Chemistry of fluid inclusions in halite from the Salina group of the Michigan basin: Implications for Late Silurian seawater and the origin of sedimentary brines

Journal Article · Thu Feb 01 04:00:00 EST 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90321-B· OSTI ID:6991233

Das, N; Horita, J; Holland, H D ^[1]

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1. Harvard Univ., Cambridge, MA (USA)

Fluid was extracted from 18 fluid inclusions in halite of the Late Silurian Salina Group exposed in the Crystal Mine on the outskirts of Detroit, Michigan. Compared with modern seawater evaporated to the same degree, the inclusion fluids are severely depleted in SO{sub 4}{sup {minus}2}, somewhat depleted in Na{sup +} and Mg{sup +2}, and greatly enriched in Ca{sup +2}. The composition of the inclusion fluids can be derived from Silurian seawater with a composition close to that of modern seawater, if it is assumed that the composition of the Silurian seawater was modified by dolomitizing CaCO{sub 3}-rich sediments and by albitizing silicate minerals during its evolution into evaporite brines. Since the evolution of the brines involved a number of chemical reactions, it is impossible to recover the initial concentration of all of the major ions in the parent Silurian seawater from the composition of the inclusion fluids alone. It is likely, however, that the m{sub K+}/m{sub Br-} ratio and the functions in Late Silurian seawater had values close to those of modern seawater. Measurements of the isotopic composition of sulfur and of Sr in anhydrite within and associated with the halite host of the fluid inclusions are consistent with previous measurements of {delta}{sup 34}S in Silurian marine anhydrites and with the {sup 87}Sr/{sup 86}Sr ratios of Late Silurian marine carbonates.

• OSTI ID: 6991233
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 54:2; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
BRINES
CHEMICAL COMPOSITION
CHEMISTRY
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
HALIDE MINERALS
HALITE
HYDROGEN COMPOUNDS
INCLUSIONS
ISOTOPE RATIO
MINERALS
ORIGIN
OXYGEN COMPOUNDS
PALEOZOIC ERA
SALT DEPOSITS
SEAWATER
SEDIMENTARY BASINS
SILURIAN PERIOD
SULFATES
SULFUR COMPOUNDS
WATER