Mars's Crustal and Volcanic Structure Explained by Southern Giant Impact and Resulting Mantle Depletion

Mars features a crustal dichotomy, with its southern hemisphere covered by a thicker basaltic crust than its northern hemisphere. Additionally, the planet displays geologically recent volcanism only in its low latitude regions. Previous giant impact models coupled with simulations of mantle convecti...

Full description

Saved in:

Bibliographic Details
Published in:	Geophysical research letters Vol. 51; no. 6
Main Authors:	Cheng, K. W., Rozel, A. B., Golabek, G. J., Ballantyne, H. A., Jutzi, M., Tackley, P. J.
Format:	Journal Article
Language:	English
Published:	Washington John Wiley & Sons, Inc 28-03-2024 Wiley
Subjects:	Convection Crystallization Depletion Equator Equatorial regions geodynamical modeling giant impact Impact melts Lava Magma Mantle convection Mars Mars volcanoes Martian dichotomy Mathematical models Northern Hemisphere Numerical models Planetary mantles Ponds Residues Southern Hemisphere Volcanic activity Volcanism Volcanoes
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Mars features a crustal dichotomy, with its southern hemisphere covered by a thicker basaltic crust than its northern hemisphere. Additionally, the planet displays geologically recent volcanism only in its low latitude regions. Previous giant impact models coupled with simulations of mantle convection have shown that the crustal dichotomy can be explained by post‐impact melt crystallization that emplaced a thick crust in the southern hemisphere. In this study, we show that the depleted residue left behind by the original post‐impact crustal formation can spread laterally, potentially persisting beneath the northern hemisphere to the present‐day. Such a large‐scale mantle province would concurrently explain both the prevalence of long‐term magmatism on Mars and its strong preference for localized equatorial regions. Plain Language Summary Mars has a thicker crust in the southern hemisphere than in the north hemisphere, this difference is named the Martian dichotomy. Various theories have been suggested in order to explain its origin. We focus in the present study on a southern giant impact hypothesis. By using numerical models, we study the fate of a magma pond that is created by a giant impact. As this pond cools, a crust is formed on the top, leaving behind a residue at depth. We show that this residue can spread below the crust to the opposite hemisphere of the planet, that is, the northern hemisphere. We show that this causes, additionally to the dichotomy, also a north‐south difference in both the thermal and compositional structure of the interior of Mars. The advantage of our model is that it can concurrently explain the Martian dichotomy and the location of large and small martian volcanoes near the equator. Key Points Mantle convection modeling is performed to study the consequence of a giant impact until present day A thick crust is formed on the impacted hemisphere, suggesting a southern giant impact origin for the Martian crustal dichotomy Long‐lived melting produced preferentially at low‐latitude region in our models can explain the observed Martian volcanism
ISSN:	0094-8276 1944-8007
DOI:	10.1029/2023GL105910