Analysis of sediments from two wind-driven upwelling systems, Guaymas and Cariaco basins, using the alkenonebased U_37^(K^' ) paleothermometer yielded high-resolution records of sea surface temperatures (SST) from 1700 to 2000 AD. The trends in the U
K'/37 index reveal steady SST increases of 1 to 2°C at both sites since...
Iron is considered to play a large role in the cycling of Si in Fe-limited regions of the ocean, but little is known about its role in Si biogeochemistry outside these areas. Here, we present published sediment trap data, new nutrient profiles and high resolution sedimentary records (Si isotopes, Biogenic...
Nitrogen isotopes are an important tool for evaluating past biogeochemical cycling from the paleoceanographic record. However, bulk sedimentary nitrogen isotope ratios, which can be determined routinely and at minimal cost, may be altered during burial and early sedimentary diagenesis, particularly outside of continental margin settings. The causes and detailed mechanisms...
Subduction zone earthquake and tsunami hazards affect tens of millions worldwide and the recurrence of these disasters can be evaluated with paleoseismic techniques, because earthquake cycles (and their supercycles) typically span many millennia. In these three chapters, I discuss a suite of analyses I use to evaluate the sedimentary record...
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Sandra G. Pa on, my mother. Her support of me has been infi nite.
Robert W. Pa
Large barite (BaSO4) structures mark cold seeps in the southern San Clemente Basin. Barium flux to San Clemente sediments is two to three times greater than fluxes measured in surrounding California Borderland basins. Analyses of sediment trap material, water column samples, sediments and pore water indicate that expected bariumbearing mineral...
New K-Ar age determinations on
basalts, basaltic andesites, and ash flow
tuffs from the central Western Cascades in
Oregon range in age from 32 to 3 Ma. The
ages decrease from west to east and with
increasing elevation. Volcanism has been
continuous throughout the evolution of the
Western Cascades, with...
Small, mountainous river systems have been increasingly studied due to their importance as sources of fluvial sediment and organic matter to the coastal ocean. Thus far, studies of small, mountainous river systems have focused on rivers with very high sediment loads. The well-studied Eel River dispersal system in northern California...
Accurately estimating the vertical flux of material reaching the seafloor from the overlying surface waters is essential for the paleoceanographic reconstruction of a wide variety of oceanic processes. Two approaches are currently being used. One consists of estimating mass accumulation rates (MAR) between dated horizons as the product of linear...