Nadja Drabon, Harvard
Schedule
Fri Oct 11 2024 at 02:00 pm
UTC-05:00Location
5734 S. Ellis Avenue, Chicago, IL, United States, Illinois 60637 | Chicago, IL
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Title: Hadean Zircon From South Africa: Insights Into Early Surface EnvironmentsAbstract: The early Earth remains largely enigmatic due to a paucity of a rock record from its first half-billion years, the Hadean Eon. The only physical insights into this time period derive from zircon crystals, most famously from the Jack Hills in Australia. I will talk about a new location with Hadean zircon in South Africa and elucidate how, combined with existing data from the Jack Hills and other locations, we can start constructing a framework for the Hadean Earth. Through the analysis of trace element geochemical and Hf and O isotopic data from 4.2 to 3.3-billion-year-old zircons, I will assess the evolution of the early crust, the evidence for liquid water, and the nature of mantle outgassing. Our findings indicate the formation of notably long-lived crust with mantle affinity during the early stages of Earth’s history. Oxygen isotopes in zircon confirm the presence of low-temperature fluids on Earth’s surface, increasing confidence that liquid water may have been widespread on Hadean Earth. By 4.2 Ga, the mantle oxygen fugacity was likely already similar to today, suggesting outgassing dominated by CO2, SO2, H2O and N2. While conditions may have been less conducive to prebiotic chemistry compared to the more reducing environment of the Urey-Miller experiment, the possible presence of abundant Fe2+ and a pH buffered ocean may still have facilitated amino acid production. These findings offer the possibility of a hospitable environment for life, in agreement with recent molecular clock data suggesting a Hadean origin of the Last Universal Common Ancestor.
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Where is it happening?
5734 S. Ellis Avenue, Chicago, IL, United States, Illinois 60637Event Location & Nearby Stays:
