Solid-state sintering can cause explosivity and seismogenic unstable sliding during dome-building eruptions

Data accompanying manuscript of the same name. The hydraulic and rheological properties of the shear zones that develop during lava dome eruptions govern the potential for explosive and seismic behavior at those volcanoes. In previous hot-pressing experiments we showed solid-state sintering can cause the crystalline gouge that fills volcanic shear zones to lose porosity and permeability and lithify on the timescale of years. We present the results of torsion experiments in which we document, for the first time, the rheological behavior of gouge at the temperature-normal stress-strain rate conditions expected in volcanic shear zones, and determine the effect of shear on the rate of solid-state sintering. Gouge sheared at 500°C, 50 or 100 MPa normal stress and 10-4 to 10-3 s-1 does not sinter, exhibits strain-independent behavior and deforms by distributed granular flow. In contrast, gouge sheared at 900°C, 50 or 100 MPa normal stress and 10-5 to 10-3 s-1 is sintered, exhibits strain-weakening behavior and shows microstructural evidence of strain localization as well as significant lithification. Samples sheared at 900°C for <1 h have measured final porosities and permeabilities comparable to gouge samples hot-pressed at the similar temperature-pressure conditions for 60 h, indicating shearing significantly enhances sintering. We use results to develop a model that can predict time-temperature-pressure-dependent densification by solid-state sintering under both static conditions and during shear. Finally, we propose that sintering-driven lithification can cause deforming shear zones to transition from aseismic stable sliding to unstable seismogenic sliding, perhaps resulting in the drumbeat seismicity observed at dome-building volcanoes. Included in data repository: - experimental log, including conditions of experiment, date, sample dimensions, UMN Paterson ID number, etc. - mechanical data for all deformation experiments - mechanical data for experiments used for jacket correction - measured porosities, determined by image analysis - BSE images used for image analysis - measured permeabilities, determined using flow-through permeameter - BSE mosaics (in power point, affinity designer, pdf files) for all samples本数据集配套同名研究论文手稿。 熔岩穹丘喷发过程中形成的剪切带，其水力与流变学特性决定了相关火山发生爆发性活动与地震活动的可能性。在既往热压实验中，我们已证实：充填于火山剪切带的结晶断层泥（crystalline gouge）可发生固态烧结（solid-state sintering），在数年尺度内丧失孔隙度（porosity）与渗透率（permeability）并发生岩化。 本研究展示了扭转实验（torsion experiments）的结果——我们首次在火山剪切带预期的温度-法向应力-应变速率（strain rate）条件下，测得断层泥的流变学行为，并明确了剪切作用对固态烧结速率的影响。在500℃、50或100 MPa法向应力、10⁻⁴至10⁻³ s⁻¹应变速率下剪切的断层泥未发生烧结，表现出应变无关行为，以分散颗粒流方式发生变形。 与之相反，在900℃、50或100 MPa法向应力、10⁻⁵至10⁻³ s⁻¹应变速率下剪切的断层泥发生了烧结，表现出应变弱化行为，同时存在应变局部化（strain localization）的微观结构证据与显著岩化现象。在900℃下剪切时长不足1小时的样品，其最终测得的孔隙度与渗透率，与在相近温压条件下热压60小时的断层泥样品相当，这表明剪切作用可显著强化固态烧结过程。 基于上述实验结果，我们构建了一个模型，可预测静态条件与剪切过程中，固态烧结导致的、依赖于时间-温度-压力的致密化过程。最后，我们提出：由烧结驱动的岩化作用可使活动剪切带从无震稳定滑动转变为不稳定发震滑动，这或许能够解释穹丘喷发型火山观测到的节律性地震活动（drumbeat seismicity）。 本数据集仓库包含以下内容： - 实验日志：包含实验条件、实验日期、样品尺寸、UMN帕特森编号（UMN Paterson ID）等信息 - 所有变形实验的力学数据 - 用于护套校正实验的力学数据 - 通过图像分析测得的孔隙度数据 - 用于图像分析的背散射电子（Back Scattered Electron, BSE）图像 - 使用渗流渗透率仪（flow-through permeameter）测得的渗透率数据 - 所有样品的背散射电子拼接图像（以PowerPoint、Affinity Designer、PDF格式存储）