Magmatic evolution of impact‐induced Martian mantle plumes and the origin of Tharsis

Abstract

[1] Tharsis province is a major center of Martian volcanic activity characterized by large gravity and topography anomalies. The origin of Tharsis is debated. One hypothesis is that the province was produced by melting associated with a mantle plume from the coremantle boundary. An alternative hypothesis is that Tharsis formed by a plume associated with an impact. Recent studies have shown that this hypothesis is plausible from a geodynamical point of view and that long-lived impact plumes might play a role in areoid evolution. In this study, the magmatic evolution of impact-induced thermochemical mantle plumes is investigated with fully three-dimensional spherical shell simulations of mantle convection. Melt volumes and emplacement rates predicted by the model can satisfy observational constraints on Tharsis development.

Modeling impact volcanism as a possible origin for the Ontong Java Plateau

“…In the impact model, mantle inherently hotter than normal is not required, so the absence of pre-eruption uplift is not a problem, and postvolcanic subsidence may be subdued. The suggestion that long-lived mantle plumes may also be triggered by large impacts (Jones et al, 2002;Elkins-Tanton et al, 2004) has now been pursued for Mars (Reese et al, 2004), and implications for comparative planetary studies are ongoing, but outside the scope of this paper.…”

An episodic slab-rollback model for the origin of the Tharsis rise on Mars: Implications for initiation of local plate subduction and final unification of a kinematically linked global plate-tectonic network on Earth

“…Melts concentrated in the downrange region, possibly induced by the directivity of the oblique impact ( Fig. 17B; e.g., Pierazzo and Melosh, 1999;Reese et al, 2004). Note that the elliptical shape of Hellas Basin was clearly created by an oblique impact (e.g., Melosh, 1989).…”

“…The lack of crustal magnetization across most of the Tharsis rise may have been caused by later thermal demagnetization related to either impact-induced crustal remelting (e.g., Acuña et al, 1999;Connerney et al, 1999;Reese et al, 2004) or magmatic accretion as a result of plume activities Lillis et al, 2009). Impact-induced demagnetization implies that the Tharsis crust www.gsapubs.org | Volume 4 | Number 6 | LITHOSPHERE is mostly an old crust formed prior to the shutdown of the Martian dynamo; it subsequently went through remelting and thermal heating during major impact in the Tharsis region when the dynamo had stopped operation.…”

“…This subduction was probably terminated shortly after its initiation because of the polarity of the subduction. This inference is based on the results of numerical modeling on the thermal effects of large impacts, which show that the region below and surrounding an impact basin is hotter than regions away from the impact site (e.g., Reese et al, 2004). This thermal structure dictates whether an impact-induced subduction is sustainable or not.…”

“…Although understanding of this large topographic feature, occupying 25% of the Martian surface, has been the focal point of several excellent syntheses (Zuber, 2001;Phillips et al, 2001;Solomon et al, 2005;Nimmo and Tanaka, 2005;Carr and Head, 2010;Golombek and Phillips, 2010), its tectonic origin remains debated. Existing models involve construction of the highland either from below (magmatic underplating-induced hotspot activity or mantle upwelling; Carr, 1974;Wise et al, 1979;Masson, 1996a, 1996b;Harder and Christensen, 1996;Baker et al, 2007;Dohm et al, 2007;Zhong, 2009) or from above (voluminous volcanic deposits induced by impacts or some forms of lithospheric deformation as inducers; Solomon and Head, 1982;Sleep, 1994;Stevenson, 2001;Reese et al, 2004;Golabek et al, 2011).…”