The Deep Mantle Subduction Flux

EAR-0309992白色这个项目的目标是估计俯冲到地幔深处的物质的不相容元素组成。俯冲到深部地幔的物质(“深地幔俯冲通量”)的组成不同于在板块边界俯冲的物质的组成(“海沟俯冲通量”)，因为这种物质的一部分进入俯冲带岩浆(“弧通量”)。由于深部地幔俯冲通量等于海沟俯冲通量减去弧通量，因此在已知海沟俯冲通量和弧通量的情况下，可以确定地幔深俯冲通量。现在已经对俯冲带过程有了足够深入的了解，并有足够的文献数据来完成这项工作。这项研究将确定8个弧的海沟俯冲、弧和深部地幔俯冲通量。将开展新的分析工作，以估计安第斯南部火山带附近俯冲的沉积物的不相容和同位素组成；否则，这项研究将利用以前在网上数据库中公布的数据。对深地幔俯冲通量的估计应允许对有关地球演化的广泛观点进行更多的定量检验，包括(1)深地幔羽流中存在循环洋壳和沉积物的命题，(2)俯冲带岩浆作用是大陆壳形成的主要机制，以及(3)沉积物俯冲是对陆壳的成分和体积的重要控制。更广泛的影响包括研究生培训(这项研究将构成一篇博士论文)和代表人数不足的群体的一名成员参与研究。

EAR-0309992WhiteThe objective of this project is to estimate the incompatible element composition of material subducted into the deep mantle. The composition of material subducted into the deep mantle (the "deep mantle subduction flux") differs from the composition of material subducted at the plate boundary (the "trench subduction flux") because some fraction of this material finds its way into subduction zone magmas ("the arc flux"). Since the deep mantle subduction flux is equal to the trench subduction flux less the arc flux, the deep mantle subduction flux can be determined if the trench subduction flux and arc fluxes are known. There is now a sufficiently advanced understanding of subduction zone processes and sufficient literature data for this to be done. This study will determine the trench subduction, arc, and deep mantle subduction fluxes for 8 arcs. New analytical work will be carried out to estimate the incompatible and isotopic composition of sediment being subducted adjacent the Andean southern volcanic zone; the study will otherwise make use of previously published data available in on-line databases. Estimates of the deep mantle subduction flux should allow more quantitative tests of broad ideas about the evolution of the Earth, including (1) the proposition that recycled oceanic crust and sediment is present in deep mantle plumes, (2) that subduction zone magmatism is the principal mechanism of the continental crust creation, and (3) that sediment subduction is an important control on the composition and volume of the continental crust. Broader impacts include graduate training (the study will constitute a doctoral dissertation) and participation of a member of an underrepresented group in research.