Hypersaline brine diagenesis and evolution in the Dead Sea - Lake Lisan system (Israel)
- Hebrew Univ., Jerusalem (Israel)
Water soluble salts were extracted from 57 aragonite and detrital laminae, sampled from the Pleistocene Lake Lisan sediments. The solutions and solids were analyzed for Ca, Mg, Na, K, Sr, Cl, SO{sub 4} and bicarbonate. Average Na/Cl, Mg/Ca, Sr/Ca, Mg/Cl, Ca/Cl, Sr/Cl, K/Cl, K/Na, and K/Mg ratios, calculated for seven stratigraphic elevations in the Lisan column, indicate that the Dead Sea rift sediment/brine system has remained practically closed for 70,000 years. The soluble salts reflect both the hydrologic evolution of the lake as well as diagenetic processes. Mg/Ca ratios systematically decrease in younger sediments, and this decline is accompanied by a 1.5-4 fold Sr enrichment in aragonite solubles relative to salts extracted from detrital laminae. The major process responsible for these observations is dolomitization of Sr-rich aragonite by interstitial brine. Diagenesis was triggered by slow desiccation of the lakes sediments after the Lisan waters started to recede due to a change in climate. Very sharp chemical gradients, which developed in the sediments after deposition, have been preserved because further diagenesis was quenched by the advancing dry-out. H{sub 2}O-loss by evaporation induced diffusional migration of Na and Cl from aragonite laminae into adjacent detrital layers. This lowered the Na/Cl ratio in the aragonite and raised it in the detritus relative to the initial (Dead Sea) Na/Cl ratio of 0.26. The early Lisan brine was similar in its chemical composition and total salinity to that of the present Dead Sea.
- OSTI ID:
- 7254177
- Journal Information:
- Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 53:1; ISSN GCACA; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
Similar Records
Origin of Na-Ca-Cl brines in Jurassic and Cretaceous reservoirs of Gulf Coast
Mobile inorganic constituents in peat and their loss during diagenesis
Related Subjects
580000* -- Geosciences
ACID CARBONATES
ALKALINE EARTH METAL COMPOUNDS
ARAGONITE
BRINES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CENOZOIC ERA
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
DEAD SEA
DIAGENESIS
DOLOMITE
EVAPORATION
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGY
GROUND WATER
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INTERSTITIAL WATER
LAKES
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERALS
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PLEISTOCENE EPOCH
QUATERNARY PERIOD
SALINITY
SALTS
SOLUBILITY
STRATIGRAPHY
SULFIDES
SULFUR COMPOUNDS
SURFACE WATERS
WATER