Academic literature on the topic 'Mineralogy – South Africa'

The melanic horizon is 1 of 5 diagnostic topsoil horizons distinguished in the South African soil classification system. Melanic soils span a wide spectrum, ranging from those that intergrade with a vertic to those that intergrade with a humic horizon. Melanic soils are therefore expected to vary considerably with respect to a variety of physical, chemical, and clay mineralogical properties. The objective of the present study was to determine the clay mineral compositions of melanic horizons from 58 modal profiles and to establish to what extent melanic soil properties are related to clay mineralogy. Special emphasis was placed on the characterisation of the clay fraction in terms of group and species identification. X-ray diffractometry was employed almost exclusively as the investigative technique in mineral identification and quantification. Melanic A horizons showed a large degree of variation with regard to their clay mineral associations. More than half of the soils were dominated by smectite, 30% by kaolinite, and the rest by an association of about equal proportions of mica, kaolinite, and smectite. Talc and hydroxy-interlayered vermiculite occurred in a number of soils while one horizon was dominated by an illite/smectite interstratification. The smectite component was identified as belonging to either beidellite or vermiculite species, depending on the method employed. About a quarter of the smectitic soils contained montmorillonite as well but not as the dominant swelling phase. mollisols, clay mineralogy, layer charge.

The results of the 35th Session of the International Geological Congress held in 2016 in Cape Town (South Africa) are discussed in this paper. The major scientific problems discussed at the most popular sections are considered. Among them are the early stages in the evolution of the Earth, studies of mineral resources worldwide, the problems of the deep Earth structure, as well as modern fields of mineralogy.

ABSTRACTThe Waterberg platinum deposit is an extraordinary example of a vein-type hydrothermal quartz-hematite-PGE (platinum-group element) mineralization. This study concentrates on the geochemical character of the ores and the platinum-group mineral (PGM) assemblage by application of reflected-light and scanning electron microscopy followed by electron probe microanalysis.The PGM-bearing quartz veins show multiple banding indicating numerous pulses of fluid infiltration. Mineralization was introduced contemporaneously with the earliest generation of vein quartz and hematite. High oxygen and low sulfur fugacities of the mineralizing fluids are indicated by hematite as the predominant opaque mineral and the lack of sulfides.The ‘Waterberg type’ mineralization is characterized by unique metal proportions, namely Pt>Pd>Au, interpreted as a fingerprint to the cradle of the metals, namely rocks and ores of the Bushveld Complex, or reflecting metal fractionation during ascent of an oxidized, evolving fluid. The PGM assemblage signifies three main depositional and alteration events. (1) Deposition of native Pt and Pt–Pd alloys (>90% of the PGM assemblage) and Pd–Sb–As compounds (Pt-rich isomertieite and mertieite II) from hydrothermal fluids. (2) Hydrothermal alteration of Pt by Cu-rich fluids and formation of Pt–Cu alloys and hongshiite [PtCu]. (3) Weathering/oxidation of the ores producing Pd/Pt-oxides/hydroxides.Platinum-group element transport was probably by chloride complexes in moderately acidic and strongly oxidizing fluids of relatively low salinity, and depositional temperatures were in the range 400–200°C. Alternatively, quartz and ore textures may hint to noble metal transport in a colloidal form and deposition as gels.The source of the PGE is probably in platiniferous rocks or ores of the Bushveld Complex which were leached by hydrothermal solutions. If so, further Waterberg-type deposits may be present, and a prime target area would be along the corridor of the Thabazimbi-Murchison-Lineament where geothermal springs are presently still active.

The Townlands iron-rich ultramafic pegmatite is a relatively large pipelike body situated in the western corner of Rustenburg Section, Rustenburg Platinum Mines. It is characterised by a strong negative magnetic signature and transgresses the noritic layered sequence of the upper critical zone of the Bushveld Complex. The layered rocks are downwarped in the vicinity of the pipe and are in sharp contact with the pegmatitic material. The pegmatite varies in composition between dunite and wehrlite, with the marginal zones being more wehrlitic in composition. Olivine (Fo₃₀ - Fo₅₂) and clinopyroxene (Wo₄₅En₃₀Fs₂₅ - Wo₄₅En₃₇Fs₁₈) are the dominant constituents and accessory phases include ilmenite, Ti -magnetite, apatite, amphiboles, chlorite-group minerals, biotite, ilvaite and a host of unusual ore minerals. The Fe-Ti oxides exhibit exsolution textures typically found in slowly cooled igneous rocks and temperatures of formati on are consi dered to be in excess of 800°C. The UG2 chromitite leader layers intersected by borehole TLP.l are enriched in Fe and Ti and exhibit compositions intermediate between chromite and Ti-magnetite. The ore mineral assemblage includes a primary sulphide assemblage consisting of troilite, chalcopyrite, cubanite and pentlandite, and an array of unusual phases formed by late-stage secondary processes. The unusual sulphides mooihoekite and haycockite, that occur in certain parts of the pegmatite, are considered to have formed by partial replacement of the primary assemblage and a possible paragenetic sequence is discussed. Mineral compositions and whole rock geochemical data are consistent with an origin for the pegmatite by crystallization from a fractionated melt. It is suggested that intercumulus fluids, trapped during the crystallization of the noritic layered sequence, accumulated in an area of structural weakness, in response to an increasing overburden pressure and/or tectonic activity. Evidence is also presented that indicates that the Townlands pegmatite may consist of at least two separate, but adjoining pegmatite bodies.
KMBT_363
Adobe Acrobat 9.54 Paper Capture Plug-in

Banded iron-formations (BIFs) are chemically precipitated sedimentary rocks in which Fe-rich bands or laminae alternate with Fe-poor ones. They formed within a specific time-span of the geological record. Their occurrence is restricted between 2.3 and 1.9 Ga, and characterises virtually all the major Precambrian-aged sedimentary basins of the world. The Precambrian Transvaal Basin in Griqualand West, South Africa, is noted for its well-developed BIF units. The Kuruman and Griquatown BIFs comprising the Asbesheuwels Subgroup (up to 1000m thick) are the best known and thickest of these. As far as metallogenesis is concerned, the Kuruman BIF is of major importance, for it carries the world's largest crocidolite (blue asbestos) deposits. The uppermost, youngest member of iron-formation deposition in the Griqualand West Sequence is represented by the Voëlwater BIF. The direct association between the latter and the giant Mn-deposits of the Kalahari Field, renders the Voëlwater association unusual, if not unique, in the geological record. The Voëlwater BIF represents a typical example of the so-called "Superior-type", and in the area of study it has undergone late-diagennetic to low-grade metamorphic processes. This is evident from the mineralogical composition and textural signature of the various BIF lithologies. Specifically, the minerals that make up the Voëlwater BIF are mainly chert(quartz), Fe-oxides (magnetite and hematite), Fe-silicates (greenalite, stilpnomelane, minnesotaite, riebeckite, Fe-mica), Fe-carbonates (members of the dolomite-ankerite series and siderite), calcite and pyrite. Soft-sediment deformation structures and shear-stress indicators are abundant in carbonate-rich and granular, silicate-rich BIF lithologies respectively. The bulk chemical composition of the study rocks is relatively simple and is characterised by the abundance of essentially three elements, namely Si, Fe, and Ca, which make up more than 90% of the total chemical composition of the Voëlwater BIFs. The detrital component of the study rocks is negligible. Mn-enrichments characterise all the transitional lithologies towards the interbedded Mn-orebodies, as well as the well-developed, hematitic BIF-unit between the Ongeluk lavas and the lower Mn-horizon. In terms of trace element composition, no significant enrichments or depletions, were encountered, except for some unusually high values of Sr and Ba and Co in carbonate-rich and Mn-rich lithologies respectively. Geochemical comparisons on the basis of major, trace and light rare-earth element composition verified the similarity between the Voëlwater BIF and other major Superior-type BIFs of the world (e.g. Kuruman, Griquatown, Sokoman, Biwabik, Gunflint, Mara-Mamba, Brockman, etc.). The processes that led to the formation of the Voëlwater BIFs may have been very similar to the ones described in various genetic models proposed in recent years. They would have involved a combination of: i. hydrothermal processes related to mid-ocean ridge (MOR) or hot-spot activity that acted as major iron suppliers; ii. storm-mixing in stratified oceans (bottom, anoxic, Fe⁺² reservoir-thermo- pycnocline zone-upper, mixed, SiO₂-saturated layer), largely dictated by seasonal changes and contemporaneous volcanism; iii. periodic, convection-driven upwelling mechanisms acting as major Fe-precipitators; and, iv. organic carbon productivity that was responsible for the anoxic diagenesis of the initial sediment. However, the origin of Fe and Mn for the genesis of the Voëlwater sediments was difficult to explain with typical convection-cell models in active mid-ocean ridges, in contrast to previous hypotheses. Instead, large-scale endogenous processes in the form of magma convection, underplating, differentiation and associated degassing, may have played a critical role in the supply of metals for the formation of large amounts of BIFs in the Precambrian. The present study of the Voëlwater BIF also bears strong implications regarding the metallogenesis of Mn in the Precambrian. The common association of Mn with carbonate-bearing sediments, the transitional character of the Voëlwater BIF towards carbonate lithologies (Mooidraai dolomites) and the critical timing of the deposition of the former in terms of the Precambrian atmospheric-lithospheric- hydrospheric evolution, may be important indicators for the exploration of large Mn-deposits in Precambrian sedimentary basins of the world.

The variations in the composition, specifically the Cr20 S content and the Cr:Fe ratio, and the morphology of the Lower Group (LG) and Middle Group (MG) chromitite seams of the Critical Zone (CZ) across the western Bushveld Complex, including the Ruighoek and Brits sections, is investigated by means of whole-rock chemical data, both major and trace elements analysis, XRD and electron microprobe data. As a result ofthe paucity of exposed or developed LG1 - LG5 chromitite seams in the western Bushveld Complex, this study is confined to the investigation of the compositional variations of the LG6 to MG4 chromitite seams. In only one section, the Ruighoek section, was the entire succession of chromitite seams, from the LG1 - MG4, exposed. The silicate host rocks from the LG6 pyroxenite footwall to the collar of the CC2 drillcore (lower uCZ) in the Rustenburg section were sampled. This study reviews the compositional trends of the silicate host rocks, as the compositional variations of the chromitite seams reflect the chemical evolution of the host cumulate environment and, to a lesser degree, the composition onhe interstitial mineral phases in the chromitite seams. The compositional variations of the LG and MG chromitite seams are attributed to the compositional contrast between the replenishing magma and the resident magma. The chemical trends of the LG and MG chromitite layers and the host cumUlate rOCKS do not support the existence of two compositionalfy dissimilar magmas in the CZ, rather the cyclic layering of the CZ and the chemical variations of the chromitite seams are attributed to the mixing of primitive magma with the resident magma, both of which have essentially similar compositions. The compositional variations of the LG and MG chromitite seams along strike away from the supposed feeder site (Union section) to the distal facies (Brits section) are attributed to the advanced compositional contrast between the resident magma and the replenishing primitive magma pulses. The CZ is characterized by reversals in fractionation trends and this is attributed to the compositional evolution of the parental magma and not to the replenishment of the resident magma by influxes of grossly dissimilar magma compositions. The Cr20 S content and the Cr:Fe ratio of the MG chromitite layers increase from the Ruighoek (near proximal) section to the Brits section (distal facies). This is attributed to the advanced compositional contrasts between the resident magma and the replenishing primitive magma. In contrast, the Cr20 3 content and Cr:Fe ratios ofthe LG6 and LG8a chromitite seams decreases eastwards from the Ruighoek section. The average Cr:Fe ratio for the western Bushveld Complex is between 1.5 and\2.0, nonetheless, a progressively lower Cr:Fe ratio is noted from the LG1 chromitite up through to the MG4 chromitite seam in the Ruighoek section. tn the LG2 - LG4 chromitite interval a deviation to higher.lratios is encountered. A progressive substitution of Cr by AT and Fe in the Cr-spinel crystal lattice characterizes the chromitite succession from the LG1 seam up through the chromitite succession to MG4. The petrogeneSiS of the chromitite seams of the CZ is attributed to magma mixing and fractional crystallization of a single magma type.

Scheelite, wolfram Ite and cassIterIte mIneralizat ion is hosted wIthin numerous quartz-tourmaline-feldspar-fluorite veins at Van Rooi's Vley, N.W. Cape Province . MineralizatIon and hydrothermal alteration within, and around, these veins is hIghly complex and reflects the intricate interaction of hydrotherma l activity upon a structurally deformed sequence of ProterozoIc med ium to high-grade gneisses. Four distinct stages of alteration and mineralization occurred, including a l ate 'epithermal stage'. Although the location of mineralization was strongly controlled by st ructure, the concentration of mineralizati on was controlled by physicochemical variables, of which host-rock geochemistry was particularly important . Further W/Sn mineralization occurs on a local scale, some of which is spatia lly related to minor leucogranite dykes. Leucogranite bodies are not uncommon within the region and some are enriched in Wand Sn. By comparing FIB ra tio s,W/Sn ratios, the alteration mineralogy, the ore mineralogy and the Fe-content of tourmaline, the deposits within the Van Rooi's Vley area can be placed into a 'proximal' to 'distal' classification, with respect to a common source of mineralizing hydrothermal fluids. The Van Rooi's Vley deposit, whilst affiliated to greisen-style deposits, represents a ' distal' quartz-vein lode deposit.
KMBT_363
Adobe Acrobat 9.53 Paper Capture Plug-in

This study of the lower part of the Rustenburg Layered Suite in the Western Bushveld Complex is based mainly on drill core samples from three localities, which are approximately 130 km apart. The NG-sequence, situated in the northwestern sector of the complex (Union Section, R.P.M.) extends from the floor of the complex to the base of the upper Critical Zone. The sequence is ca. 1800 m thick and it comprises mainly ultramafic cumulates, namely pyroxenites, olivine pyroxenites, harzburgites and dunites. Norites and anorthos ites are present only in minor proportion. Within the upper half of the NG-sequence ten prominent chromitite layers are correlated with the LGI MG4-interval. Correlation is also established between published sequences and the two other sequences studied, located 8 km and 55 km, respectively, east of Rustenburg. Whole-rock chemical data (major and trace elements), microprobe and Sr isotope data are presented. Petrographic studies provide modal analyses and measurements of grain size. All petrographic, mineralogical and other geochemical data point to an origin of the cumulates of the NG-sequence by crystallization from liquids of the U-type lineage and derivatives thereof. No evidence is found for the involvement of parental liquids with a distinctly different composition or crystallization order (A-liquids). However, subtle compositional variations of the parental liquids are evident in slight changes of the Cr content in orthopyroxene or in variations of Sr isotope ratio. The NG-sequence is characterized by intervals with reversed fractionation trends caused by repeated influxes of pristine magma (during periods of high magmatic activity) resulting in a high degree of rejuvenation. These intervals are overlain by others with a normal fractionation trend, interpreted as cumulates formed in periods with low or no magmatic activity, in which fractional crystallization controlled bulk composition of the evolving liquid. The Lower Zone in the NG-sequence is dominated by a progressive shift towards more primitive compositions, while in the Critical Zone fractionation was the major operating process in the magma chamber. However, during deposition of the pyroxenitic lower Critical Zone several replenishment events occurred, during which fresh Cr-rich magma was emplaced. Massive chromitite layers were deposited after mixing between the newly emplaced magma and the resident residual liquid shifted bulk compositions into the primary field of chrome-spinel. Cumulus plagioclase crystallized after bulk composition of the residual liquid was driven to the orthopyroxene plagioclase cotectic by continued fractional crystallization; this occurred once in the Lower Zone, yielding a single, thin norite layer, and again in the upper Critical Zone of the NG-sequence. A facies model is proposed based on the stratigraphic and compositional variations along strike in the Western Bushveld Complex. This model explains the variations by means of the position of the sequence with regard to a feeder system. The olivine- and orthopyroxene-rich, but plagioclase-poor NG-sequence represents the proximal facies, while the SF-sequence (poor in ferromagnesian phases, but plagioclase-rich) is developed as a distal facies, close to the Brits graben.

Union Section of Rustenburg Patinum Mines is situated in the northwestern part of the Bushveld Complex, some twenty kilometres north of the Pilanesberg Alkaline Complex. The mining lease area covers a roughly triangular segment of Lower, Critical and Main Zone rocks, transgressed to the north and south by magnetite-bearing ferrogabbro of the Upper Zone. The Main Zone at Union Section is the focus of this study. The prime source of sample material for the study is the deep exploration borehole SK2, but additional, supplementary samples were collected on surface and underground, as well as from a second surface exploration borehole, SK4. In line with the recommendations of SACS (1980), the top of the Critical Zone, and therefore the base of the Main Zone, is taken to be the top of the Bastard Cyclic Unit. Sharpe (1985) suggested that the succession from the base of the Main is an isotopically separate entity Zone up to the Pyroxenite Marker from the rest of the Bushveld layered succession. This is not strictly true, as there is evidence that more than one parental magma was involved in the formation of this interval. It is, however, true that there are fundamental differences, particularly in isotopic makeup, between the Main Zone rocks below the pyroxenite Marker and those above (the latter having been assigned by Molyneux (1970) to subzone C of the Main Zone). Kruger et al. (1986, in press) suggested that the Pyroxenite Marker marks the base of the Upper Zone, and this convention is adhered to here. The implication of this is that the rocks which formerly constituted subzone C of the Main Zone are now considered part of the Upper Zone. The Main Zone rocks below the pyroxenite Marker were originally subdivided by Molyneux (1970) into two subzones, A and B. The results of the present study indicate that this subdivision is not justified. Instead, eight units have been distinguished in the Main Zone on geochemical, petrological and mineralogical bases. Each of these units is characterized by a coherent set, or progression, of chemical and petrological characteristics. The specific assignment of genetic connotations to these units has been deliberately avoided , at least until further studies of the Main Zone prove this to be justified. The demarcation of the eight units is illustrated in the composite diagram (Fig. 34) in the back pocket of this work, and the reasons for the subdivisions are listed in Table 6 (at the end of chapter 7 of this thesis). Until the late 1970's, it was thought that most layered cumulates formed by crystal settling (Wager and Brown, 1968). More recently, there has been a fundamental conceptual change, and many workers now believe that most cumulate rocks formed by in situ crystallization at the floor and walls of the magma chamber (McBirney and Noyes, 1979, Irvine, 1980a; Campbell, 1987). There is, however, some evidence for the physical separation of phases undergoing cotectic crystallization, particularly in the Upper Critical Zone and lower part of the Main Zone (Eales et al., 1986). This process, which has been alluded to in the past by various authors (Ferguson and Botha, 1963; Vermaak, 1976) involves the flotation of early-formed plagioclase crystals due to their positive bouyancy in tholeiitic liquids. The result is an apparent decoupling of the chemistry of pyroxene and plagioclase, as in unit IV of the Main Zone, where plagioclase becomes more anorthitic upwards, whilst pyroxene becomes more iron-rich. There is some substantial evidence, particularly in reversals in the strontium isotope initial ratio and the orthopyroxene Mg/(Mg+Fe) ratio , for multiple intrusion in the Main Zone. Although the largest and most important magma influx in the Main Zone was a high-R₀ aluminous tholeiite, as suggested by Sharpe (1985), the intrusive history of the Main Zone is believed to be far more complex than Sharpe (op. cit.) suggested. Significantly, there is strong evidence for small influxes of Upper Zone-type (Fe-rich tholeiite) magma in the upper reaches of the Main Zone. These are believed to be precursors to the major influx of Upper Zone-type magma at the pyroxenite Marker (Kruger et al, 1986, in press). The fate of intercumulus liquids in cumulate rocks has recently recieved substantial attention (Sparks et al., 1985; Morse, 1986; Barnes, 1986: Campbell, 1987). It is believed that the migration, or at least redistribution, of intercumulus liquids has played a vital role in modifying fractionation trends in the Main Zone. More importantly, the accumulation of late-stage intercumulus liquids is believed to be responsible for the formation of the Fe-rich ultramafic pegmatite bodies that interrupt the layered cumulates in borehole SK2
Adobe Acrobat 9.53 Paper Capture Plug-in

The main Karoo Basin of South Africa contains a relatively continuous sequence of continental deposits that accumulated over a 100 million year period from Permo-Carboniferous (280 Ma) to early Jurassic (180 Ma). In the southwestern region of the basin the Karoo succession is approximately 4 000 m thick, the upper half of which consists of vertebrate fossil-bearing fluvial rocks of the Beaufort Group. This study deals with Lower Beaufort (Adelaide Subgroup) strata belonging to the Teekloof Formation which are exposed in the cast-west trending erosional escarpment between the towns of Beaufort West and Fraserburg in the central Cape Province. The 450-mctre succession consists mainly of vertically accreted floodplain mudrocks with interbedded continuous sheets of fine-grained sandstone that bear evidence of having accumulated by lateral accretion on the inner banks of meandering channels. The mudrocks contain numerous fossilized skeletons of therapsid "mammal-like" reptiles as well as more primitive cotylosaurs and a few amphibians. Rarely, impressions of Glossopteris leaves and equisetalcan stems are found although root moulds are relatively abundant. Several types of calcareous nodules and sheets occur in the mudrocks and arc interpreted as evidence of calcic palaeosols that formed under semi-arid climatic conditions. This is an interdisciplinary study that integrates a conventional sedimentary facies analysis with investigations of the taphonomy of in situ therapsid fossils and the nature and distribution of palaeosols. Such an approach has not previously been applied to any of the Karoo strata. The results contain descriptive and quantitative information on sedimentary processes, palaeohydrology, absolute time represented in the stratigraphic record and the topography, soils and habitats of the ancient landscape. These are summarized into a palaeoenvironmental synthesis of the Teckloof Formation.

Thesis (MScAgric)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: In the humid Graskop region of Mpumalanga Province, South Africa, there is an anomalous body of highly weathered black, manganiferous oxisols derived from dolomite. With Mn contents as high as 17%, potential large-scale Mn release is an environmental concern under current, acid generating, forestry practices. This study aims at establishing the factors which may affect the stability of the manganiferous oxisols of Graskop and in the process, investigating some of the morphological, mineralogical and chemical properties of these unique soils. Typically, the soils show a reddish, nodule-rich horizon, containing 3-4% Mn, grading through a red and black mottled zone into a black (5YR 2.5/1) apedal subsoil with >7% Mn. The Mn gradient down the profile as well as the abundant nodule content of the upper subsoil horizons implies that Mn mobilization and redistribution are active pedogenic processes. The exceptional Mn content of these soils is complemented with Fe and Al concentrations of up to 10 and 8%, respectively, and anomalously high trace element levels in particular Ni and Zn (as high as 541 and 237 mg kg-1, respectively) which are at the upper limit of cited world natural maxima for soils. The Mn mineral lithiophorite [(Al,Li)MnO2(OH)2], dominates the mineralogy of the soils with accessory amounts of birnessite, gibbsite, goethite, hematite, maghemite, kaolinite, aluminous chlorite and mica - a mineral suite reflecting that of well weathered soils. With the pH of the soil being at or close to the point of zero charge (4.5-5.5) the soils show isoelectric equilibrium. The very low buffer capacity results in metal dissolution commencing with the first increment of titrated acidity. Manganese dissolution is relatively minor considering the large potential for release and is highly overshadowed by Al release. The apparent resilience of the Mn phase to added acidity may relate to the overwhelming poise of the soils which maintains robust, oxic conditions despite the usual instability of Mn oxides at low pH. Manganese release and soil redox properties are substantially affected by drying especially in the organic rich topsoils. Using various redox analyses, evidence is shown for involvement of Mn(III)-organic complexes in the drying reactions. Using this and information gained in a real time, attenuated total reflectance Fourier transform infrared(ATR-FTIR) spectroscopic study, a mechanism is suggested which may account for the observed Mn release and the loss of Cr oxidising capacity commonly observed in dried soils. The information provided by the ATR-FTIR study showed the decrease in surface pH of a clay film, from 5 to below 2, as well as the shift in coordination nature of sorbed oxalate from a more outer-sphere association to a more inner-sphere association concomitant with the removal of free water from the clay surface. This spectroscopic evidence for these chemical changes which accompany surface drying not only provides further insight into the reactions involving Mn oxides in soils but also highlights the suitability of ATR-FTIR for real time, in situ investigation into the chemistry of the drying water interface. From these results it is concluded that Mn release from the manganiferous oxisols, under acid generation of the kind known to occur in pine plantations, is less that anticipated. On the other hand, desiccation of the topsoil results in substantial Mn release with a suggested mechanism which involves a Mn(III) intermediate.
AFRIKAANSE OPSOMMING: ‘n Onreelmatige grondliggaam van hoogs verweerde, swart, mangaanhoudende oxisols wat uit dolomiet ontwikkel het, word in die humiede Graskop streek van die Mpumalanga Provinsie van Suid-Afrika aangetref. Die hoë Mn-inhoud (tot 17%) van hierdie oxisols is van groot omgewings-belang weens die potensiële grootskaalse Mn-vrystelling onder huidige, suur-genererende bosbou praktyke. Hierdie studie beoog om die faktore wat die stabiliteit van die mangaanhoudende oxisols van Graskop affekteer, vas te stel. Tesame hiermee word die morfologiese, mineralogiese en chemiese eienskappe van hierdie unieke gronde ondersoek. Kenmerkend van hierdie gronde is ‘n rooi, nodule-ryke horison met 3-4% Mn aan die oppervlakte. Bogenoemde horison verander met toename in diepte in ‘n rooi en swart gevlekte sone wat weer in ‘n swart (5YR 2.5/1) apedale ondergrond met >7% Mn oorgaan. Die Mn gradiënt in die profiel sowel as die hoë nodule-inhoud van die boonste grondhorison dui daarop dat Mn-mobilisasie en -herverspreiding huidige aktiewe pedogenetiese prosesse in die profiele is. Fe en Al, met konsentrasies van 10% en 8% onderskeidelik, word saam met die onreelmatig hoë Mn inhoud aangetref. Baie hoë vlakke van Ni en Zn (so hoog as 541 en 237 mg.kg-1 onderskeidelik) wat hoër is as aangehaalde wêreld natuurlike maksimum waardes, word ook aangetref. Die mineralogie van die gronde word deur die Mn mineraal litioforiet [(Al,Li)MnO2(OH)2] gedomineer. Bykomstige hoeveelhede van birnessiet, gibbsiet, goethiet, hematiet, maghemiet, kaoliniet, aluminiumryke chloried en mika word ook aangetref. Hierdie minerale samestelling is kenmerkend van hoogs verweerde gronde. Met die pH van die grond in die omgewing van die punt van geen lading (4.5 – 5.5), word ‘n iso-elektriese ekwilibrium by die gronde aangetref. Die baie lae bufferkapasiteit het metaal-oplossing aangehelp wat met die eerste inkrement van titreerbare suurheid ‘n aanvang geneem het. Mangaan-oplossing is baie klein indien die groot potensiaal vir vrystelling asook die groot mate van Al-vrystelling in ag geneem word. Die skynbare teenwerking van die Mn fase tot toegevoegde suurheid, mag toegeskryf word aan diesterk ewewig van die gronde om sterk, oksiese kondisies, ten spyte van die normale onstabiliteit van Mn oksiedes by lae pH, te onderhou. Mangaan vrystelling en grond redoks eienskappe word beduidend deur uitdroging beïnvloed en veral in die organies-ryke bogronde. Deur van verskeie redoks analises gebruik te maak is daar bewyse van die betrokkenheid van Mn(III)-organiese komplekse in die uitdroging-reaksies gevind. Dit. en data ingesamel in ‘n “real time, attenuated total reflectance Fourier transform infrared (ATR-FTIR)” spektroskopiese studie, is gebruik om ‘n meganisme voor te stel wat die waargenome Mn vrystelling en die verlies aan Cr oksidasie kapasiteit (algemeen waargeneem in droë gronde) te kan verklaar. Die data verkry met die ATR-FTIR studie het ‘n afname in oppervlak pH van 5 na 2 van ‘n klei film asook die verskuiwing in koördinasie toestand van die gesorbeerde oksalaat van ‘n meer buite-sfeer assosiasie tot ‘n meer binne-sfeer assosiasie, gepaardgaande met die verwydering van vry water van die klei oppervlaktes, uitgewys. Die spektroskopiese bewyse vir die chemiese veranderinge wat die oppervlak uitdroging vergesel, gee nie net meer insig in die reaksies rakende Mn oksiedes in gronde nie maar onderstreep ook die toepasbaarheid van die ATR-FTIR vir intydse (“real time”), in situ ondersoeke na die chemie van die uitdrogende water kontakvlak. Vanuit hierdie resultate kan afgelei word dat Mn vrystelling vanuit mangaanhoudende oxisols onder suur genererende denne plantasies laer is as wat verwag is. Aan die ander kant sal uitdroging van die bogrond tot aansienlike Mn vrystelling, met ‘n verwagte meganisme wat Mn (III) as intermediêre toestand insluit, lei.

The Kalagadi Manganese mine in the Kuruman area of the Northern Cape Province of South Africa contains reserves of Mn ore in excess of 100Mt. Mineralization in the mine lease area is restricted within the Hotazel Formation of the Voȅlwater Subgroup, belonging to the Postmasburg Group, the upper subdivision of the Transvaal Supergroup. Surface topography is characterized by flat lying, undulation with minimal faulting and the ore are slightly metarmophosed. This study investigates the general geology of the mine, lithostratigraphic subdivision and correlation of the economic Lower Manganese Orebody (LMO) of the Kalagadi Manganese Mine in order to guide mining plan and operations once the mine is fully commissioned. At the commencement of this study, Kalagadi Manganese mine was a project under exploration with no specific geology of the mine lease area and no lithostratigraphic subdivision. The study also aimed determining the extent of lithostratigraphic correlation between the LMO economic orebodies of the Kalagadi Manganese mine with that of underground Gloria and open-pit Mamatwan mines. Four methods including petrographic microscope, Scanning electron Microscope (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses were applied mainly for the mineral identification, chemical composition and ore characterization of the Lower Manganese Orebody (LMO) at Kalagadi Manganese mine. The results of this study indicates the following: (1) Eleven textural distinct zones with economic zones restricted to the middle while the lower grade zones are confined to the top and bottom of the LMO; (2) The economic zones, comprising of Y, M, C and N subzones attain an average thickness of 10 m and are graded at an average of 40% Mn while the Mn/Fe ratio varies from 6 to 9; (3) The most economic zones are M and N subzones which are mostly characterized by oxidized ovoids and laminae, a characteristic applicable even to other zones of economic interest; (4) Braunite is the main mineral of the manganese ore and is often integrown with kutnahorite and other minerals (hematite, hausmannite, Mg-calcite, calcite, jacobsite, serpentine and garnet) which are present in variable amounts; (5) The Mg-rich calcite (Ca, Mg)CO3 is the second dominant manganese carbonate mineral and it corresponds to elevated MgO concentration and is often associated with marine environment. The occurrence of the Mgcalcite is not common in the manganese ore of this area except for the Mn-calcite, which was not determined by XRD analyses in this study; (6) MnO is the most abundant major oxide in the manganese ore while other major oxides present in decreasing order of abundance are CaO, SiO2, Fe2O3, and MgO. The oxides TiO2, Na2O, K2O, Al2O3, and Cr2O3 are depleted and are mostly  0.01wt% and  0.001wt% respectively while P2O5 concentrations are low ranging from 0.02wt% to 0.3wt%. The trace element concentrations of Ba, Zn and Sr in most borehole samples are slightly elevated ranging from 100ppm to 3.9% (36000pm) while Co, Cu, Ni, Y, As, Zr, V and La rarely exceed 50ppm. The enrichments of Cu, Zn, Ni, Co and V that are commonly associated with volcanogenic hydrothermal input in chemicals may reach up to 70ppm; (7) The mineralogical and geochemical characteristics of the manganese ore in the Kalagadi Manganese mine lease area are similar to that of Low-Grade Mamatwan-Type ore. The cyclicity (Banded Iron Formation ↔ Hematite lutite ↔ braunite lutite) and alternation of manganese and iron formation have been confirmed; and (8) The oxygen δ18O isotope values (18‰ to 22‰) indicate a slight influence of metamorphism of the manganese ore. No positive correlation exists between δ13C vs δ18O values and Mn vs δ13C values. Such observations indicate minimal action of organic carbon during manganese precipitation where the organic matter was oxidized and manganese content reduced. On the other hand, the manganese carbonates (CaO) are positively correlated with carbon isotope, this indicates diagenetic alteration and the involvement of biogenic carbonate during the formation of manganese carbonates. It is concluded that the lithostratigraphic subdivision at Kalagadi Manganese mine is best correlated physically, mineralogically and geochemically with that of Gloria mine operating in the Low Grade Mamatwan - Type ore while correlation with an open-pit Mamatwan mine is also valid.

Thesis (MScAgric)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: This study is an integral part of a multidisciplinary research project concerning the effects of soil and climate on wine quality. The motive, which led to the setting up of this project, was that producers could not determine beforehand whether a specific location would yield wines of high or low quality. If a specific cultivar were to be planted at the wrong location, then it was likely that wine of table quality would result, rather than the export quality wine that was intended. The long term objectives of this multidisciplinary project were the compilation of guidelines by means of which different sites may be classified according to their potential for the production of high quality wines, and the identification of the most important climatic and soil factors responsible for differences in wine quality and character. In this multidisciplinary project, measurements (soil water, leaf water potential, cane mass and yield) were made under dry land conditions in Sauvignon blanc vineyards at six different localities: five in the Stellenbosch district (Simonsberg, Kuils River, Helshoogte, Papegaaiberg and Devon Valley) and one in Durbanville. Each vineyard was owned by a private commercial producer. The vines were approximately 10 years old in all cases, and were trained on a hedge system. Measurements were made in plots, each of which contained 20 vines. Two different soil types were identified at each locality. Vine growth and wine quality differed markedly on these contrasting soils, even though they were located in close physical proximity. The measurements that were made at high and low production plots at each locality during this study were obtained from points which were not more than 60 m metres apart. An automatic weather station was erected halfway between the two, contrasting, experimental plots. Within the overall scope of the multidisciplinary project, the study which forms the subject of this thesis, concentrated on the effects of soil parent material as a soil forming parameter and as a possible predetermining character with regard to vine growth and wine character. From literature it was clear at the outset of this work that the geology of the coastal wine region is very complex and varies over short distances. The geological history indicates different types of rock formation and rock forming process (sedimentary, igneous as well as metamorphic), plate tectonic activity, mountain building, erosion and weathering, over a period of approximately 1 000 million years. The present landscape includes a coastal plane, hills, and eroding mountains. Statistical analyses indicated that the soils from the different localities could mainly be characterised in terms of differences in their sand size fractions. Soils from Durbanville are dominated by fine sand and correlates with the underlying phyllitic shales. Soils from Kuils River contain significantly more coarse sand when compared with the other sites. This appears to be a reflection of the underlying coarse granitic material, and implies that in situ weathering played an important role in soil development. .The data did not, however, prove that the Kuils River soils formed solely from underlying rocks. The gravel and stone fraction for the Kuils River soils were nevertheless correlated with those of the underlying parent material. Soils from Helshoogte and Simonsberg (both of which are underlain by granites), Papegaaiberg and Devon Valley (both underlain by hornfels) were not significantly dominated by any particular sand fraction. Soils from these localities therefore did not only reflect the underlying material as a source of soil parent material. This implied mixing of parent material and/or the incursion of eolian sand at Helshoogte, Simonsberg and Devon Valley. A marine incursion may have affected the soil parent material at Papegaaiberg. In order to obtain more information concerning the origins and possible mixing of parent materials prior to and during soil formation, samples from the different soil horizons in each profile were subjected to a chemical analysis. Particular emphasis was placed on potassium, which is an extremely important nutrient mineral element, from the viewpoints of vine growth and wine quality. Because the soils used in this study were all located in production vineyards, the probability that fertiliser residues would have contaminated the soils was high. The lower soil horizons were considered to be least affected by this contamination and therefore most likely to be indicative of the natural soil chemical composition. However, the lower horizon K content of the soils in this study could not be reliably correlated with any known or predicted characteristic that might link the soil parent material with local rock types. At Durbanville, both soils contained small quantities of K in the lower horizons, reflecting the underlying phyllitic shales, but at Devon Valley and Papegaaiberg, the lower horizons contained more K than expected. The soils at these localities are situated on hornfels, containing low quantities of K. The large quantities of K in the soils may have indicated that these soils are situated close to a granite/Malmesbury contact zone. Soils from Kuils River, Simonsberg and Helshoogte are situated on K-rich porhyritic granites and it was expected that these soils would contain relatively large quantities of K in the lower horizons. This, however, was not the case. It was therefore concluded that dilution with K-poor material had taken place. Such material could have been derived from higher-lying sandstones, or from eolian processes during the Cenozoic. Alternatively, the K content of the soil might have been depleted by long continued leaching. A semi-quantitative analysis of the minerals in the soil clay fractions was also carried out. The objective was to identify the clay minerals that were present in the different soil horizons and to relate the minerals to weathering conditions. Evidence linking the minerals in the clay fractions of the soil samples with the mineralogical composition of the soil parent materials was sought. The clay fraction mineralogy data indicated that all soils in the study area are in an advanced stage of weathering and are dominated by kaolinite, and in certain soils quartz. It was difficult to relate these minerals directly with soil parent material because the primary minerals originating from the soil parent materials have been extensively broken down. The simultaneous presence of quartz and gibbsite in the clay fraction of both soils at Simonsberg, Helshoogte and Durbanville as well as one soil form from bath Kuils River and Simonsberg, indicated non-uniform distribution of clay fraction minerals, indicating that different stages of weathering were present during soil formation. This could have been a result of mixing of parent materials, but may also reflect different periods of weathering of the same material. Both soils at Papegaaiberg, both soils at Devon Valley and other soils at Simonsberg and Kuils River indicated uniform clay fraction mineralogy distribution, mainly because the absence of gibbsite is related to the presence of quartz in the clay fraction. The soil characteristics, as determined in this study, were also compared with vine growth, wine quality and wine character, as obtained in the broader multidisciplinary research project. For most soils in this study, an increase in clay fraction kaolinite was associated with a reduction in vegetative growth, overall wine quality, and fresh vegetative character. An increase in clay fraction quartz was associated with higher overall wine quality. Increased shoot growth also affected fresh vegetative character positively. Better growth occurred on higher altitudes and this resulted, for Sauvignon blanc, in higher wine quality. Wines produced from vines situated on both phyllitic shales and porhyritic granites showed high quality (Durbanville and Helshoogte), but both were related to low clay fraction kaolinite content and high altitude. It was not possible to relate parent material directly with vine growth, wine quality and/or wine character. The lowest quality wines, however, were produced from vines situated on hornfels (Papegaaiberg and Devon Valley), both containing high quantities of clay fraction kaolinite and situated on low altitudes. High levels of K in soils containing high levels of clay fraction kaolinite may have been partly responsible for low wine quality obtained on such soils.
AFRIKAANSE OPSOMMING: Hierdie studie vorm 'n integrale deel van 'n multi-dissiplinêre navorsingsprojek oor die effek van grond en klimaat op wynkwaliteit. Die motivering wat gelei het tot die beplanning van hierdie projek, was dat produsente nie vooraf kon bepaal of 'n spesifieke lokaliteit wyne kan produseer van hoë of lae kwaliteit nie. Indien 'n spesifieke kultivar op die verkeerde lokaliteit geplant word, sou dit waarskynlik tot In gewone tafelwyn lei, instede van 'n wyn van uitvoergehalte. Die langtermyn doelwitte van die multi-dissiplinêre projek was om riglyne te ontwikkel om verskillende lokaliteite te klassifiseer na aanleiding van·hul potensiaal om hoë kwaliteit wyne te produseer, asook om die belangrikste klimaats- en grondfaktore verantwoordelik vir die produksie van hoê kwalitiet wyne te identifiseer. In hierdie multidissiplinêre projek was metings (plant beskikbare water, blaarwater potensiaal, lootmassa en oes) onder droêland toestande bepaal in Sauvignon blanc wingerde by ses verskillende lokaliteite: vyf in die Stellenbosch distrik (Simonsberg, Kuilsrivier, Helshoogte, Papegaaiberg and Devon Valley) en een in Durbanville. Elke wingerd is besit deur 'n kommersiêle privaatprodusent. Die stokke was ongeveer 10 jaar oud in alle gevalle en opgelei op 'n heining sisteem. Metings was in eksperimentele blokke van 20 stokke elk uitgevoer. Twee verskillende grondtipes is by elke lokaliteit identifiseer. Lootgroei en wynkwaliteit het merkbaar verskilop die kontrasterende gronde, selfs waar gronde nabyaanmekaar was. Die metings is Liitgevoer op hoë- en lae produksie eksperimentele blokke waar gronde by spesifieke lokaliteite nie verder as 60 meter was nie. 'n Outomatiese weerstasie was halfpad tussen die twee kontrasterende grondtipes by elk van die ses lokaliteite opgerig. Binne die algemene omvang van die multi-clissiplinêre projek, het die studie wat die onderwerp van hierdie tesis is, gekonsentreer op die effek van moedermateriaal as grondvormende parameter asook as moontlike voorspeller van wingerdgroei en wynkarakter. Dit was duidelik uit die literatuur dat die geologie van die Wynkusstreek baie kompleks is en oor kort afstande varieer. Die geologiese geskiedenis dui daarop dat verskillende tipes gesteentes en verskillende prosesse van gesteente-vorming (sedimentêr, stollings- en metamorfe), plaattektoniese aktiwiteit, orogenese, erosie en verwering, oor 'n periode van ongeveer 1 000 miljoen jaar plaasgevind het. Die huidige landskap sluit kusvlaktes, heuwels en geêrodeerde berge in. Statistiese analises het aangetoon dat die gronde van die verskillende lokaliteite hoofsaaklik in terme van verskille in sandgrootte fraksies onderskei kon word. Gronde van Durbanville is gedomineer deur fyn sand en korreleer met onderliggende fillietiese skalies. Gronde van Kuilsrivier bevat betekenisvol meer growwe sand wanneer dit vergelyk word met die ander lokaliteite. Dit is waarskynlik afkomstig vanaf die onderliggende growwe granitiese materiaal en impliseer dat in situ verwering 'n belangrike rol gespeel het in grondontwikkeling. Die data het egter nie bewys dat die gronde van Kuilsrivier slegs uit die onderliggende graniete gevorm het nie. Die gruisfraksies in die gronde by Kuilsrivier was tog vergelykbaar met die onderliggende materiaal. Gronde vanaf Helshoogte and Simonsberg (beide onderlê deur graniete), Papegaaiberg and Devon Valley (beide onderlê deur hornfels) was nie betekenisvol gedomineer deur 'n spesifieke sandfraksie nie. Gronde vanaf hierdie lokaliteite het dus nie slegs die onderliggende gesteentes verteenwoordig nie. Dit dui op vermenging van moedermateriaal en/of eoliese prosesse by Helshoogte, Simonsberg and Devon Valley. 'n Styging in seevlak kon die moedermateriaal by Papegaaiberg beïnvloed het. Om meer inligting omtrent die oorsprong en moontlike vermening van moedermateriaal voor grondvorming te verkry, is die verskillende grondmonsters chemies ontleed. Kalium is In uiters belangrike voedingselement wat lootgroei en wynkwaliteit kan beïnvloed. Aangesien die gronde in hierdie studie in bestaande produksieblokke voorkom, was daar 'n goeie kans dat bemestingstowwe die chemiese samestelling kon beïnvloed. Die C horisonte van die verskillende gronde was beskou as dié wat die minste deur bemesting beYnvloedsou word en die naaste aanduiding van natuurlike grondchemiese samestelling. Die C horison K-inhoude van die gronde in die studie het egter nie gekorreleer met enige eienskap wat die moedermateriaal van die gronde met die lokale gesteentetipe kon verbind nie. By Durbanville, het beide gronde klein hoeveelhede K in die C horisonte bevat, wat die onderliggende fillietiese skalies reflekteer, maar by Devon Valley en Papegaaiberg, het die C horisonte meer K bevat as wat verwag is. Die gronde by hierdie lokaliteite word onderlê deur hornfels, wat lae hoeveelhede K bevat. Die groot hoeveelhede K in hierdie gronde dui moontlik op 'n kontaksone tussen graniet en Malmesbury gesteentes in die area. Gronde vanaf Kuilsrivier, Simonsberg en Helshoogte word onderlê deur K-ryke porfiritiese graniete wat groot hoeveelhede K in die ondergronde sou bevat. Dit was egter nie die geval nie en dit was aanvaar dat verdunning van K-arme materiaal plaasgevind het. Die oorsprong van Karme materiaal was waarskynlik vanaf hoêr-liggende sandstene, of vanaf eoliese prosesse gedurende die Cenozoikum. Alternatiewelik is K inhoude van die gronde verlaag deur lang en aanhoudende loging. 'n Semi-kwantitatiewe analise van minerale in die kleifraksie was uitgevoer om te bepaal watter minerale in die kleifraksie van die verskillende gronde teenwoordig is en om die minerale met stadia van verwering te vergelyk. Dan kon die mineralogiese samestelling in verband met moedermateriaal gebring word. Resultate het aangetoon dat al die gronde in die studie in 'n gevorderde stadium van verwering is en gedomineer word deur kaoliniet, en in sekere gronde, klei fraksie kwarts. Aangesien die primêre minerale in 'n groot mate afgebreek is, was dit moeilik om die minerale in die kleifraksie direk in verband met moedermateriaal te bring. Die voorkoms van kwarts en gibbsiet in die kleifraksie in beide gronde van Simonsberg, Helshoogte en Durbanville asook een grondvorm vanaf beide Kuilsrivier en Simonsberg, het aangetoon dat verskillende stadia van verwering gedurende grondvorming in hierdie gronde voorgekom het. Dit kan die gevolg wees van vermenging van verskillende moedermateriaal, maar kan ook verskillende periodes van verwering van dieselfde materiaal aandui. Beide gronde by Papegaaiberg, beide gronde van Devon Valley die ander gronde by Simonsberg en Kuilsrivier het slegs een fase van verwering tydens grondvorming aangedui, hoofsaaklik as gevolg van die afwesigheid van gibbsiet wanneer kwarts voorkom. Grondeienskappe, soos bepaal in hierdie studie, was ook vergelyk met lootgroei, wynkwaliteit en wynkarakter, soos verkry uit die resultate van die multi-dissiplinêre projek. Vir die meeste gronde in die studie was 'n toename in kleifraksie kaoliniet geassosieer met afname in vegetatiewe groei, algemene wynkwaliteit, asook vars vegetatiewe wynkarakter. 'n Toename in kleifraksie kwarts was geassosieer met hoër algehele wynkwaliteit. 'n Toeneme in vegetatiewe groei het ook die vars vegetatiewe karakter van die wyn positief beïnvloed. Beter vegetatiewe groei het op hoër hoogtes voorgekom en dit het gelei tot hoër wynkwaliteit vir Sauvignon blanc. Wyne afkomstig van wingerde op beide fillietiese skalies en porfiritiese graniete, was van hoër kwaliteit (Durbanville and Helshoogte), maar beide was geassosieer met lae kleifraksie kaoliniet en hoë ligging. Dit was nie moontlik om moedermateriaal direk met vegetatiewe groei, wynkwaliteit en/of wynkarakter te vergelyk nie. Wyne met die laagste kwaliteit kom egter voor op hornfels (Papegaaiberg and Devon Valley), wat beide groot hoeveelhede kleifraksie kaoliniet bevat en geleê is op lae hoogtes. Hoê vlakke van K in gronde wat groot hoeveelhede kleifraksie kaoliniet bevat kan gedeeltelik verantwoordelik wees vir lae kwaliteit wyne op sulke gronde.

Potash minerals are a source of potassium, which is used for the manufacture of gunpowder and fertilizer. Commercial potash mineralization is often discovered when petroleum wells are drilled through evaporite sequences and the Gamma Ray log “goes off scale”. This is because potassium is one of the naturally occurring radioactive elements, emitting gamma rays from the 40K isotope, in its decay to 40Ar. However, not all potash minerals may be commercial sources of potassium via underground mechanical or solution mining techniques and Potassium is not the only radioactive element. For example, the mineralogy of the McNutt “Potash” member of the Salado Formation in SE New Mexico, is extremely complex, consisting of multiple thin (i.e., less than 10 ft thick) beds of six low-grade (radioactive) potash minerals, only two of which are commercial. There are also four non-radioactive evaporite minerals, one of which interferes with potash milling chemistry, and numerous claystones and Marker Beds (shales), with GR count rates comparable to the low-grade potash. Because of this complexity, traditional wireline and Logging While Drilling Potash Assay techniques, such as Gamma Ray log-to-core assay transforms, may not be sufficient to identify potentially commercial potash mineralization, for underground mining. Crain and Anderson (1966) and Hill (2019) developed linear programming, and multi-mineral analyses, respectively, to estimate Potash mineralogy and grades. However, both of these approaches require complete sets of multiple log measurements. In SE New Mexico, petroleum wells are drilled through the McNutt “Potash” member of the Salado Formation, with air, cased and drilled out to TD in the underlying sediments, with water based mud. Complete log suites are then run from TD to the casing shoe, with only the GR and neutron logs recorded through the cased evaporite sequence for stratigraphic and structural correlation. As a result, numerous oil and gas wells, in SE New Mexico, have cased hole gamma ray and neutron logs, through the Salado Evaporite. Logs, from these wells could provide a rapid Potash screening database, if used properly. A simple screening cross-plot technique, the Potash Identification (PID) plot, utilizing only Gamma Ray and Neutron Porosity, is proposed and successfully demonstrated, as a potential screening tool. This technique can be used with both open and cased-hole petroleum well logs, as well as core hole wire-line logs, and provides discrimination of commercial potash mineralization from non-commercial (potash and non-potash) radioactive mineralization. Case histories of the use of PID cross plots in the evaporite basins of Michigan, Nova Scotia, Saskatchewan, and SE New Mexico are described. The technique may also be useful in screening potential potash deposits in China, Europe, North Africa, and South America.