The Stability of a Large Gas Hydrate-Mud Volcano Field in the Northern Gulf of Mexico: Late Pleistocene to Present
Frozen natural gas deposits (gas hydrates) occur across a substantial portion of the northern Gulf of Mexico slope, and worldwide they represent a massive reservoir of organic carbon. Gas hydrate fields from this region are often associated with mud volcanism, petroleum, and natural gas expulsion at the seafloor, and thus they represent very dynamic systems. Previous work has proposed that temperature and/or pressure changes may result in sudden destabilization of gas hydrate deposits and slope erosion, however, the frequency and magnitude of these occurrences is poorly constrained. This study investigates the stability of an active gas-hydrate field, within federal lease block Mississippi Canyon 118 (MC-118) in the northern Gulf of Mexico. Sediments recovered from 10 cores comprise a 20,000-year long record of slope sedimentation surrounding the field.
A chronostratigraphic framework for the sediments hosting this active field is developed using a range of biostratigraphic and geochemical techniques, including, AMS Carbon dating and planktic foraminiferal biostratigraphy. In addition, X-ray fluorescence (XRF) core scanning is used to reconstruct variability in bulk geochemistry of the sediment cores and allows quantification of biogenic (e.g. CaCO3) and siliciclastic (e.g., Al, Ti) sediment inputs. These down-core elemental profiles provide a high-resolution framework for correlation. Spatial variability of sedimentation surrounding the field provides unique insight into slope erosion processes at MC-118. More specifically, contrasting accumulation upslope and downslope from the field, and the development of a sediment budget spanning the past 20,000 years, provides a means to evaluative the stability of the field and its impact on slope erosion and sedimentation.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009