Evidence in pre-2.2 Ga paleosols for the early evolution of atmospheric oxygen and terrestrial biota: comment and reply
Article Abstract:
Interpretations of paleosol records reveal that pre 2.2 Ga paleosols were highly oxidized with minimal or zero iron loss because they were formed under an oxic atmosphere or were positively affected by algal mats which contributed to iron remobilization. Critics, however, dispute such a hypothesis because aluminum is always reduced during iron depletion as suggested by high Ti/Al ratios. Aluminum loss was not demonstrated during the iron-reduced late Archean and early Proterozoic paleosols.
Publication Name: Geology
Subject: Earth sciences
ISSN: 0091-7613
Year: 1997
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Carbonation and decarbonation of eclogites: the role of garnet
Article Abstract:
The possibility that garnet responds with carbon dioxide was explored to examine the carbonation of clinopyroxene through the reaction dolomite + 2 coesite = diopside + 2 CO2. The location of the reaction 3 magnesite + kyanite + 2 coesite = pyrope + 3 CO2 between 5 and 11 GPa in multi-anvil apparatus was identified. The carbonation of eclogitic rocks with increasing pressure reacts with clinopyroxene at the temperatures ...1200 degrees centigrade.
Publication Name: Contributions to Mineralogy and Petrology
Subject: Earth sciences
ISSN: 0010-7999
Year: 1999
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Further comments on using carbon isotopes in paleosols to estimate the CO2 content of the palaeo-atmosphere
Article Abstract:
An analysis describing the application of carbon isotopes in palaeosols for measuring atmospheric carbon dioxide is presented. Earlier research proposed the use of calcretes and principles of physical chemistry for atmospheric analysis. However, such methods present problems for analyzing ancient atmospheres. It is also shown that the validity of the diffusion-reaction model requires geochemical and palaeopedological knowledge.
Publication Name: Journal of the Geological Society
Subject: Earth sciences
ISSN: 0016-7649
Year: 1992
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