Sedimentary Hydrocarbons, Biomarkers for Early Life

Brocks, Jochen J.

doi:10.1016/b978-0-08-095975-7.00803-2

Cited by 33 publications

(27 citation statements)

References 357 publications

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“…We also rely on cultured representatives to establish useful lipid biomarkers for the examination of the fossil residues of mat communities. The fossil residues or geolipids help to determine the community composition of ancient microbial mats, and provide information about paleoenvironments (Brocks & Summons, ). The organic biomarker record is particularly well characterized for the massive gypsum deposites associated with the ‘Messinian Salinity Crisis’ (see Sinninghe Damsté et al ., and references therein).…”

Section: Introductionmentioning

confidence: 99%

Molecular and lipid biomarker analysis of a gypsum‐hosted endoevaporitic microbial community

et al. 2013

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Modern evaporitic microbial ecosystems are important analogs for understanding the record of earliest life on Earth. Although mineral-depositing shallow-marine environments were prevalent during the Precambrian, few such environments are now available today for study. We investigated the molecular and lipid biomarker composition of an endoevaporitic gypsarenite microbial mat community in Guerrero Negro, Mexico. The 16S ribosomal RNA gene-based phylogenetic analyses of this mat corroborate prior observations indicating that characteristic layered microbial communities colonize gypsum deposits world-wide despite considerable textural and morphological variability. Membrane fatty acid analysis of the surface tan/orange and lower green mat crust layers indicated cell densities of 1.6 × 10(9) and 4.2 × 10(9) cells cm(-3) , respectively. Several biomarker fatty acids, ∆7,10-hexadecadienoic, iso-heptadecenoic, 10-methylhexadecanoic, and a ∆12-methyloctadecenoic, correlated well with distributions of Euhalothece, Stenotrophomonas, Desulfohalobium, and Rhodobacterales, respectively, revealed by the phylogenetic analyses. Chlorophyll (Chl) a and cyanobacterial phylotypes were present at all depths in the mat. Bacteriochlorophyl (Bchl) a and Bchl c were first detected in the oxic-anoxic transition zone and increased with depth. A series of monomethylalkanes (MMA), 8-methylhexadecane, 8-methylheptadecane, and 9-methyloctadecane were present in the surface crust but increased in abundance in the lower anoxic layers. The MMA structures are similar to those identified previously in cultures of the marine Chloroflexus-like organism 'Candidatus Chlorothrix halophila' gen. nov., sp. nov., and may represent the Bchl c community. Novel 3-methylhopanoids were identified in cultures of marine purple non-sulfur bacteria and serve as a probable biomarker for this group in the lower anoxic purple and olive-black layers. Together microbial culture and environmental analyses support novel sources for lipid biomarkers in gypsum crust mats.

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Section: Introductionmentioning

confidence: 99%

Molecular and lipid biomarker analysis of a gypsum‐hosted endoevaporitic microbial community

et al. 2013

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“…Although a large amount of the alkyl positive fragments in the sample matrix (Group D) are sourced in the n ‐alkane chains, the occurrence of some secondary peaks suggests that they are partly sourced from branched alkanes. This is the case with m/z + peaks at 113.13, 183.19, 197.23, and 239.27 (Brocks & Summons, ), which are characteristic of branched alkanes such as pristane (C 19 H 40 ), phytane (C 20 H 42 ), and squalane (C 30 H 62 ). The molecular peaks of such compounds are found with very low intensity ( I < 50) by TOF‐SIMS at 268.33 and 422.43, which are diagnostic of pristane and squalane.…”

Section: Resultsmentioning

confidence: 99%

Productivity Contribution of Paleozoic Woodlands to the Formation of Shale‐Hosted Massive Sulfide Deposits in the Iberian Pyrite Belt (Tharsis, Spain)

et al. 2018

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The geological materials produced during catastrophic and destructive events are an essential source of paleobiological knowledge. The paleobiological information recorded by such events can be rich in information on the size, diversity, and structure of paleocommunities. In this regard, the geobiological study of late Devonian organic matter sampled in Tharsis (Iberian Pyrite Belt) provided some new insights into a Paleozoic woodland community, which was recorded as massive sulfides and black shale deposits affected by a catastrophic event. Sample analysis using TOF‐SIMS (Time of Flight Secondary Ion Mass Spectrometer), and complemented by GC/MS (Gas Chromatrograph/Mass Spectrometer) identified organic compounds showing a very distinct distribution in the rock. While phytochemical compounds occur homogeneously in the sample matrix that is composed of black shale, the microbial‐derived organics are more abundant in the sulfide nodules. The cooccurrence of sulfur bacteria compounds and the overwhelming presence of phytochemicals provide support for the hypothesis that the formation of the massive sulfides resulted from a high rate of vegetal debris production and its oxidation through sulfate reduction under suboxic to anoxic conditions. A continuous supply of iron from hydrothermal activity coupled with microbial activity was strictly necessary to produce this massive orebody. A rough estimate of the woodland biomass was made possible by accounting for the microbial sulfur production activity recorded in the metallic sulfide. As a result, the biomass size of the late Devonian woodland community was comparable to modern woodlands like the Amazon or Congo rainforests.

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“…As has been learned from studies of the early fossil record on Earth, the combination of field investigations and detailed laboratory analyses is required to confirm potential biosignatures in early Archean rocks (4000–3200 million years ago, Ma), as various postdepositional processes often have obscured or may even have destroyed signs of life (e.g., Brocks and Summons ; Djokic et al. ).…”

Section: Objective 2: Assess and Interpret The Potential Biological Hmentioning

confidence: 99%

The potential science and engineering value of samples delivered to Earth by Mars sample return

Beaty¹,

Grady²,

McSween³

et al. 2019

Meteorit & Planetary Scien

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Executive Summary Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the team is to re‐evaluate and update the sample‐related science and engineering objectives of a Mars Sample Return (MSR) campaign. The iMOST team has also undertaken to define the measurements and the types of samples that can best address the objectives. Seven objectives have been defined for MSR, traceable through two decades of previously published international priorities. The first two objectives are further divided into sub‐objectives. Within the main part of the report, the importance to science and/or engineering of each objective is described, critical measurements that would address the objectives are specified, and the kinds of samples that would be most likely to carry key information are identified. These seven objectives provide a framework for demonstrating how the first set of returned Martian samples would impact future Martian science and exploration. They also have implications for how analogous investigations might be conducted for samples returned by future missions from other solar system bodies, especially those that may harbor biologically relevant or sensitive material, such as Ocean Worlds (Europa, Enceladus, Titan) and others. Summary of Objectives and Sub‐Objectives for MSR Identified by iMOST This objective is divided into five sub‐objectives that would apply at different landing sites. 1.1 Characterize the essential stratigraphic, sedimentologic, and facies variations of a sequence of Martian sedimentary rocks. 1.2 Understand an ancient Martian hydrothermal system through study of its mineralization products and morphological expression. 1.3 Understand the rocks and minerals representative of a deep subsurface groundwater environment. 1.4 Understand water/rock/atmosphere interactions at the Martian surface and how they have changed with time. 1.5 Determine the petrogenesis of Martian igneous rocks in time and space. This objective has three sub‐objectives: 2.1 Assess and characterize carbon, including possible organic and pre‐biotic chemistry. 2.2 Assay for the presence of biosignatures of past life at sites that hosted habitable environments and could have preserved any biosignatures. 2.3 Assess the possibility that any life forms detected are alive, or were recently alive. Summary of iMOST Findings Several specific findings were identified during the iMOST study. While they are not explicit recommendations, we suggest that they should serve as guidelines for future decision making regarding planning of potential future MSR missions. The samples to be collected by the Mars 2020 (M‐2020) rover will be of sufficient size and quality to address and solve a wide variety of scientific questions. Samples, by definition, are a statistical representation of a larger entity...

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Sedimentary Hydrocarbons, Biomarkers for Early Life

Cited by 33 publications

References 357 publications

Molecular and lipid biomarker analysis of a gypsum‐hosted endoevaporitic microbial community

Molecular and lipid biomarker analysis of a gypsum‐hosted endoevaporitic microbial community

Productivity Contribution of Paleozoic Woodlands to the Formation of Shale‐Hosted Massive Sulfide Deposits in the Iberian Pyrite Belt (Tharsis, Spain)

The potential science and engineering value of samples delivered to Earth by Mars sample return

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