TY - JOUR

T1 - Thin crust and exposed mantle control sulfide differentiation in slow-spreading ridge magmas

AU - Ciazela, Jakub

AU - Dick, Henry J.B.

AU - Koepke, Juergen

AU - Pieterek, Bartosz

AU - Muszynski, Andrzej

AU - Botcharnikov, Roman

AU - Kuhn, Thomas

N1 - Funding information: We thank editor Brendan Murphy and Claude Herzberg, John Mavrogenes, and an anonymous reviewer for their thorough and insightful comments. In addition, we would like to acknowledge D. Neave, F. Ridolfi, J. Feige, C. Zhang, F. Holtz, and L. Kirchhoff from the Leibniz Universität Hannover, and M. Ciazela, J. Nowak, and A. Zelazniewicz from the Polish Academy of Sciences. This research was funded by a Diamond Grant of the Polish Ministry of Science and Higher Education (DI2012 2057 42 to J. Ciazela), and partially supported by the European Association of Geochemistry (Early Career Science Ambassador grant to J. Ciazela) and the U.S. National Science Foundation (grants OCE1434452 and OCE1637130 to H. Dick).

PY - 2017/10

Y1 - 2017/10

N2 - Gabbroic veins enclosed in mantle peridotite from oceanic core complexes next to oceanic transform faults demonstrate sub-crustal crystallization of silicate minerals from a mid-oceanic ridge basalt (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 MORBs 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. We show that the concentrations of Cu, Zn, As, Ga, Pb, Sb, and Tl in the Kane Megamullion MORBs rise linearly with melt differentiation expressed by decreasing MgO and Ni content. The low-pressure fractional crystallization within the crust thus occurs at sulfide-undersaturated conditions. Sulfide-undersaturated MORBs 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.

AB - Gabbroic veins enclosed in mantle peridotite from oceanic core complexes next to oceanic transform faults demonstrate sub-crustal crystallization of silicate minerals from a mid-oceanic ridge basalt (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 MORBs 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. We show that the concentrations of Cu, Zn, As, Ga, Pb, Sb, and Tl in the Kane Megamullion MORBs rise linearly with melt differentiation expressed by decreasing MgO and Ni content. The low-pressure fractional crystallization within the crust thus occurs at sulfide-undersaturated conditions. Sulfide-undersaturated MORBs 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.

UR - http://www.scopus.com/inward/record.url?scp=85030025998&partnerID=8YFLogxK

U2 - 10.1130/G39287.1

DO - 10.1130/G39287.1

M3 - Article

AN - SCOPUS:85030025998

VL - 45

SP - 935

EP - 938

JO - Geology

JF - Geology

SN - 0091-7613

IS - 10

ER -