9416602 COLLIER This study will make use of a new analytical technique, Laser Ablation of solids, integrated with an Inductively-Coupled Plasma Mass Spectrometer (LA-ICP-MS) to determine high-resolution profiles of a group of trace elements in the hydrous iron oxide phases of ferromanganese deposits. Target samples range from slowly accumulating hydrogenous crusts to rapidly accumulating hydrothermal crusts and shallow-water nodules with the goal to study the paleochemistry of V, Mo and other minor/trace elements present in seawater as oxyanions (including P, U, As, Se, Cr, and others). Although the concentration of these elements in the crust may be complicated by a variety of factors it is hypothesized that the ratios between various oxyanions scavenged by the iron oxide phases can be related to their paleo-ratios in seawater and possibly to environmental conditions at the time of deposition. The determination of other elements, including REEs and 232Th, will aid in the interpretation of crust chemistry. 230Th will be determined in the younger portions of rapidly-formed samples in order to refine chronologies. The high sensitivity of the ICP-MS, coupled with the sampling resolution of laser ablation (approximately 50 um) contribute to the long-term goal of significantly improving the utility of ferromanganese crusts for paleoceanographic studies.
