Thermally altered marine dissolved organic matter in hydrothermal fluids

Rossel, Pamela E.; Stubbins, Aron; Rebling, Tammo; Koschinsky, Andrea; Hawkes, Jeffrey A.; Dittmar, Thorsten

doi:10.1016/j.orggeochem.2017.05.003

Cited by 57 publications

(58 citation statements)

References 69 publications

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“…3f, S1i) and has been frequently reported from other hydrothermal sites (e.g., Simoneit, 1984;Weston and Woolhouse, 1987;Clifton et al, 1990;Simoneit et al, 2009). As the hydrothermal system of the Magadi basin consists of a dilute ground water reservoir, deep brines, and recycled lake brines (Eugster, 1970;Jones et al, 1977), it appears plausible that immature organic compounds from the lake environment have been thermally altered by hydrothermal cycling, resulting, inter alia, in a loss of functional groups (cf., McCollom and Seewald, 2003;Hawkes et al, 2016;Rossel et al, 2017). Consequently, the n-alkanes from bitumens might represent stable thermal alteration products of originally functionalized compounds, such as linear fatty acids and n-alkanols.…”

Section: Hydrothermal Impact On Organic Mattermentioning

confidence: 99%

“…200 °C km −1 ; Wheildon et al, 1994) and were not deeply buried at the time of the Green Bed chert deposition. PAHs are common in dissolved organic matter from hydrothermal fluids (e.g., Konn et al, 2009, 2012, McCollom et al, 2015Rossel et al, 2017), but may also derive from wildfires. Incomplete combustion of biomass may be a relevant source particularly in LM-1694 and LM-1699, as Flu/(Flu+Py) ratios of about 0.61 (see Table 2) are considered indicative for a wildfire origin (Yunker et al, 2002).…”

Section: Hydrothermal Impact On Organic Mattermentioning

confidence: 99%

See 1 more Smart Citation

Organic signatures in Pleistocene cherts from Lake Magadi (Kenya), analogs for early Earth hydrothermal deposits

Reinhardt¹,

Goetz²,

Duda³

et al. 2019

Preprint

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Abstract. Organic matter in Archean hydrothermal cherts may provide an important archive for molecular traces of earliest life on Earth. The geobiological interpretation of this archive, however, requires a sound understanding of organic matter preservation and alteration in hydrothermal systems. Here we report on organic matter (including molecular biosignatures) enclosed in hydrothermally influenced cherts of the Pleistocene Lake Magadi (Kenya; High Magadi Beds and Green Beds) &#8211; important analogs for Archean cherts. The Magadi cherts contain low organic carbon (<&#8201;0.4&#8201;wt.%) that occurs in form of finely dispersed clots, layers, or encapsulated within microscopic carbonate rhombs. Both, extractable (bitumen) and non-extractable organic matter (kerogen) was analyzed. The bitumens contain immature <q>biolipids</q> like glycerol mono- and diethers (e.g., archaeol and extended archaeol), fatty acids and &#8211; alcohols indicative for, inter alia, thermophilic cyanobacteria, sulfate reducers, and haloarchaea. However, co-occurring <q>geolipids</q> such as n-alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) indicate that a fraction of the bitumen has been thermally altered to early or peak oil window maturity. This more mature fraction likely originated from defunctionalization of dissolved organic matter and/or hydrothermal petroleum formation at places of higher thermal flux. Like the bitumens, the kerogens also show variations in thermal maturities, which can partly be explained by admixture of thermally pre-altered macromolecules. However, findings of archaea-derived isoprenoid moieties in some of the kerogens indicate that a fast sequestration of microbial lipids into kerogen must have occurred while hydrothermal alteration was active. We posit that such early sequestration may enhance the survival of molecular biosignatures during in-situ hydrothermal (and post-depositional) alteration through deep time. Furthermore, the co-occurrence of organic matter with different thermal maturities in the Lake Magadi cherts suggests that similar findings in Archean hydrothermal deposits could partly reflect original environmental conditions, and not exclusively post-depositional overprint or contamination. Our results support the view that kerogen in Archean hydrothermal cherts may contain important information on early life. Our study also highlights the suitability of Lake Magadi as an analog system for hydrothermal chert environments on the Archean Earth.

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Section: Hydrothermal Impact On Organic Mattermentioning

confidence: 99%

Section: Hydrothermal Impact On Organic Mattermentioning

confidence: 99%

Organic signatures in Pleistocene cherts from Lake Magadi (Kenya), analogs for early Earth hydrothermal deposits

Reinhardt¹,

Goetz²,

Duda³

et al. 2019

Preprint

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“…Many of the Archean cherts are associated with hydrothermal settings, including shallow marine and terrestrial environments (e.g., Brasier et al, 2002;Duda et al, 2016Duda et al, , 2018Djokic et al, 2017;Hickman-Lewis et al, 2018). In such environments, organic compounds may rapidly decompose due to elevated temperature and pressure conditions (Hawkes et al, 2015(Hawkes et al, , 2016Rossel et al, 2017) and may also be redistributed via hydrothermal cycling in the form of bitumen (e.g., Weston and Woolhouse, 1987;Clifton et al, 1990;Leif and Simoneit, 1995) or kerogen (Duda et al, 2018). The interpretation of organic signatures in Archean hydrothermal cherts therefore requires detailed knowledge on the preservation, alteration, and distribution pathways of organic matter in such environments.…”

Section: Introductionmentioning

confidence: 99%

Organic signatures in Pleistocene cherts from Lake Magadi (Kenya) – implications for early Earth hydrothermal deposits

et al. 2019

View full text Add to dashboard Cite

Abstract. Organic matter in Archean hydrothermal cherts may provide an important archive for molecular traces of the earliest life on Earth. The geobiological interpretation of this archive, however, requires a sound understanding of organic matter preservation and alteration in hydrothermal systems. Here we report on organic matter (including molecular biosignatures) enclosed in hydrothermally influenced cherts of the Pleistocene Lake Magadi (Kenya; High Magadi Beds and Green Beds). The Magadi cherts contain low organic carbon (< 0.4 wt %) that occurs in the form of finely dispersed clots, layers, or encapsulated within microscopic carbonate rhombs. Both extractable (bitumen) and non-extractable organic matter (kerogen) were analyzed. The bitumens contain immature “biolipids” like glycerol mono- and diethers (e.g., archaeol and extended archaeol), fatty acids, and alcohols indicative for, inter alia, thermophilic cyanobacteria, sulfate reducers, and haloarchaea. However, co-occurring “geolipids” such as n-alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) indicate that a fraction of the bitumen has been thermally altered to early or peak oil window maturity. This more mature fraction likely originated from defunctionalization of dissolved organic matter and/or hydrothermal petroleum formation at places of higher thermal flux. Like the bitumens, the kerogens also show variations in thermal maturities, which can partly be explained by admixture of thermally pre-altered macromolecules. However, findings of archaea-derived isoprenoid moieties (C20 and C25 chains) in kerogen pyrolysates indicate rapid sequestration of some archaeal lipids into kerogen while hydrothermal alteration was active. We posit that such early sequestration may enhance the resistance of molecular biosignatures against in situ hydrothermal and post-depositional alteration. Furthermore, the co-occurrence of organic matter with different thermal maturities in the Lake Magadi cherts suggests that similar findings in Archean hydrothermal deposits could partly reflect original environmental conditions and not exclusively post-depositional overprint or contamination. Our results support the view that kerogen in Archean hydrothermal cherts may contain important information on early life. Our study also highlights the suitability of Lake Magadi as an analog system for hydrothermal chert environments on the Archean Earth.

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“…Hydrothermal fluids also contain hydrocarbons generated during thermal alteration of microbial biomass (Dittmar, 2008;Konn et al, 2011;Reeves et al, 2014). In addition to biogenic sources, dissolved organic compounds may be derived from thermal alteration of dissolved organic matter initially present in circulating seawater (Hawkes et al, 2016;Rossel et al, 2017) and abiotic processes that occur during hydrothermal circulation (Lang et al, 2010;Lin et al, 2017;McCollom and Seewald, 2007;McDermott et al, 2015a;Proskurowski et al, 2008). We posit that information on the composition of organic compounds delivered to the water column by hydrothermal fluids can help identify the source of these compounds, and the roles that they play in deep-sea carbon cycling.…”

Section: Introductionmentioning

confidence: 99%

Dissolved organic carbon compounds in deep-sea hydrothermal vent fluids from the East Pacific Rise at 9°50′N

Longnecker

Sievert

Sylva

et al. 2018

Organic Geochemistry

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Deep-sea hydrothermal vents are unique ecosystems that may release chemically distinct dissolved organic matter to the deep ocean. Here, we describe the composition and concentrations of polar dissolved organic compounds observed in low and high temperature hydrothermal vent fluids at 9°50'N on the East Pacific Rise. The concentration of dissolved organic carbon was 46 µM in the low temperature hydrothermal fluids and 14 µM in the high temperature hydrothermal fluids. In the low temperature vent fluids, quantifiable dissolved organic compounds were dominated by water-soluble vitamins and amino acids. Derivatives of benzoic acid and the organic sulfur compound 2,3-dihydroxypropane-1-sulfonate (DHPS) were also present in low and high temperature hydrothermal fluids. The low temperature vent fluids contain organic compounds that are central to biological processes, suggesting that they are a byproduct of biological activity in the subseafloor. These compounds may fuel heterotrophic and other metabolic processes at deep-sea hydrothermal vents and beyond.

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Thermally altered marine dissolved organic matter in hydrothermal fluids

Cited by 57 publications

References 69 publications

Organic signatures in Pleistocene cherts from Lake Magadi (Kenya), analogs for early Earth hydrothermal deposits

Organic signatures in Pleistocene cherts from Lake Magadi (Kenya), analogs for early Earth hydrothermal deposits

Organic signatures in Pleistocene cherts from Lake Magadi (Kenya) – implications for early Earth hydrothermal deposits

Dissolved organic carbon compounds in deep-sea hydrothermal vent fluids from the East Pacific Rise at 9°50′N

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