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

February 1, 2003

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 potentially productive aquifers of varied thickness. The location and depth of the subbasins can be estimated 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 gravity 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 exploratory drill-hole information, interpreted seismic-refraction profiles, and location of bedrock lithology from surficial geologic mapping. The resulting map of alluvial-fill thickness suggests large areas of thin alluvium that separate deep structural subbasins.

Citation Information

Publication Year 2002
Title Estimation of alluvial-fill thickness in the Mimbres ground-water basin, New Mexico, from interpretation of isostatic residual gravity anomalies
DOI 10.3133/wri024007
Authors Charles E. Heywood
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Water-Resources Investigations Report
Series Number 2002-4007
Index ID wri024007
Record Source USGS Publications Warehouse
USGS Organization New Mexico Water Science Center