PP44A-07:
Mid-ocean ridge bathymetry records past variations in sea level: evidence from spectral analysis of abyssal hills and implications for 100 ky glacial cycles.
Thursday, 18 December 2014: 5:30 PM
Peter J Huybers, Harvard University, Cambridge, MA, United States, Suzanne M Carbotte, Lamont-Doherty Earth Obs, Palisades, NY, United States, Richard F Katz, University of Oxford, Oxford, United Kingdom and Charles H Langmuir, Harvard Univ, Cambridge, MA, United States
Abstract:
Evidence has accumulated from continental tephra, marine tephra, and abyssal hill topography that deglaciation drives volcanism. Additional analysis of abyssal topography flanking mid-ocean ridges is presented indicating the presence of excess energy near periods corresponding to precession, obliquity, and 100 ky variations. Wavelength is transformed into period using independently estimated spreading rates. This topographic structure is consistent with the expected response of mid-ocean ridge productivity and evolved crustal thickness to changes in pressure associated with variations in sea level. If ridge CO2 emissions track these indications of ridge productivity, decreased emissions as a result of deglaciation are implied, constituting a negative feedback. CO2 emissions would be delayed, however, because of transit times from the base of the melt zone, and a simple delayed oscillator is presented for how delayed negative feedbacks could be important for setting the 100 ky glacial cycle period.
