CENTENNIAL-MILLENNIAL SCALE STABILITY OF A LARGE GAS HYDRATE FIELD IN THE NORTHERN GULF OF MEXICO

Deposits of methane hydrate “ice” underlie a substantial portion of the continental margins, representing a massive reservoir of the greenhouse gas methane, and a potentially important energy source. Dissociation of this methane hydrate has been previously implicated as a driver of climate change. Evidence from marine sedimentary records spanning the Cenozoic suggests that immense volumes of methane can be instantaneously introduced into the oceans/atmosphere, via pressure and/or temperature destabilization of these deposits. Yet many important questions remain about the stability of methane hydrates, the precise factors that trigger rapid dissociation events, and the connection to climate change. This study investigates centennial-millennial scale variability of an active gas-hydrate field in the Gulf of Mexico during the late Pleistocene and Holocene, using a depth transect of sediment cores collected above and below the site. Sediments recovered from 6 cores comprise a 15,000 year long record of slope sedimentation. A suite of sedimentologic (grain size), paleontologic (reworked nannofossils), and geochemical (e.g., barium, carbon isotopes of foraminifera tests) indicators of sediment transport and gas hydrate eruption will be measured in the cores from the depth transect. These data will be used to discern stability of the gas hydrate deposits and their connection to recent paleoclimate and depositional events in the Gulf of Mexico. Contrasting deposition above and below the field will be used to evaluate the role of gas hydrate destabilization on continental slope erosion over the past 15,000 years. Initial work has focused on XRF-scanning of the cores, and indicates pronounced changes in Ba/Al, suggestive of gas hydrate eruption events.