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Interpreting fluid pressure anomalies in shallow intraplate argillaceous formations

June 1, 2015

Investigations have revealed several instances of apparently isolated highs or lows in pore fluid potential in shallow (< ~ 1 km depth) argillaceous formations in intraplate settings. Formations with the pressure anomalies are distinguished by (1) smaller ratios of hydraulic conductivity to formation thickness and (2) smaller hydraulic (or pressure) diffusivities than those without anomalies. This is consistent with transient Darcian flow caused by strain at rates of ~ 10−17 to 10-16 s-1, by significant perturbing events in the past 104 to 106 annum or by some combination of the two. Plausible causes include erosional downwasting, tectonic strain, and glaciation. In this conceptualization the anomalies provide constraints on formation-scale flow properties, flow history, and local geological forcing in the last 106 annum and in particular indicate zones of low permeability (10−19–10−22 m2) that could be useful for isolation of nuclear waste.

Citation Information

Publication Year 2015
Title Interpreting fluid pressure anomalies in shallow intraplate argillaceous formations
DOI 10.1002/2015GL064140
Authors Christopher E. Neuzil
Publication Type Article
Publication Subtype Journal Article
Series Title Geophysical Research Letters
Series Number
Index ID 70155009
Record Source USGS Publications Warehouse
USGS Organization National Research Program - Eastern Branch

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