Present-day interior structures of Mercury and Earth | © Nicola Tosi
Nicola Tosi vom DLR Berlin präsentiert seine Forschung in einem Vortrag mit dem Titel Coupled core–mantle evolution of two end-member planets: Earth and Mercury. Der Vortrag findet auf englischer Sprache statt.
Co-Host ist dieses Mal Carolin Weber.
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Coupled core–mantle evolution of two end-member planets: Earth and Mercury
Abstract
Earth and Mercury are the only terrestrial planets that currently host dynamo-generated magnetic fields, both of which have likely been active for much of their histories. Despite this similarity, their core–mantle evolution paths diverged markedly. On Earth, plate tectonics and a mobile surface enabled sustained and efficient cooling of the interior, likely since the Archean, possibly following an earlier stagnant- or sluggish-lid phase. This long-term cooling may have supported a thermally driven dynamo for billions of years. More recently, inner core nucleation introduced an additional energy source, with compositional convection associated with inner core growth powering the modern dynamo. In contrast, Mercury’s 4-billion-year-old surface indicates long-term operation in a stagnant-lid regime. Inefficient mantle cooling limited core heat loss, restricting any thermally driven dynamo to the earliest few hundred million years. The early formation and growth of a stably stratified layer at the top of the liquid core further reduced the thickness of the convecting dynamo region, making sustained dynamo action increasingly difficult and posing a major challenge for explaining Mercury’s present-day magnetic field. I will discuss the main uncertainties and challenges in reconciling magnetic field observations for Earth and Mercury with additional geological and geophysical constraints on their long-term thermal evolution, within the framework of global one-dimensional models of the coupled evolution of mantle and core.