Hi
@Proctalgia
Below is a link to a description of the geology of Syerston and an extract from that link. I'm not sure if precious metals is the right terminology in the extract below. Ni, Co and Scandium might be valuable but they aren't precious.
Like I'd guessed the metals/deposits at Syerston are the result of weathering processes and are shallow. Also unlike some large Ni-Co deposits in WA that result from the weathering of extruded magmas (komatiites) this one appears to originate from an intrusive magma and the metals are associated with the weathering of the very (dunitic) core of the intrusion.
The prospectivity of RIM's ground for similar deposits would all depend on how well these intrusions have been mapped or interpreted from geophysical surveys and then also how near to the surface any newly found intrusion exists. Without the core of the intrusion being near to the surface like at Syerston it would be useless as the core will have not been weathered so couldn't have formed a deposit. As mentioned however in my previous post a buried intrusion of this type might still have good prospectivity for a primary sulphide deposit that could host Ni-Cu- PGM and other more minor minerals. The platinum at Fifield had to have come from somewhere.
Often alteration/metamorphism can alter the geophysical properties of the rocks so things like magnetic signatures are not always totally reliable when outlining the boundaries of rock units if those boundaries can't be determined by surface observation/mapping. Generally ultramafic rocks contain more minerals with higher magnetic susceptibilities than less basic rock types so tend to stand out in magnetics images. But as I said alteration/metamorphism can sometimes erase the magnetic signals so if you are serious in looking you'd need to use other techniques in combination. Cheap broad spaced RAB drilling would be as good a method as any if you are serious. You could quickly rule out potential with drilling as these intrusions are pretty large in scale and wouldn't be that easy to miss. Geophysical methods like EM could also then be employed to find primary sulphide deposits associated with these intrusions once the intrusions are located with shallow drilling. I'll take a closer look when I get time. Esh
http://www.cleanteq.com/wp-content/...STON-PROJECT-GEOLOGY-AND-RESOURCE_31-1-17.pdf
"The Syerston project is a typical surficial deposit hosted within a Tertiary age lateritic weathered
profile. Metal enhancement of the minerals of economic interest occurred during a secondary process ascribed principally to chemical weathering of the underlying metal rich ultramafic rocks. During weathering, selective leaching of more soluble elements such as magnesium and silica occurred, leaving a highly iron-enriched residue in base and precious metals. Further enrichment occurred during mechanical weathering and erosion.
The Tout Ultramafic Complex is one such intrusive body which underlies the laterite at the
Syerston Project. The complex is concentrically zoned, ultramafic in the core grading to mafic
material on the outer edge i.e. igneous rocks composed chiefly of mafic, dark minerals in the
core, diminish outwards. Accelerated preferential weathering over the ultramafic core has
resulted in the laterite profile reaching its maximum thickness of 35-40m over the core and thinning out laterally over surrounding less mafic rocks. Nickel and cobalt mineralisation is concentrated on mainly with in the goethite layer over the dunite core, with scandium
mineralisation being more concentrated in the pyroxenite surrounding the dunite."
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