USING ROVER-ANALOGOUS INSTRUMENTATION TO DISCRIMINATE BETWEEN VOLCANIC AND SEDIMENTARY PROCESS IN SUCCESSIONS DOMINATED BY IGNEOUS CHEMISTRY

Many of the outcrops observed on Mars, including those at Jezero Crater, contain abundant layered material which lack substantial extensive chemical alteration and may have undergone substantial aeolian modification. Such outcrops have proven challenging in terms of discriminating among emplacement mechanisms. Features of volcanic flows, which might readily be identified on Earth by surficial textures and vesicular habits, are difficult to discriminate from sedimentary strata containing igneous clasts, wherein wind abrasion has modified surface textures and plucked sedimentary grains. Even the presence of a glass phase, common in volcanic rocks, is non-diagnostic, as these phases would be common in volcanic rocks but could also result from incorporation of glasses into a later sedimentary material. Pyroclastic deposition can further complicate identification, and common diagnostic features, such as accretionary lapilli, may be difficult to differentiate unambiguously from impact spherule deposits, diagenetic concretions, or transported clasts. In assessing deposits on Mars, the difficulty is compounded because chemical composition can be non-diagnostic, context is often poorly constrained, and dust cover and wind abrasion can obscure visual identification of features.

Determining a reliable pathway for discriminating among volcanic and sedimentary emplacement is critical to rover-supported missions; we must understand whether the methods we use sufficiently allow us to identify different deposition hypotheses, and which instruments provide the most clarity for rapid, accurate interpretation. To address these issues, the GeoHeuristics Operational Strategies Testing (GHOST) team explored the science operations decision-making process at a Jezero-analog field site, using commercial, off-the-shelf technology to minimize variables related to rover and equipment function, and better isolate the science operations decision-making process. At Tungulending, on the Tjörnes peninsula in the north of Iceland, we characterized fine-grained, basaltic sedimentary deposits derived from diverse paleoenvironments that are interleaved with primary basaltic deposits (lavas, ash, etc) of similar composition. Here we report on our findings that compare rover-driven science methods to this terrestrial baseline.