Premium
The Syrtis Major volcano, Mars: A multidisciplinary approach to interpreting its magmatic evolution and structural development
Author(s) -
Lillis Robert J.,
Dufek Josef,
Kiefer Walter S.,
Black Benjamin A.,
Manga Michael,
Richardson Jacob A.,
Bleacher Jacob E.
Publication year - 2015
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1002/2014je004774
Subject(s) - geology , silicic , volcano , caldera , lava , mantle plume , geochemistry , magma , sill , mafic , mantle (geology) , petrology , magma chamber , geophysics , seismology , lithosphere , tectonics
Very weak crustal magnetic fields over the Syrtis Major volcanic complex imply almost total thermal demagnetization via magmatic intrusions over a large area less than ~4 Ga. We fit a model of these intrusions and the resulting thermal demagnetization to maps of crustal magnetic field strength at 185 km altitude. The best fits are most consistent with a “dog bone”‐shaped region of intrusive material, elongated approximately north‐south, with an area of ~350,000 km 2 and an inferred volume of ~4–19 × 10 6 km 3 . Such a large volume is best explained by a long‐lived mantle plume beneath the Syrtis edifice. A free‐air gravity anomaly high over the Syrtis Major caldera is consistent with dense mafic residue remaining at depth following crystal fractionation that produced the silicic magmas seen at the surface. The elongation of this region is consistent with ascent and north‐south emplacement of magma enabled by structures parallel to and associated with the preexisting Isidis impact basin.