A Dissertation Submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the degree of Master of Science / AC 2018

Various methods and techniques developed by researchers worldwide for enhancement and processing ATM, MSS· and TM remotely sensed data are tested. on LANDSAT 5 Thematic Mapper data from a part of the Barberton Greenstone Belt straddling the border between the Republic of South Africa and the Kingdom of Swaziland. Various enhancement techniques employed to facilitate the extraction of structural features and lineaments, and the findings Of the ensuing photogeologlcal interpretation are compared with existing geological maps~ Methods for the detection of zones of hydrothermal alteration. are also considered. The reflectance from vegetation, both natural and cultivated, and the possible reduction of the interference caused by this reflectance, are considered in detail. Partial unmixing of reflectances through the use of various methods and techniques, some of which are readily available from the literature, are performed and its effectiveness tested. Since large areas within the study area are covered by plantations, the interfereiice from the two types of vegetation present (i.e. natural and cultivated), were initially considered separately. In an attempt to isolate the forested areas from the natural vegetation, masks derived through image classification were used to differentially enhance the various features. Results indicate that the use of any particular method to the exclusion of all others will seriously limit the scope of conclusions possible through interpretation of the information present. Enhancement of information in one domain will inadvertently lead to the suppression of information from one or more of the coexisting domains. A series of results from a sequence of procedures interpreted in parallel will in every case produce information of a higher decision making quality. / AC2017

A Dissertation Submitted to the Faculty of Science; University of the Witwatersrand, Johannesburg; for the Degree of Doctor of Philosophy / A volcanological study of the Onverwacht Group in the southwestern part of the Archaean (-3.5 - 3.2 Ga) Barberton greenstone belt (BGB), South Africa, shows that volcanic extrusion rates of the Komati and Hooggenoeg Formations must have been high to have maintained the degree of submarine sheet flooding that is evident. It is concluded that the volcanic attributes of the Komati and Hooggenoeg Formations are not typical of MOR crust, as has been claimed, but rather closely resemble those of modern oceanic plateaus. The shear-zone-bound basal contact of the Komati Formation suggests that the top of the ancient oceanic plateau was allochthonously emplaced and delaminated from its basal (intrusive) part. (Abbreviation abstract) / AC2017

Thesis (M.Sc.)--University of the Witwatersrand, Science Faculty (Geology), 1997. / The Sterkspruit Intrusion, in the south-western portion of the Barberton greenstone belt, is a sill-like body containing rocks of gabbroic to dioritic composition. It is hosted by a sequence of komatiitic basalts and komatiites of the Lower Onverwacht Group. The intrusion is considered unique in this area in that it lacks ultramafic components and has no affinities with the surrounding mafic- to- ultramafic lavas. The gabbroic suite also contains an unusual abundance of quartz, and the chill margin shows an evolved quartz-normative, tholeiitic parental magma. Based on petrographic and geochemical evidence, the intrusion can be subdivided into four gabbroic zones and a quartz diorite, which is an end product of a differentiating magma. The chill margin records an MgO content of 4.8%, an Mg# of 42, an Si02 value of 52.5% and a normative plagioclase composition of An44. The sill-like nature of the body, indicated by geochemical trends, and the steep sub-vertical layering, point to a body that has been tilted along with the surrounding lavas. This constrains the relative age of the body to be older than the emplacement of the Kaap Valley and Nelshoogte Plutons, which caused the regional deformation observed in the Nelshoogte Schist Belt. A sequence of tholeiitic to andesitic basalts from the Kromberg Formation in the Upper Onverwacht Group, have compositions which can be correlated with the Sterkspruit Intrusion. It is possible that this body represents a subvolcanic magma chamber, which acted as a feeder to tholeiitic lavas higher up in the volcanic sequence. The Sterkspruit Mafic Dyke Swarm intruded the southern Nelshoogte Schist Belt and displays intra-dyke chemical variation. / AC2017

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. / The Sterkspruit Intrusion, in the south-western portion of the Barberton greenstone belt, is a sill-like body containing rocks of gabbroic to dioritic composition, It is hosted by a sequence of komatilitic basalts and komatilites of the Lower Onverwacht Group. The intrusion is considered unique in this area in that it lacks ultramafic components and has no affinities with the surrounding mafic- to- ultramafic lavas, The gabbroic suite also contains an unusual abundance of quartz, and the chill margin shows an evolved quartz-normative, tholelitic parental magma. ( Abbreviation abstract ) / AC2017

Thesis submitted for the degree of Master of Science in the Faculty of Science, University of the Witwaiersrand, Johannesburg. / The following is an account of the stiatigiaphy, structure, metamorphism and mineralization in a complexly deformed area of the northwest part of the Barberton Mountain Land. It is situated at the eastern extremity of the Jamestown Hills and covets a region along the contact zone between the ancient layered rocks of the Archaean Complex and the Nelspruit Granite. In the first section is given a fairly comprehensive account of previous work done in the Barberton region- especially as it applies to the area under discussion. This is followed by a consideration of the petrology and stratigraphy of the area and a description of the various structures encountered. A more detailed statistical treatment of the minor structures is also included and from these results an attempt is made to unravel the tectonic history of the area and to fit it into the regional structural pattern of the Mountain Land as a whole. The area mapped consists of two basically Identical successions separated by a major high angled thrust fault. The northern succession, which has been quite strongly thermally metamorphosed, represents the fairly steeply south dipping northern limb of the Lily Syncline. That to the south has suffered very little metamorphism and forms part of the northern limb of the Eureka Syncline. A well developed and layered basic suite of rocks lying below the Fig-tree Series .and constituting the basal zone of the Lily Syncline, is classed in the Onverwacht Series, It lies in direct contact with the Nelspruit Granite and is considered to represent a metamorphosed succession of impure dolomites with arenaceous and minor shaly horizons, together probably with some basic and acid lavas. The Onverwacht rocks are overlain by metamorphosed Fig-tree shales and "lavas", and these in turn by metamorphosed conglomerates and quartzites of the Moodies System. At the base of the homfelses lies the Consort "Contact" or Consort "Bar", a siUcified, mineralized zone which is the main ore horizon of the Consort Mine. The homfelses grade into rocks which have been termed "lavas" but which are thought to be mote of the nature of crystalline tuffs. The succession to the south of the Main Fault Is on a broad scale Identical to the one just described above, differing mainly in metamorplilc state. Thus, whereas the Onverwacht rocks of the northern succession have been converted to hornblende and tremolite-actinollte schists, similar rocks to the south of the Main Fault have been changed to carbonate-bearing talc and chlorite phylUtes. The basic Intrusive rocks of the Jamestown are considered to be of a much smaller distribution than was previously thought,and are represented mainly by the massive bodies of pure serpentinite. There is a possibility however; that certain of the purer talc- carbonate schists along the Kaap Rivet,represent altered ultrabasic intmsives. The Nelspruit gneiss and migmatlte is considered to represent a completely granitized pre-Swaziland System sequence which at a much later date acted as the basement upon which the layered rocks of the Mountain Land were deposited, A re-moblllzed border phase of this migmatite was largely responsible for the contact metamorphism around the edge of the Mountain Land and late hydrothermal solutions from this same intrusive granite resulted in the mineralization of the area. The isolated patches of black amphibolites situated well within the granite outcrop area, are considered to be isolated downfolded remnants of a once mote extensive sheet of Onverwacht. Their high grade metamorphic state, as with the Onverwacht rocks along the immediate contact zone. Is due to the effects of the Intrusive granites plus the re-heaied migmatite. Three distinct facies of contact metamorphism (related to the Nelspruit Granite) ate recognised in the area. The area can be divided into three fairly distinct structural zones, each one characterized by the good development (as compared to the other zones) of one or mote particular types or styles of deformation. Thus in the Consort Mine area (Zone I), a northwest-trending fold system is the strongest and most apparent structural feature. In the southern part of the area (Zone U), minor ctenulation and conjugate folds are very well developed. In the rocks along the granite contact zone (Zone IH), a metamorphic fabric and well/developed lineations associated with strong shearing, are the most noteworthy structural features. ’ Special attention was devoted to the accurate observation and recording of minor structural features. As a result of this, 4 distinct phases of deformation, corresponding fairly closely to those described by Ramsay (1963), were recognised. The first resulted in strong folding about northeast-trending axes and caused the formation of the major synclines (Including the Eureka and Lily Synclines) and the major faults (Including the Lily, Main Southern and Woodstock Faults). The first period was followed by the widespread development of cleavage, associated with which is the marked flattening and elongation of conglomerate pebbles,and development of various types of lineations including the alignment of metamotphic minerals along the immediate contact belt. Certain of the lineations appear to have formed mainly after crystallization of the granite, and are closely connected with the mechanical deformation (in the form of strong differential shearing) which affected the rocks along the contact. At a late stage during the 2nd period, hydrothermal solutions from the granites entered zones of strong shearing and structural disturbance which had started to develop in the layered rocks. The initial development of the 3rd fold stmctures (especially in the northwest part of the Mountain Land) is considered to have played an important part In the localization of these ore fluids. Both the 1st. and 2nd formed stmctures have been strongly deformed by a northwest-trending fold system. These 3rd phase folds teach their best development in the Consort Mine area where they constitute by far the strongest stmctural feature. This period of folding,which during the very early stages probably played a part in the localisation of the ore fluids, outlasted the mineralizing episode and in the Consort Mine area, strongly deformed the mineralized "Contact”. The marked inflection in the northwest part of the Mountain Land, including the "bending" of the Eureka and Ulundi Synclines, occuned at this stage. Most of the major faults truncate the 3rd folds and are thought to have formed, or to have been rejuvenated,at a late stage during this period of deformation. The 4th and final phase of deformation is represented by the fairly widespread development of minor crenulation and conjugate folds. Their development is largely controlled by the rock types and they only occur in lithologically favourable varieties. The maximum deforming stress which caused these folds must have been nearly vertical. These 4th structures are completely separate and unrelated to the main northwest-trending fold system (3rd structures) with which they were classed by Ramsay (1963), From an economic point of view, three zones of potential mineralization, corresponding in all cases to zones of strong shearing and stmcmral disturbance, occur in the area. The most Important is the silicified and mineralized zone (within the northern limb of the Lily Syncline) between basic schists of the Onverwacht and the overlying Fig-tree homfelses, known as the Consort "Contact" or Consort "Bar". Another potential zone of mineralization is the westward extension of the so-called Lily Fault which occupies exactly the same stratigraphic position as the Consort "Contact", viz. between shales and basic rocks of the Flg-uee and Onverwacht Series respectively, but within the northern limb of the Eureka Syncline. Finally, certain shaly horizons within the "footwall" quartzitic layers of the Consort Mine area also show signs of weak mineralization. / AC 2018

Thesis submitted for the degree of Master of Science in the Faculty of Science, University of the Witwatersrand, Johannesburg. / The following is an account of the stiatigiaphy, structure, metamorphism and mineralization in a complexly deformed area of the northwest part of the Barberton Mountain Land. It is situated at the eastern extremity of the Jamestown Hills and covets a region along the contact zone between the ancient layered rocks of the Archaean Complex and the Nelspruit Granite. In the first section is given a fairly comprehensive account of previous work done in the Barberton region- especially as it applies to the area under discussion. This is followed by a consideration of the petrology and stratigraphy of the area and a description of the various structures encountered. A more detailed statistical treatment of the minor structures is also included and from these results an attempt is made to unravel the tectonic history of the area and to fit it into the regional structural pattern of the Mountain Land as a whole. The area mapped consists of two basically Identical successions separated by a major high angled thrust fault. The northern succession, which has been quite strongly thermally metamorphosed, represents the fairly steeply south dipping northern limb of the Lily Syncline. That to the south has suffered very little metamorphism and forms part of the northern limb of the Eureka Syncline. A well developed and layered basic suite of rocks lying below the Fig-tree Series .and constituting the basal zone of the Lily Syncline, is classed in the Onverwacht Series, It lies in direct contact with the Nelspruit Granite and is considered to represent a metamorphosed succession of impure dolomites with arenaceous and minor shaly horizons, together probably with some basic and acid lavas. The Onverwacht rocks are overlain by metamorphosed Fig-tree shales and "lavas", and these in turn by metamorphosed conglomerates and quartzites of the Moodies System. At the base of the homfelses lies the Consort "Contact" or Consort "Bar", a siUcified, mineralized zone which is the main ore horizon of the Consort Mine. The homfelses grade into rocks which have been termed "lavas" but which are thought to be mote of the nature of crystalline tuffs. The succession to the south of the Main Fault Is on a broad scale Identical to the one just described above, differing mainly in metamorplilc state. Thus, whereas the Onverwacht rocks of the northern succession have been converted to hornblende and tremolite-actinollte schists, similar rocks to the south of the Main Fault have been changed to carbonate-bearing talc and chlorite phylUtes. The basic Intrusive rocks of the Jamestown are considered to be of a much smaller distribution than was previously thought,and are represented mainly by the massive bodies of pure serpentinite. There is a possibility however; that certain of the purer talccarbonate schists along the Kaap Rivet,represent altered ultrabasic intmsives. The Nelspruit gneiss and migmatlte is considered to represent a completely granitized pre-Swaziland System sequence which at a much later date acted as the basement upon which the layered rocks of the Mountain Land were deposited, A re-moblllzed border phase of this migmatite was largely responsible for the contact metamorphism around the edge of the Mountain Land and late hydrothermal solutions from this same intrusive granite resulted in the mineralization of the area. The isolated patches of black amphibolites situated well within the granite outcrop area, are considered to be isolated downfolded remnants of a once mote extensive sheet of Onverwacht. Their high grade metamorphic state, as with the Onverwacht rocks along the immediate contact zone. Is due to the effects of the Intrusive granites plus the re-heaied migmatite. Three distinct facies of contact metamorphism (related to the Nelspruit Granite) ate recognised in the area. The area can be divided into three fairly distinct structural zones, each one characterized by the good development (as compared to the other zones) of one or mote particular types or styles of deformation. Thus in the Consort Mine area (Zone I), a northwest- trending fold system is the strongest and most apparent structural feature. In the southern part of the area (Zone U), minor ctenulation and conjugate folds are very well developed. In the rocks along the granite contact zone (Zone IH), a metamorphic fabric and well/developed lineations associated with strong shearing, are the most noteworthy structural features. ’ Special attention was devoted to the accurate observation and recording of minor structural features. As a result of this, 4 distinct phases of deformation, corresponding fairly closely to those described by Ramsay (1963), were recognised. The first resulted in strong folding about northeast-trending axes and caused the formation of the major synclines (Including the Eureka and Lily Synclines) and the major faults (Including the Lily, Main Southern and Woodstock Faults). The first period was followed by the widespread development of cleavage, associated with which is the marked flattening and elongation of conglomerate pebbles,and development of various types of lineations including the alignment of metamotphic minerals along the immediate contact belt. Certain of the lineations appear to have formed mainly after crystallization of the granite, and are closely connected with the mechanical deformation (in the form of strong differential shearing) which affected the rocks along the contact. At a late stage during the 2nd period, hydrothermal solutions from the granites entered zones of strong shearing and structural disturbance which had started to develop in the layered rocks. The initial development of the 3rd fold stmctures (especially in the northwest part of the Mountain Land) is considered to have played an important part In the localization of these ore fluids. Both the 1st. and 2nd formed stmctures have been strongly deformed by a northwest-trending fold system. These 3rd phase folds teach their best development in the Consort Mine area where they constitute by far the strongest stmctural feature. This period of folding,which during the very early stages probably played a part in the localisation of the ore fluids, outlasted the mineralizing episode and in the Consort Mine area, strongly deformed the mineralized "Contact”. The marked inflection in the northwest part of the Mountain Land, including the "bending" of the Eureka and Ulundi Synclines, occuned at this stage. Most of the major faults truncate the 3rd folds and are thought to have formed, or to have been rejuvenated,at a late stage during this period of deformation. The 4th and final phase of deformation is represented by the fairly widespread development of minor crenulation and conjugate folds. Their development is largely controlled by the rock types and they only occur in lithologically favourable varieties. The maximum deforming stress which caused these folds must have been nearly vertical. These 4th structures are completely separate and unrelated to the main northwest-trending fold system (3rd structures) with which they were classed by Ramsay (1963), From an economic point of view, three zones of potential mineralization, corresponding in all cases to zones of strong shearing and stuctural disturbance, occur in the area. The most Important is the silicified and mineralized zone (within the northern limb of the Lily Syncline) between basic schists of the Onverwacht and the overlying Fig-tree homfelses, known as the Consort "Contact" or Consort "Bar". Another potential zone of mineralization is the westward extension of the so-called Lily Fault which occupies exactly the same stratigraphic position as the Consort "Contact", viz. between shales and basic rocks of the Flg-uee and Onverwacht Series respectively, but within the northern limb of the Eureka Syncline. Finally, certain shaly horizons within the "footwall" quartzitic layers of the Consort Mine area also show signs of weak mineralization. / AC 2018

Graduation date: 1985

No description available.

M.Sc. (Geology) / The Main Reef Complex (MRC) section is developed in the Zwartkoppie and Sheba Formations of the Onverwacht and Fig Tree Group respectively. The section is represented by three shear zones, associated with a prominent anticlinal structure, locally known as the Birthday No.2 anticline. This tight isoclinal structure is marked by a chert unit, with a core of green quartz-carbonate schist, and is overlain and surrounded by greywackes and shales of the Sheba Formation. At depth the main mineralized fracture occurs to the south of, and parallel to the Birthday No.2 chert bar. Above the crest of the anticlinal structure gold mineralization is associated with three shear zones (which transgress the bedding of the greywackes and shales) known as the No .. I, No. 2 and No. 3 Fractures. Pyrite and arsenopyrite are the main ore minerals, with minor amounts of chalcopyrite, sphalerite, tetrahedrite and pyrrhotite. Pyrite mineralization is ubiquitously developed along the shear zones, while arsenopyrite mineralization is restricted to certain areas. Assay data of the greywackes and shales show that there is a correlation between gold contents and the abundance of arsenopyrite. Gold has been observed in association with all the sulphide minerals present, and as inclusions within pyrite and arsenopyrite. Electron microprobe analyses have revealed significant levels of gold in arsenopyrite, probably as submicroscopic inclusions.