Off-axis Sills of Guaymas Basin: Implications for Thermogenic-carbon Flux of a Sedimented Rift Basin

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

This is a project to conduct a 10.5-day cruise to collect deep-towed sidescan sonar and chirp sub-bottom profile data, CTD measurements, water samples, and TowCam imagery over a large region of the off-axis seafloor in Guaymas Basin in order to identify areas of venting fluid and gas. This work will test the hypothesis that substantial venting of carbon-rich fluid and gas occurs off axis in Guaymas Basin as a result of thermogenic reactions driven by off-axis magmatic intrusion into organic-rich sediments. These data will identify bathymetric and sub-bottom features such as mounds, pock marks, and faults that are indicative of present and past venting; image and photograph high backscatter features such as bacterial mats, authigenic carbonate, or biological communities that are indicative of fluid flux; and provide a means, through analysis of water samples, to distinguish between biogenic and thermogenic sources of methane and other hydrocarbons in the off-axis sedimented ridge setting. This work supports IODP Birth of Oceans Mission Proposal and IODP proposal 658 Full related to sill production and methane generation during breakup of N. Atlantic. Broader Impacts This effort will contribute to knowledge of sources and sinks in the global carbon cycle, which is a strong forcing function in past and present climate change. The project promotes international collaboration through the participation of Dr. Bill Bandy and Dr. Carlos Mortera of Universidad Nacional Autónoma de México, and it promotes education through the participation of two U.S. and two Mexican graduate students in the research cruise and subsequent analyses.