Evidence for a Diagenetic Origin of Vera Rubin Ridge, Gale Crater, Mars: Summary and Synthesis of <i>Curiosity</i>'s Exploration Campaign

TLDR

Vera Rubin Ridge is a distinct geomorphic feature on lower Aeolis Mons identified in orbital data by its texture, topography, and hematite spectral signature. This paper reviews Curiosity’s exploration of VRR and proposes that the ridge formed through diagenetic hardening of rocks that were later eroded by wind. Curiosity performed extensive remote sensing, sampled dozens of contact targets, drilled three ridge outcrops and one below, and analyzed diagenetic cementation that enhanced ferric spectral absorptions. The ridge strata were deposited in a lacustrine environment as part of the Murray formation, contain dispersed red hematite and isolated gray hematite patches with Fe‑rich nodules, and provide evidence of long‑term aqueous activity and diagenetic alteration on Mars.

Abstract

Abstract This paper provides an overview of the Curiosity rover's exploration at Vera Rubin ridge (VRR) and summarizes the science results. VRR is a distinct geomorphic feature on lower Aeolis Mons (informally known as Mount Sharp) that was identified in orbital data based on its distinct texture, topographic expression, and association with a hematite spectral signature. Curiosity conducted extensive remote sensing observations, acquired data on dozens of contact science targets, and drilled three outcrop samples from the ridge, as well as one outcrop sample immediately below the ridge. Our observations indicate that strata composing VRR were deposited in a predominantly lacustrine setting and are part of the Murray formation. The rocks within the ridge are chemically in family with underlying Murray formation strata. Red hematite is dispersed throughout much of the VRR bedrock, and this is the source of the orbital spectral detection. Gray hematite is also present in isolated, gray‐colored patches concentrated toward the upper elevations of VRR, and these gray patches also contain small, dark Fe‐rich nodules. We propose that VRR formed when diagenetic event(s) preferentially hardened rocks, which were subsequently eroded into a ridge by wind. Diagenesis also led to enhanced crystallization and/or cementation that deepened the ferric‐related spectral absorptions on the ridge, which helped make them readily distinguishable from orbit. Results add to existing evidence of protracted aqueous environments at Gale crater and give new insight into how diagenesis shaped Mars' rock record.