The Case for Ancient Hot Springs in Gusev Crater, Mars

Ruff, Steven W.; Campbell, Kathleen A.; Kranendonk, Martin J. Van; Rice, M. S.; Farmer, Jack D.

doi:10.1089/ast.2019.2044

Cited by 66 publications

(58 citation statements)

References 104 publications

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“…In comparison with Mars the formation of smectite minerals was also well investigated in the Columbia Hills at the Gusev crater, where the morphological and mineralogical evidence of hydrothermal alteration are well exposed [91,92]. The smectite observed include saponite [93,94] which is a typical product of the hydrothermal alteration in line with the smectite formed in our experiment.…”

Section: Insight Into Alteration Processes From the Experimental Datasupporting

confidence: 77%

Volcanic Holocrystalline Bedrock and Hydrothermal Alteration: A Terrestrial Analogue for Mars

et al. 2020

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Clay minerals have been detected on Mars to outcrop mainly as alteration of ancient bedrock, and secondarily, as deposition from aqueous environments or interlayered with evaporitic deposits on Mars. In order to better constrain the alteration environments, we focused on the process to form clays from volcanic rocks and experimentally reproduced it at different temperature and pH. A fresh, holocrystalline alkali-basalt sample collected in the Mount Etna volcanic sequence has been used as analogue of the Martian unaltered bedrock. Previous works considered only volcanic glass or single mineral, but this may not reflect the full environmental conditions. Instead, we altered the bulk rock and analyzed the changes of primary minerals to constrain the minimum environmental parameters to form clays. We observed that under acidic aqueous solution (pH ~ 3.5–5.0) and moderate temperature (~150–175 °C), clinopyroxene and plagioclase are altered in smectite in just a few days, while higher temperature appear to favor oxides formation regardless of pH. Plagioclases can also be transformed in zeolite, commonly found in association with clays on Mars. This transformation may occur even at very shallow depth if a magmatic source is close or hydrothermalism is triggered by meteoritic impact.

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Section: Insight Into Alteration Processes From the Experimental Datasupporting

confidence: 77%

Volcanic Holocrystalline Bedrock and Hydrothermal Alteration: A Terrestrial Analogue for Mars

et al. 2020

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“…Given that silica is known to be an exceptional preserver of microfossils and other biosignatures (e.g., Knoll, 1985;Trewin, 1996), and can act as a potential shield to UV radiation (Phoenix et al, 2002), it becomes a very attractive beacon by which to guide the search for life on Mars, whether or not photosynthesizers existed there. At Columbia Hills, the presence of nodular opaline silica with digitate structures, similar to those from El Tatio sinter known to have been microbially mediated (Ruff and Farmer, 2016;Ruff et al, 2019), provide exciting opportunities to investigate whether life may have ever existed on Mars Cady et al, 2018).…”

Section: Life On Marsmentioning

confidence: 99%

“…Since modern to ancient (*3.5 Ga) terrestrial hot spring systems on Earth that display varying degrees of crystallization preserve signs of microbial life (e.g., Ruff and Farmer, 2016;Djokic et al, 2017Djokic et al, , 2020Ruff et al, 2019), the well-preserved martian hydrothermal deposits become promising astrobiological targets. Hot springs have also been suggested as candidate environments for the origin of life on Earth (Damer and Deamer, 2015;Deamer and Georgiou, 2015;Van Kranendonk et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Biomolecules from Fossilized Hot Spring Sinters: Implications for the Search for Life on Mars

et al. 2020

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Hot spring environments are commonly dominated by silica sinters that precipitate by the rapid cooling of silicasaturated fluids and the activity of microbial communities. However, the potential for preservation of organic traces of life in silica sinters back through time is not well understood. This is important for the exploration of early life on Earth and possibly Mars. Most previous studies have focused on physical preservation in samples <900 years old, with only a few focused on organic biomarkers. In this study, we investigate the organic geochemistry of hot spring samples from El Tatio, Chile and the Taupo Volcanic Zone, with ages varying from modern to *9.4 ka. Results show that all samples contain opaline silica and contain hydrocarbons that are indicative of a cyanobacterial origin. A *3 ka recrystallized, quartz-bearing sample also contains traces of cyanobacterial biomarkers. No aromatic compounds were detected in a *9.4 ka opal-A sample or in a modern sinter breccia sample. All other samples contain naphthalene, with one sample also containing other polyaromatic hydrocarbons. These aromatic hydrocarbons have a thermally mature distribution that is perhaps reflective of geothermal fluids migrating from deep, rather than surface, reservoirs. These data show that hot spring sinters can preserve biomolecules from the local microbial community, and that crystallinity rather than age may be the determining factor in their preservation. This research provides support for the exploration for biomolecules in opaline silica deposits on Mars.

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“…Amorphous silica is present on the surface of Mars 29,63,64 , and is already targeted as the most promising source for the search for extraterrestrial life. The fossil-preserving potential of amorphous silica has been mostly observed in samples that formed in hydrothermal environments 25,26,65 , whereas opaline silica deposits have been identified as originating from the weathering of its silicate crust 66,67 . The future landing site of NASA's next rover missions on Mars (Mars 2020) includes opaline silica that is thought to be of weathering origin 68 .…”

Section: Discussionmentioning

confidence: 99%

Arthropod entombment in weathering-formed opal: new horizons for recording life in rocks

Chauviré

Houadria

Donini

et al. 2020

Sci Rep

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Animal fossils preserved in various geological materials, such as limestone, claystone, or amber, provide detailed information on extinct species that is indispensable for retracing the evolution of terrestrial life. Here, we present the first record of an animal fossil preserved in opal formed by weathering with such high-resolution details that even individual cuticle hairs are observed. the fossil consists of the exoskeleton of a nymphal insect belonging to the order Hemiptera and either the family Tettigarctidae or the Cicadidae. This identification is based on anatomical details such as the tibial and femoral morphology of the forelegs. the exoskeleton of the insect was primarily zeolitized during the alteration of the host rocks and later sealed in opal deposited by silica-rich fluids derived from the continental weathering of the volcanic host rocks. organic matter is preserved in the form of amorphous carbon. This finding makes opal formed by rocks weathering a new, complementary source of animal fossils, offering new prospects for the search for ancient life in the early history of Earth and possibly other terrestrial planets such as Mars, where weathering-formed opal occurs. Most invertebrate fossil records where anatomical details are well preserved are from amber or lacustrine or fluvial sedimentary rocks 1. These fossils have provided evolutionary evidence of ancestral traits and extinct species, retracing the evolution of life. Here, we describe an insect fossil in opal-a variety of silica-in which the degree of preservation is comparable (Fig. 1) 2. Silica minerals exist in various species ranging in structure from amorphous to crystalline. Opal is the main species of amorphous silica that precipitates from saturated or near-saturated silica-rich aqueous fluids produced by the alteration of the earth's crust. One of the main sources of silica for opal formation (and hence the eventual silicification of fossils) are volcanic rocks, especially volcanic ashes due to their inherent porosity and glass abundance 3-8. Among opals, the most sought-after type is precious opal, which differs from common opal only by the presence of colored patches (called play-of-color) that appear to move as the stone is viewed from different angles, an optical phenomenon attributed to the diffraction of visible light by a regular arrangement of silica spheres 9,10. Both precious and common opal form mainly in two geological settings: (1) hydrothermal alteration occurring when hot water circulates underground and precipitates opal when the temperature drops, e.g., as siliceous sinter (a hard incrustation around hot springs); and (2) continental weathering that occurs when meteoric waters percolate, hydrolyzing silicate while transforming the rock into a soil. In both contexts, the dissolved silica exists as silicic acid (H 4 SiO 2) in aqueous solution. Silicic acid will polymerize into silica during a variation in physical or chemical conditions, primarily pH and temperature 11. The degradation of organic matter may favor t...

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The Case for Ancient Hot Springs in Gusev Crater, Mars

Cited by 66 publications

References 104 publications

Volcanic Holocrystalline Bedrock and Hydrothermal Alteration: A Terrestrial Analogue for Mars

Volcanic Holocrystalline Bedrock and Hydrothermal Alteration: A Terrestrial Analogue for Mars

Biomolecules from Fossilized Hot Spring Sinters: Implications for the Search for Life on Mars

Arthropod entombment in weathering-formed opal: new horizons for recording life in rocks

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