DOI: 10.1016/j.epsl.2017.12.038
Scopus记录号: 2-s2.0-85039791804
论文题名: Unraveling the dynamics of magmatic CO2 degassing at Mammoth Mountain, California
作者: Peiffer L. ; Wanner C. ; Lewicki J.L.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 484 起始页码: 318
结束页码: 328
语种: 英语
英文关键词: CO2 degassing
; Mammoth Mountain
; monitoring
; numerical modeling
; TOUGH2
Scopus关键词: Degassing
; Gases
; Hazards
; Landforms
; Low permeability reservoirs
; Monitoring
; Numerical models
; Petroleum reservoir engineering
; Seismology
; Sensitivity analysis
; Transport properties
; Volcanoes
; Controlling current
; Fault reactivation
; Hazard mitigations
; Hydrothermal fluids
; Mammoth Mountain
; Temporal fluctuation
; Temporal variability
; TOUGH2
; Carbon dioxide
; carbon dioxide
; carbon emission
; degassing
; magma
; numerical model
; permeability
; pollution monitoring
; temporal variation
; California
; Mammoth Mountain
; United States
英文摘要: The accumulation of magmatic CO2 beneath low-permeability barriers may lead to the formation of CO2-rich gas reservoirs within volcanic systems. Such accumulation is often evidenced by high surface CO2 emissions that fluctuate over time. The temporal variability in surface degassing is believed in part to reflect a complex interplay between deep magmatic degassing and the permeability of degassing pathways. A better understanding of the dynamics of CO2 degassing is required to improve monitoring and hazards mitigation in these systems. Owing to the availability of long-term records of CO2 emissions rates and seismicity, Mammoth Mountain in California constitutes an ideal site towards such predictive understanding. Mammoth Mountain is characterized by intense soil CO2 degassing (up to ∼1000 t d−1) and tree kill areas that resulted from leakage of CO2 from a CO2-rich gas reservoir located in the upper ∼4 km. The release of CO2-rich fluids from deeper basaltic intrusions towards the reservoir induces seismicity and potentially reactivates faults connecting the reservoir to the surface. While this conceptual model is well-accepted, there is still a debate whether temporally variable surface CO2 fluxes directly reflect degassing of intrusions or variations in fault permeability. Here, we report the first large-scale numerical model of fluid and heat transport for Mammoth Mountain. We discuss processes (i) leading to the initial formation of the CO2-rich gas reservoir prior to the occurrence of high surface CO2 degassing rates and (ii) controlling current CO2 degassing at the surface. Although the modeling settings are site-specific, the key mechanisms discussed in this study are likely at play at other volcanic systems hosting CO2-rich gas reservoirs. In particular, our model results illustrate the role of convection in stripping a CO2-rich gas phase from a rising hydrothermal fluid and leading to an accumulation of a large mass of CO2 (∼107–108 t) in a shallow gas reservoir. Moreover, we show that both, short-lived (months to years) and long-lived (hundreds of years) events of magmatic fluid injection can lead to critical pressures within the reservoir and potentially trigger fault reactivation. Our sensitivity analysis suggests that observed temporal fluctuations in surface degassing are only indirectly controlled by variations in magmatic degassing and are mainly the result of temporally variable fault permeability. Finally, we suggest that long-term CO2 emission monitoring, seismic tomography and coupled thermal–hydraulic–mechanical modeling are important for CO2-related hazard mitigation. © 2017 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/110065
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Departamento de Geología, CICESE, Ensenada, B.C., Mexico; Institute of Geological Sciences, University of Bern, Bern, Switzerland; U.S. Geological Survey, Menlo Park, CA, United States
Recommended Citation:
Peiffer L.,Wanner C.,Lewicki J.L.. Unraveling the dynamics of magmatic CO2 degassing at Mammoth Mountain, California[J]. Earth and Planetary Science Letters,2018-01-01,484