Layered mafic-ultramafic intrusions
As I worked in Africa for ten years of my career, I had the opportunity to contribute to the development of new concepts regarding the origin of layering in layered mafic – ultramafic complexes such as the Great Dyke of Zimbabwe or the Bushveld Complex of South Africa. This research, at the time supported by the mining industry, is still relevant today in the exploration for precious metals including platinum, palladium, and others.
I stumbled upon layering first in the Bushveld Granites where such igneous structure had not been much described and I proposed a new sill model to explain the emplacement of these hot magmas at high structural levels in the Early Proterozoic crust of the Kaapvaal Craton (Ferré et al., 1999; Wilson et al., 2000).
The initial research on the Bushveld Granites sparked my interest in layering in mafic-ultramafic complexes such as the Rustenberg Suite of the Bushveld Igneous Complex or the Karoo large sills in South Africa. My main contribution was to provide a unifying explanation for multi-scale layering in such large intrusions (Ferré et al., 2000; Ferré et al., 2009).
As I moved from South Africa to the United States at the University of Minnesota in 2000, I naturally developed an interest for the Duluth Complex, one of the largest mafic-ultramafic intrusions. I specifically worked on on the Sonju Lake intrusion, for which a new emplacement model was proposed (Maes et al., 2007)
More recently, as I was teaching geology field camp in Montana, I collaborated with the Stillwater Mine to investigate the origin of layering in the J-M platinum producing reef and led in 2016 a GSA Penrose Conference on layered mafic intrusions in Red Lodge, MT.
2016 GSA Penrose Conference participants near the Picket Pin deposit (sponsored by GSA and NSF grant # 1621858)