Sediment Thickness Data in the Aleutian and Bowers Basins of the Bering Sea

Sediment thickness information for the Aleutian and Bowers Basins in the Bering Sea comes from
single-channel and multichannel seismic reflection data from 15 cruises that surveyed the Aleutian and Bowers Basins
and the intervening Bowers Ridge.  Seismic horizons were picked on peak reflection amplitudes, on reflection seismic
data sampled at 4 milliseconds, using KingdomSuite seismic interpretation software.
One text file (BeringSea-KingdomSuiteNav-2017Dec19.csv) in CSV (comma-separated values)
format is a complete navigation file, containing seismic trace positions for all of the seismic lines
in the KingdomSuite project,
including for seismic lines and segments of seismic lines where seismic horizons were not picked due to poor
data quality or location outside of the compilation area.
Two other CSV files contain seismic horizon picks in two-way traveltime (TWT).
The first CSV file (BeringSeaHorizonPicks-SedimentInterval-2017Dec19.csv) contains picks of the seabed and the top of
igneous basement, along with derived values of the interval TWT
of the intervening sediment and the thickness of the sediment based on a TWT-to-thickness relationship developed from stacking
velocities of the high-quality, long-streamer multichannel seismic reflection cruise MGL1111 in the Aleutian Basin.
The second CSV file (BeringSeaHorizonPicks-MinimumSedimentInterval-2017Dec19.csv)
contains information where the basement reflection is beyond the maximum TWT of the seismic record; this file
tabulates the TWT of the seabed pick, the record length (9 seconds in all cases), and the interval TWT and thickness values of
the minimum sediment thickness based on the knowledge that the basement must be deeper than detectable with those
records.  This situation occurred for 3 seismic cruises (F187, F286, and F386) where they crossed thick sediments
immediately north of Bowers Ridge.
A raster grid of sediment thickness in GeoTIFF format (AleutianBowersBasins-SedimentThicknessGrid.tif) was created where seismic
horizon picks were of sufficient spatial density to create a gridded model.  Because the seismic line orientation was unfavorable
for gridding in areas where sediments were thickest (north of Bowers Ridge) and thinnest (atop Bowers Ridge), a CSV file of
manually determined minimum and maximum sediment thickness constraints (AleutianBowersBasins-SedimentThickness-ManualConstraints.csv)
was used to guide the gridding algorithm to minimize gridding artifacts related to line orientation in these areas.
These manual constraints are points selected between the seismic survey lines, with assigned thickness values that
guide the gridding algorithm to output grid values consistent with the regional sediment thickness trends, as defined
by the seismic lines in the Bowers Ridge region.
In addition, a masking polygon file (AleutianBowersBasins-GridPolygon.shp) in shapefile format was used to output
gridded values only where input data were sufficient for gridding.    Each data file, along with a corresponding
CSDGM FGDC-compliant metadata file, is provided in its own zip archive file.

Tags: aleutian-basin, bering-sea, bowers-basin, bowers-ridge, geoscientificinformation, maps-and-atlases, stratigraphic-thickness, usgs-669dbb19d34eef99d5abb3ad
Organization: Department of the Interior