Thickness of the chemical weathering zone and implications for erosional and climatic drivers of weathering and for carbon-cycle feedbacks
A. Joshua West, Dept. of Earth Sciences, University of Southern California, 3651 Trousdale Parkway, Los Angeles, California 90089, USA. Posted online 29 June 2012; doi: 10.1130/G33041.1.
The thin veneer at Earth's surface, known as the Critical Zone, plays host to a range of chemical reactions that are critical for generating and sustaining the resources that support life and shape the natural environment. The chemical breakdown of minerals, known as chemical weathering, is one of the most important of these chemical reactions. Until now, little has been known about where chemical weathering takes place, with soils typically thought to define the most important interface across which rocks break down chemically and physically. The analysis presented here challenges this assumption, indicating that chemical weathering takes place across a distributed zone that is often at least partly hosted in soils, but may also include bedrock, for example along fractures at depth. As a result, even landscapes with minimal soil may generate significant weathering fluxes. Moreover, because the total flux of material associated with erosion is high in these settings, they may play disproportionately important roles in global geochemical cycles. The ultimate message is that just because landscapes don't have soils doesn't mean that they aren't significant players in the global exchange between the solid rock that makes up the bulk of the Earth and the life-sustaining surface.
Origin of giant wave ripples in snowball Earth cap carbonate
Michael P. Lamb et al., Division of Geological and Planetary Sciences, California Inst
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Geological Society of America