Digital data for depth to basement in the deep-sea basins of the Pacific continental margin (cowbsm) based on data collected in 1984.

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What does this data set describe?

Title:
Digital data for depth to basement in the deep-sea basins of the Pacific continental margin (cowbsm) based on data collected in 1984.
Abstract:
Digital vector data for the contours of depth to basement for the deep-sea basins of the Pacific continental margin offshore of Washington, Oregon, and California. The data were interpreted from GLORIA (Paskevich and others, 2011) sidescan data and related seismic-reflection data. The data were published as USGS maps in paper format (Gardner and others, 1992, 1993a, 1993b).
Supplemental_Information:
Additional information about the field activities from which this data set was derived are available online at

http://walrus.wr.usgs.gov/infobank/f/f184sc/html/f-1-84-sc.meta.html

http://walrus.wr.usgs.gov/infobank/f/f284nc/html/f-2-84-nc.meta.html

http://walrus.wr.usgs.gov/infobank/f/f384nc/html/f-3-84-nc.meta.html

http://walrus.wr.usgs.gov/infobank/f/f484wo/html/f-4-84-wo.meta.html

Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in ArcGIS format, this metadata file may include some ArcGIS-specific terminology.

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(modified from Gardner and others, 1992)

The U.S. Geological Survey conducted a series of cruises in 1984, EEZSCAN 84 (EEZ-SCAN 84 Scientific Staff, 1986; U.S. Geological Survey activities F-1-84-SC, F-2-84-NC, F-3-84-NC, F-4-84-WO), to collect reconnaissance data on the newly proclaimed Exclusive Economic Zone (EEZ), the area out to 200 nautical miles from the coastline of the United States. The cruises systematically surveyed the entire conterminous United States west coast EEZ using the Geological Long-Range Inclined Asdic (GLORIA) side-scan sonar, a 160-cubic-inch airgun seismic-reflection profiler, a 3.5-kHz high-resolution seismic-reflection profiler, a 10-kHz echo sounder, and a proton-precession magnetometer. The nominal trackline spacing throughout the survey was 30 km.

Derivative maps of sediment thickness (Gardner and others, 1992a, 1993a, 1993b) and depth to basement (Gardner and others, 1992b, 1993c, 1993d)) in the basins of the west coast EEZ were compiled from both the sonar-image data and the deep-penetration seismic data obtained on these cruises. Only EEZ-SCAN 84 data were used for the map compilations because available data from other cruises in this region are sparsely located, have poor navigational control, or were obtained with seismic systems that were not powerful enough to resolve oceanic basement. Sediment thickness and depth to basement were determined only in the deep-ocean basin regions because the seismic system used on the EEZ-SCAN 84 cruises could not resolve oceanic basement beneath the thick sediments of the continental slope. All the data used to compile the maps are presented in the "Atlas of the Exclusive Economic Zone, Western Conterminous United States" (EEZ-SCAN 84 Scientific Staff, 1986) and are now available online (Paskevich and others, 2011).

Basement Outcrops

GLORIA imagery was used to locate areas of basement outcrop throughout the region. Where possible, sediment thickness on and immediately adjacent to basement outcrops was measured from seismic data. Where there was no bathymetric or seismic control, a seamount peak was assumed to have no sediment cover.

Data Reduction

Acoustic basement in the basins, invariably oceanic Layer 2, was observed on all of the seismic records. One-way traveltime was measured from the seafloor to acoustic basement. Because the trackline spacing of about 30 km is relatively large compared to the data density along track, the sediment thickness was measured every 0.5 hour or at an interval of approximately 7.5 km. Water depth was measured with a 10-kHz profiler. Depth to basement was calculated using the sea surface as the zero datum and adding the corrected water depth (Carter, 1980) to the sediment thickness. Acoustic travel times were converted to depths by first calculating a regression equation from the interval velocity versus depth data of Connard and others (1984). Their data base comprises a compilation of all available Deep Sea Drilling Project data plus wide-angle refraction data, which were collected in Cascadia Basin west of Oregon and represents the best data set available for the United States west coast EEZ. The regression equation was integrated to determine sediment thickness as a function of one-way traveltime. The resulting equation is

z = 1400t + 0 .5t ^ 2

where z is sediment thickness in meters, and t is one-way traveltime in seconds. Sediment thicknesses calculated using this equation were compared to values calculated from the general equation of Carlson and others (1986). Values for sediment thickness calculated by the two equations differed by no greater than 10 percent throughout the range of travel times.

References Cited

Carlson, R.L., Gangi, A.F., and Snow, K.R., 1986, Empirical reflection-traveltime/ depth and velocity/depth functions for the deep-sea sediment column: Journal of Geophysical Research, v. 91, no. B8, p. 8249-8266.

Carter, D.J.T., 1980, Echo-sounding correction tables: Taunton, United Kingdom, Hydrographic Department, Ministry of Defence, 150 p.

Chase, T.E., Wilde, Pat, Normark, W.R, Miller, C.P., Seekins, B.A., and Young, J.D., 1981, Offshore topography of the Western United States between 32 and 49 North latitudes: U.S. Geological Survey Open-File Report 81-443, scale 1:864,518 at 38 latitude, 2 sheets, http://pubs.er.usgs.gov/publication/ofr81443

Connard, G., Couch, R., Keeling , K., Roy, J., and Troseth, S., 1984, Abyssal plain and continental net-objective sedimentary thicknesses, in Kulm, L.D., and others, eds., Western North America continental margin and adjacent ocean floor off Oregon and Washington, Atlas 1 of Regional Atlas Series, Ocean Margin Drilling Program: Woods Hole, Mass., Marine Science International, sheet 7.

EEZ-SCAN 84 Scientific Staff, 1986, Atlas of the Exclusive Economic Zone, Western Conterminous United States: U.S. Geological Survey Miscellaneous Investigations Series I-1792, scale 1:500,000, 152 p., http://pubs.er.usgs.gov/publication/i1792
  1. How might this data set be cited?
    Grim, Muriel S., and Wong, Florence L., 2015, Digital data for depth to basement in the deep-sea basins of the Pacific continental margin (cowbsm) based on data collected in 1984.: U.S. Geological Survey, Coastal and Marine Geology Program, Pacific Coastal and Marine Science Center, Santa Cruz and Menlo Park, CA.

    This is part of the following larger work.

    Wong, Florence L., and Grim, Muriel S., 2015, Depth-to-basement, sediment-thickness, and bathymetry data for the Deep-Sea Basins offshore of Washington, Oregon, and California: U.S. Geological Survey Open-File Report OF 2015-1118, U.S. Geological Survey, Reston, VA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -131.0851
    East_Bounding_Coordinate: -119.0350
    North_Bounding_Coordinate: 48.3066
    South_Bounding_Coordinate: 30.7495
  3. What does it look like?
    http://pubs.usgs.gov/of/2015/1118/cowbsm.jpg (JPEG)
    thumbnail image of cowbsm.shp
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1984
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • String (1257)
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.0001. Longitudes are given to the nearest 0.0001. Latitude and longitude values are specified in Decimal seconds. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    Attribute Table
    Table containing attribute information associated with the data set. (Source: Producer defined)
    LTYPE
    Vector line feature type (Source: Producer defined)
    ValueDefinition
    depth2bsmtcontour of depth to basement
    nodataseamount boundary, depth unknown
    scratchboundary enclosing data
    DEPTH_M
    depth to basement (Source: Producer defined)
    Range of values
    Minimum:-5400
    Maximum:-800
    Units:meter
    LENGTH_M
    Vector length (Source: Producer defined)
    Range of values
    Minimum:46
    Maximum:1040810
    Units:meter
    Entity_and_Attribute_Overview:
    
    
    Additional DEPTH_M values:
     -9999 = scratch boundary
     -9998 = boundary of seamount peak (mapped from GLORIA imagery) with undefined depth
    
    
    Seamount peaks were mapped only for the central area between Cape Mendocino and Point Conception.
    Entity_and_Attribute_Detail_Citation:
    The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Muriel S. Grim
    • Florence L. Wong
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
    Florence L. Wong
    U.S. Geological Survey
    Geologist, GIS Coordinator
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5327 (voice)
    (650) 329-5190 (FAX)
    fwong@usgs.gov

Why was the data set created?

These data are intended for science researchers, students, policy makers, and the general public. The data can be to display geologic and oceanographic information.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 1990 (process 1 of 3)
    Muriel Grim digitized and edited mylar source maps provided by J.V. Gardner. Original data were formatted for MAPGEN application (Evenden, 1985; Grim, 1992).
    Date: 1993 (process 2 of 3)
    Florence Wong converted data files to ArcInfo format.
    Date: 2011 (process 3 of 3)
    ArcInfo coverage converted to shapefile and projected to geographic coordinate system.
  3. What similar or related data should the user be aware of?
    Gardner, J.V., Cacchione, D.A., Drake, D.E., Edwards, B.D., Field, M.E., Hampton, M.A., Karl, H.A., Kenyon, N.H., Masson, D.G., McCulloch, D S, and Grim, M S, 1992, Map showing depth to basement in the deep-sea basins of the Pacific continental margin, Point Conception to Point Loma: U. S. Geological Survey Miscellaneous Investigations Series I-2089-A, 1 sheet.

    Online Links:

    Other_Citation_Details: scale: 1:1,000,000; Gardner and others (1992)
    Gardner, J.V., Cacchione, D.A., Drake, D.E., Edwards, B.D., Field, M.E., Hampton, M.A., Karl, H.A., Kenyon, N.H., Masson, D.G., McCulloch, D S, and Grim, M S, 1993, Map showing depth to basement in the deep-sea basins of the Pacific continental margin, Cape Mendocino to Point Conception: U. S. Geological Survey Miscellaneous Investigations Series I-2090-A, 1 sheet.

    Online Links:

    Other_Citation_Details: scale: 1:1,000,000; Gardner and others (1993a)
    Gardner, J.V., Cacchione, D.A., Drake, D.E., Edwards, B.D., Field, M.E., Hampton, M.A., Karl, H.A., Kenyon, N.H., Masson, D.G., McCulloch, D S, and Grim, M S, 1993, Map showing depth to basement in the deep-sea basins of the Pacific continental margin, Strait of Juan de Fuca to Cape Mendocino: U. S. Geological Survey Miscellaneous Investigations Series I-2091-A, 1 sheet.

    Online Links:

    Other_Citation_Details: scale: 1:1,000,000; Gardner and others (1993b)
    Paskevich, Valerie F., Wong, Florence L., O'Malley, John J., Stevenson, Andrew J., and Gutmacher, Christina E., 2011, GLORIA sidescan-sonar imagery for parts of the U.S. Exclusive Economic Zone and adjacent areas: Open-File Report 2010-1332, U.S. Geological Survey, Menlo Park, California.

    Online Links:


How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Not available.
  2. How accurate are the geographic locations?
    Comparison of lines delimiting seamounts and ETOPO1 contours indicate a horizontal offset of as much as 10 km in random directions.
  3. How accurate are the heights or depths?
    Not determined.
  4. Where are the gaps in the data? What is missing?
    Complete
  5. How consistent are the relationships among the observations, including topology?
    Attributes mean the same thing throughout the data set.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
Use_Constraints:
These data are not to be used at scales greater than 1:500,000.

This information is not intended for navigational purposes.

Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data.

Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.

This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.

Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: Florence L. Wong
    Geologist, GIS Coordinator
    USGS, MailStop 999, 345 Middlefield Road
    Menlo Park, CA
    USA

    (650) 329-5327 (voice)
    (650) 329-5190 (FAX)
    fwong@usgs.gov
  2. What's the catalog number I need to order this data set? cowbsm_shp.zip
  3. What legal disclaimers am I supposed to read?
    This information is not intended for navigational purposes.
    
    
    This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
    
    
    Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: Apr-2015
Last Reviewed: Apr-2014
Metadata author:
U.S. Geological Survey (USGS) Coastal and Marine Geology (CMG)
Attn: Florence L. Wong
Geologist, GIS Coordinator
USGS, MailStop 999, 345 Middlefield Road
Menlo Park, CA
USA

(650) 329-5327 (voice)
(650) 329-5190 (FAX)
fwong@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata ("CSDGM version 2") (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/westcoast/OFR2015-1118/cowbsm_shp.faq.html>
Generated by mp version 2.9.49 on Fri Sep 13 15:01:14 2019