The Deep Mantle Subduction Flux

该项目的目的是估计俯冲到深部地幔的物质的不相容元素组成。俯冲到深地幔的物质组成（“深地幔俯冲通量”）不同于在板块边界俯冲的物质组成（“海沟俯冲通量”），因为这些物质的一部分会进入俯冲带的岩浆（“弧通量”）。由于深地幔俯冲通量等于海沟俯冲通量减去弧通量，所以只要知道海沟俯冲通量和弧通量，就可以确定深地幔俯冲通量。现在对俯冲带的过程有了足够深入的了解，并有足够的文献资料来完成这一工作。本研究将确定8个弧的海沟俯冲、弧和深地幔俯冲通量。将开展新的分析工作，估计安第斯南部火山带附近俯冲沉积物的不相容成分和同位素组成；除此之外，这项研究将利用联机数据库中以前发表的数据。对深地幔俯冲通量的估计应该允许对关于地球演化的广泛观点进行更多的定量检验，包括：(1)在深地幔柱中存在回收的海洋地壳和沉积物的主张，(2)俯冲带岩浆活动是大陆地壳形成的主要机制，(3)沉积物俯冲是对大陆地壳组成和体积的重要控制。更广泛的影响包括研究生培训（该研究将构成一篇博士论文）和研究中代表性不足的群体成员的参与。

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.