Evaporite diagenesis driven by synsedimentary evolution of brines
Back-reaction of brines has modified cyclic shallow water carbonate-sulfate-halite sequences (Permian) in the Palo Duro basin, Texas Panhandle. Successive parts of regressive evaporite cycles were deposited from progressively more highly evaporated seawater. The reaction of the brine with sediments deposited during earlier parts of each cycle was the major force criving diagenetic reactions and determining the final mineralogy. Normal marine limestones at the base of cycles were dolomitized in the shallow subsurface environments by brines that precipitated brine-pool evaporites in the upper parts of cycles. Gypsum dehydrated to anhydrite at burial depths of 1-2m beneath the brine-pool floor as brine salinity increased toward halite saturation. Diagenetic limpid dolomite and anhydrite replacing halite were probably derived from mixed meteoric and evaporated-marine brines squeezed from mudstone beds during compaction in the shallow subsurface. Anhydrite and halite pervasively cemented and partly replaced carbonates and gypsum. The resulting low permeability limited later diagenetic alteration, so that the early diagenetic textures and mineralogy were preserved in the burial environment. Reduction in permeability occurred before the transgression initiating the next cycle; the only major result of the introduction of seawater into the evaporite environment was dissolution of the last-deposited few meters of halite.
- OSTI ID:
- 6469496
- Report Number(s):
- CONF-880301-
- Country of Publication:
- United States
- Language:
- English
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ALKALINE EARTH METAL COMPOUNDS
ANHYDRITE
BRINES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CALCIUM SULFATES
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATE ROCKS
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EVAPORITES
EXPLORATION
FEDERAL REGION VI
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
GROUND WATER
HYDROGEN COMPOUNDS
HYDROLOGY
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
METEORIC WATER
MINERAL RESOURCES
MINERALS
NATURAL GAS DEPOSITS
NORTH AMERICA
OXYGEN COMPOUNDS
PALEOZOIC ERA
PERMIAN PERIOD
PETROGENESIS
PETROLEUM DEPOSITS
PETROLEUM GEOLOGY
RESOURCES
ROCKS
SEAWATER
SEDIMENTARY ROCKS
SEDIMENTATION
SOURCE ROCKS
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
TEXAS
USA
WATER
WATER CHEMISTRY