LATE JURASSIC ROCKS OF THE COLORADO PLATEAU AS DEPOSITIONAL AND DIAGENETIC ANALOGS TO GALE CRATER, MARS
Five primary lithofacies are present in both the Colorado Plateau and the Mars rocks: silt-/claystone, sandstone, and conglomerate, sulfates and carbonates. Both terrestrial and martian silt-/claystone lithofacies are interpreted as lacustrine depositional environments due to parallel laminated, massive, and vuggy sedimentary structures. Fluvial features are also present in the analog units and the Gale Crater rocks such as cross-bedded sandstones and imbricated conglomerates. Both the Tidwell Member and the Wanakah Formation contain meters-thick horizons of gypsum analogous to sulfates in the rocks at Gale Crater. Additionally, gypsum veins are present in the Tidwell Member and at Gale Crater. Thin, laminated limestones are common in the Tidwell Member and the Wanakah Formation and the Brushy Basin Member hosts a 3-4m thick limestone sabkha deposit. Carbonates are also found at Gale Crater. Concretions are present in all the Colorado Plateau units and at Gale Crater.
Research on the Brushy Basin Member, the Tidwell Member and the Wanakah Formation will inform the Mars Science Laboratory mission on important scientific questions: 1. What is the depositional environment?, 2. What is the history of fluid-rock-(biota?) interactions, 3. What past chemical environments (i.e., fluid composition) existed during deposition and diagenesis?, and 4. What types of biomarkers can we expect to find?