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Estimation of alluvial-fill thickness in the Mimbres ground-water basin, New Mexico, from interpretation of isostatic residual gravity anomalies

Water-Resources Investigations Report 2002-4007

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Abstract

The geologic structure of the Mimbres ground-water basin in southwest New Mexico is characterized by north- and northwest-trending structural subbasins. Sedimentation of Miocene and Pliocene age has filled and obscured the boundaries of these subbasins and formed poten- tially productive aquifers of varied thickness. The location and depth of the subbasins can be esti- mated from analysis of isostatic residual gravity anomalies. Density contrasts of various basement lithologies generate complex regional gravity trends, which are convolved with the gravity signal from the Miocene and Pliocene alluvial fill. An iterative scheme was used to separate these regional gravity trends from the alluvial-fill grav- ity signal, which was inverted with estimated depth-density relations to compute the thickness of the alluvial fill at 1-kilometer spacing. The thickness estimates were constrained by explor- atory drill-hole information, interpreted seismic- refraction profiles, and location of bedrock lithol- ogy from surficial geologic mapping. The result- ing map of alluvial-fill thickness suggests large areas of thin alluvium that separate deep structural subbasins.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Estimation of alluvial-fill thickness in the Mimbres ground-water basin, New Mexico, from interpretation of isostatic residual gravity anomalies
Series title:
Water-Resources Investigations Report
Series number:
2002-4007
Edition:
-
Year Published:
2002
Language:
ENGLISH
Description:
15 p. : maps (some col.) ; 28 cm.