Rocks are continuously chemically weathered through a reaction with compounds contained in the atmosphere and in rain. As a result, rocks are dissolved, the remaining solid form soils, and continents are undergoing a slow "chemical denudation." To measure the rate of chemical denudation of Earth's surface, geochemists have used the chemical composition of the dissolved load of rivers (calcium, magnesium, potassium, sodium, silica), which transport the products of continental rock weathering to the ocean. Julien Bouchez and colleagues show how, during some weathering reactions, oxygen and hydrogen can also be released from rocks. For other types of reactions, oxygen and hydrogen can be incorporated into soils, partially compensating for chemical denudation. Therefore, oxygen and hydrogen atoms are involved in most chemical weathering reactions and thus influence chemical denudation rates. Presently, the way geochemists measure river chemical composition does not account for this fact.
Plate tectonic influences on Neoproterozoic-early Paleozoic climate and animal evolution
N. Ryan McKenzie et al., Department of Geological Sciences, Jackson School of Geosciences, University of Texas, Austin, Texas 78712, USA; email@example.com. Published online ahead of print on 6 Jan. 2014, http://dx.doi.org/10.1130/G34962.1.
The initial diversification of animals paralleled some of the most dramatic episodes of climate and environmental change in Earth history. N. Ryan McKenzie and colleagues compile global Neoproterozoic-early Paleozoic detrital zircon age data to trac
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