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Porosity production in weathered rock: Where volumetric strain dominates over chemical mass loss.

ABSTRACT: Weathering in the critical zone causes volumetric strain and mass loss, thereby creating subsurface porosity that is vital to overlying ecosystems. We used geochemical and geophysical measurements to quantify the relative importance of volumetric strain and mass loss---the physical and chemical components of porosity---in weathering of granitic saprolite of the southern Sierra Nevada, California, USA. Porosity and strain decrease with depth and imply that saprolite more than doubles in volume during exhumation to the surface by erosion. Chemical depletion is relatively uniform, indicating that changes in porosity are dominated by processes that cause strain with little mass loss. Strain-induced porosity production at our site may arise from root wedging, biotite weathering, frost cracking, and the opening of fractures under ambient topographic stresses. Our analysis challenges the conventional view that volumetric strain can be assumed to be negligible as a porosity-producing mechanism in saprolite.

SUBMITTER: Hayes JL

PROVIDER: S-EPMC6750914 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Porosity production in weathered rock: Where volumetric strain dominates over chemical mass loss.

Hayes Jorden L JL Riebe Clifford S CS Holbrook W Steven WS Flinchum Brady A BA Hartsough Peter C PC

Science advances 20190918 9

Weathering in the critical zone causes volumetric strain and mass loss, thereby creating subsurface porosity that is vital to overlying ecosystems. We used geochemical and geophysical measurements to quantify the relative importance of volumetric strain and mass loss---the physical and chemical components of porosity---in weathering of granitic saprolite of the southern Sierra Nevada, California, USA. Porosity and strain decrease with depth and imply that saprolite more than doubles in volume du ...[more]

PMID: 31555724

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Dataset Information

Porosity production in weathered rock: Where volumetric strain dominates over chemical mass loss.

Publications

Porosity production in weathered rock: Where volumetric strain dominates over chemical mass loss.

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