The geological history of Nili Patera, Mars

Abstract

Nili Patera is a 50 km diameter caldera at the center of the Syrtis Major Planum volcanic province.The caldera is unique among Martian volcanic terrains in hosting: (i) evidence of both effusive and explosive volcanism, (ii) hydrothermal silica, and (iii) compositional diversity from olivine-rich basalts to silica-enriched units. We have produced a new geological map using three mosaicked 18 m/pixel Context Camera digital elevation models, supplemented by Compact Remote Imaging Spectrometer for Mars Hyperspectral data. The map contextualizes these discoveries, formulating a stratigraphy in which Nili Patera formed by trapdoor collapse into a volcanotectonic depression. The distinctive bright floor of Nili Patera formed either as part of a felsic pluton, exposed during caldera formation, or as remnants of welded ignimbrite(s) associated with caldera formation-both scenarios deriving from melting in the Noachian highland basement. After caldera collapse, there were five magmatic episodes: (1) a basaltic unit in the caldera's north, (2) a silica-enriched unit and the associated Nili Tholus cone, (3) an intrusive event, forming a~300 m high elliptical dome; (4) an extrusive basaltic unit, emplaced from small cones in the east; and (5) an extreme olivine-bearing unit, formed on the western caldera ring fault. The mapping, together with evidence for hydrated materials, implies magmatic interaction with subsurface volatiles. This, in an area of elevated geothermal gradient, presents a possible habitable environment (sampled by the hydrothermal deposits). Additionally, similarities to other highland volcanoes imply similar mechanisms and thus astrobiological potential within those edifices.

The origin of life as a planetary phenomenon

“…[e.g.,(36)(37)(38)(39)(40)]. In one particularly relevant example, igneous dikes in Valles Marineris are seen crosscutting light-toned bedrock, with the possible expression of thermal alteration in adjacent contact zones [see Brustel et al (41) and their Fig.…”

Geology of central Libya Montes, Mars: Aqueous alteration history from mineralogical and morphological mapping

“… Figure 10 (Hashir MTRDR) about here Due to its composition and appearance, we favor the interpretation of Mustard et al (2007) and Tornabene et al (2008) that the caprock unit could be attributed to remnants of volcanic deposits generated from later stages of the evolution of the plume associated with Syrtis Major (Fawdon et al, 2015;Fawdon, 2016). As the primary focus of this study is on the aqueous minerals, we will not delve into further detail on the origin of this unit.…”

Quantified Aeolian Dune Changes on Mars Derived From Repeat Context Camera Images

“…Our main study area is the Nili Patera dune field (8.7°N, 67.3°E; Figure b), which contains some of the fastest known moving bedforms on Mars (~0.5–0.8 m/EY; 5–16 m 3 m −1 EY −1 ; e.g., Bridges, Ayuob, et al, ; Chojnacki et al, ). The Nili Patera dune field is found in the southwest quadrant of Nili Patera, a ~50 km wide caldera, part of the Hesperian‐aged Syrtis Major Planum volcanic complex (e.g., Fawdon et al, ). Discrete, symmetric barchan dunes (typically 200–400 m in length) with southwest trending slip faces transition into barchanoid dunes and an eventual sand sheet across the ~15 km long dune field (~425 km 2 ).…”