title: Geophysical imaging reveals topographic stress control of bedrock weathering.
abstract: Bedrock fracture systems facilitate weathering, allowing fresh mineral surfaces to interact with corrosive waters and biota from Earth's surface, while simultaneously promoting drainage of chemically equilibrated fluids. We show that topographic perturbations to regional stress fields explain bedrock fracture distributions, as revealed by seismic velocity and electrical resistivity surveys from three landscapes. The base of the fracture-rich zone mirrors surface topography where the ratio of horizontal compressive tectonic stresses to near-surface gravitational stresses is relatively large, and it parallels the surface topography where the ratio is relatively small. Three-dimensional stress calculations predict these results, suggesting that tectonic stresses interact with topography to influence bedrock disaggregation, groundwater flow, chemical weathering, and the depth of the "critical zone" in which many biogeochemical processes occur.
authors.affiliation: Department of Geology and Geophysics and Wyoming Center for Environmental Hydrology and Geophysics, University of Wyoming, Laramie, WY 82071, USA. jstclai4@uwyo.edu sgmoon@mit.edu.
authors.forename: J
authors.initials: J
authors.lastname: St Clair
authors.affiliation: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. jstclai4@uwyo.edu sgmoon@mit.edu.
authors.forename: S
authors.initials: S
authors.lastname: Moon
authors.affiliation: Department of Geology and Geophysics and Wyoming Center for Environmental Hydrology and Geophysics, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: W S
authors.initials: WS
authors.lastname: Holbrook
authors.affiliation: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Perron
authors.affiliation: Department of Geology and Geophysics and Wyoming Center for Environmental Hydrology and Geophysics, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Riebe
authors.affiliation: Department of Geology and Geophysics, University of Hawaii, Honolulu, HI 96822, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Martel
authors.affiliation: Department of Geology and Geophysics and Wyoming Center for Environmental Hydrology and Geophysics, University of Wyoming, Laramie, WY 82071, USA.
authors.forename: B
authors.initials: B
authors.lastname: Carr
authors.affiliation: Department of Geography and Environmental Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
authors.forename: C
authors.initials: C
authors.lastname: Harman
authors.affiliation: Hydrologic Science and Engineering Program, Colorado School of Mines, Golden, CO 80401, USA.
authors.forename: K
authors.initials: K
authors.lastname: Singha
authors.affiliation: Nicholas School of the Environment, Duke University, Durham, NC 27708, USA.
authors.forename: D deB
authors.initials: Dd
authors.lastname: Richter