Spatial Patterns of Hydrothermal Deposition on the Juan de Fuca Ridge over the Past 500,000 years

Thursday, 2 February 2017
Marina/Gretel (Hobart Function and Conference Centre)
Kassandra Costa1, Jerry F McManus2, Jennifer L Middleton3, Charles H Langmuir4, Peter J Huybers5, Gisela Winckler1, Sujoy Mukhopadhyay6 and Liviu Giosan7, (1)Lamont -Doherty Earth Observatory, Palisades, NY, United States, (2)Columbia University of New York, Palisades, NY, United States, (3)Harvard University, Earth and Planetary Sciences, Cambridge, MA, United States, (4)Harvard University, Department of Earth and Planetary Sciences, Cambridge, MA, United States, (5)Harvard University, Cambridge, MA, United States, (6)University of California Davis, Earth and Planetary Sciences, Davis, CA, United States, (7)Woods Hole Oceanographic Inst, Woods Hole, MA, United States
Abstract:
Hydrothermal systems play an important role in modern marine chemistry, but little is known about how they may have varied on 100,000 year timescales. Here we present high resolution records of metal fluxes within sediment cores covering the last 500,000 years of hydrothermal deposition on the flanks of the Cleft Segment of the Juan de Fuca Ridge. Six adjacent, gridded cores were analyzed by x-ray fluorescence for Cu, Fe, Mn, Ni and Zn concentrations and normalized to 230Thxs0 to generate metal fluxes. Because of potential diagenetic overprinting of Mn and Ni in the sedimentary record, Fe, Cu and Zn are identified as the most reliable proxies for hydrothermal activity on the Juan de Fuca Ridge. The proximity of the cores permitted an assessment of the spatial variability of hydrothermal deposition, and two major sources were identified: northern-sourced plumes and southern-sourced plumes. These sources appear relatively long-lived, suggesting that stable hydrothermal “neighborhoods” of vents cluster over magmatic centers with similar plume chemistry and trajectory.
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