1. Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, Texas 77058, USA
2. NASA Johnson Space Center, Mail Code KR, Houston, Texas 77058, USA
3. Department of Geology, University of California Davis, One Shield Avenue, Davis, California 95616, USA

Correspondence to: V. Debaille¹ Correspondence and requests for materials should be addressed to V.D. (Email: debaille@lpi.usra.edu).

Abstract

Resolving early silicate differentiation timescales is crucial for understanding the chemical evolution and thermal histories of terrestrial planets¹. Planetary-scale magma oceans are thought to have formed during early stages of differentiation, but the longevity of such magma oceans is poorly constrained. In Mars, the absence of vigorous convection and plate tectonics has limited the scale of compositional mixing within its interior², thus preserving the early stages of planetary differentiation. The SNC (Shergotty–Nakhla–Chassigny) meteorites from Mars retain 'memory' of these events^{3, 4, 5}. Here we apply the short-lived ¹⁴⁶Sm–¹⁴²Nd and the long-lived ¹⁴⁷Sm–¹⁴³Nd chronometers to a suite of shergottites to unravel the history of early silicate differentiation in Mars. Our data are best explained by progressive crystallization of a magma ocean with a duration of 100 million years after core formation. This prolonged solidification requires the existence of a primitive thick atmosphere on Mars that reduces the cooling rate of the interior⁶.

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