oxydation-events; geochemistry; cosmochemistry; mantle-evolution
Ravindran Arathy, Mezger Klaus, Balakrishnan S., Kooijman Ellen, Schmitt Melanie, Berndt Jasper (2020), Initial 87Sr/86Sr as a sensitive tracer of Archaean crust-mantle evolution: Constraints from igneous and sedimentary rocks in the western Dharwar Craton, India, in Precambrian Research
, 337, 105523-105523.
Maltese Alessandro, Mezger Klaus (2020), The Pb isotope evolution of Bulk Silicate Earth: Constraints from its accretion and early differentiation history, in Geochimica et Cosmochimica Acta
, 271, 179-193.
Pandey Om Prakash, Mezger Klaus, Ranjan Sameer, Upadhyay Dewashish, Villa Igor M., Nägler Thomas F., Vollstaedt Hauke (2019), Genesis of the Singhbhum Craton, eastern India; implications for Archean crust-mantle evolution of the Earth, in Chemical Geology
, 512, 85-106.
Smit M.A., Scherstén A., Næraa T., Emo R.B., Scherer E.E., Sprung P., Bleeker W., Mezger K., Maltese A., Cai Y., Rasbury E.T., Whitehouse M.J. (2019), Formation of Archean continental crust constrained by boron isotopes, in Geochemical Perspectives Letters
Smit Matthijs A., Mezger Klaus (2017), Earth’s early O2 cycle suppressed by primitive continents, in Nature Geoscience
, 10(10), 788-792.
Babechuk Michael, O’Sullivan Edel, McKenna Cora, Rosca Carolina, Nägler Thomas, Schoenberg Ronny, Kamber Balz, Ultra-trace element characterization of the central Ottawa River basin using a rapid, lexible, and low-volume ICP-MS method, in Aquatic Geochemistry
One major goal of this research project will be to study distinct key events in Earth`s history that were fundamental in influencing subsequent planetary evolution that eventually led to a planet that could be geologically active, support plate tectonics, make it habitable and maintain this habitability. An essential ingredient of any habitable planet is water that exists in its liquid form at part of the time. The origin of water and other volatile components on Earth is still not understood. In this project we will study the origin of volatiles on Earth by measuring the isotopes of tin, the heaviest among the volatile elements that also has a large spread in isotope masses. This element will be studied in different types of meteorites from primitive and differentiated solar system bodies. This element will serve as a surrogate for the source and origin of volatiles in terrestrial planets. A further key event in the evolution of the Earth is the formation of extensive felsic continental crust that is concomitant with the depletion of the mantle in incompatible elements. The beginning of the major crust formation episode is some time in the Archean, but its exact timing is still quite obscure. It can be observed that the mantle derived rocks seem to indicate major mantle heterogeneity at 3.8 Ga followed by a time of a much more homogeneous mantle that becomes heterogeneous again after ca. 3.5 Ga and this degree of heterogeneity continues until today. It is not perfectly clear if this dramatic change reflects a real geologic process (i.e. homogenization of a mantle during the the Hadean and and Early Archean that was differentiated during the magma ocean stage of the Earth) or may be (partially?) due to analytical problems, particularly the back extrapolation in time of isotope ratio measurements on rocks with complex geologic histories. To study this intriguing observation it is planned to obtain high precision isotope ratio measurements on well preserved paleo-Archean rocks with a simple geologic history. Such rocks are exposed in the Singhbum Craton (India) and include mostly igneous and sedimentary rocks that were geologically unaffected since 3.2 Ga and thus belong to the most pristine paleo-Archean rock suites known. These rocks allow a precise determination of initial isotope ratios (Nd, Sr, Hf, Pb) that will yield a firm constraint on mantle heterogeneity for the time of their genesis and thus new insights into the chemical differentiation processes during the early stages of Earth`s history at a time when crustal growth seems to have accelerated significantly. Another key event and turning point in Earth`s history is the second major increase in atmospheric oxygen that appeared in the Neoproterozoic (i.e, Neoproterozoic Oxygenation Event (NOE)). The most significant current question regarding this increase is whether it was an effect or a cause of biological evolution. If ocean oxygenation at 0.8 Ga resulted from the diversification of photosynthetic life-forms, the Mo isotopic composition of microbialites will reveal a shift in the proportion of oxic to reducing Mo sinks. If the NOE represents the Earth's response to a significant modification in the supply of terrestrial weathering products to the ocean due to non-biological (i.e. geologic / tectonic) changes, elevated Mo concentration should be detected in microbialites, without concomitant variations in Mo isotopic compositions.