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234U/238U and δ87Sr in peat as tracers of paleosalinity in the Sacramento-San Joaquin Delta of California, USA


Publication Date


Drexler, J.Z., J. Paces, C.N. Alpers, L. Windham-Myers, L. Neymark, T. Bullen, and H.E. Taylor, 2014, 234U/238U and δ87Sr/86Sr in Peat as Tracers of Paleosalinity in the Sacramento-San Joaquin Delta of California. Applied Geochemistry 40: 164-179.


The purpose of this study was to determine the history of paleosalinity over the past 6000+ years in the Sacramento-San Joaquin Delta (the Delta), which is the innermost part of the San Francisco Estuary. We used a combination of Sr and U concentrations, δ87Sr values, and 234U/238U activity ratios (AR) in peat as proxies for tracking paleosalinity. Peat cores were collected in marshes on Browns Island, Franks Wetland, and Bacon Channel Island in the Delta. Cores were dated using 137Cs, the onset of Pb and Hg contamination from hydraulic gold mining, and 14C. A proof of concept study showed that the dominant emergent macrophyte and major component of peat in the Delta, Schoenoplectus spp., incorporates Sr and U and that the isotopic [...]


(other) :
Judith Drexler

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