A long section of serpentinized depleted mantle peridotite
C. Johan Lissenberg, Andrew McCaig, Susan Q. Lang, Peter Blum, Natsue Abe, William J. Brazelton, Rémi Coltat, Jeremy R. Deans, K.L. Dickerson, Marguerite Godard, Barbara E. John, Frieder Klein, Rebecca Kuehn, Kuan-Yu Lin, Haiyang Liu, Ethan Lopes, Toshio Nozaka, Andrew J. Parsons, Vamdev Pathak, Mark K. Reagan, Jordyn Robare, Ivan P. Savov, Esther M. Schwarzenbach, O.J. Sissmann, Gordon Southam, Fengping Wang, C.G. Wheat, Lesley Anderson, Sarah Treadwell
Abstract
The upper mantle is critical for our understanding of terrestrial magmatism, crust formation, and element cycling between Earth's solid interior, hydrosphere, atmosphere, and biosphere. Mantle composition and evolution have been primarily inferred by surface sampling and indirect methods. We recovered a long (1268-meter) section of serpentinized abyssal mantle peridotite interleaved with thin gabbroic intrusions. We find depleted compositions with notable variations in mantle mineralogy controlled by melt flow. Dunite zones have predominantly intermediate dips, in contrast to the originally steep mantle fabrics, indicative of oblique melt transport. Extensive hydrothermal fluid-rock interaction is recorded across the full depth of the core and is overprinted by oxidation in the upper 200 meters. Alteration patterns are consistent with vent fluid composition in the nearby Lost City hydrothermal field.