V24A-01
SeaVOICE: Sea-going Experiments to Test Potential Linkages among Sea Level Change, Ocean Ridge Volcanism, and Hydrothermal Activity.
Tuesday, 15 December 2015: 16:00
102 (Moscone South)
Charles H Langmuir1, Suzanne M Carbotte2, Peter J Huybers3, Jerry F McManus4, Sujoy Mukhopadhyay5, Gisela Winckler6, Bridgit Boulahanis4, Kassandra Costa6, David Ferguson7, Katz Richard8, Yinqi Li1 and Jennifer L Middleton3, (1)Harvard University, Department of Earth and Planetary Sciences, Cambridge, MA, United States, (2)Lamont-Doherty Earth Obs, Palisades, NY, United States, (3)Harvard University, Cambridge, MA, United States, (4)Columbia University of New York, Palisades, NY, United States, (5)University of California Davis, Davis, CA, United States, (6)Lamont -Doherty Earth Observatory, Palisades, NY, United States, (7)Harvard University, Earth and Planetary Sciences, Cambridge, MA, United States, (8)University of Oxford, Oxford, United Kingdom
Abstract:
Changes in sea level influence the pressure of the solid Earth over entire ocean basins. While the absolute changes in sea level caused by glacial cycles are small relative to ocean depths, the temporal variations in sea level can lead to pressure changes of similar order to mantle upwelling rates, with the potential to significantly perturb short term rates of melt production at ocean ridges (Huybers and Langmuir, EPSL, 2009). Such changes could then lead to fluctuations in crustal thickness, magma composition and hydrothermal activity. To investigate possible relationships between glacial cycles and ocean ridge processes, we carried out an 18 day cruise of mapping and sediment coring to the Cleft Segment of the Juan de Fuca ridge. High resolution bathymetry was obtained on the west side of the ridge axis to beyond 1Ma to test whether abyssal hill fabric shows periodicities consistent with glacial cycles. Nine successful piston cores up to 7.6m in length provide a sedimentary record back to more than 600kyr to test for spatial and temporal variations in hydrothermal activity. Oxygen isotope stratigraphy on these cores is systematic and provides good age constraints. Short cores near the ridge axis provide a record of the current trace of hydrothermal activity in youngest sediments. Several of the cores impacted basement and recovered a basement sample. Above basement, basaltic glass shards were recovered in the bottom meter of sediment, raising the possibility of temporal records of basalt chemical compositions using the age constraints the sediments provide. The glass samples provide a unique and new perspective on ridge volcanism, since previous off-axis samples were restricted to dredging old fault scarps. Cores can be taken anywhere, raising the potential for global time series studies of ridge volcanism. The coupled bathymetry, sediment geochemistry and magmatic glass compositions hold the promise of a definitive advance in our understanding of the relationship between sea level change and ridge volcanism.
