Mobilisation of deep crustal sulfide melts as a first order control on upper lithospheric metallogeny
Magmatic arcs are terrestrial environments where lithospheric cycling and recycling of metals and volatiles is enhanced. However, the first-order mechanism permitting the episodic fluxing of these elements from the mantle through to the outer Earth’s spheres has been elusive. To address this knowledge gap, we focus on the textural and minero-chemical characteristics of metal-rich magmatic sulfides hosted in amphibole-olivine-pyroxene cumulates in the lowermost crust. We show that in cumulates that were subject to increasing temperature due to prolonged mafic magmatism, which only occurs episodically during the complex evolution of any magmatic arc, Cu-Au-rich sulfide can exist as liquid while Ni-Fe rich sulfide occurs as a solid phase. This scenario occurs within a ‘Goldilocks’ temperature zone at ~1100–1200 °C, typical of the base of the crust in arcs, which permits episodic fractionation and mobilisation of Cu-Au-rich sulfide liquid into permeable melt networks that may ascend through the lithosphere providing metals for porphyry and epithermal ore deposits.
NERC grant NE/P017053/1 and NE/P017312/1 “FAMOS: from arc magmas to ores” awarded to the DAH at the University of Leicester and IM at Cardiff University, respectively; Australian Research Council grant ”Metal Sources and Transport Mechanisms in the Deep Lithosphere” Centre of Excellence for Core to Crust Fluid Systems (CCFS, CE11E0070) awarded to MF at the University of Western Australia.
CitationHolwell, D.A., Fiorentini, M.L., Knott, T.R. et al. Mobilisation of deep crustal sulfide melts as a first order control on upper lithospheric metallogeny. Nat Commun 13, 573 (2022). https://doi.org/10.1038/s41467-022-28275-y
Author affiliationSchool of Geography, Geology and the Environment
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