Collaborative Research; Studies of Channelized Flow in the Mariana Forearc: Pore Fluid Geochemistry, Sedimentology, and Heat Flow

9633688费舍尔海洋地球科学研究的一个主要重点是阐明海洋中溶解物种的全球化学质量平衡。这些计算中的一个主要不确定性是对与流经收敛边界的流体相关的通量的估计。对于某些化学物种来说，这种遗漏意义重大。在确定全球物质平衡的更好估计之前，必须确定俯冲带喷发流体的化学成分，并且必须了解形成这些流体的成岩反应。最近关于这一问题的工作主要集中在以大量俯冲沉积为特征的俯冲带。然而，在这些地区，厚层沉积物序列中的成岩反应可能会掩盖来自俯冲洋壳的流体的主要信号。目前推荐的项目将侧重于马里亚纳弧前区域的流体流动和流体化学。在这一地区，沉积物的吸积是最小的，流体流动和化学研究应该为理解来自洋壳的流体的主要化学特征提供极好的指导。远程车辆采样、水面舰船取心以及沉积物热流体和孔隙流体的测量相结合，将提供马里亚纳地区三个区域的数据，这些区域的流体似乎沿着断裂带导流。除了解决重要的科学问题外，该项目还将为该区域拟议的海洋钻探提供重要的背景信息。***

9633688 Fisher A major focus of marine geoscience research is elucidating global chemical mass balance for dissolved species in the oceans. A major uncertainty in these calculations is an estimate for fluxes associated with fluid flow through convergent margins. For some chemical species this omission is significant. Before better estimates of global mass balances can be determined, the chemical composition of venting fluids from subduction zones must be determined and the diagentic reactions that form these fluids must be understood. Recent work on this problem has focussed on subduction zones characterized by large accumulations of underthrust sediment. In such regions, however, the diagentic reactions in the thick sediment sequences may obscure the primary signal of fluids from the underthrusting ocean crust. The present recommended project will focus on fluid flow and chemistry of fluids from the Mariana forearc region. Sediment accretion is minimal in this area, and study of fluid flow and chemistry should provide an excellent guide to understanding primary chemical signature of fluids derived from the ocean crust. A combination of remote vehicle sampling, coring from surface ship, and measurements of sediment heat fluid and pore fluids will provide data from three areas in the Marianas where fluid flow appears to be channelized along fault zones. In addition to addressing significant scientific questions, the project will provide important background information for proposed ocean drilling in this region. ***