کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4676981 1634733 2015 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
An irregular feather-edge and potential outcrop of marine gas hydrate along the Mauritanian margin
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
An irregular feather-edge and potential outcrop of marine gas hydrate along the Mauritanian margin
چکیده انگلیسی


• We provide the first description of the feather-edge of marine hydrate using three-dimensional seismic data.
• The landward extent of it, offshore of Mauritania is irregular and this may be typical for other margins.
• Hydrate that occurs at or below the seabed is rare along the margin.

The dissociation of marine hydrate that surrounds continental margins is thought to be an agent for past and future climate change. As the water depth decreases landwards, the base of the hydrate stability zone progressively shallows until hydrate can occur at or immediately below the seabed where an increase in bottom water temperature can cause dissociation. But the true extent of these most vulnerable hydrate deposits is unknown. Here we use exceptional quality three-dimensional (3-D) seismic reflection imagery offshore of Mauritania that reveals a rare example of a bottom simulating reflection (BSR) that intersects the seabed and delineates the feather-edge of hydrate. The BSR intersects the seabed at the ∼636 m isobath but along the 32 km of the margin analysed, the intersection is highly irregular. Intersections and seismic evidence for hydrate less than ∼4.3 m below the seabed occur in seven small, localised areas that are 0.02–0.45 km2 in extent. We propose gas flux below the dipping base of the hydrate to these places has been particularly effective. The intersections are separated by recessions in the BSR where it terminates below the seabed, seawards of the 636 m isobath. Recessions are areas where the concentration of hydrate is very low or hydrate is absent. They are regions that have been bypassed by gas that has migrated landwards along the base of the hydrate or via hydraulic fractures that pass vertically through the hydrate stability zone and terminate at pockmarks at the seabed. An irregular feather-edge of marine hydrate may be typical of other margins.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 423, 1 August 2015, Pages 202–209
نویسندگان
, , , , ,