Collaborative Research: 10Be and 9Be in Volcanic Arc Lavas: Investigation of Sediment Recycling

最近对不同地质环境中的Be-10In~250火山岩的测量表明，年轻的近地表海洋沉积物被俯冲并并入千岛、阿留申、中美洲、秘鲁-智利和新不列颠弧区的弧岩浆中。BE-10数据与会聚边缘的地球物理和构造研究相结合表明，沉淀物可能在俯冲板块的地块中俯冲，因为在远洋沉积物厚度近似等于下降盆地的垂直位移的地方，Be-10弧状熔岩的浓度最高。宾夕法尼亚大学加速器最近的改进使较小样本的分析更加准确，卡内基大学最近获得的I.C.P.光谱仪使Be-9的测量成为可能。该项目将测量矿物分离物、新的火山弧熔岩和现有样品的子集的Be-10/Be-9比值和锶、钕和铅同位素组成。在可能的情况下，将把结果与其他地球化学研究结合起来，并在地球物理研究的范围内加以评价，以便得出火山弧沉积物俯冲和再循环的综合模式。

Recent measurements of Be-10 in ~250 volcanic rocks from various geologic settings indicate that that young, near-surface oceanic sediments are subducted and incorporated in arc magmas in the Kurile, Aleutian, Central America, Peru-Chile and New Britain arcs. Integration of Be-10 data with geophysical and structural studies of convergent margins suggests that sedfiments may be subducted in grabens in the subducting plate, as Be-10 concentrations an arc lavas are highest where the pelagic sediment thickness approximately equals vertical displacement of the down- dropped basins. Recent improvements in the University of Pennsylvania accelerator permit smaller samples to be analyzed more precisely, and the recent acqusition of an I.C.P. spectrometer at Carnegie permits measurement of Be-9. This project is to measure Be-10/Be-9 ratios and Sr, Nd and Pb isotopic compositions for mineral seperates, new volcanic arc lavas, and a subset of the existing sample collection. Wherever possible results will be combined with other geochemical studies and evaluated in the context of geophysical studies in order to arrive at an integrated model of sediment subduction and recycling at volcanic arcs.