Paleochemistry of V, Mo and Other Oxyanions as Recorded in Ferromanganese Deposits

9416602煤矿本研究将利用一种新的分析技术--激光烧蚀固体，与电感耦合等离子体质谱(LA-ICPMS)相结合，以确定锰铁矿床水合氧化铁相中一组微量元素的高分辨率剖面。目标样品范围从缓慢积累的含水结壳到快速积累的热液结壳和浅水结核，目的是研究海水中以氧离子形式存在的V、Mo和其他微量/微量元素(包括P、U、As、Se、Cr等)的古化学。尽管这些元素在地壳中的浓度可能受各种因素的影响而变得复杂，但可以假设，被氧化铁相清除的各种氧阴离子之间的比例可能与它们在海水中的古比例有关，也可能与沉积时的环境条件有关。其他元素的测定，包括稀土和232Th，将有助于解释地壳化学。将在快速形成的样品的较年轻部分确定第230年代，以完善年代学。电感耦合等离子体质谱的高灵敏度，加上激光消融的采样分辨率(约50微米)，有助于实现显著提高铁锰结壳在古海洋学研究中的效用的长期目标。

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.