Collaborative Research: Expedition 322 Objective Research on Sediment-Pore Water Interactions Controlling Sediment Cementation and Deformation in the NanTroSEIZE Drilling Transect

胶结作用影响控制沉积物强度和变形的机械性能。少量的颗粒包覆水泥可以大大提高沉积物的强度。因此，即使是很小的胶结作用也可能影响盆地的固结，并控制增生边缘的变形。颗粒涂层硅水泥对菲律宾海板块沉积物物理性质的影响，因为它接近四国盆地中部和西南部的南海海槽俯冲带，以前的工作记录了深海钻探项目站点297和大洋钻探计划站点1173和1177的样品。在这些地点，散布在整个半远洋沉积物中的少量玻璃在埋葬时被改变为硅胶。凝胶覆盖颗粒接触，并抑制沉积物固结。胶结沉积物具有异常的孔隙度、地震速度和硬度。随着进一步的埋藏、构造变形的开始和温度的升高，胶结物溶解和机械破裂导致沉积物骨架的刚性急剧降低和崩溃（即孔隙度损失）。不同地点之间沉积物热历史、流体流动和孔隙水化学的差异如何控制胶结带位置和范围的变化？将具有瞬态特性的胶结单元并入边缘楔形体如何影响变形的性质和分布？为了回答这些问题，将确定IODP场地C 0011和C 0012的硅水泥分布，并将对场地C 0011、C 0012、1173和1177进行多组分反应传输建模。将确定NanTroSEIZE钻探现场C 0011和C 0012的样品的剪切波速度，以定位异常强化区域。为研究沉积物-孔隙水相互作用而选定的四个地点提供了一系列沉积物积累和热历史。这些结果将允许检查流体流速和热状态对四国盆地沉积物中二氧化硅胶结的垂直位置和程度的影响。拟议的调查解决的主要目标之一，南开海槽地震带实验（NantroSEIZE），以确定地质差异如何影响机械性能，渗透率，流体流动，孔隙压力，剪切强度，和地震破裂过程中的南开边缘。拟议的研究可能会改变我们的理解增生边缘的过程，揭示了以前低估控制楔变形。通过检查控制进入俯冲带的沉积物胶结的过程，拟议的研究具有社会意义，因为它促进了对潜在危险的孕震边缘机制的理解。变形特征通过边缘楔控制流体排出。因此，沉积物胶结和变形影响边缘水文地质和流体压力，这与应变积累和地震活动的板块界面。地震学家、地球化学家和水文地质学家将对拟议的研究感兴趣。这项工作通过资助一名研究生在新墨西哥州技术（NMT），西班牙裔服务机构，提高人力资源。拟议的项目将改善NMT用于研究和教学的设施。外展工作包括通过俄勒冈州州立大学的SMILE项目（http：//smile.oregonstate.edu/）以及COAS正在进行的成人教育项目（http：//literacyworks.org/ocean/）传播孕震区过程。此外，Pi？FS将与COSEE合作？]太平洋伙伴关系（www.coseepacificpartnerships.org）通过参加他们的一个？科学酒吧之夜h在纽波特，或讨论环太平洋地区与地震有关的过程。

Cementation affects the mechanical properties that control sediment strength and deformation. A small volume of grain coating cement can greatly increase sediment strength. Therefore, even minor cementation may affect consolidation in basins and control deformation in accretionary margins. The effects of grain-coating silica cement on the physical properties of sediment on the Philippine Sea plate as it approaches the Nankai Trough subduction zone in the central and southwestern portions of the Shikoku Basin were documented by previous work on samples from Deep Sea Drilling Project Site 297 and Ocean Drilling Program Sites 1173 and 1177. At these sites, a small amount of glass disseminated throughout hemipelagic sediment is altered to a silica gel upon burial. The gel coats grain contacts, and inhibits sediment consolidation. The cemented sediment has anomalous porosity, seismic velocity, and rigidity. With further burial, onset of tectonic deformation, and increasing temperature, cement dissolution and mechanical breakdown leads to dramatic reduction in rigidity and collapse of the sediment framework (i.e. porosity loss). How do differences in sediment thermal history, fluid flow, and pore water chemistry between sites control shifts in the location and extent of the cemented zone? How does the incorporation of cemented units with transient properties into the margin wedge influence the nature and distribution of deformation? Toward answers to these questions, the silica cement distribution at IODP Sites C0011 and C0012 will be determined, and multicomponent reactive transport modeling for Sites C0011, C0012, 1173, and 1177 will be performed. The shear-wave velocity of samples from NanTroSEIZE drilling sites C0011 and C0012 will be determined to locate regions of anomalous strengthening. The four sites selected for examining sediment-pore water interactions provide a range of sediment accumulation and thermal histories. The results will allow examination of the effects of fluid flow rate and thermal state on the vertical location and extent of silica cementation in the Shikoku Basin sediments. The proposed investigation addresses one of the main goals of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE); to determine how geologic differences affect mechanical properties, permeability, fluid flow, pore pressure, shear strength, and earthquake rupture processes within the Nankai margin. The proposed study may transform our understanding of accretionary margin processes by shedding light on a previously underappreciated control on wedge deformation. By examining processes that control cementation of sediment entering a subduction zone, the proposed research has societal relevance as it advances understanding of the mechanisms at play in potentially hazardous seismogenic margins. Deformation features control fluid drainage through a margin wedge. Therefore, sediment cementation and deformation impact margin hydrogeology and fluid pressure, which are related to strain accumulation and seismicity on the plate interface. The proposed research will be of interest to seismologists, geochemists, and hydrogeologists. This work enhances human resources by funding a graduate student at New Mexico Tech (NMT), a Hispanic-Serving Institution. The proposed project will enhance facilities used for both research and teaching at NMT. Outreach efforts include dissemination of seismogenic zone processes through The SMILE program at Oregon State University (http://smile.oregonstate.edu/), and through an ongoing Adult Education program at COAS (http://literacyworks.org/ocean/). In addition, the Pi?fs will work with the COSEE?]Pacific Partnerships (www.coseepacificpartnerships.org) by participating in one of their ?gscience pub nights?h in Newport, OR discussing earthquake related processes around the Pacific Rim.