New discoveries at Woolsey Mound, MC118, northern Gulf of Mexico

Woolsey Mound, a 1km-diameter carbonate-gas hydrate complex in the northern Gulf of Mexico, is the site of the Gulf’s only seafloor monitoring station-observatory in its only research reserve, Mississippi Canyon 118. Active venting, outcropping hydrate, and a thriving chemosynthetic community recommend the site for study. Since 2005, the Gulf of Mexico Hydrates Research Consortium has been conducting multidisciplinary studies to 1. Characterize the site, 2. Establish a facility for real-time monitoring-observing of gas hydrates in a natural setting, 3. Study the effects of gas hydrates on seafloor stability, 4. Establish fluid migration routes and estimates of fluid-flux at the site, 5. Establish the interrelationships between the organisms at the vent site and the association-dissociation of hydrates. A variety of novel geological, geophysical, geochemical and biological studies has been designed and conducted, some in survey mode, others in monitoring mode. Geophysical studies involving merging multiple seismic data acquisition systems accompanied by the application of custom processing techniques verify communication of surface features with deep structures. Supporting geological data derive from innovative recovery techniques. Geochemical sensors, used experimentally in survey mode, including aboard an AUV, double as monitoring devices. A suite of pore-fluid sampling devices has returned data that capture change at the site in daily increments; using only noise as an energy source, hydrophones have returned daily fluctuations in physical properties. Ever-expanding capabilities of a custom-ROV have been determined by research needs. Processing of new as well as conventional data via unconventional means has resulted in the discovery of new features…..vents, faults, benthic fauna…..and modification of others including pockmarks, hydrate outcrops, vent activity, and water-column chemical plumes. Though real-time monitoring awaits communications and power link to land, periodic data-collection reveals a carbonate-hydrate mound, part of an immensely complex hydrocarbon system

Spatial Distribution of Seafloor Bio-Geological and Geochemical Processes as Proxies of Fluid Flux Regime and Evolution of a Carbonate/Hydrates Mound, Northern Gulf of Mexico

Woolsey Mound, a carbonate/hydrate complex of cold seeps, vents, and seafloor pockmarks in Mississippi Canyon Block 118, is the site of the Gulf of Mexico Hydrates Research Consortium\u27s (GOMHRC) multi-sensor, multi-disciplinary, permanent seafloor observatory. In preparation for installing the observatory, the site has been studied through geophysical, biological, geological, and geochemical surveys. By integrating high-resolution, swath bathymetry, acoustic imagery, seafloor video, and shallow geological samples in a morpho-bio-geological model, we have identified a complex mound structure consisting of three main crater complexes: southeast, northwest, and southwest. Each crater complex is associated with a distinct fault. The crater complexes exhibit differences in morphology, bathymetric relief, exposed hydrates, fluid venting, sediment accumulation rates, sediment diagenesis, and biological community patterns. Spatial distribution of these attributes suggests that the complexes represent three different fluid flux regimes: the southeast complex seems to be an extinct or quiescent vent; the northwest complex exhibits young, vigorous activity; and the southwest complex is a mature, fully open vent. Geochemical evidence from pore-water gradients corroborates this model suggesting that upward fluid flux waxes and wanes over time and that microbial activity is sensitive to such change. Sulfate and methane concentrations show that microbial activity is patchy in distribution and is typically higher within the northwest and southwest complexes, but is diminished significantly over the southeast complex. Biological community composition corroborates the presence of distinct conditions at the three crater complexes. The fact that three different fluid flux regimes coexist within a single mound complex confirms the dynamic nature of the plumbing system that discharges gases into bottom water. Furthermore, the spatial distribution of bio-geological processes appears to be a valid indicator of multiple fluid flux regimes that coexist at the mound. (C) 2013 Elsevier Ltd. All rights reserved

Challenges In Imaging the Deep Seabed: Examples From Gulf of Mexico Cold Seeps

Applying improved processing techniques to increasingly high resolution data can produce extremely high resolution results that reveal features invisible on standard resolution images. Increasing demand for resources from the deep sea demands imaging the seabed in ever-more remote areas with increased accuracy. For economic, safety, and legal reasons, lessors of offshore real estate survey the seafloor and shallow sub-seafloor prior to conducting seafloor operations. A standard geohazards survey includes multibeam bathymetry, side-scan sonar and CHIRP subbottom profiling and will yield useful data at 5–25 m (16–82 ft) resolution. However, higher resolution surveys are now possible and, though more time-consuming (and costly), yield potentially critical information not visible in coarser resolution surveys: morphologic features, structure, biota, etc. Recovering such information has become increasingly important for reasons that include 1) identification of natural seafloor features (i.e., fault traces, protected seafloor communities, seeps, mud volcanoes); 2) selection/elimination of target locations; 3) identification of unnatural features (shipwrecks, instruments, pipelines); 4) siting structures on the seafloor; and 5) instrument location/recovery. Using coarser resolution surveying for regional studies, then focusing higher resolution surveys on areas of particular interest, and applying meticulous processing of acoustic data, our team has produced 1 m (3 ft) resolution seafloor images that have enabled us to identify a host of small-scale features not routinely imaged at coarser resolutions. Here we present significant results including small-scale morphologic features associated with seeps, instrument locations, and benthic fauna habitat in the Gulf of Mexico

Challenges In Imaging the Deep Seabed: Examples From Gulf of Mexico Cold Seeps

Applying improved processing techniques to increasingly high resolution data can produce extremely high resolution results that reveal features invisible on standard resolution images. Increasing demand for resources from the deep sea demands imaging the seabed in ever-more remote areas with increased accuracy. For economic, safety, and legal reasons, lessors of offshore real estate survey the seafloor and shallow sub-seafloor prior to conducting seafloor operations. A standard geohazards survey includes multibeam bathymetry, side-scan sonar and CHIRP subbottom profiling and will yield useful data at 5–25 m (16–82 ft) resolution. However, higher resolution surveys are now possible and, though more time-consuming (and costly), yield potentially critical information not visible in coarser resolution surveys: morphologic features, structure, biota, etc. Recovering such information has become increasingly important for reasons that include 1) identification of natural seafloor features (i.e., fault traces, protected seafloor communities, seeps, mud volcanoes); 2) selection/elimination of target locations; 3) identification of unnatural features (shipwrecks, instruments, pipelines); 4) siting structures on the seafloor; and 5) instrument location/recovery. Using coarser resolution surveying for regional studies, then focusing higher resolution surveys on areas of particular interest, and applying meticulous processing of acoustic data, our team has produced 1 m (3 ft) resolution seafloor images that have enabled us to identify a host of small-scale features not routinely imaged at coarser resolutions. Here we present significant results including small-scale morphologic features associated with seeps, instrument locations, and benthic fauna habitat in the Gulf of Mexico