--> Abstract: Geometry of Gulf Coast Aquifers, Houston-Galveston, Texas, by Charles W. Kreitler, Edgar H. Guevera, George Granata, Dawn G. McKalips; #90967 (1977).

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Abstract: Geometry of Gulf Coast Aquifers, Houston-Galveston, Texas

Charles W. Kreitler, Edgar H. Guevera, George Granata, Dawn G. McKalips

Freshwater aquifers of the Houston to Galveston area of Texas are composed of fluvial and deltaic facies of Pliocene-Pleistocene age. Sandstone geometry has been described by percent-sand maps, two maps based on genetically derived units, and four maps based on arbitrarily defined units. The Alta Loma Sand and the section above the Alta Loma Sand are the genetic units. The four arbitrary units are for the intervals 0 to 500 ft, 500 to 1,000 ft, 1,000 to 1,500 ft, and 1,500 to 2,000 ft. From the surface to 2,000-ft depth, dip-oriented trends with high percentages of sand are superposed. These trends are recognized as deltaic-distributary-channel complexes.

Aquifers are extensively cut by growth faults. A percent-sand map of the Alta Loma shows that the thickest sands are on the downthrown (coastward) side of growth faults that cut the unit. Detailed electric-log correlations across growth faults in the shallow subsurface show displacements of 50 to 100% of the thickness of individual sand beds.

Aquifer geometry affects aquifer hydrology. Sandstone geometry of the distributary channels enhances permeability in the dip direction. Fault displacement of sandstone beds, however, decreases horizontal permeability and retards recharge from stratigraphically up-dip parts of the aquifer. The stacking of distributary channels with high sand content facilitates vertical recharge or discharge.

AAPG Search and Discovery Article #90967©1977 GCAGS and GC Section SEPM 27th Annual Meeting, Austin, Texas