Filters: Tags: {"type":"USGS Scientific Topic Keyword"} (X) > partyWithName: Carolyn Ruppel (X)
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In spring and summer 2017, the U.S. Geological Survey’s Gas Hydrates Project conducted two cruises aboard the research vessel Hugh R. Sharp to explore the geology, chemistry, ecology, physics, and oceanography of sea-floor methane seeps and water column gas plumes on the northern U.S. Atlantic margin between the Baltimore and Keller Canyons. Split-beam and multibeam echo sounders and a chirp subbottom profiler were deployed during the cruises to map water column backscatter, sea-floor bathymetry and backscatter, and subsurface stratigraphy associated with known and undiscovered sea-floor methane seeps. The first cruise, known as the Interagency Mission for Methane Research on Seafloor Seeps and designated as field...
The T-3 (Fletcher's) Ice Island in the Arctic Ocean was the site of a scientific research station re-established by the Naval Arctic Research Laboratory starting in 1962. Starting in 1963, the USGS acquired marine heat flow data and coincident sediment cores at sites in Canada Basin, Nautilus Basin, Mendeleev Ridge, and Alpha Ridge as the ice island drifted in the Amerasian Basin. At least 584 heat flow penetrations were attempted, and data were reported at 356 of these. This dataset is the enhanced version of the original data table from Lachenbruch and others (2019; see cross-reference), incorporating additional information such as the probable dates of measurement, physiographic province and surficial geology...
Categories: Data Release - Revised;
Tags: Alpha Ridge,
Amerasian Basin,
Arctic,
Arctic Ocean,
Canada Basin,
Bottom simulating reflections (BSRs) are seismic features that are imaged in marine sediments using high-energy, impulsive seismic sources such as air guns or generator-injector guns. BSRs often cut across sediment stratigraphy and are interpreted as marking the deepest depth at which gas hydrate can exist. Gas hydrate is a naturally occurring and widely distributed frozen form of water and gas (usually methane) stable at low temperatures (up to about 25 degrees Celsius [°C]) and intermediate pressures (those that usually correspond to greater than 500 meters water depth). BSRs have been mapped in all the world’s oceans, in inland seas (such as the Black Sea), and in Lake Baikal in Russia. This data release consists...
Categories: Data;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: Alaska,
Amazonia,
Antarctica,
Arctic,
Argentina,
Chemosynthetic environments support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. Hundreds of methane seeps have been documented along the U.S. Atlantic margin (USAM), and detailed investigations at a few seeps have revealed distinct environments containing mussels, microbial mats, authigenic carbonates, and soft sediments. The dominant mussel Bathymodiolus childressi contains methanotrophic endosymbionts but is also capable of filter feeding. We used SIA (δ13C, δ 5N, and δ34S) and an isotope mixing model (MixSIAR) to estimate resource contribution to B. childressi and characterize food webs at two seep sites (Baltimore Seep: 400 m and Norfolk Seep: 1500 m depths) along...
The present-day distribution of subsea permafrost beneath high-latitude continental shelves has implications for sea level rise and climate change since the Last Glacial Maximum (~20,000 years ago). Because permafrost can be spatially associated with gas hydrate (which may be thermodynamically stable within the several hundred meters above and below the base of permafrost), the contemporary distribution of subsea permafrost also has implications for the persistence of permafrost-associated gas hydrate beneath shallow waters at high latitudes, particularly on margins that were not glaciated at the Last Glacial Maximum. On the U.S. Beaufort Sea margin offshore northern Alaska, researchers have sometimes assumed that...
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