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SUMMARY:The use of chemostratigraphy and geochemical vectoring as an explo
 ration tool for platinum group metals in the Platreef\, Bushveld Igneous C
 omplex\, South Africa: A case study on the Sandsloot and Overysel farms
DTSTART;VALUE=DATE-TIME:20141002T074500Z
DTEND;VALUE=DATE-TIME:20141002T080000Z
DTSTAMP;VALUE=DATE-TIME:20261007T222617Z
UID:indico-contribution-3953@events.saip.org.za
DESCRIPTION:Speakers: Tshipeng Mwenze (University of the Western Cape)\nTh
 e paucity of geochemical criteria for stratigraphic correlations and defin
 ing the styles of mineralisation pose serious problems in locating PGE-ric
 h zones in the Platreef. This study is therefore aimed at identifying and 
 appraising process-based mineralogical/ geochemical criteria which may be 
 useful in stratigraphic correlations and characterizing the nature and sty
 les of PGE mineralisation. In addition\, the work investigated the possibl
 e use of geochemical vectoring as a tool to locate the PGE-rich zones. Bor
 eholes OY 482 and SS 330\, drilled at the Overysel and Sandsloot farms res
 pectively\, were logged\, and a total of 119 quarter cores were sampled fo
 r petrographic studies. The elemental contents in the rocks were determine
 d by XRF and ICP-OES analyses and were evaluated using various statistical
  and mass balance techniques.\nIn borehole OY 482\, where the floor rock i
 s Archaean granite\, the Platreef consists of three feldspathic pyroxenite
  sills referred to as Lower\, Middle and Upper Platreef units\, from the b
 ottom to the top\, respectively. The results show that the Lower and Upper
  Platreef units have higher median values of Mg# (0.58 and 0.57) and Ni/Cu
  (0.68 and 0.75) when compared to the Middle Platreef (Mg#: 0.54 and Ni/Cu
 : 0.67) which may not be totally suggestive of two magmatic intrusive puls
 es. In borehole SS 330\, where the floor rock is dolomite\, the rocks cons
 ist of clinopyroxenites and olivine clinopyroxenites (variably serpentinis
 ed). These two units are intercalated with each other and are products res
 ulting from the injection of Platreef magma sills within the dolomite floo
 r rock.\nThe hierarchical clustering and mass balance calculations show th
 at when compared to the Platreef feldspathic pyroxenites\, which have high
 er SiO2\, Al2O3 and Fe2O3 median contents\, the clinopyroxenites possess h
 igher CaO median content whereas the olivine clinopyroxenites have higher 
 MgO and LOI median contents. The PGE-rich zones (i.e. Pt+Pd) in clinopyrox
 enites are marked by low Ca/Mg median values\, whereas in both\, the olivi
 ne clinopyroxenites and the Platreef units\, these zones are marked by hig
 h Mg/Fe median values. \nThe suggested base metal index [(Cu/Zn) x (Ni/Co)
 ] used to vector towards PGE-rich zones\, which reflects the presence of t
 he base metal sulphides (BMS)\, correlates with the Pt+Pd in the BMS-rich 
 zones. This is not always the case in zones of low BMS contents which may 
 reflect changes in the mineralogy of the BMS.\nIn conclusion\, the two bor
 eholes studied show contrasting petrographic and geochemical attributes. T
 his dissimilarity is mainly due to the fact that borehole OY 482 comprises
  Platreef magmatic rocks whereas borehole SS 330 intersected metamorphic/ 
 metasomatic rocks.\n\nhttps://events.saip.org.za/event/40/contributions/39
 53/
LOCATION:Matjiesfontein's Lord Milner Hotel Conference Room\, Matjiesfonte
 in Station
URL:https://events.saip.org.za/event/40/contributions/3953/
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