Seminar

The first eon of the Earth, Hadean, is no doubt critical for its evolution towards a habitable planet and the origin of life. However, almost no petrologic record preserved for this piece of history because of the intense geological reworking. Batch experiments were conducted to simulate the interaction between the early Earth's ultramafic crust and H2O-CO2 atmosphere in order to investigate its influence on the early Earth's evolution including the minerals, the atmosphere and the ocean. Electron microscopic observations show that the secondary minerals produced in the experiments mainly include phyllosilicates, carbonates and Fe-oxide. The GC measurement showed that hydrogen and short hydrocarbons were produced in the batch experiments. The productivities of CH4, C2H6 and C3H8 positively correlated with experiment temperature. Our results imply that clay minerals and carbonates should have formed extensively in early Hadean by the intense interaction between the ultramafic rocky crust and the H2O-CO2 atmosphere. Rapid sequestration of the atmospheric CO2 caused by the precipitation of carbonates might have led to the rapid cooling of the Earth’s atmosphere and the formation of Earth’s earliest ocean. The intense interaction also lead to the abiotic formation of H2 and short hydrocarbons, which might accumulated to a relatively high concentration in the proto-atmosphere and help the early Earth keep its surface warm with a faint young Sun.