Thomas Lamont (Geology) had a paper titled, "Porphyry copper formation driven by water fluxed crustal anatexis during flat-slab subduction," published on Nov. 4 in Nature Geoscience.

It has long been recognized that many of the worlds largest porphyry copper deposits (copper ore formed by magmatic-hydrothermal fluids associated with granitic intrusions that host most of the world's copper and other metals) occur along convergent plate boundaries and formed during distinct periods of flat-slab subduction (slab dip <15 degrees). However the mechanism by which magmatism and copper mineralization occurs in such geodynamic settings has remained unclear as flat-slab subduction should remove the mantle wedge and therefore limit any mantle melting, ultimately preventing magmatism and mineralisation. In this study, we address this problem as we show that porphyry copper deposits in Arizona (the world's 2nd largest copper province) formed as a result of volatile mediated melting of the Arizona lower crust that was pre-enriched in metals between 73-60 million years ago - the exact same time of porphyry copper mineralisation (73-56 million years ago) and flat-slab subduction of the Farallon Plate beneath western North America (70-40 million years ago). These results imply that water released by dehydration mineral reactions on the leading edge of a flat-slab, interacts with lower crustal rocks, which reduces the melting temperature and causes extensive water-rich magmas which re-mobilizes the metals stored at the base of the lower crust and allows advection of these metals to the surface without any significant magma input from the mantle. This can explain why flat-slab subduction settings are fundamental to forming porphyry copper deposits, and therefore should be targeted for future mineral exploration to support societies green energy goals.