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| Titel |
Paleosols and composition of the late archean atmosphere |
| VerfasserIn |
Yoram Teitler, P. Philippot, M. Gérard, F. Fluteau |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040302
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| Zusammenfassung |
| The 2.77Gy old Mount Roe basalt paleosol at Whim Creek, Pilbara craton, Western
Australia, is a reference weathering profile, used for constraining maximum concentrations of
atmospheric oxygen and greenhouse gases (CO2, CH4) during the late Archean. This
paleosol is developed at the top of a vesicular, subaerial basaltic flow exposed along two
km-scale horizons located about 5 km away from each other. It mainly consists of fresh
footwall basalt progressively grading to a 5 meters thick brecciated chloritic-rich zone
showing evidence of corestone weathering. The chloritic-rich zone is overlain by a 5 meters
thick sericitic-rich zone. Bedded-parallel deposits of diaspore/pyrophyllite containing
carbonaceous material were found in the sericite zone of the Mount Roe #2 horizon. These
deposits have already been described roughly at the same stratigraphic level in the
Mount Roe #1 horizon, about 5 km away. The origin of these deposits is not clear;
however, field observations such as the occurrence of spherical diaspore/pyrophyllite
zones within the sericite might suggest that they are preserved remains of a later
metasomatic event. Micro-mineralogy and fluid inclusions analysis are in progress in
order to test this hypothesis. Preliminary Raman spectroscopy analyses indicate
that organic matter is well preserved and did not experience high remobilisation. |
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