Out of rock: A new look at the morphological and geochemical preservation of microfossils from the 3.46 Gyr-old Strelley Pool Formation

Delarue, Frédéric; Robert, François; Derenne, Sylvie; Tartèse, Romain; Jauvion, Clément; Bernard, Sylvain; Pont, Sylvain; Gonzalez-Cano, Adriana; Duhamel, Rémi; Sugitani, Kenichiro

doi:10.1016/j.precamres.2019.105472

Cited by 24 publications

(31 citation statements)

References 54 publications

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“…The ancient fossil record carries key information on the first steps of the history of life on Earth 1–3 . Yet, although ancient microfossils may still comprise (partially preserved) biogenic organic material 4–10 , the identification of traces of life in ancient rocks has always been fraught with difficulties pertaining to fossilization and burial-induced degradation processes 11–14 . As a result, the interpretation of the Archean palaeobiological record is full of controversies, among which the most famous one is centered on filamentous microstructures found in black chert veins within the 3.46 Ga Apex Basalt (Pilbara Craton, Western Australia) 15,16 .…”

Section: Introductionmentioning

confidence: 99%

The degradation of organic compounds impacts the crystallization of clay minerals and vice versa

Jacquemot

Viennet

Bernard

et al. 2019

Sci Rep

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Expanding our capabilities to unambiguously identify ancient traces of life in ancient rocks requires laboratory experiments to better constrain the evolution of biomolecules during advanced fossilization processes. Here, we submitted RNA to hydrothermal conditions in the presence of a gel of Al-smectite stoichiometry at 200 °C for 20 days. NMR and STXM-XANES investigations revealed that the organic fraction of the residues is no longer RNA, nor the quite homogeneous aromatic-rich residue obtained in the absence of clays, but rather consists of particles of various chemical composition including amide-rich compounds. Rather than the pure clays obtained in the absence of RNA, electron microscopy (SEM and TEM) and diffraction (XRD) data showed that the mineralogy of the experimental residues includes amorphous silica and aluminosilicates mixed together with nanoscales phosphates and clay minerals. In addition to the influence of clay minerals on the degradation of organic compounds, these results evidence the influence of the presence of organic compounds on the nature of the mineral assemblage, highlighting the importance of fine-scale mineralogical investigations when discussing the nature/origin of organo-mineral microstructures found in ancient rocks.

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Section: Introductionmentioning

confidence: 99%

The degradation of organic compounds impacts the crystallization of clay minerals and vice versa

Jacquemot

Viennet

Bernard

et al. 2019

Sci Rep

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“…There are ongoing investigations on deeper characterization of lab-made silica biomorphs, their formation and preservation under different P-T conditions, as well as on the high-resolution structural characterization on adsorbed carbonaceous compounds in laboratory analogues. And, fortunately, recent developments in in-situ analysis (isotopic, molecular, compositional, structural) help significantly in the identification of other features of life beyond morphology, allowing a more accurate identification of Archean microfossils [90][91][92][93][94][95][96][97][98][99][100]. The boundary between life and non-life becomes fuzzier and fuzzier as we get further in deep time, when shapes of living organisms were simpler and their preservation was more difficult.…”

Section: Silica/carbonate Biomorphsmentioning

confidence: 99%

Mineral self-organization on a lifeless planet

García‐Ruiz

Zuilen

Bach

2020

Physics of Life Reviews

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It has been experimentally demonstrated that, under alkaline conditions, silica is able to induce the formation of mineral selfassembled inorganic-inorganic composite materials similar in morphology, texture and nanostructure to the hybrid biomineral structures that, millions of years later, life was able to self-organize. These mineral self-organized structures (MISOS) have been also shown to work as effective catalysts for prebiotic chemical reactions and to easily create compartmentalization within the solutions where they form. We reason that, during the very earliest history of this planet, there was a geochemical scenario that inevitably led to the existence of a large-scale factory of simple and complex organic compounds, many of which were relevant to prebiotic chemistry. The factory was built on a silica-rich high-pH ocean and powered by two main factors: a) a quasi-infinite source of simple carbon molecules synthesized abiotically from reactions associated with serpentinization, or transported from meteorites and produced from their impact on that alkaline ocean, and b) the formation of self-organized silica-metal mineral composites that catalyze the condensation of simple molecules in a methane-rich reduced atmosphere. We discuss the plausibility of this geochemical scenario, review the details of the formation of MISOS and its catalytic properties and the transition towards a slightly alkaline to neutral ocean.

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“…Therefore, the trace of Martian biomolecules might be preserved on Phobos. Detailed analyses of speci c elements (e.g., P and S) and isotopic ratios (e.g., 13 C/ 12 C and 15 N/ 14 N ratios) may provide important data to investigate potential biosignatures (e.g., Delarue et al, 2020). It should be noted that there is a survival bias of organic molecules by the impact.…”

Section: Possible Martian Materialsmentioning

confidence: 99%

Analytical Protocols for Phobos Regolith Samples Returned by the Martian Moons Exploration (MMX) Mission

Fujiya

Furukawa

Sugahara

et al. 2020

Preprint

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Japan Aerospace Exploration Agency (JAXA) will launch a spacecraft in 2024 for a sample return mission from Phobos (Martian Moons eXploration: MMX). Touchdown operations are planned to be performed twice at different landing sites on the Phobos surface to collect >10 g of the Phobos surface materials with coring and pneumatic sampling systems on board. The Sample Analysis Working Team (SAWT) of MMX is now designing analytical protocols of the returned Phobos samples to shed light on the origin of the Martian moons as well as the evolution of the Mars-moon system. Observations of petrology and mineralogy, and measurements of bulk chemical compositions and stable isotopic ratios of, e.g., O, Cr, and Ti can provide crucial information about the origin of Phobos. If Phobos is a captured asteroid composed of primitive chondritic materials, as inferred from its reflectance spectra, the nature of organic matter as well as bulk H, N, and Zn isotopic compositions characterize the volatile materials in the samples and constrain the type of the captured asteroid. Cosmogenic and solar wind components, most pronounced in noble gas isotopic compositions, can reveal surface processes on Phobos. Long- and short-lived radionuclide chronometry such as 53Mn-53Cr and 87Rb-87Sr systematics can date pivotal events like impacts, thermal metamorphism, and aqueous alteration on Phobos. It should be noted that the Phobos regolith is expected to contain a small amount of materials delivered from Mars, which may be physically and chemically different from any Martian meteorites in our collection and thus are particularly precious. The analysis plan will be designed to detect such Martian materials, if any, from the returned samples dominated by the Phobos building blocks in curation procedures at JAXA before they are processed for further analyses.

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Out of rock: A new look at the morphological and geochemical preservation of microfossils from the 3.46 Gyr-old Strelley Pool Formation

Cited by 24 publications

References 54 publications

The degradation of organic compounds impacts the crystallization of clay minerals and vice versa

The degradation of organic compounds impacts the crystallization of clay minerals and vice versa

Mineral self-organization on a lifeless planet

Analytical Protocols for Phobos Regolith Samples Returned by the Martian Moons Exploration (MMX) Mission

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