Evidence of regionally distributed tectono-volcanism in a floor fractured crater of North-Central Arabia Terra, Mars

Abstract

Arabia Terra features many tectonic structures, which have been correlated to episodes of incipient tectonics, massive impacts, and controls on fluvial systems. However, the extent of regionally distributed tectono-volcanism and its effects on local structures remains unknown. To characterize the prevalence of volcanically driven processes in this region, we investigate the geomorphic features of an unnamed ?85-km diameter and 3.6 Ga old floor-fractured crater (FFC) in North-Central Arabia Terra. Widespread crater floor rocks resemble layered sedimentary deposits. Nevertheless, the central crater floor hosts mounds and linear ridges, which have higher thermal inertia than the surroundings, indicating a provenance distinct from the sedimentary units. Crosscutting relationships suggest that the mounds and ridges are stratigraphically overlying the layered sedimentary rocks. Morphologically and morphometrically, the mounds and ridges resemble known Martian and terrestrial volcanic cone and dike systems. Unlike other FFCs of Arabia Terra, the dikes and cone azimuths consistently orient in the NW-SE direction, implying that regional tectonic controls on their formation overrode localized effects of the crater-forming impact. Our observations collectively support magma intruding and erupting along regionally controlled tectonic structures; the migration of magma was perhaps facilitated by the impact that formed the host crater. Consequently, the studied FFC may represent a category of hitherto unrecognized numerous, small-scale volcanic centers controlled by regional tectono-volcanism within Arabia Terra. This is also consistent with regionally distributed magmatic systems in the late Noachian to early Hesperian, associated with a thermally eroded crust.