Faults in carbonate rocks show both seismic and aseismic deformation processes, leading to a wide range of slip velocities. We deformed two centimeter‐scale cores of Carrara marble at 25°C and imaged the nucleation and growth of faults using dynamic synchrotron X‐ray microtomography. The first sample experienced a constant confinement of 30 MPa and no pore fluid. The second sample experienced confinement in the range 35–23 MPa and water as a pore fluid at 10 MPa pore pressure. We increased the axial stress by steps until creep deformation occurred and imaged deformation in 4‐D. The samples deformed with a quasi‐constant or increasing strain rate when the differential stress was constant, a process called creep. However, for both samples, we also observed transient events that include the acceleration of creep, that is, creep bursts, phenomena similar to slow slip events that occur in continental active faults. During these transient creep events, strain rates increase and correlate in time with strain localization and the slow development of system‐spanning fault networks. In both samples, the acceleration of opening and shearing of microfractures accommodated creep bursts. High‐resolution time‐lapse X‐ray microtomography imaging and digital image correlation during triaxial deformation quantify creep in laboratory faults at subgrain spatial resolution. This work demonstrates that transient creep events, that is, creep bursts or slow slip events, correlate with the nucleation and slow growth of faults and not only with slip on preexisting faults.

中文翻译：

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在4D同步X射线成像三轴压缩实验中观察到的大理石蠕变爆裂与断裂共同发生

碳酸盐岩的断层同时显示出地震和地震的变形过程，从而导致了广泛的滑动速度。我们在25°C下使卡拉拉大理石的两个厘米级岩心变形，并使用动态同步X射线断层摄影术对断层的形核和生长进行了成像。第一个样品经历了30 MPa的恒定限制，并且没有孔隙流体。第二个样品在35-23 MPa的范围内受到限制，并且在10 MPa的孔隙压力下以水作为孔隙流体。我们逐步增加轴向应力，直到发生蠕变变形并在4D中成像变形为止。当压差恒定时，样品以准恒定或增加的应变率变形，这一过程称为蠕变。但是，对于这两个样本，我们还观察到了瞬态事件，其中包括蠕变的加速，即蠕变爆发，与大陆活动断层中发生的缓慢滑动事件相似的现象。在这些瞬态蠕变事件中，应变率会增加，并与应变本地化和系统跨度的故障网络的缓慢发展及时相关。在这两个样品中，微裂缝的张开和剪切加速都适应了蠕变爆发。三轴变形过程中的高分辨率延时X射线显微照相成像和数字图像相关性可量化亚粒度空间分辨率下实验室断层的蠕变。这项工作证明了瞬态蠕变事件，即蠕变爆发或缓慢滑动事件，不仅与先前存在的断层的滑动有关，而且与断层的形核和缓慢生长相关。应变率会增加，并与应变局部化以及跨系统的故障网络发展缓慢及时相关。在这两个样品中，微裂缝的张开和剪切加速都适应了蠕变爆发。三轴变形过程中的高分辨率延时X射线显微照相成像和数字图像相关性可量化亚粒度空间分辨率下实验室断层的蠕变。这项工作证明了瞬态蠕变事件，即蠕变爆发或缓慢滑动事件，不仅与先前存在的断层的滑动有关，而且与断层的形核和缓慢生长相关。应变率会增加，并与应变局部化以及跨系统的故障网络发展缓慢及时相关。在这两个样品中，微裂缝的张开和剪切加速都适应了蠕变爆发。三轴变形过程中的高分辨率延时X射线显微照相成像和数字图像相关性可量化亚粒度空间分辨率下实验室断层的蠕变。这项工作证明了瞬态蠕变事件，即蠕变爆发或缓慢滑动事件，不仅与先前存在的断层的滑动有关，而且与断层的形核和缓慢的生长相关。三轴变形过程中的高分辨率延时X射线显微照相成像和数字图像相关性可以量化亚粒度空间分辨率下实验室断层的蠕变。这项工作证明了瞬态蠕变事件，即蠕变爆发或缓慢滑动事件，不仅与先前存在的断层的滑动有关，而且与断层的形核和缓慢生长相关。三轴变形过程中的高分辨率延时X射线显微照相成像和数字图像相关性可量化亚粒度空间分辨率下实验室断层的蠕变。这项工作证明了瞬态蠕变事件，即蠕变爆发或缓慢滑动事件，不仅与先前存在的断层的滑动有关，而且与断层的形核和缓慢生长相关。