Accession Number:

ADA453266

Title:

Coordinated, High-Resolution Studies of Hydrated Sediments

Descriptive Note:

Conference paper

Corporate Author:

NAVAL RESEARCH LAB STENNIS SPACE CENTER MS SEAFLOOR SCIENCES DIRECTORATE

Report Date:

2005-05-05

Pagination or Media Count:

8.0

Abstract:

The Naval Research Laboratory NRL has been conducting coordinated investigations of marine gas hydrates based on precise co-location of both direct sediment cores and data from a deep-tow multichannel seismic system. The seismic instrument known as the Deep Towed AcousticsGeophysics System DTAGS was developed by NRL to support detailed studies of deep-ocean marine sediments by towing both the seismic source 220Hz - 1kHz, 200 dB 1 square Pa 1m and 48 channel hydrophone array 300 m above the seafloor in up to 6km deep water. This instrument has proven to ideal for studies of marine gas hydrates. Data from this system have been used to study the impact of hydrate dissociation on sediment properties on and near the Blake Ridge and on the Cascadia Margin. Investigations in the Gulf of Mexico are schedules for Spring 2005. Using bottom mounted acoustic transponders for long baseline LBL navigation, we have been able to co-locate the deep-tow seismic data with sediment cores, water samples, etc. to constrain models for processes that create and dissociate marine gas hydrates in much greater detail than previously possible. We show relationships between geologic features resolved with the seismic data and geochemical evidence for variability in methane flux through the seafloor. We also present preliminary results from lattice-gas numerical simulations of gas-fluid flow through complex sediments where parameters are predicated on results obtained with DTAGS and associated geochemical samples.

Subject Categories:

  • Industrial Chemistry and Chemical Processing
  • Physical and Dynamic Oceanography
  • Geography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE