Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Geology 45 (2017): 935-938, doi:10.1130/G39287.1.
Description:
Gabbroic veins enclosed in mantle peridotite from ocean core complexes next to
oceanic transform faults demonstrate sub-crustal crystallization of silicate minerals
from a MORB-like melt. Cooler lithosphere there may also affect sulfide crystallization
and the metal budget of the lower and upper crust but the related sulfide behavior is
poorly understood. Here, we use chalcophile elements to trace sulfide crystallization in
a suite of MORB's erupted at the Kane Megamullion south of the Kane Fracture Zone
along the Mid-Atlantic Ridge. Cool lithosphere there is inferred from a low magma
supply, and lithostratigraphic evidence for thin crust with abundant mantle rock
exposed to the seafloor (Dick et al., 2008). We show that the concentrations of Cu, Zn,
As, Ga, Pb, Sb and Tl in the Kane Megamullion MORB's rise linearly with melt
differentiation expressed by decreasing MgO and Ni content. The low-pressure
fractional crystallization within the crust thus occurs at sulfur-undersaturated
conditions. Sulfur-undersaturated MORB's are unusual. At the Kane Megamullion,
however, the thin crust allows melt to more extensively interact with the shallow and
serpentinized mantle. We argue that sulfur and chalcophile elements have been lost
from the melt due to sulfide crystallization during melt-rock reaction in the shallow
mantle.
Description:
This research was funded by a Diamond Grant of
the Polish Ministry of Science and Higher Education (DI2012 2057 42 to Ciazela), and
partially supported by the European Association of Geochemistry (Early Career Science
Ambassador grant to Ciazela) and the National Science Foundation (grant #’s
OCE1434452 and OCE1637130 to Dick).
Keywords:
MORB
;
Sulfides
;
Chalcophile elements
;
Mantle-melt reaction
;
Slow-spreading ridges
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
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