Abstract: Very little is known of Earth’s early chemical evolution due to the paucity of preserved rocks from this period. Short-lived radionuclides provide a unique tool to probe these early periods of terrestrial evolution. The 146Sm - 142Nd short-lived chronometer with a half-life of ~100 Myr has been extensively used to study the early crust-mantle differentiation on Earth. This talk will outline the state of the art in this field with high-precision 142Nd/144Nd measurements revealing primordial differentiation of Earth to form mafic crustal reservoirs as early as 4.4 Ga. I will also discuss how an accurate determination of the nucleosynthetic makeup of material precursors of terrestrial planets is important towards the robust application of short-lived decay chronometers to investigate early planetary differentiation. Stable isotopes, in particular that of Ti, on the other hand, have recently emerged as a novel tracer for continental crust composition. I will present the Ti isotope data for a globally representative set of sedimentary rocks that show secular variations in the average upper continental crust composition, allowing us to infer the co-evolution of Earth’s tectonics, surface redox conditions, and the biosphere through deep time.

Meeting ID: 944 2649 3601
Passcode: 070134