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The AAPG/Datapages Combined Publications Database

GCAGS Transactions

Abstract


Gulf Coast Association of Geological Societies Transactions
Vol. 44 (1994), Pages 217-224

Controls on the Deposition of Bedded Halite within the Haynesville Formation, Champion-Klepac No. 1 Core, Southwestern Alabama

Rachel A. Eustice, Lynton S. Land

ABSTRACT

The Upper Jurassic Haynesville Formation in the Champion-Klepac No. 1 core, Clarke County, southwestern Alabama, is a cyclic, bedded halite deposit that was deposited in three distinct depositional environments. In ascending tratigraphic order, these environments are (1) 125 ft (38 m) of stacked shallow-water, chevron-dominated salt pans, (2) two cumulate halite units, 140 ft (44.5 m) and 52 ft (16 m) thick, deposited in deeper coastal salinas, and (3) 440 ft (134 m) of intercalated evaporites and siliciclastics deposited in a series of muddy salt pans and siliciclastic sabkhas.

Within the basal 265 ft (82.5 m) of halite (chevron and lower cumulate facies), bromide concentrations rise systematically from 56 to 440 ppm, reflecting an increase in evaporative concentration and the incorporation of solutes from dense, pre-concentrated brines into the brine pans. 87Sr/86Sr through these two zones increase from the 87Sr/86Sr of coeval seawater (0.7067) near the base of the salt to 0.7084 in the cumulate zone. The radiogenic 87Sr/86Sr cannot be explained unless a source of radiogenic Sr is involved other than the input of radiogenic meteoric water into the system. Above this zone, bromide concentrations fall from 359 to 53 ppm, and then stabilize at approximately 85 ppm, indicating increased recycling of solutes (dissolution of preexisting salts) and precipitation from less evaporated brines. The 87Sr/86Sr of these deposits ranges from 0.7070 to 0.7074, consistent with the addition of radiogenic Sr from meteoric water and siliciclastics to evaporated Late Jurassic Kimmeridgian seawater.


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