globalchange  > 气候变化与战略
DOI: 10.1073/pnas.2003451117
论文题名:
Seismic refraction tracks porosity generation and possible CO2 production at depth under a headwater catchment
作者: Gu X.; Mavko G.; Ma L.; Oakley D.; Accardo N.; Carr B.J.; Nyblade A.A.; Brantley S.L.
刊名: Proceedings of the National Academy of Sciences of the United States of America
ISSN: 0027-8424
出版年: 2020
卷: 117, 期:32
起始页码: 18991
结束页码: 18997
语种: 英语
Scopus关键词: carbon dioxide ; carbonic acid ; chlorite ; ground water ; mineral ; pyrite ; unclassified drug ; Article ; catchment area (hydrology) ; controlled study ; dissolution ; flow ; gas ; microbial respiration ; oxidation ; physical parameters ; porosity ; priority journal ; rock ; seismic refraction ; soil ; soil erosion ; storage ; surface property ; velocity ; weathering
英文摘要: In weathered bedrock aquifers, groundwater is stored in pores and fractures that open as rocks are exhumed and minerals interact with meteoric fluids. Little is known about this storage because geochemical and geophysical observations are limited to pits, boreholes, or outcrops or to inferences based on indirect measurements between these sites. We trained a rock physics model to borehole observations in a well-constrained ridge and valley landscape and then interpreted spatial variations in seismic refraction velocities. We discovered that P-wave velocities track where a porosity-generating reaction initiates in shale in three boreholes across the landscape. Specifically, velocities of 2.7 ± 0.2 km/s correspond with growth of porosity from dissolution of chlorite, the most reactive of the abundant minerals in the shale. In addition, sonic velocities are consistent with the presence of gas bubbles beneath the water table under valley and ridge. We attribute this gas largely to CO2 produced by 1) microbial respiration in soils as meteoric waters recharge into the subsurface and 2) the coupled carbonate dissolution and pyrite oxidation at depth in the rock. Bubbles may nucleate below the water table because waters depressurize as they flow from ridge to valley and because pores have dilated as the deep rock has been exhumed by erosion. Many of these observations are likely to also describe the weathering and flow path patterns in other headwater landscapes. Such combined geophysical and geochemical observations will help constrain models predicting flow, storage, and reaction of groundwater in bedrock systems. © 2020 National Academy of Sciences. All rights reserved.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164091
Appears in Collections:气候变化与战略

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作者单位: Gu, X., Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States, Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, United States; Mavko, G., Stanford Rock Physics Laboratory, Stanford University, Palo Alto, CA 94305, United States; Ma, L., Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States; Oakley, D., Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, United States; Accardo, N., Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States; Carr, B.J., Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, United States; Nyblade, A.A., Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States; Brantley, S.L., Department of Geosciences, Pennsylvania State University, University Park, PA 16802, United States, Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA 16802, United States

Recommended Citation:
Gu X.,Mavko G.,Ma L.,et al. Seismic refraction tracks porosity generation and possible CO2 production at depth under a headwater catchment[J]. Proceedings of the National Academy of Sciences of the United States of America,2020-01-01,117(32)
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