Fault zone damage and chemical reactions at depth in the San Andreas Fault Zone: A study of SAFOD drill core samples

圣安德烈亚斯断层带深层断层带损伤和化学反应：SAFOD 钻芯样本研究

• 批准号: 116858641
• 负责人: Dr. Christoph Janssen
• 金额: --
• 依托单位: Department of Earth and Planetary Science
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/116858641?language=en
• 关键词: Fault; zone; damage; chemical; reactions

The results of the first funding period, particularly the proof of several weakening and hardening mechanisms operating in the fault gouge of four SAFOD core samples (e.g. amorphous material, nano-scale pore spaces, dissolution-precipitation processes, intracrystalline plasticity) inspired a more detailed study of microstructures in order to specify the cause of mechanical weakness along the San Andreas Fault (SAF). Therefore we applied for and received four additional core samples from different depths and different distances to the fault contact. In particular, we will focus on: • The analysis of dominant microstructures in the new SAFOD samples. Based on our previous experience we will predominantly use the transmission electron microscopy (TEM). These studies have proven to be the most powerful tool for analyzing microstructures. The cutting of foils with the focused ion beam technique (FIB) allows identifying microstructures down to the nm scale without damage. • The observed microstructures will be interpreted in view of their implication for fault weakening mechanisms integrating previous results of the core samples from the first funding period. • The observed agglomeration of flocculated clay particles in previous samples calls for further detailed TEM investigations of clay minerals. • Some vein-calcites show evidence for intense intracrystalline plasticity (deformation twins and dislocation creep). We will measure dislocation and twin densities in calcite veins in the new sample set. The results will be used for stress estimations based on paleo-piezometric relationships. • First results of stable isotope analyses of vein calcites provide indications that the fluids were dominantly derived from deeper sources. We will further analyze stable isotopes with the aim to characterize the origin of fluids penetrating the fault gouge. • Mercury porosimetry and the BET gas adsorption methods will be used to measure the connected rock porosity pore volume and pore surface areas of our new samples. Porosity data will be used to roughly estimate permeability. • SAFOD microstructures will be compared to samples recently obtained from the Taiwan Chelungpu fault Drilling Project (TCDP).

第一个供资期的结果，特别是四个SAFOD岩心样品断层泥中几种弱化和硬化机制（例如非晶材料、纳米级孔隙、溶解-沉淀过程、晶内塑性）的证据，激发了对微观结构的更详细研究，以确定圣安德烈斯断层（SAF）沿着机械弱化的原因。因此，我们申请并收到了来自不同深度和距离断层接触面不同距离的另外四个岩心样本。我们将特别关注：· 新SAFOD样品中的主要显微组织分析。根据我们以前的经验，我们将主要使用透射电子显微镜（TEM）。这些研究已被证明是分析微观结构的最有力的工具。使用聚焦离子束技术（FIB）切割箔可以识别低至nm级的微结构，而不会造成损坏。· 观察到的微观结构将被解释为故障弱化机制的影响，整合以前的结果，从第一个资助期的核心样本。· 在以前的样品中观察到的絮凝粘土颗粒的团聚要求进一步详细的粘土矿物的TEM调查。· 一些脉状方解石显示出强烈的晶内塑性（变形孪晶和位错蠕变）。我们将在新的样品组中测量方解石脉中的位错和孪晶密度。结果将用于基于古测压关系的应力估计。· 脉状方解石稳定同位素分析的初步结果表明，流体主要来自更深的来源。我们将进一步分析稳定同位素，目的是描述渗透断层泥的流体的来源。· 压汞法和BET气体吸附法将被用来测量我们的新样品的连接岩石孔隙度、孔隙体积和孔隙表面积。孔隙度数据将用于粗略估计渗透率。· SAFOD的显微结构将与最近从台湾车笼埔断层钻探计划（TCDP）获得的样品进行比较。

项目成果

Low-temperature deformation in calcite veins of SAFOD core samples (San Andreas Fault) — Microstructural analysis and implications for fault rheology

• DOI: 10.1016/j.tecto.2011.05.014
• 发表时间: 2011-08
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: E. Rybacki;C. Janssen;R. Wirth;Kai Chen;H. Wenk;D. Stromeyer;G. Dresen

Amorphous material in SAFOD core samples (San Andreas Fault): Evidence for crush‐origin pseudotachylytes?

SAFOD 岩心样本中的非晶态材料（圣安德烈亚斯断层）：压碎起源的假速水剂的证据？

• DOI: 10.1029/2009gl040993
• 发表时间: 2010
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Janssen;Rybacki;Naumann;Kemnitz;Dresen
• 通讯作者: Dresen

Faulting processes in active faults – Evidences from TCDP and SAFOD drill core samples

活动断层中的断层过程 – 来自 TCDP 和 SAFOD 钻芯样本的证据

• DOI: 10.1016/j.jsg.2014.04.004
• 发表时间: 2014
• 期刊: Journal of Structural Geology
• 影响因子: 3.1
• 作者: Janssen;Morales;Naumann;Kienast;Dresen
• 通讯作者: Dresen

Clay fabrics in SAFOD core samples

• DOI: 10.1016/j.jsg.2012.07.004
• 发表时间: 2012-10
• 期刊: Journal of Structural Geology
• 影响因子: 3.1
• 作者: C. Janssen;W. Kanitpanyacharoen;H. Wenk;R. Wirth;L. Morales;E. Rybacki;M. Kienast;G. Dresen

Mechanical twinning in quartz: Shock experiments, impact, pseudotachylites and fault breccias

• DOI: 10.1016/j.tecto.2011.06.016
• 发表时间: 2011-09
• 期刊: Tectonophysics
• 影响因子: 2.9
• 作者: H. Wenk;C. Janssen;T. Kenkmann;G. Dresen