Date(s) - Wednesday, 16/09/2020
5:30 pm - 6:00 pm AWST
Irish Club of WA - Subiaco
MEGWA: CSIRO – Complexly zoned pyroxene: A possible indicator for Ni-Cu sulfide mineralisation
Wednesday 16 September
5:30pm – 6:00pm
Irish Club, 61 Townshend Rd, Subiaco, Western Australia
Magmatic sulphide Ni-Cu-(PGE) deposits occur in small, usually differentiated, mafic or mafic-ultramafic intrusions. Such intrusions are common in a variety of settings around the world, but only a very small proportion contain economically exploitable sulfides. If mineralised and barren intrusions could be discriminated from sparse sampling at early exploration stages, then exploration for deposits of this type could be streamlined.
To this end, a number of pyroxene-bearing samples from small intrusions containing magmatic sulphide deposits have been investigated using X-ray fluorescence microscopy. The mineralised intrusions represent the Noril’sk-Talnakh camp, Siberia; the Kotalahti nickel belt in Finland; Ntaka in Tanzania, and the east Tianshan Ni province in NW China.
The mineralised intrusions commonly display complex Cr-zonation within both clinopyroxene and/or orthopyroxene. A number of barren intrusions from these regions have also been imaged but evidently lack such zonation.
We propose that this distinctive style of chemical zonation in pyroxene, coupled with other features such as semi-dendritic olivines and intermittent chromite saturation, is a prospectivity indicator in intrusion-hosted magmatic sulphide deposits. These features can be distinguished using desktop or lab based XRF mapping techniques and occasionally can be observed in thin section.
The information in this talk is freely available in the recently published open access article: https://doi.org/10.3389/feart.
About The speaker
Louise is a postdoctoral researcher at CSIRO. She obtained her bachelors and honours in geology from James Cook University, Townsville and in 2018 graduated with a PhD from the Australian National University (ANU). During her PhD she focussed on the experimental partitioning of trace elements between plagioclase, clinopyroxene and melt to understand what controls trace element signatures in these common minerals. Currently she is focussed on investigating the trace element signatures in minerals as possible indicators for economic mineralisation.