Citation:
Citation_Information:
Originator: Robert P. Kucks
Publication_Date: 1999
Title:
Isostatic residual gravity anomaly data grid for the conterminous US
Online_Linkage:
Larger_Work_Citation:
Citation_Information:
Originator: Phillips, Jeffrey D.
Originator: Duval, Joseph S.
Originator: Ambroziak, Russell A.
Publication_Date: 1993
Title:
National geophysical data grids; gamma-ray, gravity, magnetic
and topographic data for the conterminous United States
Series_Information:
Series_Name: U.S. Geological Survey Digital Data Series
Issue_Identification: DDS-9
Online_Linkage: http://pubs.er.usgs.gov/publication/ds9
Description:
Abstract:
The grid of isostatic residual gravity anomaly data was produced
from the grid of Bouguer gravity anomaly data (see Bouguer gravity
metadata) by using an Airy-Heiskanen compensation model with three
parameters. The depth to the compensating root at sea level was
chosen to be 30 km. The density contrast across the root was chosen
to be 0.35 grams per cubic centimeter, and the the density of the
topography was chosen to be 2.67 grams per cubic centimeter.
Purpose:
Isostatic residual gravity anomaly maps are produced by subtracting
long-wavelength anomalies produced by masses deep within the crust
or mantle from the Bouguer anomaly map. The long-wavelength anomalies
are assumed to result from isostatic compensation of topographic loads.
Isostatic residual gravity anomaly maps therefore reveal more clearly
than Bouguer gravity anomaly maps the density distributions within
the upper crust that are of interest in many geologic and tectonic
studies.
Supplemental_Information:
Digital Data Series DDS-9 (CD-ROM) contains gridded geophysical
data (isostatic gravity anomaly data only defined here) images
generated from the data, software for displaying and analyzing
the images, software for processing potential-field geophysical
data, and documentation files that describe the data and
software.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 1998
Ending_Date: 1999
Currentness_Reference: reprocessing for SDD website
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -125
East_Bounding_Coordinate: -65
North_Bounding_Coordinate: 49
South_Bounding_Coordinate: 25
Keywords:
Theme:
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: isostatic anomaly
Theme_Keyword: gravitational field (earth)
Theme_Keyword: geophysics
Theme_Keyword: geospatial datasets
Theme:
Theme_Keyword_Thesaurus: ISO 19115 Topic Category
Theme_Keyword: geoscientificInformation
Place:
Place_Keyword_Thesaurus: none
Place_Keyword: United States
Access_Constraints: None
Use_Constraints: None
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Robert P. Kucks
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing address
Address:
Box 25046, MS 964
Denver Federal Center
City: Denver
State_or_Province: CO
Postal_Code: 80225-0046
Country: USA
Contact_Voice_Telephone: (303) 236-1405
Contact_Electronic_Mail_Address: rkucks@usgs.gov
Data_Set_Credit:
The compilation of onshore data consisted of nearly one million
Bouguer gravity anomaly values computed by using a reduction
density of 2.67 grams per cubic centimeter. The offshore
data consisted of approximately 800,000 free-air gravity
anomaly values. The isostatic calculation was produced from these
data
USGS employees: Simpson and Jachens
Native_Data_Set_Environment:
At the USGS, these data are stored in several binary gridded data
formats on UNIX and PC systems. Data have been distributed in
GEOSOFT GXF (an ASCII interchange format), Arc/Info export (e00),
and ER Mapper binary format.