Identification and mapping of dikes with relatively primitive compositions in Thaumasia Planum on Mars: Implications for Tharsis volcanism and the opening of Valles Marineris

Abstract

[1] We have identified several exposed dikes in Thaumasia Planum Mars using THEMIS, CTX, HiRISE and CRISM data. These dikes extend from tens to $100 kilometers in length with average widths of $50 m. They display classic 'en echelon' patterns while cross-cutting preexisting geologic features, including extensive wrinkle ridges. Both the dikes and associated fissure eruption products have very blocky morphologies with $38% higher thermal inertia than the surrounding regions. The dikes are all enriched in Mgrich olivine relative to surrounding terrain, and a subset also contains elevated high-calcium pyroxene, both of which indicate relatively primitive magma compositions. We propose that these dikes might have served as feeders for the olivine-enriched flood basalts in this region, and may be derived from the Tharsis plume. These observations provide further evidence that the opening of Valles Marineris was facilitated by tectonic stresses following paths of preferential weakness along preexisting structures such as fractures and faults like those indicated by these dikes.

Revised CRISM spectral parameters and summary products based on the currently detected mineral diversity on Mars

“…Although the feature extends across the CRISM VNIR‐IR detector boundary, longward of 1.5 µm olivine spectra is relatively featureless (Figure 2). Olivine has been detected where Noachian‐aged materials are exposed in early Hesperian crater floors and intercrater plains in the southern highlands [ Rogers and Fergason , 2011], in the basin ring massifs and ejecta of the Argyre, Hellas, and Isidis basins [ Hoefen et al ., 2003; Tornabene et al ., 2008; Mustard et al ., 2009; Bishop et al ., 2013], in intercrater dunes, ejecta, and deposits in the northern plains where subjacent Noachian rocks have been exposed [ Poulet et al ., 2007], in sands and bedrock material on the floor of Valles Marineris [ Edwards et al ., 2008], in isolated blocks surrounding Hellas basin [ Ody et al ., 2013], and in dikes in several locations including the walls of Valles Marineris [ Flahaut et al ., 2011], in Thaumasia Planum [ Huang et al ., 2012], and near the dichotomy boundary [ Pan and Ehlmann , 2014].…”

Subsurface Geometry and Emplacement Conditions of a Giant Dike System in Elysium Fossae, Mars

“…Other possible dike outcrops have been found as exposures in canyon walls in Valles Marineris, and in the uplifted regions of Thaumasia. At both locations, spectroscopy data from the CRISM instrument has allowed the identification of long linear bands of olivine‐pyroxene‐rich rocks (Flahaut et al., 2011; Huang et al., 2012; Viviano‐Beck et al., 2017). The most likely interpretation for these structures is that they are exposed dikes.…”

“…The two volcanic provinces of Tharsis and Elysium show multitude of large volcanoes, smaller shield edifices, unrooted cones, lava flows, and volcanic plains of a wide range of ages (Greeley et al., 2000; Hartmann & Berman, 2000; Head & Wilson, 1994; Jaeger et al., 2010; Werner, 2009). In recent years, direct and indirect evidence of dike systems on Mars has been found (Flahaut et al., 2011; Head et al., 2003; Huang et al., 2012; Plescia, 2003). Field, geomatics, and seismic data on Earth show that dike emplacement is associated with the development of long, narrow v‐shaped cracks and flat‐floor grabens (Mastin & Pollard, 1998; Rubin, 1992; Rubin & Pollard, 1988).…”

Carbonate and Silicate Minerals in a Gullied Crater within Eridania Basin, Terra Sirenum, Mars

“…Observatoire pour la Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) spectrometer onboard the Mars Express spacecraft (e.g., Bibring et al, 2005;Bibring et al, 2006, Mustard et al, 2005, as well as with the CRISM instrument (e.g., Huang et al, 2012). The minerals are predominantly found in "dark sand and crater ejecta" within basalt-rich areas (Bibring et al, 2005), such as lava flows, and shy away from the younger, Northern Lowland areas (Bibring et al, 2006).…”

“…Recent lava flows also demonstrate an HCP-LCP mixture, such as the Hesperian Syrtis Major volcanics (Mustard et al, 2005). Moreover, in the Thaumasia Planum, spectra containing mixtures of HCP and olivine are found within "plains and a wrinkle ridge" that are incised by olivine (forsterite) dikes (Huang et al, 2012). The mixture is identified by the shape of the 1.0µm feature of the HCP spectra, and dike formation is believed to be tied to the development of Tharsis (Huang et al, 2012).…”