Table 1.
Possible Formation Scenarios, Science Questions Arising From This Study, and Testable Predictions for Jezero Olivine-Carbonate Lithology
| Scenarios | Observations | In situ testable hypothesis or observable | ||
|---|---|---|---|---|
| 1. Olivine Emplacement/composition/grain size | 2. Partial carbonatization | 3. Associated Mg/Fe-phyllo | ||
| Volcanic succession on early Martian crust (Hamilton & Christensen, 2005; Tornabene et al., 2008), by dyke driven volcanism (Bramble et al., 2017) with accompanying deuteric alteration; serpentinization reactions driven by heat of volcanic emplacement (Brown et al., 2010; Viviano et al., 2013) | √√√ | √√√ | √√√ | Lava flow units in stratigraphic section, potentially cumulate clast textures and large grain sizes |
| Impact-driven hydrothermal activity by a melt sheet (Hoefen et al., 2003; Mustard et al., 2007, 2009) serpentinization reactions driven by hydrothermal activity from heat of impact (Osinski et al., 2013) | √√ | √√√ | √√ | Superposed impact melt sheet |
| Emplacement by olivine-rich pyroclastic ash flow at low temperature (Kremer et al., 2019; Mandon et al. 2019) | √√√ | √ | Pyroclastic ash unit in stratigraphic section, small grain sizes | |
| Subsurface alteration under thicker CO2 atmosphere; serpentinization reactions driven by diagenesis and upper crustal hydrothermal processes (Edwards & Ehlmann, 2015; van Berk & Fu, 2011) | √√√ | √√√ | Indicators of subsurface alteration in carbonate and zoning (van Berk & Fu, 2011) | |
| Hydrothermal alteration in thermal springs environment (Walter & Des Marais, 1993) or alteration of volcanic tephra by ephemeral waters (Ruff et al., 2014) | √√√ | √√ | Mineralogical and physical evidence of tephra-like deposits showing hydrothermal alteration | |
| Deep subsurface reservoir of carbonate exposed by meteor impact (Glotch & Rogers, 2013; Michalski & Niles, 2010) | √√√ | √√ | Layering, exposure in deep crater walls or peaks | |
| Cold ophiolite-hosted serpentinization, as in the terrestrial analogs in California (Campbell et al., 2002; Schulte et al., 2006) or the Oman ophiolite (Paukert et al., 2012) | √√ | √√ | √√ | Low temperature serpentinization minerals |
| Low temperature leaching, as in terrestrial analog of Antarctic carbonate rinds (Doran et al., 1998) | √√ | √ | Carbonate in surface rinds | |
| Precipitation of carbonate directly into shoreline of shallow lake (Horgan & Anderson, 2018) or dry lake (Baldridge et al., 2009; Marion et al., 2009) or marine basin, includes scenarios of Noachian Martian ocean preserved at Nili Fossae (Russell et al., 2014) | √ | √√ | Marginal carbonates, Carbonate reefs, microbiolites, stromatolites exhalative/smoker structures | |
| Hydrothermal formation of carbonates and clays from an olivine-bearing Martian basalt under a thick CO2 atmosphere (Dehouck et al., 2014; Pollack et al., 1987) or under a high pressure and temperature atmosphere (Cannon et al., 2017) | √√√ | √√ | √√√ | High temperature or pressure mineral phases |
| Deposition of olivine/carbonate sediment in a large aeolian dune field, such as the lower unit of the Burns Formation (Grotzinger et al., 2005) | √√ | √ | √ | Aeolian sedimentary features in the carbonate |
Note. No ticks indicates that the scenario cannot address this question, one tick indicates that the scenario might account for this question; two ticks indicate that it partially deals with the question, and three ticks mean it specifically addresses the question. See discussion in section 5.4.