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

合作研究：Expedition 322 沉积物与孔隙水相互作用的客观研究控制 NanTroSEIZE 钻探断面的沉积物胶结和变形

• 批准号: 1059924
• 负责人: Marta Torres
• 金额: $ 13.65万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1059924&HistoricalAwards=false
• 关键词: Collaborative; Research; Expedition; 322; Objective

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.

胶结作用影响控制沉积物强度和变形的机械特性。少量的颗粒涂层水泥可以大大增加沉积物的强度。因此，即使是轻微的胶结作用也可能影响盆地固结并控制增生边缘的变形。先前对深海钻探项目现场样本的研究记录了当菲律宾海板块接近四国盆地中部和西南部的南海海槽俯冲带时，颗粒涂层硅水泥对菲律宾海板块沉积物物理性质的影响297 和海洋钻探计划站点 1173 和 1177。在这些站点，散布在半远洋沉积物中的少量玻璃在埋葬。凝胶覆盖颗粒接触面，并抑制沉积物固结。胶结沉积物具有异常孔隙度、地震速度和刚性。随着进一步埋藏、构造变形的开始和温度的升高，胶结物溶解和机械分解导致沉积物框架的刚性和塌陷（即孔隙度损失）急剧下降。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纳入边缘楔块如何影响变形的性质和分布？为了回答这些问题，将确定 IODP 站点 C0011 和 C0012 的硅水泥分布，并对站点 C0011、C0012、1173 和 1177 进行多组分反应输运建模。将确定来自 NanTroSEIZE 钻探地点 C0011 和 C0012 的样品的剪切波速度，以定位异常强化区域。选择用于研究沉积物-孔隙水相互作用的四个地点提供了一系列沉积物积累和热历史。这些结果将有助于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。拟议的调查涉及南海海槽地震带实验（NanTroSEIZE）的主要目标之一；确定地质差异如何影响南开边缘内的力学特性、渗透率、流体流动、孔隙压力、剪切强度和地震破裂过程。这项研究可能会通过揭示先前未被充分认识的楔形变形控制来改变我们对增生边缘过程的理解。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，因为它增进了对潜在危险的地震边缘发挥作用的机制的理解。变形特征控制通过边缘楔块的流体排出。因此，沉积物胶结和变形影响边缘水文地质和流体压力，而这些与板块界面上的应变积累和地震活动有关。拟议的研究将引起地震学家、地球化学家和水文地质学家的兴趣。这项工作通过资助西班牙裔服务机构新墨西哥理工学院 (NMT) 的一名研究生来增强人力资源。拟议的项目将增强 NMT 用于研究和教学的设施。外展工作包括通过俄勒冈州立大学的 SMILE 计划 (http://smile.oregonstate.edu/) 以及 COAS 正在进行的成人教育计划 (http://literacyworks.org/ocean/) 传播地震带过程。 。此外，Pi?fs 将与 COSEE?]Pacific Partnerships (www.coseepacificpartnerships.org) 合作，参加他们在俄勒冈州纽波特举办的一场“gscience 酒吧之夜”活动，讨论环太平洋地区地震相关过程。