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

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。在这些计算中的一个主要的不确定性是通过收敛边缘的流体流动相关的通量的估计。对于某些化学物质而言，这一遗漏意义重大。在更好地估计全球物质平衡之前，必须确定俯冲带的喷发流体的化学成分，并了解形成这些流体的成岩反应。最近关于这个问题的工作集中在俯冲带，其特征是大量的俯冲带沉积物的积累。然而，在这些区域，厚沉积物序列中的成岩反应可能会掩盖来自下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。这一区域的沉积物堆积极少，对流体流动和化学性质的研究应能为了解来自洋壳的流体的主要化学特征提供很好的指导。 远程车辆采样，从水面船上取芯，沉积物热流体和孔隙流体的测量相结合，将提供数据，从三个地区在马里亚纳群岛的流体流动似乎是渠道化沿着断层带。除了解决重要的科学问题外，该项目还将为拟议在该区域进行的海洋钻探提供重要的背景资料。 ***

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. ***