A large portion of South west Africa/Namibia is underlain by 2 great orogens. They are the Irumide (Sinclair/Rehoboth) and Damara Orogenies. The L-shaped Irumide Province forms part of a belt which extends over the subcontinent from Namaqualand to as far as Zambia. The volcano-sedimentary sequences of the Irumide are believed to have formed in intracratonic rifts and pull-apart basins during the period 1400 to 900 Ma. The evolution of the NW trending Sinclair Group proceeded by means of 3 major cycles each beginning with the emplacement of basic to intermediate magmas followed by felsic ones. The cycle ended off with subsidence, deposition of immature clastic debris and final tilting of the volcano-clastic sequence. It was suggested that the extensive calc-alkaline lavas present, developed within a magmatic arc above a subduction zone, but this proposal has not been generally accepted. The NE trending Klein Aub-Witvlei Basins consist essentially of red bed alluvial fans and lacustrine sediments with minor volcanics near the base. The red beds and aeolian sediments were deposited in an arid climatic condition. The regional greenschist facies metamorphism and deformation is attributed to a major tectono-thermal event at 1100 Ma. The Damara Orogen (900 - 550 Ma) forms part of the Pan-African mobile belt system of global proportions. The NE trending intracontinental branch (aulacogen) and 2 coastal branches constitute a triple junction with its focal point near Swakopmund. The NE extension of the intracontinental belt has been linked with the Lufilian Arc hosting the renown Zambian Copper Belt deposits. In South West Africa/Namibia this belt hosts many different mineral occurrences which can be grouped into rift and collision related deposits. The tectonic history of the Damara Orogen supports a geodynamic-evolution-with-time hypothesis and represents a transitional phase in which limited Wilson Cycle Tectonics was active. The Theory of Mantle Advection is invoked to explain rifting, thinning and subsidence. Extensive ensialic rifting resulted in a relatively stable Northern Carbonate Platform and several deep troughs hosting turbiditic sequences. Crustal rupture in the Khomas Trough allowed for the emplacement of ocean floor tholeiites known as the Matchless Amphibolite Belt. Subsequent ocean closure and collision resulted in deformation, metamorphism and generation of predominantly S-type granites. The southern continental plate was partially overridden by the northern plate during final collision at 550 Ma. These low angle thrust faults allowed for the emplacement of the Naukluft Nappe Complex on top of younger Nama sediments. The break up of Gondwanaland during the Mesozoic with the splitting of the Atlantic Ocean was responsible for the intrusion of anorogenic alkaline ring complexes along the extension of the NE trending transform faults within the intracontinental branch of the Damara Orogen. A close relationship between the tectonic setting and mineral deposits has been recognized in both the Irumide and Damara Orogenies. In the Irumide, stratiform syngenetic copper deposits are hosted by alluvial fan, playa and lacustrine sediments. The uninterrupted sedimentation from the Irumide to Damara Orogen resulted in similar stratiform copper deposits during the early stages of rifting. In the Damara Orogen the rifting (extensional) phase is characterized by 4 main mineralizing systems: diagenetic/syngenetic (Kupferschiefer-type), epigenetic/hydrothermal Cu-Pb-Zn (Mississippi Valley-type), volcanogenic cupriferous pyrite (Besshi-type) and volcano-exhalative Pb-Zn (Red Sea-type). The collision (compressional) phase was accompanied by 4 main mineralizing processes: epigenetic/hydrothermal Cu-Pb-Zn, hydrotheral/metasomatic Sn-W-rare earth, metamorphogenic Au and U-bearing anatectic melts. The key to the selection of viable exploration targets lies in the understanding of the field evidence and the geodynamics modelling to explain the evolution of the orogen and its associated mineral deposits.

The study area is situated in the Southern Central Zone of the intracontinental Pan-African Damara Orogen, approximately 20km NNE of Navachab Gold Mine in the Karibib district of Namibia. Mesothermal vein systems with Cu-Fe±Au mineralization are hosted by amphibolite facies calcitic and dolomitic marbles belonging to the Navachab Member of the Karibib Formation, and are best developed around the defunct Onguati Copper Mine, Brown Mountain and Western Workings areas. The Onguati study area is located in the saddle region of a moderately-to-gently inclined anticlinorium that experienced significant flattening during NNW-SSE-directed compression. The parallelogram arrangement of ENE- and NNE-trending thrusts and reverse faults that surround the Onguati study area may have developed when the direction of greatest principle subregional stress was oriented WSW-ESE. These structures define part of a Riedel shear system and later faults may have developed in the position of R and P shears respectively. Significant strain partitioning occurred between the ductile calcitic marbles which host the best developed, shear-related vein systems and the more competent dolomitic marbles. The thickness distributions of veins in the marbles of the Onguati Mine, Brown Mountain and Western Workings areas conform to a fractal or power-law distribution, The most intensely mineralized vein systems in the Onguati Mine and Western Workings calcitic marbles share similar low fractal dimensions (D-values) of 0.41 and 0.37 respectively. Veins In the calcitic and dolomitic marbles of the Brown Mountain area and in the dolomitic marbles of Western Workings have elevated D-values (>0.60) and are poorly mineralized. The low D-values «0.40) of the well mineralized vein systems reflect the higher degree of fracture connectivity. These vein systems were capable of efficiently draining and localizing large volumes of mineralizing fluids from crustal-scale structures. A metamorphic devolatization model is proposed where the entire Damaran metasedimentary and meta-volcanic package is seen as a large source area of very low concentrations of Cu, Au and other metals. Localization of deformation into crustal-scale faults and shear zones led to regional-scale hydrothermal fluid flow and focussing into the upstream fracture networks of the Onguati study area. Strong mineralization resulted when fluids encountered the reactive marble lithologies

A thesis submitted to the Faculty of Science (Geology), for the Degree of Doctor of Philosophy,University of the Witwatersrand, Johannesburg,1979 / This study is concerned with the geological history and porphyry- type copper molybdenum of the southeastern Richtersveld Province, in southern South West Africa. An area of approximately 300 km2 centred on the Haib copper prospect, was mapped at a scale of 1:10 000 and subsequently reduced. Observations of facies changes, textural changes, structural and other geological features were recorded and processed. Field work was followed by petrological and geochemical investigations. [Abbreviated Abstract. Open document to view full version] / WS2017