The Chaotic Terrains of Mercury Reveal a History of Planetary Volatile Retention and Loss in the Innermost Solar System
Rodriguez, J. Alexis P. (Planetary Science Institute (USA))
Leonard, Gregory J. (University of Arizona. Department of Planetary Sciences)
Kargel, Jeffrey S. (Planetary Science Institute (USA))
Domingue, Deborah (Planetary Science Institute (USA))
Berman, Daniel (Planetary Science Institute (USA))
Banks, Maria (NASA Goddard Space Flight Center)
Zarroca Bonet, Mario (Universitat Autònoma de Barcelona. Departament de Geologia)
Linares, Rogelio (Universitat Autònoma de Barcelona. Departament de Geologia)
Marchi, Simone (Southwest Research Institute (USA))
Baker, Victor R. (University of Arizona. Department of Hydrology and Atmospheric Sciences)
Webster, Kevin D. (Planetary Science Institute (USA))
Sykes, Mark (Planetary Science Institute (USA))

Data:	2020
Resum:	Mercury's images obtained by the 1974 Mariner 10 flybys show extensive cratered landscapes degraded into vast knob fields, known as chaotic terrain (AKA hilly and lineated terrain). For nearly half a century, it was considered that these terrains formed due to catastrophic quakes and ejecta fallout produced by the antipodal Caloris basin impact. Here, we present the terrains' first geologic examination based on higher spatial resolution MESSENGER (MErcury Surface Space ENvironment GEochemistry and Ranging) imagery and laser altimeter topography. Our surface age determinations indicate that their development persisted until ~1. 8 Ga, or ~2 Gyrs after the Caloris basin formed. Furthermore, we identified multiple chaotic terrains with no antipodal impact basins; hence a new geological explanation is needed. Our examination of the Caloris basin's antipodal chaotic terrain reveals multi-kilometer surface elevation losses and widespread landform retention, indicating an origin due to major, gradual collapse of a volatile-rich layer. Crater interior plains, possibly lavas, share the chaotic terrains' age, suggesting a development associated with a geothermal disturbance above intrusive magma bodies, which best explains their regionality and the enormity of the apparent volume losses involved in their development. Furthermore, evidence of localized, surficial collapse, might reflect a complementary, and perhaps longer lasting, devolatilization history by solar heating.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Geomorphology ; Inner planets
Publicat a:	Scientific reports, Vol. 10 (March 2020) , art. 4737, ISSN 2045-2322

DOI: 10.1038/s41598-020-59885-5
PMID: 32179758

14 p, 7.7 MB

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