The major-ion composition of Cenozoic seawater: the past 36 million years from fluid inclusions in marine halite

Abstract

Fluid inclusions from ten Cenozoic (Eocene-Miocene) marine halites are used to quantify the major-ion composition (Mg2+, Ca2+, K+, Na+, SO42-, and Cl-) of seawater over the past 36 My. Criteria used to determine a seawater origin of the halites include: (1) stratigraphic, sedimentologic, and paleontologic observations; (2) Br- in halite; (3) delta S-34 of sulfate minerals; (4) Sr-87/Sr-86 of carbonates and sulfates; and (5) fluid inclusion brine compositions and evaporation paths, which must overlap from geographically separated basins of the same age to confirm a "global" seawater chemical signal. © 2013, American Journal of Science.