On-line Gravity and Magnetic Maps of Kansas
This page is a combination of KGS Open-file Repts.
96-51 and 97-72 by Joseph M. Kruger,
Kansas Geological Survey, Lawrence, KS
62,606 gravity-station measurements were taken by the KGS. In
eastern Kansas, the original data are spaced approximately 1 mile east-west
by 1 mile north-south. In western Kansas, the data are spaced 2 miles apart
north-south and 1 mile east-west. The data were corrected for tidal changes
and machine drift using base stations and software written at the KGS.
Topographic maps were used for location and elevation information.
After reduction to Bouguer anomoly values, the data were gridded with a
two-pass, 8-directional gridding algorithm. A second-order polynomial surface
was calculated to remove a regional westward decrease in gravity values caused
in part by thickening of the crust. The resulting second-order residual grid,
previously used in several KGS open-file reports, was brought into ER Mapper
software for analysis.
These colored images are displayed with apparent relief created by vertical
illumination. Blues represent lowest residual Bouguer gravity values;
reds represent highest residual Bouguer gravity values. Steeper gradients
are indicated by darker shading.
- Small (640 by 480 pixels) maps. Various
overlays, from 43k to 107k, JPEG images.
- Medium (1117 by 651 pixels) maps. Various
overlays, from 142k to 269k, JPEG images.
- Perspective plots. Various
overlays, from 93k to 155k, JPEG images.
- 1:2,000,000-scale maps. Various
overlays. These are large JPEG images at 300-420k.
- Compressed versions of the 1:2,000,000-scale maps. The maps have been
saved as TIFF files, compressed with ZIP.
- Compressed versions of the 1:1,000,000-scale maps. The 28 by 15
inch maps have been saved as 100 dpi TIFF files, compressed with ZIP.
Approximately 45,000 line-miles of digitally recorded aeromagnetic data
were acquired at 1/4-mile intervals along east-west flight lines spaced 2
miles apart across Kansas. North-south tie lines were flown
approximately 20 miles apart. The data were leveled using the tie lines and
a least-squares algorithm. Three elevations were used in flying over Kansas.
One jump occurs in the middle of the state and shows up as a north-south
artifact in the maps. The other elevation change, in western Kansas,
is less apparent.
The grid was reduced to the pole using inclination of 65 degrees and
declination of 7 degrees. Reduction to the pole was performed to improve the
resolution and shape of anomalies. In addition, this process roughly centers
anomalies over their causative bodies. Grids used in published and open-file
KGS maps were brought into ER Mapper software to create these images.
These colored images are displayed with apparent relief created by vertical
illumination. Blues represent lowest magnetic values;
reds represent highest magnetic values. Steeper gradients
are indicated by darker shading.
- Small (640 by 480 pixels) maps. Various
overlays, from 48k to 109k, JPEG images.
- Medium (1117 by 651 pixels) maps. Various
overlays, from 163k to 284k, JPEG images.
- Perspective plots. Various
overlays, from 118k to 174k, JPEG images.
- 1:2,000,000-scale map. Various overlays.
These are large JPEG images at 330-425k.
- Compressed versions of the 1:2,000,000-scale maps. The maps have been
saved as TIFF files, compressed with ZIP.
- Compressed versions of the 1:1,000,000-scale maps. The 28 by 15
inch maps have been saved as 100 dpi TIFF files, compressed with ZIP.
The following maps display a combination of gravity and magnetic data on one
map. In some cases, gravity data is represented by color and the magnetic
information is represented by the apparent relief shading. Other maps
with the attributes reversed are also shown.
References and related publications
- The following maps represent the data used in the images presented here..
- M-41D Aeromagnetic Map of Kansas, Reduced to a Horizontal Plane
and Reduced to the Pole, by J. Xia, R. Miller, and D. W. Steeples,
scale 1:1,000,000, 1995
- M-41E Residual Bouguer Gravity Map of Kansas, the Second-order
Regional Trend Removed, by J. Xia, R. Miller, D. W. Steeples, and
D. Adkins-Heljeson, scale 1:1,000,000, 1995
Please see the References Page for additional
publications or open-file reports concerning gravity and magnetics data of
Kansas.
For information on these KGS publications, please contact the
Publications Sales Office of
the Kansas Geological Survey.
Kansas Geological Survey, Petroleum Research Section
Updated August 25, 1997
Please send comments to webadmin@kgs.ku.edu
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