气候变化领域集成服务门户(CCPortal): Seismic refraction tracks porosity generation and possible CO2 production at depth under a headwater catchment

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DOI	10.1073/pnas.2003451117
	Seismic refraction tracks porosity generation and possible CO2 production at depth under a headwater catchment
	Gu X.; Mavko G.; Ma L.; Oakley D.; Accardo N.; Carr B.J.; Nyblade A.A.; Brantley S.L.
发表日期	2020
ISSN	0027-8424
起始页码	18991
结束页码	18997
卷号	117 期号:32
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.
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
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/160849
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...
推荐引用方式 GB/T 7714	Gu X.,Mavko G.,Ma L.,et al. Seismic refraction tracks porosity generation and possible CO2 production at depth under a headwater catchment[J],2020,117(32).
APA	Gu X..,Mavko G..,Ma L..,Oakley D..,Accardo N..,...&Brantley S.L..(2020).Seismic refraction tracks porosity generation and possible CO2 production at depth under a headwater catchment.Proceedings of the National Academy of Sciences of the United States of America,117(32).
MLA	Gu X.,et al."Seismic refraction tracks porosity generation and possible CO2 production at depth under a headwater catchment".Proceedings of the National Academy of Sciences of the United States of America 117.32(2020).