Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Five areas proximal to the world class Namakwa Sands heavy mineral deposit have been
studied and include the farms Houtkraal Remainder Portion 2, Houtkraal Remainder, Geelwal
Karoo, Graauwduinen and Rietfontein. These are locally referred to as the satellite deposits
and are sub-economic occurrences. The primary objective of the study was to quantify the
mineralogy and mineral chemistry, determine the provenance of the heavy mineral suite and
draw a comparison between the satellite deposits and the Namakwa Sands deposit from an
exploratory point of view. Methodology used to achieve the above objectives included optical
microscopy, Scanning Electron Microscope (SEM), Laser Ablation Inductively Coupled
Plasma Mass Spectrometry (LA-ICP-MS), Quantitative Evaluation of Minerals by Scanning
Electron Microscopy (QEMSCAN), X- Ray Fluorescence (XRF) and Zr-geothermometry of
rutile.
The five satellite areas contain the same heavy mineral suite but mineral proportions differ.
The total heavy mineral population (THM) are diverse and consist of ilmenite and its
alteration products (hydrated ilmenite, pseudorutile and leucoxene), magnetite, hematite,
spinel, rutile, tourmaline, pyroxene, amphibole, garnet, aluminosilicates, staurolite,
corundum, epidote, zircon, monazite and sphene. Ilmenite and garnet are the two most
dominant heavy minerals present. The valuable heavy minerals (VHM) suite consists of
ilmenite, zircon, rutile and leucoxene.
The mineralogy of the satellite areas and chemistry of the ore minerals (rutile, zircon,
ilmenite and leucoxene) are similar to the Namakwa Sands deposit. The whole spectrum of ilmenite alteration products (hydrated ilmenite, pseudorutile, and
leucoxene) is present and allowed the quantitative use of the alteration index. The indices is
low (22-24%) and indicates that the surficial deposits have formed under arid to semi-arid
climatological conditions which preserved the pristine character of most of the minerals.
This allowed reliable provenance studies using the characteristics of most of the heavy
mineral suite, which showed that the minerals were derived from a diversity of source rocks.
These included mainly medium to high-grade metamorphites and felsic intrusives of the
underlying Mesoproterozoic Namaqualand Metamorphic Complex and a minor contribution from the Neoproterozoic Gariep Supergroup. This relationship indicates a limited transport
distance from source to depositional basin.
Mineral ratios in particular the THM-VHM relationship showed that the deposits located
close to the shoreline such as Geelwal Karoo, Graauwduinen and Rietfontein have a
relatively low proportion of valuable heavy minerals whereas those more inland such as
Houtkraal Remainder Portion 2 and Houtkraal Remainder are close to unity.
Heavy mineral concentration as such is low in the satellite areas and the mechanism to
increase the concentration is clearly not only a function of distance from the present shoreline
but is also topographically controlled. Steep sided linear depressions channelled the
unconsolidated sediments and heavy minerals were upgraded into economic concentrations
by aeolian processes. The quality of the valuable heavy minerals in the satellite areas
however is similar to those of the adjacent Namakwa Sands deposit. This study has
demonstrated that Houtkraal Remainder is the northeasterly continuation of the red aeolian
sand (RAS) associated East Mine orebody and offers the best exploration potential. / AFRIKAANSE OPSOMMING: Vyf areas proksimaal aan die Namakwa Sands swaar mineral afsetting is bestudeer en sluit in
Houtkraal Remainder, Houtkraal Remainder Portion 2, Geelwal Karoo, Graauwduinen en
Rietfontein. Hierdie areas word plaaslik na verwys as satelliet afsettings en is subekonomies.
Die hoofdoel van hierdie studie was om die mineralogie en mineral chemie te kwantifiseer,
die oorsprong van die swaar mineraal suite te bepaal asook n vergelyking te tref tussen die
satelliet areas en die Namakwa Sands afsetting vanuit n verkennende eksplorasie oogpunt.
Optiese mikroskopie, SEM, LA-ICP-MS, QEMSCAN, XRF en die Zr-geotermometer van
rutiel is gebruik om bostaande doele te bereik.
Die vyf satellite areas bestaan uit dieselfde swaar minerale maar mineral proporsies verskil.
Die totale swaar mineraal populasie is divers en bestaan uit ilmeniet en ilmeniet se
veranderingsprodukte (gehidreerde ilmeniet, pseudorutiel en leukokseen), magnetiet,
hematiet, spinel, rutiel, toermalyn, pirokseen, amfibool, granaat, aluminiumsilikate,
stauroliet, korund, epidoot, sirkoon, monasiet and sfeen. Ilmenite en granaat is die twee mees
dominante swaar minerale teenwoordig. Die waardevolle swaar mineraal populasie bestaan
uit ilmeniet, rutiel, sirkoon en leukokseen.
Die mineralogie van die satelliet areas en die chemie van die erts minerale (rutiel, sirkoon,
ilmeniet en leukokseen) is dieselfde as die van die Namakwa Sands afsetting.
Die hele spektrum ilmeniet veranderingsprodukte is teenwoordig en het die kwantitatiewe
gebruik van die alterasie indeks toegelaat. Die alterasie indekse is laag (22-24%) en dui aan
dat die oppervak afsettings gevorm het tydens droë tot semi droë toestande wat die eertydse
karakter van meeste minerale bewaar het. Deurdat die karakter van meeste minerale behoue gebly het, kon provenans studies toegepas
word op die swaar mineraal suite. Provenans studies het aangedui dat die swaar minerale
afkomstig is van n verskeidenheid van bron gesteentes. Dit sluit in medium tot hoë graad
metamorfe gesteentes en felsiese intrusies van die Mesoproterosoïese Namakwaland
Metamorfiese Kompleks met n geringe bydrae van die Neo Proterosoïese Gariep Supergroep.
Hierdie verhouding dui n beperkte vervoer afstand aan vanaf die bron tot by die afsettings
omgewing. Mineraal vehoudings spesifiek die totale swaar mineraal-waardevolle swaar mineraal
verhoudings dui aan dat afsettings na aan die kus soos Geelwal Karoo, Graauwduinen en
Rietfontien n lae inhoud van waardevolle swaar minerale het teenoor afsettings soos
Houtkraal Remainder Portion 2 en Houtkraal Remainder wat meer land in is met verhoudings
na aan eenheid.
Swaar mineral konsentrasie is laag in die satellite areas en die meganisme verantwoordelik
vir die toename in konsentrasie is nie net n funksie van die afstand van die bestaande kuslyn
nie maar word ook deur topografie beheer. Steil sydige lineêre depressies kanaliseer die
ongekonsolideerde sediment en swaar minerale en word opgradeer tot ekonomiese
konsentrasies deur wind prossese. Die kwaliteit van die waardevolle swaar minerale in die
satelliet areas is egter dieselfde as die van die aangrensende Namakwa Sands afsetting.
Hierdie studie het gewys dat Houtkraal Remainder is die noordelike voortsetting van die Rooi
Aeoliese Sand geassosieerde Oos Myn ertsliggam en bied die beste eksplorasie potensiaal.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/71980 |
| Date | 12 1900 |
| Creators | Carelse, Candice |
| Contributors | Rozendaal, Abraham, Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 394 p. : ill., maps |
| Rights | Stellenbosch University |
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