Cumulate causes for the low contents of sulfide-loving elements in the continental crust

Jenner, Frances Elaine (2017). Cumulate causes for the low contents of sulfide-loving elements in the continental crust. Nature Geoscience, 10(7) pp. 524–529.

DOI: https://doi.org/10.1038/ngeo2965

Abstract

Despite the economic importance of chalcophile (sulfide-loving) and siderophile (metal-loving) elements (CSEs), it is unclear how they become enriched or depleted in the continental crust, compared with the oceanic crust. This is due in part to our limited understanding of the partitioning behaviour of the CSEs. Here I compile compositional data for mid-ocean ridge basalts and subduction-related volcanic rocks. I show that the mantle-derived melts that contribute to oceanic and continental crust formation rarely avoid sulfide saturation during cooling in the crust and, on average, subduction-zone magmas fractionate sulfide at the base of the continental crust prior to ascent. Differentiation of mantle-derived melts enriches lower crustal sulfide- and silicate-bearing cumulates in some CSEs compared with the upper crust. This storage predisposes the cumulate-hosted compatible CSEs (such as Cu and Au) to be recycled back into the mantle during subduction and delamination, resulting in their low contents in the bulk continental crust and potentially contributing to the scarcity of ore deposits in the upper continental crust. By contrast, differentiation causes the upper oceanic and continental crust to become enriched in incompatible CSEs (such as W) compared with the lower oceanic and continental crust. Consequently, incompatible CSEs are predisposed to become enriched in subduction-zone magmas that contribute to continental crust formation and are less susceptible to removal from the continental crust via delamination compared with the compatible CSEs.

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About

• Item ORO ID
• 50893
• Item Type
• Journal Item
• ISSN
• 1752-0908
• Project Funding Details

• Funded Project Name	Project ID	Funding Body
  Mantle volatiles: processes, reservoirs and fluxes	NE/M000427/1	NERC
  Te and Se Cycling and Supply (TeaSe)	NE/M010848/1	NERC

• Keywords
• economic geology; geochemistry; geology; mineralogy
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Research Group
• Health and Wellbeing PRA (Priority Research Area)
• Depositing User
• Frances Jenner