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

[633415 . Fryer]海洋地球科学研究的一个主要焦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，一个主要的不确定性是对通过收敛边缘的流体流动的通量的估计。对于某些化学物质，这种遗漏是很重要的。在更好地估计全球质量平衡之前，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。最近对这一问题的研究主要集中在俯冲带，其特征是逆冲下沉积物的大量堆积。然而，在这些地区，厚沉积层序中的成岩反应可能掩盖了逆冲下洋壳流体的主要信号。目前建议的项目将侧重于来自马里亚纳弧前区域的流体流动和流体化学。该地区的沉积物沉积极少，流体流动和化学研究将为理解海洋地壳流体的主要化学特征提供良好的指导。远程车辆采样、水面船舶取心、沉积物热流体和孔隙流体测量相结合，将提供来自马里亚纳三个地区的数据，这些地区的流体流动似乎是沿着断裂带通道化的。除了解决重要的科学问题外，该项目还将为该地区拟议的海洋钻探提供重要的背景信息。＊＊＊

9633415 Fryer 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. ***