Serpentinization-driven evolution of the early Earth atmosphere and mantle
Abstract
The surface of the early Earth was likely covered by a thick atmosphere of CO 2 and H 2 O. Their thermal blanketing effect maintained a hot surface (Abe, 1993; Elkins-Tanton, 2008), and the subsequent evolution of the Earth is determined by how efficiently those greenhouse gases were removed from the atmosphere (Zahnle et al., 2007). The rate of removal is mostly controlled by the reactions between the mantle and the ocean-atmosphere system. Such reactions can be efficient in the Hadean if the solidification of a magma ocean results in a high-Mg# peridotite layer at the top (Miyazaki and Korenaga, 2019), which are highly reactive with CO 2 and H 2 O. Resulting serpentinization reactions could efficiently sequester CO 2 into the mantle and cool down the surface. Also, the reaction between olivine and water can release H 2 , which could result in a reducing atmospheric in the Hadean. To quantify the effect of these reactions, we model the coupled evolution of the atmosphere and mantle. Our model tracks the thermo-chemical evolutions of atmosphere using the photochemical reaction model (Ozaki et al., 2018), where the serpentinization of the mantle is also considered. We aim to explore how these reducing reactions can change the thermal and redox states of the early Earth. Such a reducing condition can provide an energy source for the first form of life and thus may be crucial for the habitability in the Hadean.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMMR51A..05M
- Keywords:
-
- 1030 Geochemical cycles;
- GEOCHEMISTRY;
- 1060 Planetary geochemistry;
- GEOCHEMISTRY;
- 3630 Experimental mineralogy and petrology;
- MINERALOGY AND PETROLOGY;
- 8409 Atmospheric effects;
- VOLCANOLOGY