Thin crust and exposed mantle control sulfide differentiation in slow-spreading ridge magmas
Dick, Henry J. B.
MetadataShow full item record
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.
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.
Suggested CitationPreprint: Ciazela, Jakub, Dick, Henry J. B., Koepke, Juergen, Pieterek, Bartosz, Muszynski, Andrzej, Botcharnikov, Roman, Kuhn, Thomas, "Thin crust and exposed mantle control sulfide differentiation in slow-spreading ridge magmas", 2017-07, https://doi.org/10.1130/G39287.1, https://hdl.handle.net/1912/9313
Showing items related by title, author, creator and subject.
Smith, Deborah K.; Escartin, Javier E.; Schouten, Hans A.; Cann, Johnson R. (The Oceanography Society, 2012-03)In the classic mid-ocean ridge model, new seafloor is generated through a combination of magmatic diking feeding lava flows at the spreading axis, and the formation of short-offset, high-angle normal faults that dip toward ...
Hydrothermal activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge) : distribution, heatflux, and geological controls Escartin, Javier E.; Barreyre, Thibaut; Cannat, Mathilde; Garcia, Rafael; Gracias, Nuno; Deschamps, Anne; Salocchi, Aura; Sarradin, Pierre-Marie; Ballu, Valerie (2015-09)We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment, to evaluate the distribution of hydrothermal activity. We have ...
Escartin, Javier E.; Smith, Deborah K.; Cann, Johnson R.; Schouten, Hans A.; Langmuir, Charles H.; Escrig, Stéphane (2008-08)The formation of oceanic detachment faults is well established from inactive, corrugated fault planes exposed on seafloor formed along ridges spreading at less than 80 km/My1-4. These faults can accommodate extension for ...