H. Kalucha, M. M. Douglas, M. P. Lamb, Y. Ke, W. W. Fischer
{"title":"Low But Persistent Organic Carbon Content of Hyperarid River Deposits and Implications for Ancient Mars","authors":"H. Kalucha, M. M. Douglas, M. P. Lamb, Y. Ke, W. W. Fischer","doi":"10.1029/2023JE008182","DOIUrl":null,"url":null,"abstract":"<p>Mars has many well-exposed fluvial ridges and fluvio-deltaic basins; in two of these locations, the Curiosity and Perseverance rovers are currently searching for signs of habitability. The distribution of organic carbon that might persist in ancient fluvial deposits present on Mars is not well understood. In this study, we set out to assess the preservation potential of organic carbon in a hyperarid fluvial environment with observations and analyses of the Amargosa River in Death Valley, California (United States). The lower reaches of the Amargosa River in Badwater Basin are nearly devoid of plants and contain low gradient, meandering channels, making them a valuable terrestrial analog for early martian fluvial systems. We analyzed sediment taken from fluvial deposits exposed in cutbanks of two bends of a meandering channel. We found total organic carbon abundances that were on average 0.15% up to a meter below the surface. X-ray diffraction and electron microscopy analyses revealed a suite of high redox potential mineral phases (including iron and manganese oxides) mixed with detrital and authigenic silicates, carbonate, and sulfate salts at or close to redox equilibrium with pore fluids in contact with the atmosphere. This finding highlighted that organic carbon can persist in fluvial deposits at low abundance despite oxidizing conditions and saturated sediments and suggested that ancient fluvial deposits on Mars may retain traces of organics in fine-grained deposits if they are present during deposition.</p>","PeriodicalId":16101,"journal":{"name":"Journal of Geophysical Research: Planets","volume":null,"pages":null},"PeriodicalIF":3.9000,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geophysical Research: Planets","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1029/2023JE008182","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Mars has many well-exposed fluvial ridges and fluvio-deltaic basins; in two of these locations, the Curiosity and Perseverance rovers are currently searching for signs of habitability. The distribution of organic carbon that might persist in ancient fluvial deposits present on Mars is not well understood. In this study, we set out to assess the preservation potential of organic carbon in a hyperarid fluvial environment with observations and analyses of the Amargosa River in Death Valley, California (United States). The lower reaches of the Amargosa River in Badwater Basin are nearly devoid of plants and contain low gradient, meandering channels, making them a valuable terrestrial analog for early martian fluvial systems. We analyzed sediment taken from fluvial deposits exposed in cutbanks of two bends of a meandering channel. We found total organic carbon abundances that were on average 0.15% up to a meter below the surface. X-ray diffraction and electron microscopy analyses revealed a suite of high redox potential mineral phases (including iron and manganese oxides) mixed with detrital and authigenic silicates, carbonate, and sulfate salts at or close to redox equilibrium with pore fluids in contact with the atmosphere. This finding highlighted that organic carbon can persist in fluvial deposits at low abundance despite oxidizing conditions and saturated sediments and suggested that ancient fluvial deposits on Mars may retain traces of organics in fine-grained deposits if they are present during deposition.
期刊介绍:
The Journal of Geophysical Research Planets is dedicated to the publication of new and original research in the broad field of planetary science. Manuscripts concerning planetary geology, geophysics, geochemistry, atmospheres, and dynamics are appropriate for the journal when they increase knowledge about the processes that affect Solar System objects. Manuscripts concerning other planetary systems, exoplanets or Earth are welcome when presented in a comparative planetology perspective. Studies in the field of astrobiology will be considered when they have immediate consequences for the interpretation of planetary data. JGR: Planets does not publish manuscripts that deal with future missions and instrumentation, nor those that are primarily of an engineering interest. Instrument, calibration or data processing papers may be appropriate for the journal, but only when accompanied by scientific analysis and interpretation that increases understanding of the studied object. A manuscript that describes a new method or technique would be acceptable for JGR: Planets if it contained new and relevant scientific results obtained using the method. Review articles are generally not appropriate for JGR: Planets, but they may be considered if they form an integral part of a special issue.