Regional geohydrology of the northern Louisiana salt-dome basin; Part II, Geohydrologic maps of the Tertiary aquifers and related confining layers

Ryals, G. N.

Abstract:

Regional geohydrologic maps show the altitude of the base and the thickness of the aquifers of Tertiary age and related confining layers in the northern Louisiana salt-dome basin. The limit of freshwater in aquifers is also shown. The basin has an area of about 3,000 square miles, and four geologic units of Tertiary age contain regional aquifers. From oldest (deepest) to youngest, the aquifers are in the Wilcox Group, Carrizo Sand, Sparta Sand, and Cockfield Formation. As the Wilcox is hydraulically interconnected with the overlying Carrizo, they are treated as one hydrologic unit, the Wilcox-Carrizo aquifer. The aquifers are separated by confining layers that retard water movement. In the northwestern part of the area, the Wilcox-Carrizo aquifer is separated from the underlying sand facies of the Nacatoch Sand (Cretaceous age) by a confining layer composed of the Midway Group (Tertiary age) and the underlying Arkadelphia Marl and an upper clay and marl facies of the Nacatoch Sand (both of Cretaceous age). In the remainder of the area, the Wilcox-Carrizo aquifer is separated from an underlying Cretaceous aquifer comprised of the Tokio Formation and Brownstown Marl by the Midway Group and several underlying Cretaceous units which in order of increasing age are the Arkadelphia Maril, Nacatoch Sand, Saratoga Chalk, Marlbrook Marl , and Annona Chalk. The Wilcox-Carrizo aquifer is separated from the Sparta aquifer by the overyling Cane River Formation. The Sparta aquifer is separated from the Cockfield aquifer by the overlying Cook Mountain Formation. (USGS)

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USGS Numbered Series

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29493

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Ryals, G. N.

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ENGLISH

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iii, 6 p. :ill., maps (some col.) ;28 cm.

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U.S. Geological Survey, Water Resources Division,

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Water-Resources Investigations Report

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WRI

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83-4135

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Regional geohydrology of the northern Louisiana salt-dome basin; Part II, Geohydrologic maps of the Tertiary aquifers and related confining layers; 1984; WRI; 83-4135; Ryals, G. N.

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1984

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citation/reference

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Regional geohydrology of the northern Louisiana salt-dome basin; Part II, Geohydrologic maps of the Tertiary aquifers and related confining layers; 1984; WRI; 83-4135; Ryals, G. N.