Are secular variations in seawater chemistry reflected in the compositions of basinal brines?

Jeffrey S. Hanor, Jennifer C. McIntosh

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

It has been proposed that brines in Phanerozoic sedimentary basins inherited their chemistries and salinities from evaporated paleoseawaters during times when the world oceans were Ca-rich and SO4-poor, such as the Silurian and Devonian. However, the compositions of typical Silurian and Devonian-hosted brines in the Illinois and Michigan basins show significant deviations from calculated Silurian seawater evaporation trends, reflecting instead, diagenetic control of compositions. In addition, brines in many basins show evidence for the dissolution of halite being an important source of salinity in addition to, or instead of, evaporated seawater. As long as there is halite present, generation of salinity could continue to occur long after the deposition of evaporites and the influx of evaporated seawater. Thus, even the concept of assigning an age to a basinal brine is problematic given the dynamics of fluid flow, mixing, and solute transport which can occur in sedimentary sequences.

Original languageEnglish (US)
Pages (from-to)153-156
Number of pages4
JournalJournal of Geochemical Exploration
Volume89
Issue number1-3 SPEC. ISS.
DOIs
StatePublished - Apr 1 2006
Externally publishedYes

Keywords

  • Basinal brines
  • Connate
  • Diagenesis
  • Seawater

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Economic Geology

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