association of amphibolite and crustal sourced quartzo-feldspathic gneiss and locally derived paragneisses. Interaction between the biotite granite and the pelitic enclaves generated a biotite garnet granite. Geothermobarometry suggests temperatures of metamorphism to a maximum of 770°c for the Nagle Dam Formation and c.850°C at a pressure of 6 kb for the Valley Trust Formation. Potential magmatic temperatures of c.760°C at 5 kb are derived for the Mgeni batholith. High Mn garnets within late veins indicate subsequent intrusion at higher levels. Derivation of a tectonic model for the Valley of a Thousand Hills is assisted by a revaluation of the chemical tectonic discrimination plots as source or initiator discriminators. These indicate an origin for the Nagle Dam Formation in an arc environment, while the bimodal orthogneiss association of the Valley Trust Formation and the A-type character of the Mgeni batholith suggests their evolution during extensional events. Geothermobarometry defines an isothermal decompression path, possibly generated during a collision event, superimposed on which is a potential midcrustal heating event, resultant on the intrusion of the Mgeni batholith. These data can be integrated with revised lithotectonic data from the southern portion of the Natal Province to derive a regional model. This comprises: the collision of a number of arcs with associated splitting to form backarcs, sedimentation, and failed rift systems; syn-collisional S-type magmatism, contemporaneous with isothermal decompression of the region; and a series of pulses of post-orogenic granites. / Thesis (Ph.D.)-University of Natal, Durban, 1999.

The Jurassic Rooi Rand dolerite dyke swarm was emplaced sub-parallel to the Lebombo Monocline during the initial stages of Gondwana breakup. The dykes extend northwards from the southern Lebombo region in northern KwaZulu-Natal, into central Swaziland, spanning a distance of approximately 200 kilometres with a width between 10 and 22 kilometres. Detailed mapping of a 600m-Iong section on the Pongolo River, established at least eleven phases of intrusion. Each dyke age was systematically sampled and analysed for whole-rock major, trace and rare earth element composition, as well as mineral chemistry. Selected samples were analysed for stable isotopes. In addition to notable intra-dyke chemical variations, there is also a high degree of inter-dyke mineralogical and geochemical variation, each dyke age bearing distinct geochemical characteristics. The apparent geochemical trend is not one of simple fractionation with time. Dyke chemistries are closely linked to magma genesis and magma volumes with time. Evolution of the magmas may be described in terms of varying degrees of partial melting and fractional crystallization, with a small degree of crustal contamination. Major, trace and rare earth element data indicate a lithospheric mantle source for the majority of dyke phases, and an asthenospheric source for only two of the eleven ages. Contrary to this, isotopic data (oxygen and radiogenic) indicate an enriched asthenospheric source for all the dolerites. This suggests that all ages may have originally been derived from the asthenosphere, with the majority of ages being intruded into the lithospheric mantle to later undergo partial melting and fractional crystallization, with some contamination. Previous studies assumed an asthenospheric source with depleted MORB-like rare earth element profiles to be representative for the majority of Rooi Rand dolerites. The Rooi Rand dolerites appear to display a geochemical link with the southern Sabie River Basalt Formation, as well as the Lebombo rhyolites. Magmatic evolution of the dykes was intimately linked to the initial rifting processes of lithospheric stretching and asthenospheric upwelling, which in this case concluded in a classic failed rift situation. / Thesis (M.Sc.)-University of Natal, 1996.

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.

Estuaries are dynamic features of a coastline whose sediments are influenced by riverine and marine processes. Periodic events such as floods, as well as variations in mouth status, greatly affect the energy levels within an estuary and subsequently the amount of sediment erosion and deposition that takes place. Concurrently, pollutants are transported and deposited into estuaries and can reside in the sediments for many years. The estuaries of the eThekwini Municipality in KwaZulu-Natal, South Africa, are exposed to a variety of pollutants; however with the expanding industrial sector within this region, metal contamination is of concern. This study investigates the sedimentology and geochemical variations of six estuaries within the municipality namely, the uTongati, uMdloti, uMgeni, Isipingo and uMbokodweni estuaries as well as the Durban Harbour. To determine the spatial variations in estuarine sedimentology, sediment cores were collected longitudinal to the estuary axis. The core samples were analysed for sediment colour, texture and organic matter content. To assess the geochemical variations, core samples were analysed for Zn, Cu, Cr, Ni, Pb, As, Fe, Al, Ca, S, P, Mg, Mn, Cd and V concentrations. Some samples were also carbon dated to provide a temporal aspect to the sediment and geochemical variations. Descriptive and graphic techniques were used to examine the sedimentology within the estuaries; and the geochemical data was analysed with the use of multivariate statistics. Additionally, pollution indices and sediment quality guidelines were utilized to assess the pollution levels within the sediments. The results indicated that lower energy environments caused by protracted mouth closures in the uMdloti and Isipingo estuaries accounted for large amassing of fines. In contrast, the accumulation of mixed coarse and fine sediments in the uTongati and uMgeni estuaries was an indication of high fluvial flows and open mouth conditions. All carbon dated ages for all estuaries were greater than 700 years which may be attributed to a combination of scouring effects from past and recent flood events and also possibly due to the deposition of re-worked older sediments from upstream. Low metal concentrations were found within the sediments of all estuaries, and the presence of fines and organic matter governed their concentration variations with depth. The uMgeni and uMbokodweni estuaries which are located immediately downstream of industrial and urban areas, were found to contain relatively higher concentrations of elements Pb, Cu, As and Ni. These metals showed high enrichment within the sediments; however actual concentrations were below sediment quality guideline levels. General pollution levels within all estuaries were very low, and can be attributed to the climatic influences within this region which has a ‘cleansing’ effect on the estuarine environments in removing contaminants. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2014.