HR: 16:15h
AN: PP14B-02    [Abstracts]
TI: The Use of Scanning XRF Technology in Terrestrial Paleoclimatology and Paleohydrology
AU: * Tierney, J
EM: jtierney@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, MS22, Woods Hole, MA 02543 United States
AU: Giosan, L
EM: lgiosan@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, MS22, Woods Hole, MA 02543 United States
AU: Donnelly, J P
EM: jdonnelly@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, MS22, Woods Hole, MA 02543 United States
AU: Shuman, B
EM: bshuman@umn.edu
AF: University of Minnesota, 414 Social Science Tower, Minneapolis, MN 55455 United States
AB: Traditional X-ray Fluorescence (XRF) is a commonly utilized method for discrete analysis of elemental geochemistry in sediments. The standard methodology that demands destructive collection of large subsamples and may be undesirable when a multi-proxy approach is important for the completion of study, or when high-resolution analysis of elemental signatures is imperative. One of the newest XRF technologies, the XRF core scanner, however, provides an elegant solution to such analytical dilemmas by providing rapid, high-resolution (sub-mm), and non-destructive elemental and densitometric analyses of sediment cores. Preliminary results from the new ITRAX XRF Corescanner at Woods Hole Oceanographic Institution illustrate the potential of the new technology for generating geochemical reconstructions of paleoclimatological, paleohydrological, and diagenetic conditions using sediments from both marine and terrestrial environments. Examples are drawn from inland lakes, deltas and other coastal settings, as well as river-influenced continental margins. Flood layer correlation between proximal and distal cores in the apical Danube floodplain is possible by using Si and Zr/Ti as proxies for grain size. While fine sand layers are visible in the proximal core near the levee, variations in grain size are very similar, but subtler in the distal core. Extensive and rapid spatial correlation of flood layers is possible when using the grain-size proxies and they reveal that intensive flooding occurred during the Little Ice Age. Work on lake sediments from New England shows that Ti and Fe data are strongly inversely correlated with sediment organic content. Decreases in organic content and increases in soil derived Ti and Fe and grain size likely reflect lower lake levels. Ground penetrating radar records confirm the presence of shoreline features at elevations lower than the modern shoreline that correlate with these high Ti and Fe and low organic units. At least three lowstands are evident in the early Holocene segment of the records at about 9500, 9000, and 8400 cal. years before present. Relatively shallow lakes reveal an increase in the frequency of these low organic and higher Ti and Fe units following a prominent lowstand feature around 5600 cal. years ago.
DE: 1817 Extreme events
DE: 1820 Floodplain dynamics
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4950 Paleoecology
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005