Marine barite is a ubiquitous minor component of particulate matter and pelagic sediments which is relatively insoluble, thus can be used as a recorder of a variety of seawater chemical characteristics and applied to a variety of paleoceanographic studies.

The goal of the work was to evaluate the potential of marine barite as a reliable monitor of paleo-chemistry and productivity of the ocean.

After modifying a method doe quantitative separation of marine barite from sediments the research proceeded in five directions:

(1) Barite samples separated from core top sedimentsas well as from 1.5 to 35 Myr old sediments record the Sr isotopic composition of contemporaneous seawater. These results indicate that marine barite could be used for reconstruction of seawater Sr isotopic composition and for Sr isotope stratigraphy.

(2) The 226-Ra activity in marine barite shows a decay curve down-core suggesting that barite behaves as a colsed system after burial and that it could be used for estimating Holocene sedimentation rates.

(3) The degree of remineralization of Ba at the sediment-water interface was estimated by measuring pore water Ba concentrations.

(4) An empirical correlation between barite accumualtion rate in sediments and export production was established and used to determine glacial interglacial changes in export production in the Equatorial Pacific.

(5) Nd isotopes in barite were measured and compared to those expected in seawater. Results suggest that marine barite may record seawater Nd isotopes but samples need to be better purified.