The geology of the Graauwduinen heavy mineral sand deposit, west coast of South Africa

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dc.contributor.advisorRozendaal, Abrahamen_ZA
dc.contributor.authorCilliers, Lambertus Marthiniusen_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Earth Sciences.en_ZA
dc.date.accessioned2012-08-27T11:36:47Z
dc.date.available2012-08-27T11:36:47Z
dc.date.issued1995
dc.descriptionThesis (MSc)--Stellenbosch University, 1995. en_ZA
dc.description.abstractENGLISH ABSTRACT: The sedimentology, mineralogy and stratigraphy of the Graauwduinen heavy mineral sand deposit 40km north of the Olifants River mouth on the west coast of South Africa were investigated. Deposition of the heavy mineralĀ­ enriched sediments is described in terms of marine and aeolian processes active in a north-facing bay bound by a southern headland. The most characteristic feature of the deposit is the presence of two palaeo-strandlines at 20m and 35m a.m.s.l., displaying extremely high concentrations of heavy minerals and situated at the base of two successions. These units formed during relative sea-level stillstands at the respective elevations. The two basal marine units are each overlain by a sequence of aeolian sediments which accreted onto the margin of the regressing sea after the stillstands at 20m and 35m a.m.s.l., respectively. Palaeontological evidence indicates an early Pliocene (1.7-1.8 Ma) age for the 20m strandline. Mineralogically the sequence matures from the basal marine units to the subsurface and surface aeolian units, with a low degree of alteration displayed by the Fe-Ti mineral assemblage. Mineral chemistry provenance studies indicate high grade metamorphic gneisses and phyllites as the probable source of the heavy minerals. Sediment supply to the Graauwduinen heavy mineral concentrating system was by the ephemeral Sout River, 5km north of the deposit, and indirectly by northward-moving longshore drift from the Olifants River, 40km to the southen_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die sedimentologie, mineralogie en stratigrafie van die Graauwduinen swaarmineraal sand afsetting ongeveer 40km ten noorde van die Olifantsrivier mond is ondersoek. Afsetting van hierdie swaarmineraal voorkoms word toegeskryf aan marine en eoliese sedimentologiese prosesse wat aktief was inn baai begrens deur n suidelike landpunt. Van die mees karakteristieke eienskappe van die afsetting is die voorkoms van twee palaeo-strande op n hoogte van 20m en 35m bo seevlak, wat n besondere hoe swaarmineraal konsentrasie vertoon. Hierdie eenhede het gevorm gedurende periodes van seevlak stilstand. Die twee basale mariene eenhede is oorle deur n opeenvolging van eoliese sande wat afgesit is na hierdie periodes en tydens seevlak regressie. Paleontologiese gegewens dui op n Plioseen ouderdom (1.7-1.8 Ma) vir die 20m strand. Mineralogiese studies toon dat die rypheid van die sedimente toeneem vanaf die basale mariene lae na die oorliggende eoliese lae. Ertsminerale soos ilmeniet toon weinig in situ verandering. Provenans studies deur middel van mineraal chemie bevestig die brongebied van die swaarminerale as 'n hoe graad metamorfe, gneis en filliet gedomineerde terrein. Sediment aanvoer vanaf die binneland was hoofsaaklik deur die paleo-rivierlope van nabygelee Soutrivier, sowat 5km noord van die afsetting, maar ook deur noordwaarts bewegende kusstrome wat sediment vervoer het vanaf die Olifantsrivier gelee 40km na die suide.af_ZA
dc.description.versionMastersen_ZA
dc.format.extent232 pages : illustrations (some color), mapsen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/54890
dc.language.isoen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshGeology, Stratigraphicen_ZA
dc.subject.lcshMineralogy -- South Africa -- West Coasten_ZA
dc.subject.lcshSedimentation and deposition -- South Africa -- West Coasten_ZA
dc.subject.lcshHeavy minerals --Environmental aspects -- Graauwduinenen_ZA
dc.subject.lcshPlacer deposits -- South Africaen_ZA
dc.subject.nameUCTDen_ZA
dc.titleThe geology of the Graauwduinen heavy mineral sand deposit, west coast of South Africaen_ZA
dc.typeThesisen_ZA
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