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| Data Series 138: Nebraska, Kansas, and Oklahoma Isostatic Gravity Anomaly Map |
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The colors on this isostatic residual gravity map reflect variations in the Earth's gravity field caused primarily by lateral
variations in density in the rocks that make up the upper part of the Earth's
crust. An isostatic residual gravity grid was derived from Bouguer anomaly
data. This grid was created by removing from the Bouguer gravity grid a model
of the gravity expression caused by deficiencies in mass (compensating mass)
that supports topographic loads. The calculation of the isostatic model used
averaged digital topography, a crustal thickness of 20 km, a crustal density
of 2.67 g/cc, and a density contrast between the crust and upper mantle of
0.30 g/cc. The anomalies and patterns on the map reveal details of subsurface
geology including the location of buried faults, sedimentary basins, plutons,
and uplifted basement rocks. Positive anomalies (red colors) delineate rocks
denser than the surrounding rocks. Negative anomalies (blue colors) delineate
rocks less dense than the surrounding rocks. The displayed grid has an illumination
from the northeast.
The grids for this map in two formats are available from the data directory as neksok_iso.***
Top || NE, KS, & OK Mag || References || Crustal Team
