Year: 2025
Type: article
Abstract: We quantify the redox capacity ( d O 2 ) by redox titration—defined as the quantity of oxygen required to fully oxidize a sample—for rocks spanning Earth's upper mantle to surface sediments. The values span three orders of magnitude, with the greatest variability in metamorphic and surface rocks that host both highly reduced (rich in carbon and sulfur) and oxidized materials. In contrast, exhumed lower‐crustal and mantle rocks display more uniform values of d O 2 . This distribution reflects not a progressive net planetary oxidation, but active redox partitioning , shaped by far‐from‐equilibrium biological chemistry, surface processes, and tectonic cycling. Unlike thermodynamic potentials such as μ O 2 , the compositional variable d O 2 directly constrains the redox structure of Earth's shallow lithospheric reservoirs. This framework provides an experimentally grounded and physically intuitive metric for quantifying redox transfers and assessing their geophysical consequences.
Source: Geophysical Research Letters
DOI: 10.1029/2025gl117642
Institution: University of Lausanne
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,190
OpenAlex ID: W4417496736