http://www.vliz.be/imisdocs/publications/228699.pdf

Discrete suspended particles of barite and the barium cycle in the open ocean

An empirical correlation between marine barite (BaSO4) accumulation rate in core-top sediment samples from two equatorial Pacific transects (at 140°W and 110°W) and the estimated primary productivity of the overlying water column were used to evaluate glacial to interglacial changes in productivity. Fluctuations in barite accumulation rates down-core indicate that during glacial periods of the past 450,000 years, the productivity in the central and eastern equatorial Pacific was about two times that during intervening interglacial periods. This result is consistent with other evidence that productivity was high in the eastern and central equatorial Pacific during the last glacial.

https://science.sciencemag.org/content/sci/274/5291/1355.full.pdf

Glacial to Interglacial Fluctuations in Productivity in the Equatorial Pacific as Indicated by Marine Barite

Dymond et al. (1992) have recently proposed an algorithm to reconstruct paleoproductivity from biogenic Ba (bio-Ba) accumulation rates in sediments. Their equation is based on sediment trap data which indicate that Corg/bio-Ba ratios in settling particles are higher in the western Atlantic compared to the Pacific. From this observation they have suggested that the flux of bio-Ba to the seafloor may depend on dissolved Ba concentrations in intermediate and deep waters which are significantly higher in the Pacific compared to the Atlantic. Accordingly, they have introduced a factor related to dissolved Ba concentration in their equation as a variable which strongly influences paleoproductivity estimates. In an attempt to confirm the proposed dependency of bio-Ba fluxes to the seafloor on dissolved Ba concentrations in seawater we have compiled additional data on organic carbon and bio-Ba fluxes in the deep sea. These data confirm Dymond et al.'s findings that settling particles have significantly higher Corg/bio-Ba in the western Atlantic compared to the Pacific. However, we also found lower ratios in traps deployed in the North Atlantic, similar to those found in the Pacific, while in the Panama Basin we found ratios as high as those in the western Atlantic. From these observations we conclude that dissolved Ba concentration is not an important factor in regulating the flux of bio-Ba to the seafloor. Instead, we propose that high Corg/bio-Ba ratios found in the western Atlantic, the Panama Basin, the Arabian Sea, and some stations in the Nordic Seas result from the addition of refractory organic carbon from nearby continents, shelves, or slopes. If that is confirmed, the algorithm proposed by Dymond et al. (1992) could be simplified and could provide a powerful means to estimate paleoproductivity. In addition, deviations from the Corg/bio-Ba ratios in settling particles could be used to estimate the input of continental or shelf-derived refractory organic matter into the deep sea.

Biogenic barium fluxes to the deep sea: Implications for paleoproductivity reconstruction

Minerals in the barite (BaSO4)–celestine (SrSO4) solid solution series, (Ba,Sr)SO4, occur in a remarkably diverse range of sedimentary, metamorphic, and igneous geological environments which span geological time from the Early Archean (~3.5 Ga) to the present. The purpose of this chapter is to review: (1) the controls on the chemical and isotopic composition of barite and celestine and (2) the geological environments in which these minerals form. Some health risks are associated with barite, and these are discussed near the end of this chapter.

Although complete solid solution exists between BaSO4 and SrSO4 most representatives of the series are either distinctly Ba-rich or Sr-rich. Hence, it is convenient to use the term barite to refer to not only the stochiometric BaSO4 endmember but also to those (Ba,Sr)SO4 solid solutions dominated by Ba. Similarly, the term celestine will refer here not only to the stoichiometric SrSO4 endmember but to solid solutions dominated by Sr. Such usage is in accord with standard mineral nomenclature. The Committee on Mineral Names and Nomenclature of the International Mineralogical Association recognizes “celestine” as the official name for SrSO4. However, the name “celestite” is still commonly used in the literature.

### Geological significance of barite and celestine

Most of the barite which exists in the Earth’s crust has formed through the mixing of fluids, one containing Ba leached from silicate minerals, and the other an oxidized shallow fluid, such as seawater, which contains sulfate. Large deposits of barite represent areas of focused fluid flow and mineral precipitation and thus aid in the reconstruction of the hydrogeologic history of the Earth’s crust. The stability of barite is redox sensitive, and the presence or absence of this mineral helps to constrain interpretation of paleoredox conditions. Pelagic barite, the precipitation of which is biologically mediated, may …

A. Horowitz

Papers

Geochemistry of barium in pelagic sediments