Part 4 - Berg - Hughes Center

following: green, red, and pink conglomeratic lithic arenites and fine- to coarse-grained,
feldspathic arenites, interbedded with red and greenish gray shales and siltstones. Lithic
arenites contain basalt, chert, quartzite, and dolomite rock fragments; plagioclase is the
predominant feldspar. The sandstones have low textural and mineralogic maturities.
Eagle Mills red beds and associated intrusive igneous rocks (diabase and basalt dikes and
sills) represent the fillings of grabens or rift basins that actively subsided during
deposition in alluvial, fluvial-deltaic, and lacustrine paleoenvironments.
Middle Jurassic (Werner, Louann)
Werner Formation
The Werner Formation unconformably overlies both the Eagle Mills and Morehouse
Formations and grades into the overlying Louann Salt; north of the limit of the salt, the
Werner is overlain unconformably by the Norphlet (Bishop, 1967). Hazzard et al. (1947)
mentioned the Werner contains a lower red bed member consisting of red shale and
sandstone, commonly conglomeratic at the base, and an upper anhydrite member of
relatively pure, dense, granular anhydrite. They reported that the members are
conformable, and that the Werner-Louann sequence represents a continuous cycle of
deposition.
The Werner anhydrite underlies the greater part of south Arkansas and is present in
north Louisiana. About 50 ft of red beds and sandstone between the Werner anhydrite
and the dark shale of the Morehouse in the A-1 Tensas Delta well is probably the
equivalent Werner red bed member. Several workers in the region have reported apparent
excessive thickness of Louann Salt as compared to the average 50 to 100 ft of underlying
Werner anhydrite (Andrews, 1960).
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