气候变化领域集成服务门户(CCPortal): Fluid Influx Promotes Local Strengthening of the Creeping Xianshuihe Fault, Eastern Tibet

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DOI	10.1029/2023JB026682
	Fluid Influx Promotes Local Strengthening of the Creeping Xianshuihe Fault, Eastern Tibet
	Wu, Qiong; Li, Haibing; Chevalier, Marie-Luce; Si, Jialiang; Pan, Jiawei; Li, Chunrui; Li, Yalin
发表日期	2023
ISSN	2169-9313
EISSN	2169-9356
卷号	128 期号:7
英文摘要	While the Xianshuihe fault displays continuous creeping behavior, it is also the most seismically active fault in the eastern Tibetan Plateau, and its earthquake mechanisms remain unclear. Here, we aim at the stick-slip portion of the creeping Qianning segment of the Xianshuihe fault to determine the characteristics of fault rocks and how fluids at depth influence fault behavior. Field survey, optical and scanning electron microscope observations, X-ray diffraction and fluorescence analyses, as well as carbon and oxygen isotope analyses were performed on the collected samples. The fault core consists of 3-5 cm-thick black fault gouge and similar to 2.5 m-thick breccia, surrounded by similar to 12 m damage zone. In contrast to fault breccia (1-8 cm in diameter), the black fault gouge, which represents the principal slip zone of repeated seismic events, contains angular quartz particles (similar to 10 mu m on average) and clays dominated by illite. The fluid-rock interactions altering silica minerals into illite, and the thermal decomposition of carbonate minerals, passively increase the relative content of quartz and feldspar (total 63%-73%) in the fault gouge. The deeply sourced CO2 (from mantle and metamorphic degassing) within the hydrothermal fluids causes carbonate precipitation in breccias (21%-53%), composed of calcite, dolomite, and aragonite. These fluid-assisted reactions lead to more abundant strong mineral phases (quartz, feldspar, and carbonates, 64%-87%) than weak clays (12%-36%) within the fault core, and locally strengthen the fault, which inhibits slow release of stress at shallow depth and promotes seismic rupture of the fault. Plain Language Summary Large earthquakes are less likely to occur along active faults with slow slip that can release tectonic stress continuously (thus called creeping fault). However, numerous large earthquakes still occur along a typical creeping section of the Xianshuihe fault in eastern Tibet. Here, we better constrain the structural, mineralogical, and geochemical properties of fault rocks formed by earthquakes in the creeping Qianning segment of the Xianshuihe fault to understand its earthquake mechanism. The study outcrop consists of 3-5 cm-thick black fault gouge, similar to 2.5 m-thick breccia, and similar to 12 m damage zone. Intense fluid-assisted alteration of silica minerals and thermal decomposition of carbonate minerals result in the passive enrichment of quartz and feldspar (total 63%-73%) in the black fault gouge. The fault breccia contains abundant carbonate minerals (21%-53%), resulting from carbonate precipitation associated with the influx of hydrothermal fluids enriched in CO2 at depth. Therefore, these fluid-assisted chemical reactions lead to more abundant strong mineral phases (quartz, feldspar, and carbonates, 64%-87%) than weak clays (12%-36%) within the fault core, which locally strengthen the fault and promote the occurrence of earthquakes on this creeping fault.
英文关键词	VELOCITY FRICTION EXPERIMENTS; GUANXIAN-ANXIAN FAULT; CRACK SEAL VEIN; WENCHUAN EARTHQUAKE; INTERNAL STRUCTURE; ROCK INTERACTION; SEISMIC SLIP; THERMAL PRESSURIZATION; PRESSURE SOLUTION; WESTERN SICHUAN
WOS研究方向	Geochemistry & Geophysics
WOS记录号	WOS:001018744500001
来源期刊	JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283172
作者单位	China Geological Survey; Institute of Geology, Chinese Academy of Geological Sciences; Ministry of Natural Resources of the People's Republic of China; Chinese Academy of Geological Sciences; China University of Geosciences - Beijing; Southern Marine Science & Engineering Guangdong Laboratory; Southern Marine Science & Engineering Guangdong Laboratory (Guangzhou)
推荐引用方式 GB/T 7714	Wu, Qiong,Li, Haibing,Chevalier, Marie-Luce,et al. Fluid Influx Promotes Local Strengthening of the Creeping Xianshuihe Fault, Eastern Tibet[J],2023,128(7).
APA	Wu, Qiong.,Li, Haibing.,Chevalier, Marie-Luce.,Si, Jialiang.,Pan, Jiawei.,...&Li, Yalin.(2023).Fluid Influx Promotes Local Strengthening of the Creeping Xianshuihe Fault, Eastern Tibet.JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH,128(7).
MLA	Wu, Qiong,et al."Fluid Influx Promotes Local Strengthening of the Creeping Xianshuihe Fault, Eastern Tibet".JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 128.7(2023).