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  • 1.
    Bengtson, Stefan
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Astolfo, Alberto
    Paul Scherrer Institute.
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Broman, Curt
    Stockholm University.
    Marone, Federica
    Paul Scherrer Institute.
    Stampanoni, Marco
    ETH Zürich.
    Deep-biosphere consortium of fungi and prokaryotes in Eocene sub-seafloor basalts.2014In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 12, no 6, p. 489-496Article in journal (Refereed)
    Abstract [en]

    The deep biosphere of the subseafloor crust is believed to contain a significant part of Earth’s biomass, but because of the difficulties of directly observing the living organisms, its composition and ecology are poorly known. We report here a consortium of fossilized prokaryotic and eukaryotic microorganisms, occupying cavities in deep-drilled vesicular basalt from the Emperor Seamounts, Pacific Ocean, 67.5 meters below seafloor (mbsf). Fungal hyphae provide the framework on which prokaryote-like organisms are suspended like cobwebs and iron-oxidizing bacteria form microstromatolites (Frutexites). The spatial interrelationships show that the organisms were living at the same time in an integrated fashion, suggesting symbiotic interdependence. The community is contemporaneous with secondary mineralizations of calcite partly filling the cavities. The fungal hyphae frequently extend into the calcite, indicating that they were able to bore into the substrate through mineral dissolution. A symbiotic relationship with chemoautotrophs, as inferred for the observed consortium, may be a prerequisite for the eukaryotic colonization of crustal rocks. Fossils thus open a window to the extant as well as the ancient deep biosphere.

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  • 2.
    Bengtson, Stefan
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Rasmussen, Birger
    Curtin University.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Muhling, Janet
    Curtin University.
    Broman, Curt
    Stockholm University.
    Marone, Federica
    Stampanoni, Marco
    Bekker, Andrey
    University of California Riverside.
    Fungus-like mycelial fossils in 2.4-billion-year-old vesicular basalt.2017In: Nature Ecology & Evolution, ISSN 2397-334X, Vol. 1, no 6, p. 1-6, article id 0141Article in journal (Refereed)
    Abstract [en]

    Fungi have recently been found to comprise a significant part of the deep biosphere in oceanic sediments and crustal rocks. Fossils occupying fractures and pores in Phanerozoic volcanics indicate that this habitat is at least 400 million years old, but its origin may be considerably older. A 2.4-billion-year-old basalt from the Palaeoproterozoic Ongeluk Formation in South Africa contains filamentous fossils in vesicles and fractures. The filaments form mycelium-like structures growing from a basal film attached to the internal rock surfaces. Filaments branch and anastomose, touch and entangle each other. They are indistinguishable from mycelial fossils found in similar deep-biosphere habitats in the Phanerozoic, where they are attributed to fungi on the basis of chemical and morphological similarities to living fungi. The Ongeluk fossils, however, are two to three times older than current age estimates of the fungal clade. Unless they represent an unknown branch of fungus-like organisms, the fossils imply that the fungal clade is considerably older than previously thought, and that fungal origin and early evolution may lie in the oceanic deep biosphere rather than on land. The Ongeluk discovery suggests that life has inhabited submarine volcanics for more than 2.4 billion years.

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  • 3.
    Carlsson, Diana
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Neubeck, Anna
    Stockholm University.
    Fossilized endolithic microorganisms in pillowlavas from the Troodos ophiolite, Cyprus2019In: Geosciences, E-ISSN 2076-3263, Vol. 9, no 11, article id 456Article in journal (Refereed)
    Abstract [en]

    The last decade has revealed the igneous oceanic crust to host a more abundant and diverse biota than previously expected. These underexplored rock-hosted deep ecosystems dominated Earth’s biosphere prior to plants colonized land in the Ordovician, thus the fossil record of deep endoliths holds invaluable clues to early life and the work to decrypt them needs to be intensified. Here, we present fossilized microorganisms found in open and sealed pore spaces in pillow lavas from the Troodos Ophiolite (91 Ma) on Cyprus. A fungal interpretation is inferred upon the microorganisms based on characteristic morphological features. Geochemical conditions are reconstructed using data from mineralogy, fluid inclusions and the fossils themselves. Mineralogy indicates at least three hydrothermal events and a continuous increase of temperature and pH. Precipitation of 1) celadonite and saponite together with the microbial introduction was followed by 2) Na and Ca zeolites resulting in clay adherence on the microorganisms as protection, and finally 3) Ca carbonates resulted in final fossilization and preservation of the organisms in-situ. Deciphering the fossil record of the deep subseafloor biosphere is a challenging task, but when successful, can unlock doors to life’s cryptic past.

  • 4. Chi Fru, E.
    et al.
    Ivarsson, M.
    Swedish Museum of Natural History, Department of Geology.
    Kilias, S. P.
    Frings, Patrick J
    Swedish Museum of Natural History, Department of Geology.
    Hemmingsson, C.
    Broman, C.
    Bengtson, S.
    Swedish Museum of Natural History, Department of Paleobiology.
    Chatzitheodoridis, E.
    Biogenicity of an Early Quaternary iron formation, Milos Island, Greece2015In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 13, no 3, p. 225-244Article in journal (Refereed)
    Abstract [en]

    A ~2.0-million-year-old shallow-submarine sedimentary deposit on Milos Island, Greece, harbours an unmetamorphosed fossiliferous iron formation (IF) comparable to Precambrian banded iron formations (BIFs). This Milos IF holds the potential to provide clues to the origin of Precambrian BIFs, relative to biotic and abiotic processes. Here, we combine field stratigraphic observations, stable isotopes of C, S and Si, rock petrography and microfossil evidence from a ~5-m-thick outcrop to track potential biogeochemical processes that may have contributed to the formation of the BIF-type rocks and the abrupt transition to an overlying conglomerate-hosted IF (CIF). Bulk δ13C isotopic compositions lower than -25‰ provide evidence for biological contribution by the Calvin and reductive acetyl–CoA carbon fixation cycles to the origin of both the BIF-type and CIF strata. Low S levels of ~0.04 wt.% combined with δ34S estimates of up to ~18‰ point to a non-sulphidic depository. Positive δ30Si records of up to +0.53‰ in the finely laminated BIF-type rocks indicate chemical deposition on the seafloor during weak periods of arc magmatism. Negative δ30Si data are consistent with geological observations suggesting a sudden change to intense arc volcanism potentially terminated the deposition of the BIF-type layer. The typical Precambrian rhythmic rocks of alternating Fe- and Si-rich bands are associated with abundant and spatially distinct microbial fossil assemblages. Together with previously proposed anoxygenic photoferrotrophic iron cycling and low sedimentary N and C potentially connected to diagenetic denitrification, the Milos IF is a biogenic submarine volcano-sedimentary IF showing depositional conditions analogous to Archaean Algoma-type BIFs.

  • 5. Chi Fru, Ernest
    et al.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Kilias, Stephanos
    Christoffer, Hemmingson
    Broman, Curt
    Bengtson, Stefan
    C, Chatzitheodoridis
    Biogenicity of an early Quaternary iron formation, Milos Island, Greece2015In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 13, p. 225-244Article in journal (Refereed)
  • 6. Chi Fru, Ernest
    et al.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Kilias, Stephanos P
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Marone, Federica
    Paul Scherrer Institute.
    Fortin, Danielle
    Broman, Curt
    Stampanoni, Marco
    ETH Zürich.
    Fossilized iron bacteria reveal pathway to biological origin of banded iron formation.2013In: Nature Communications, ISSN 2041-1723, Vol. 4, no 2050, p. 1-7Article in journal (Refereed)
    Abstract [en]

    Debates on the formation of banded iron formations in ancient ferruginous oceans are dominated by a dichotomy between abiotic and biotic iron cycling. This is fuelled by difficulties in unravelling the exact processes involved in their formation. Here we provide fossil environmental evidence for anoxygenic photoferrotrophic deposition of analogue banded iron rocks in shallow marine waters associated with an Early Quaternary hydrothermal vent field on Milos Island, Greece. Trace metal, major and rare earth elemental compositions suggest that the deposited rocks closely resemble banded iron formations of Precambrian origin. Well-preserved microbial fossils in combination with chemical data imply that band formation was linked to periodic massive encrustation of anoxygenic phototrophic biofilms by iron oxyhydroxide alternating with abiotic silica precipitation. The data implicate cyclic anoxygenic photoferrotrophy and their fossilization mechanisms in the construction of microskeletal fabrics that result in the formation of characteristic banded iron formation bands of varying silica and iron oxide ratios.

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  • 7.
    Chi Fru, Ernest
    et al.
    Department of Geological Sciences, 10691, Stockholm University, Stockholm, Sweden; School of Earth and Ocean Sciences, Cardiff University, Park Place, CF10 3AT Cardiff, UK.
    Kilias, Stephanos
    Department of Economic Geology and Geochemistry, Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 15784, Athens, Greece.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Rattray, Jayne E.
    Department of Geological Sciences, 10691, Stockholm University, Stockholm, Sweden.
    Gkika, Katerina
    Department of Economic Geology and Geochemistry, Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 15784, Athens, Greece.
    McDonald, Iain
    School of Earth and Ocean Sciences, Cardiff University, Park Place, CF10 3AT Cardiff, UK.
    He, Qian
    School of Chemistry, Cardiff University, Park Place, CF10 3AT Cardiff, UK.
    Broman, Curt
    Department of Geological Sciences, 10691, Stockholm University, Stockholm, Sweden.
    Sedimentary mechanisms of a modern banded iron formation on MIlos Island, Greece2018In: Solid Earth, ISSN 1869-9510, E-ISSN 1869-9529, Vol. 9, p. 573-598Article in journal (Refereed)
    Abstract [en]

    An early Quaternary shallow submarine hydrothermal iron formation (IF) in the Cape Vani sedimentary basin (CVSB) on Milos Island, Greece, displays banded rhythmicity similar to Precambrian banded iron formation (BIF). Field-wide stratigraphic and biogeochemical reconstructions show two temporal and spatially isolated iron deposits in the CVSB with distinct sedimentological character. Petrographic screening suggests the presence of a photoferrotrophic-like microfossil-rich IF (MFIF), accumulated on a basement consisting of andesites in a ∼ 150m wide basin in the SW margin of the basin. A banded nonfossiliferous IF (NFIF) sits on top of the Mn-rich sandstones at the transition to the renowned Mn-rich formation, capping the NFIF unit. Geochemical data relate the origin of the NFIF to periodic submarine volcanism and water column oxidation of released Fe(II) in conditions predominated by anoxia, similar to the MFIF. Raman spectroscopy pairs hematite-rich grains in the NFIF with relics of a carbonaceous material carrying an average δ13Corg signature of ∼ −25‰. A similar δ13Corg signature in the MFIF could not be directly coupled to hematite by mineralogy. The NFIF, which postdates large-scale Mn deposition in the CVSB, is composed primarily of amorphous Si (opal-SiO2 ⋅ nH2O) while crystalline quartz (SiO2) predominates the MFIF. An intricate interaction between tectonic processes, changing redox, biological activity, and abiotic Si precipitation are proposed to have collectively formed the unmetamorphosed BIF-type deposits in a shallow submarine volcanic center. Despite the differences in Precambrian ocean–atmosphere chemistry and the present geologic time, these formation mechanisms coincide with those believed to have formed Algoma-type BIFs proximal to active seafloor volcanic centers.

  • 8.
    Dekov, V.M.
    et al.
    Department of Ocean Sciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan.
    Kyono, K.
    Department of Ocean Sciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan.
    Yasukawa, K.
    Frontier Research Center for Energy and Resources, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan; Department of Systems Innovation, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
    Guéguen, B.
    CNRS, Univ Brest, UMR 6538 Laboratoire Géosciences Océan, F-29280 Plouzané, France; CNRS, Univ Brest, UMS 3113, F-29280 Plouzané, France.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Kamenov, G.D.
    Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL 32611, USA.
    Yamanaka, T.
    Department of Ocean Sciences, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-8477, Japan.
    Asael, D.
    Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA.
    Ishida, M.
    Department of Systems Innovation, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
    Cavalcante, L.L.
    Swedish Museum of Natural History, Department of Paleobiology.
    Kato, Y.
    Frontier Research Center for Energy and Resources, School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
    Toki, T.
    Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan.
    Ishibashi, J.-I.
    Kobe Ocean-Bottom Exploration Center, Kobe University, 5-1-1 Fukaeminami-machi, Higashinada-ku, Kobe 658-0022, Japan.
    Mineralogy, geochemistry and microbiology insights into precipitation of stibnite and orpiment at the Daiyon-Yonaguni Knoll (Okinawa Trough) hydrothermal barite deposits2022In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 610, p. 121092-121092, article id 121092Article in journal (Refereed)
    Abstract [en]

    Samples of active chimneys, chimney flanges and massive sulfides from the Daiyon-Yonaguni Knoll hydrothermal field are composed of major barite and minor stibnite and orpiment. Barite is inferred to precipitate from focused-discharge fluids composed of >40% hydrothermal end-member fluid at T = 100-240°C, whereas the stibnite and orpiment are later and lower temperature precipitates. The hydrothermal fluids from this field were subject of sub-seafloor boiling and phase separation and, consequently, are brine-rich depleted in volatile and enriched in non-volatile elements. Boiling and phase separation exerted major control on the rare earth elements (REE) partitioning in the vent fluids: high-chlorinity high-temperature fluids were enriched in light REE and low-chlorinity low-temperature fluids were enriched in heavy REE. Y/Ho molar ratio and Ce anomaly of the vent fluids suggest that the seawater has not completely reacted with the basement rocks and has not equilibrated with them. The trace element concentrations in the hydrothermal deposits suggest a complex interplay among hydrothermal, hydrogenetic and microbial processes. Sulfur isotope composition of the sulfides suggests that the sulfide S is a mixture of both basement rock and seawater S with a higher proportion of the basement rock S. The sulfate dissolved in the fluids was subjected to reduction during a slow mixing of hydrothermal fluid and seawater within the chimney walls of the Tiger and Abyss vents and this resulted in a heavy S-isotope composition of the vent fluid sulfate. Lead isotope composition of the hydrothermal deposits indicates mixing relationships suggesting that Pb and potentially other metals with similar geochemical behavior were derived from two or three sources. The Pb isotopes in the hydrothermal deposits imply that an enriched source, either sediments or extended continental lithosphere, and a depleted source, potentially back-arc mafic volcanics, are present in the area of Daiyon-Yonaguni Knoll. Filamentous orpiment found in the deposits is supposed to be either heavily mineralized fungal hyphae or pure abiogenic biomorphs. Presence of carbonaceous matter on and around the orpiment filaments suggests for microbial activity during filament formation. The filaments experienced temperature of 209.1±37.1°C which falls within the temperature range of the Daiyon-Yonaguni Knoll vent fluids. Stability phase diagrams modeling reveals that the stability of stibnite does not depend on the vent fluid chlorinity, but depends on the vent fluid temperature: the area of stibnite stability increases with decreasing vent fluid temperature and results in stibnite precipitation at low log10a of Sb2S42- and less reduced environment (Eh still <0). Orpiment is stable in a wide range of log10a of H2AsO4-, in reduced conditions and at high S activity. Barite is stable in wide range of log10a of Ba2+ and precipitates in slightly reduced to slightly oxic conditions.

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  • 9.
    Drake, Henrik
    et al.
    LineUniversitet.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Fossil svamp i Siljansringens meteoritkrater2021In: Geologiskt Forum, ISSN 1104-4721, Vol. 110, p. 18-21Article in journal (Other (popular science, discussion, etc.))
  • 10. Drake, Henrik
    et al.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Fossil svamp i Siljansringens meteoritkrater2021In: Geologiskt Forum, Vol. 110, p. 18-21Article in journal (Other (popular science, discussion, etc.))
  • 11.
    Drake, Henrik
    et al.
    Linnæus University, Department of Biology and Environmental Science, 39182 Kalmar, Sweden.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    The role of anaerobic fungi in fundamental biogeochemical cycles in the deep biosphere2018In: Fungal Biology Reviews, ISSN 1749-4613, E-ISSN 1878-0253, Vol. 32, p. 20-25Article in journal (Refereed)
    Abstract [en]

    A major part of the biologic activity on Earth is hidden underneath our feet in an environment coined the deep biosphere which stretches several kilometers down into the bedrock. The knowledge about life in this vast energy-poor deep system is, however, extremely scarce, particularly for micro-eukaryotes such as fungi, as most studies have focused on prokaryotes. Recent findings suggest that anaerobic fungi indeed thrive at great depth in fractures and cavities of igneous rocks in both the oceanic and the continental crust. Here we discuss the potential importance of fungi in the deep biosphere, in particular their involvement in fundamental biogeochemical processes such as symbiotic relationships with prokaryotes that may have significant importance for the overall energy cycling within this vast subsurface realm. Due to severe oligotrophy, the prokaryotic metabolism at great depth in the crust is very slow and dominantly autotrophic and thus dependent on e.g. hydrogen gas, but the abiotic production of this gas is thought to be insufficient to fuel the deep autotrophic biosphere. Anaerobic fungi are heterotrophs that produce hydrogen gas in their metabolism and have therefore been put forward as a hypothetical provider of this substrate to the prokaryotes. Recent in situ findings of fungi and isotopic signatures within co-genetic sulfide minerals formed from bacterial sulfate reduction in the deep continental biosphere indeed seem to confirm the fungi-prokaryote hypothesis. This suggests that fungi play a fundamental biogeochemical role in the deep biosphere.

  • 12. Drake, Henrik
    et al.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Heim, Christine
    Siljeström, Sandra
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Broman, Curt
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Åström, Mats E.
    Anaerobic consortia of fungi and sulfate reducing bacteria in deep granite fractures2017In: Nature Communications, E-ISSN 2041-1723, Vol. 8, no 55, p. 1-9Article in journal (Refereed)
    Abstract [en]

    The deep biosphere is one of the least understood ecosystems on Earth. Although most microbiological studies in this system have focused on prokaryotes and neglected microeukaryotes, recent discoveries have revealed existence of fossil and active fungi in marine sediments and sub-seafloor basalts, with proposed importance for the subsurface energy cycle. However, studies of fungi in deep continental crystalline rocks are surprisingly few. Consequently, the characteristics and processes of fungi and fungus-prokaryote interactions in this vast environment remain enigmatic. Here we report the first findings of partly organically preserved and partly mineralized fungi at great depth in fractured crystalline rock (-740 m). Based on environmental parameters and mineralogy the fungi are interpreted as anaerobic. Synchrotron-based techniques and stable isotope microanalysis confirm a coupling between the fungi and sulfate reducing bacteria. The cryptoendolithic fungi have significantly weathered neighboring zeolite crystals and thus have implications for storage of toxic wastes using zeolite barriers.

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  • 13. Drake, Henrik
    et al.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Heim, Christine
    Snoeyenbos-West, Oona
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Fossilized anaerobic and possibly methanogenesis-fueling fungi identified deep within the Siljan impact structure, Sweden2021In: Communications Earth & Environment, E-ISSN 2662-4435, Vol. 2, no 1, p. 1-11Article in journal (Refereed)
    Abstract [en]

    Recent discoveries of extant and fossilized communities indicate that eukaryotes, including fungi, inhabit energy-poor and anoxic environments deep within the fractured igneous crust. This subterranean biosphere may constitute the largest fungal habitat on our planet, but knowledge of abyssal fungi and their syntrophic interactions with prokaryotes and their concomitant metabolisms is scarce. Here we report findings of fossilized, chitin-bearing fungal hyphae at ~540 m depth in fractured bedrock of the Siljan impact structure, the largest crater in Europe. Strong 13C-enrichment of calcite precipitated with and on the fungi suggests formation following methanogenesis, and that the anaerobic fungi decomposed dispersed organic matter producing for example H2 that may have fueled autotrophic methanogens. An Eocene age determined for the calcite infers the first timing constraint of fossilized fungi in the continental igneous crust. Fungi may be widespread decomposers of organic matter and overlooked providers of H2 to autotrophs in the vast rock-hosted deep biosphere.

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  • 14.
    Drake, Henrik
    et al.
    Linnæus University, Department of Biology and Environmental Science, 39182 Kalmar, Sweden.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    Tillberg, Mikael
    Department of Biology and Environmental Science, Linnaeus University, 392 31 Kalmar, Sweden.
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Ancient microbial activity in deep hydraulically conductive fracture zones within the Forsmark target area for deep geological nuclear waste disposal, Sweden2018In: Geosciences, Vol. 8, article id 211Article in journal (Refereed)
    Abstract [en]

    Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of 13Ccalcite (􀀀36.2 to +20.2‰V-PDB) and 34Spyrite (􀀀11.7 to +37.8‰V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of 18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded.

  • 15. Drake, Henrik
    et al.
    Roberts, Nick M. W.
    Heim, Christine
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Siljeström, Sandra
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Broman, Curt
    Ivarsson, Magnus
    Åström, Mats E.
    Timing and origin of natural gas accumulation in the Siljan impact structure, Sweden2019In: Nature Communications, E-ISSN 2041-1723, Vol. 10, no 1Article in journal (Refereed)
    Abstract [en]

    Fractured rocks of impact craters may be suitable hosts for deep microbial communities on Earth and potentially other terrestrial planets, yet direct evidence remains elusive. Here, we present a study of the largest crater of Europe, the Devonian Siljan structure, showing that impact structures can be important unexplored hosts for long-term deep microbial activity. Secondary carbonate minerals dated to 80 ± 5 to 22 ± 3 million years, and thus postdating the impact by more than 300 million years, have isotopic signatures revealing both microbial methanogenesis and anaerobic oxidation of methane in the bedrock. Hydrocarbons mobilized from matured shale source rocks were utilized by subsurface microorganisms, leading to accumulation of microbial methane mixed with a thermogenic and possibly a minor abiotic gas fraction beneath a sedimentary cap rock at the crater rim. These new insights into crater hosted gas accumulation and microbial activity have implications for understanding the astrobiological consequences of impacts.

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  • 16.
    Drake, Henrik
    et al.
    Institutionen för biologi och miljö, Linneuniversitet.
    Roberts, Nick M. W.
    Geochronology and Tracers Facility, British Geological Survey.
    Reinhardt, Manuel
    Department of Biology and Environmental Science, Linnæus University.
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Kielman-Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield2021In: Communications Earth & Environment, E-ISSN 2662-4435, Vol. 2, no 1, article id 102Article in journal (Refereed)
    Abstract [en]

    Earth’s crust contains a substantial proportion of global biomass, hosting microbial life up to several kilometers depth. Yet, knowledge of the evolution and extent of life in this environment remains elusive and patchy. Here we present isotopic, molecular and morphological signatures for deep ancient life in vein mineral specimens from mines distributed across the Precambrian Fennoscandian shield. Stable carbon isotopic signatures of calcite indicate microbial methanogenesis. In addition, sulfur isotope variability in pyrite, supported by stable carbon isotopic signatures of methyl-branched fatty acids, suggest subsequent bacterial sulfate reduction. Carbonate geochronology constrains the timing of these processes to the Cenozoic. We suggest that signatures of an ancient deep biosphere and long-term microbial activity are present throughout this shield. We suggest that microbes may have been active in the continental igneous crust over geological timescales, and that subsurface investigations may be valuable in the search for extra-terrestrial life.

  • 17. Drake, Henrik
    et al.
    Roberts, Nick M. W.
    Reinhardt, Manuel
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Kielman-Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield2021In: Communications Earth & Environment, E-ISSN 2662-4435, Vol. 2, no 1, article id 102Article in journal (Refereed)
  • 18. Drake, Henrik
    et al.
    Roberts, Nick M. W.
    Reinhardt, Manuel
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Karlsson, Andreas
    Swedish Museum of Natural History, Department of Geology.
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Kielman-Schmitt, Melanie
    Swedish Museum of Natural History, Department of Geology.
    Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield2021In: Communications Earth & Environment, E-ISSN 2662-4435, Vol. 2, no 1, article id 102Article in journal (Refereed)
  • 19. Drake, Henrik
    et al.
    Roberts, Nick M. W.
    Reinhardt, Manuel
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Karlsson, Andreas
    Kooijman, Ellen
    Swedish Museum of Natural History, Department of Geology.
    Kielman-Schmitt, Melanie
    Biosignatures of ancient microbial life are present across the igneous crust of the Fennoscandian shield2021In: Communication Earth & Environment, Vol. 2, no 1, article id 102Article in journal (Refereed)
  • 20. Drake, Henrik
    et al.
    Åström, M.E.
    Heim, Christine
    Broman, Curt
    Åström, J
    Whitehouse, Martin
    Swedish Museum of Natural History, Department of Geology.
    Ivarsson, Magnus
    Siljeström, Sandra
    Sjövall, Peter
    Extreme 13C-depletion of carbonates formed during oxidation of biogenic methane in fractured granite2015In: Nature Communications, E-ISSN 2041-1723, Vol. 6Article in journal (Refereed)
  • 21.
    Ivarsson, Lena Norbäck
    et al.
    Stockholm University.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Lundberg, Johannes
    Swedish Museum of Natural History, Department of Botany.
    Sallstedt, Therese
    Swedish Museum of Natural History, Department of Paleobiology.
    Rydin, Catarina
    Stockholm University.
    Epilithic and aerophilic diatoms in the artificial environment of Kungsträdgården metro station, Stockholm, Sweden2013In: International Journal of Speleology, ISSN 0392-6672, E-ISSN 1827-806X, Vol. 42, no 3, p. 289-297Article in journal (Refereed)
    Abstract [en]

    The Kungsträdgården metro station is an artificial and urban subsurface environment illuminated with artificial light. Its ecosystem is almost completely unknown and as a first step to better understand the biology and rock wall habitats the diatom flora was investigated. A total of 12 species were found growing on the rock walls of Kungsträdgården metro station. The results show the diatom flora in Kungsträdgården to be dominated by e.g. Diadesmis contentaDiadesmis perpusillaPinnularia appendiculataNitzschia amphibiaNitzschia sinuata and Diploneis ovalis. One species, Caloneis cf. aerophila, has never been reported from Sweden before. Significant differences in the species composition between the sampling sites indicate Kungsträdgården metro station to be a heterogeneous habitat that provides different microhabitats.

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    Diatoms in Kungsträdgården metro station.pdf
  • 22.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Exit Jorden: Om livets förutsättningar i rymden2023Book (Other (popular science, discussion, etc.))
    Abstract [en]

    Could travel to Mars and alien colonies become a reality in the near future or is it just science fiction? And why should we even leave our dear home planet?

    In Exit Earth, we embark on a space journey with the final destination Mars and the founding of humanity's first colony. We look away from the technical aspects of space travel and take a closer look at how we can use microorganisms to produce food, medicine and building materials to make Mars more like Earth. We are also investigating how, with the help of biotechnology, humans can adapt to a life in space and perhaps eventually develop into a multiplanetary species that inhabits several celestial bodies.

    Whether the exploration of space is due to a rampant climate crisis or economic gains, it is something deeply human to constantly strive towards places no one has visited before.

  • 23.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Fossilized life in an Ordovician impact-induced hydrothermal system2014Conference paper (Other academic)
  • 24.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Fossilized microorganisms in subseafloor basalts2014Conference paper (Other academic)
  • 25.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Traces of Life in Basaltic Crust2023In: Encyclopedia of Astrobiology / [ed] Gargaud Muriel, Irvine William M., Amils Ricardo, Claeys Philippe, Cleaves Henderson James, Gerin Maryvonne, Rouan Daniel, Spohn Tilman, Tirard Stéphane, Viso Michel, Berlin: Springer Berlin/Heidelberg, 2023, 3, p. 1-4Chapter in book (Refereed)
  • 26.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Traces of Life in Basaltic Crust2022In: Encyclopedia of Astrobiology / [ed] Gargaud, M., et al., Springer Berlin/Heidelberg, 2022, p. 1-4Chapter in book (Refereed)
    Abstract [en]

    Traces of life in basaltic crust refer to signs of past life, including fossilized microorganisms and ichnofossils that reflect microbial activity, in mafic rock. The organisms were once engaged in an endolithic, that is, rock-dwelling lifestyle colonizing open pore space, such as fractures or vesicles, and preserved in situ upon their death. A majority of the fossil remains have been found in subseafloor basalts or ancient oceanic crust (Fig. 1), and only rarely in continental settings. Body fossils are found throughout the basaltic formations, while ichnofossils are almost exclusively found in volcanic glass of pillow lavas.

  • 27.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Traces of Life in Basaltic Crust2023In: Encyclopedia of Astrobiology, p. 3088-3091Article in journal (Refereed)
  • 28.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Oceanbottnarnas hemliga liv.2017In: Havsutsikt, ISSN 1104-0513, Vol. 2017, no 2, p. 16-18Article in journal (Other (popular science, discussion, etc.))
    Abstract [sv]

    Berggrunden under havens bottensediment är en vidsträckt men svårtillgänglig och outforskad del av vår planet, särskilt när det gäller liv. Paradoxalt nog är det, förutom haven, världens volymmässigt största livsmiljö för mikroorganismer. Med nya metoder har forskare från Naturhistoriska riksmuseet vänt upp och ner på den gängse vetenskapliga uppfattningen. I den spruckna berggrunden under havssedimenten bor inte bara de förväntade extremt tåliga bakterierna och arkéerna – de har även gott sällskap av svampar.

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  • 29.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Stampanoni, Marco
    ETH Zürich.
    Marone, Federica
    Paul Scherrer Institute.
    Tehler, Anders
    Swedish Museum of Natural History, Department of Botany.
    Fossilized fungi in subseafloor Eocene basalts.2012In: Geology, ISSN 0091-7613, Vol. 40, no 2, p. 163-166Article in journal (Refereed)
    Abstract [en]

    The deep biosphere of subseafl oor basalts is thought to consist of mainly prokaryotes (bacteria and archaea). Here we report fossilized fi lamentous microorganisms from subseafl oor basalts interpreted as fossilized fungal hyphae, probably Dikarya, rather than fossilized prokaryotes. The basalts were collected during the Ocean Drilling Program Leg 197 at the Emperor Seamounts, North Pacifi c Ocean, and the fossilized fungi are observed in carbonate-fi lled veins and vesicles in samples that represent a depth of ~150 m below the seafl oor. Three-dimensional visualizations using synchrotron-radiation X-ray tomographic microscopy show characteristic fungal morphology of the mycelium-like network, such as frequent branching, anastomosis, and septa. Possible presence of chitin in the hypha walls was detected by staining with Wheat Germ Agglutinin conjugated with Fluorescein Isothiocyanate and examination using fl uorescence microscopy. The presence of fungi in subseafl oor basalts challenges the present understanding of the deep subseafl oor biosphere as being exclusively prokaryotic.

  • 30.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Carlsson, Diana
    Swedish Museum of Natural History, Department of Paleobiology.
    Är magmatiska bergarterfossilförande?2017In: Geologiskt Forum, ISSN ISSN 1104-4721, no 94, p. 20-23Article, review/survey (Other (popular science, discussion, etc.))
    Abstract [sv]

    Förekomsten av fossil är lika starkt sammankopplad till sedimentära bergarter som magmatiska bergarter är till frånvaron av fossil. Detta har varit ett obestridbart faktum sedan geovetenskapernas gryning. Men nu börjar detta synsätt att ändra sig. Forskare vid Naturhistoriska riksmuseet utforskar ett fossilt arkiv som påträffas i sprickor och håligheter i magmatiska och vulkaniska bergarter. Detta kan spela stor roll framöver för studiet av djupbiosfären och det tidiga livet på jorden samt även för sökandet efter liv på Mars.

  • 31.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Drake, Henrik
    Linnaeus University, Kalmar.
    Francis, Warren
    University of Southern Denmark.
    Fungi in deep subsurface environments2018In: Advances in Applied Microbiology, ISSN 0065-2164, Vol. 102, p. 83-116Article in journal (Refereed)
    Abstract [en]

    The igneous crust of the oceans and the continents represents the major part of Earth's lithosphere and has recently been recognized as a substantial, yet underexplored, microbial habitat. While prokaryotes have been the focus of most investigations, microeukaryotes have been surprisingly neglected. However, recent work acknowledges eukaryotes, and in particular fungi, as common inhabitants of the deep biosphere, including the deep igneous provinces. The fossil record of the subseafloor igneous crust, and to some extent the continental bedrock, establishes fungi or fungus-like organisms as inhabitants of deep rock since at least the Paleoproterozoic, which challenges the present notion of early fungal evolution. Additionally, deep fungi have been shown to play an important ecological role engaging in symbiosis-like relationships with prokaryotes, decomposing organic matter, and being responsible for mineral weathering and formation, thus mediating mobilization of biogeochemically important elements. In this review, we aim at covering the abundance and diversity of fungi in the various igneous rock provinces on Earth as well as describing the ecological impact of deep fungi. We further discuss what consequences recent findings might have for the understanding of the fungal distribution in extensive anoxic environments and for early fungal evolution.

  • 32.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Neubeck, Anna
    Swedish Museum of Natural History, Department of Paleobiology. Stockholm University.
    The igneous oceanic crust – Earth’s largest fungal habitat?2016In: Fungal ecology, ISSN 1754-5048, E-ISSN 1878-0083, Vol. 20, p. 249-255Article in journal (Refereed)
    Abstract [en]

    In recent years the igneous oceanic crust has been recognized as a substantial microbial habitat and a scientific frontier within Geology, Biology, and Oceanography. A few successful metagenomic investigations have indicated the presence of Archaea and Bacteria, but also fungi in the subseafloor igneous crust. A comprehensive fossil record supports the presence of fungi in these deep environments and provides means of investigating the fungal presence that complements metagenomic methods. Considering the vast volume of the oceanic crust and that it is the largest aquifer on Earth, we put forward that it is the largest fungal habitat on the planet. This review aims to introduce a yet unexplored fungal habitat in an environment considered extreme from a biological perspective. We present the current knowledge of fungal abundance and diversity and discuss the ecological role of fungi in the igneous oceanic crust.

  • 33.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Marone, Federica
    Paul Scherrer Institute.
    Fungal colonies in open fractures of subseafloor basalt.2013In: Geo-Marine Letters, ISSN 0276-0460, E-ISSN 1432-1157, Vol. 33, no 4, p. 233-234Article in journal (Refereed)
    Abstract [en]

    The deep subseafloor crust is one of the few great frontiers of unknown biology on Earth and, still today, the notion of the deep biosphere is commonly based on the fossil record. Interpretation of palaeobiological information is thus central in the exploration of this hidden biosphere and, for each new discovery, criteria used to establish biogenicity are challenged and need careful consideration. In this paper networks of fossilized filamentous structures are for the first time described in open fractures of subseafloor basalts collected at the Emperor Seamounts, Pacific Ocean. These structures have been investigated with optical microscopy, environmental scanning electron microscope, energy dispersive spectrometer, X-ray powder diffraction as well as synchrotron-radiation X-ray tomographic microscopy, and interpreted as fossilized fungal mycelia.Morphological features such as hyphae, yeastlike growth and sclerotia were observed. The fossilized fungi are mineralized by montmorillonite, a process that probably began while the fungi were alive. It seems plausible that the fungi produced mucilaginous polysaccharides and/or extracellular polymeric substances that attracted minerals or clay particles, resulting in complete fossilization by montmorillonite. The findings are in agreement with previous observations of fossilized fungi in subseafloor basalts and establish fungi as regular inhabitants of such settings. They further show that fossilized microorganisms are not restricted to pore spaces filled by secondary mineralizations but can be found in open pore spaces as well. This challenges standard protocols for establishing biogenicity and calls for extra care in data interpretation.

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    Ivarsson_etal_2013_Fungal
  • 34.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Bengtson, Stefan
    Skogby, Henrik
    Lazor, Peter
    Broman, Curt
    Belivanova, Veneta
    Marone, Federica
    A fungal-prokaryotic consortium at the basalt-zeolite interface in subseafloor igneous crust2015In: PLOS ONE, E-ISSN 1932-6203Article in journal (Refereed)
  • 35.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Broman, Curt
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Håkan, Gustafsson
    Department of Biomedical Engineering (MTÖ), County Council of Östergötland, Radiation Physics, Department of Medicine and Health Sciences, Linköping University, Linköping, Sweden.
    Holm, Nils
    Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
    Biogenic Mn-oxides in subseafloor basalts2015In: PLOS ONE, E-ISSN 1932-6203, Vol. 10, no 6, article id e0128863Article in journal (Refereed)
    Abstract [en]

    The deep biosphere of the subseafloor basalts is recognized as a major scientific frontier in disciplines like biology, geology, and oceanography. Recently, the presence of fungi in these environments has involved a change of view regarding diversity and ecology. Here, we describe fossilized fungal communities in vugs in subseafloor basalts from a depth of 936.65 metres below seafloor at the Detroit Seamount, Pacific Ocean. These fungal communities are closely associated with botryoidal Mn oxides composed of todorokite. Analyses of the Mn oxides by Electron Paramagnetic Resonance spectroscopy (EPR) indicate a biogenic signature. We suggest, based on mineralogical, morphological and EPR data, a biological origin of the botryoidal Mn oxides. Our results show that fungi are involved in Mn cycling at great depths in the seafloor and we introduce EPR as a means to easily identify biogenic Mn oxides in these environments.

  • 36.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Broman, Curt
    Sturkell, Erik
    Ormö, Jens
    Siljeström, Sandra
    van Zuilen, Mark
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Fungal colonization of an Ordovician impact-induced hydrothermal system.2013In: Scientific Reports, E-ISSN 2045-2322, Vol. 3, no 3487, p. 1-6Article in journal (Refereed)
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    Ivarsson et al. 2013
  • 37.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Drake, Henrik
    Linnaeus University Faculty of Health and Life Sciences, Kalmar, Sweden.
    Neubeck, Anna
    Swedish Museum of Natural History, Department of Paleobiology. Uppsala University.
    Snoeyenbos-West, Oona
    Swedish Museum of Natural History, Department of Paleobiology. Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden.
    Belivanova, Veneta
    Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Introducing palaeolithobiology2021In: GFF, ISSN 1103-5897, E-ISSN 2000-0863, Vol. 143, no 2-3, p. 305-319Article in journal (Refereed)
    Abstract [en]

    A growing literature of deep but also surficial fossilized remains of lithobiological life, often associated with igneous rocks, necessitates the unfolding of a sub-discipline within paleobiology. Here, we introduce the term paleolithobiology as the new auxiliary sub-discipline under which fossilized lithobiology should be handled. We present key criteria that distinguish the paleolithobiological archive from the traditional one and discuss sample strategies as well as scientific perspectives. A majority of paleolithobiological material consists of deep biosphere fossils, and in order to highlight the relevance of these, we present new data on fungal fossils from the Lockne impact crater. Fungal fossils in the Lockne drill cores have been described previously but here we provide new insights into the presence of reproductive structures that indicate the fungi to be indigenous. We also show that these fungi frequently dissolve and penetrate secondary calcite, delineating the role lithobionts plays in geobiological cycles. We hope that the formalization of the sub-discipline paleolithobiology will not only highlight an overlooked area of paleobiology as well as simplify future studies of endo- and epilithic fossil material, but also improve our understanding of the history of the deep biosphere.

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  • 38.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Nordic Center for Earth Evolution (NordCEE).
    Gustavsson, Lena
    Swedish Museum of Natural History, Department of Zoology.
    Hedenäs, Lars
    Swedish Museum of Natural History, Department of Botany.
    Kronestedt, Torbjörn
    Swedish Museum of Natural History, Department of Zoology.
    Lundberg, Johannes
    Swedish Museum of Natural History, Department of Botany.
    Norbäck Ivarsson, Lena
    Södertörn University.
    Sallstedt, Therese
    Swedish Museum of Natural History, Department of Paleobiology. Nordic Center for Earth Evolution (NordCEE).
    Scheuerer, Manuela
    Sweco Rail.
    Thureborn, Olle
    Stockholm University.
    Wedin, Mats
    Swedish Museum of Natural History, Department of Botany.
    Unikt ekosystem i tunnelbanan vid Kungsträdgården2017In: Fauna och flora : populär tidskrift för biologi, ISSN 0014-8903, Vol. 112, no 1, p. 2-9Article in journal (Other (popular science, discussion, etc.))
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  • 39.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Holm, Nils
    Neubeck, Anna
    The deep biosphere of the subseafloor igneous crust2015In: Trace Metal Biogeochemsitry and Ecology of Deep-Sea Hydrothermal Vent Systems / [ed] Demina, L.L., Galkin, S.V., Springer, 2015Chapter in book (Refereed)
  • 40.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. Nordic Center for Earth Evolution (NordCEE).
    Palmgren, Kristoffer
    Lundberg, Johannes
    Swedish Museum of Natural History, Department of Botany.
    Scheuerer, Manuela
    Underjordisk svamp i Falu koppargruva2021In: Svensk Mykologisk Tidskrift, ISSN 1653-0357, Vol. 42, no 2, p. 2-10Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    Fungi in subsurface and underground environments is a rather new and underexplored field within mycology, and our understanding of these communities are sparse. However, available reports indicate a high fungal diversity with a large poriton of undescribed taxa in these settings. Here we investigate the fungal presence in the Falun copper mine, Sweden, with the aim to identify fungi useable in bioremediation processes. Thirteen of fourteen samples were successfully cultured, and nine isolates obtained in total. Further culturing and investigations are needed to understand the bioremediation abilities among the fungi, but this first reort indicates a high abundance and diversity of fungi in the underground Falun copper mine.

  • 41.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Peckmann, J
    Swedish Museum of Natural History, Department of Paleobiology.
    Tehler, Anders
    Swedish Museum of Natural History, Department of Botany.
    Broman, C
    Bach, W
    Behrens, K
    Reitner, J
    Bottcher, M.E
    Norback Ivarsson, L
    Zygomycetes in Vesicular Basanites from Vesteris Seamount, Greenland Basin - A New Type of Cryptoendolithic Fungi2015In: PLoS One, Vol. 10, article id e0133368Article in journal (Refereed)
    Abstract [en]

    Fungi have been recognized as a frequent colonizer of subseafloor basalt but a substantial understanding of their abundance, diversity and ecological role in this environment is still lacking. Here we report fossilized cryptoendolithic fungal communities represented by mainly Zygomycetes and minor Ascomycetes in vesicles of dredged volcanic rocks (basa- nites) from the Vesteris Seamount in the Greenland Basin. Zygomycetes had not been reported from subseafloor basalt previously. Different stages in zygospore formation are documented in the studied samples, representing a reproduction cycle. Spore structures of both Zygomycetes and Ascomycetes are mineralized by romanechite-like Mn oxide phases, indicating an involvement in Mn(II) oxidation to form Mn(III,VI) oxides. Zygospores still exhibit a core of carbonaceous matter due to their resistance to degradation. The fungi are closely associated with fossiliferous marine sediments that have been introduced into the vesicles. At the contact to sediment infillings, fungi produced haustoria that penetrated and scavenged on the remains of fragmented marine organisms. It is most likely that such marine debris is the main carbon source for fungi in shallow volcanic rocks, which favored the establishment of vital colonies. 

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  • 42.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Schnürer, Anna
    Swedish University of Agricultural Sciences.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Neubeck, Anna
    Swedish Museum of Natural History, Department of Paleobiology. Stockholm University.
    Anaerobic fungi: a potential source of biological H2 in the oceanic crust.2016In: Frontiers in Microbiology, E-ISSN 1664-302X, Vol. 7, no 674, p. 1-8Article in journal (Refereed)
    Abstract [en]

    The recent recognition of fungi in the oceanic igneous crust challenges the understanding of this environment as being exclusively prokaryotic and forces reconsiderations of the ecology of the deep biosphere. Anoxic provinces in the igneous crust are abundant and increase with age and depth of the crust. The presence of anaerobic fungi in deep-sea sediments and on the seafloor introduces a type of organism with attributes of geobiological significance not previously accounted for. Anaerobic fungi are best known from the rumen of herbivores where they produce molecular hydrogen, which in turn stimulates the growth of methanogens. The symbiotic cooperation between anaerobic fungi and methanogens in the rumen enhance the metabolic rate and growth of both. Methanogens and other hydrogen-consuming anaerobic archaea are known from subseafloor basalt; however, the abiotic production of hydrogen is questioned to be sufficient to support such communities. Alternatively, biologically produced hydrogen could serve as a continuous source. Here, we propose anaerobic fungi as a source of bioavailable hydrogen in the oceanic crust, and a close interplay between anaerobic fungi and hydrogen-driven prokaryotes.

  • 43.
    Ivarsson, Magnus
    et al.
    Swedish Museum of Natural History, Department of Paleobiology. University of Southern Denmark, Department of Biology and Nordic Center for Earth Evolution, Campusvej 55, Odense M, DK-5230, Denmark.
    Skogby, Henrik
    Swedish Museum of Natural History, Department of Geology.
    Phichaikamjornwut, Bongkot
    Gems and Jewelry Program, Faculty of Science, Srinakharinwirot University, Bangkok, Thailand .
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Siljeström, Sandra
    RISE Research Institutes of Sweden, Bioscience and Materials/Chemistry and Materials, Stockholm, Sweden.
    Ounchanum, Prayote
    Department of Geological Sciences, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.
    Boonsong, Apichet
    Department of Geological Sciences, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.
    Kruachanta, M
    Department of Geological Sciences, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand .
    Marone, Federica
    Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland.
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology.
    Sara, Holmström
    Stockholm University, Department of Geological Sciences, Stockholm, Sweden.
    Intricate tunnels in garnets from soils and rivere sediments in Thailand - possible endolithic microborings2018In: PLOS ONE, E-ISSN 1932-6203, Vol. 13, no 8, article id e0200351Article in journal (Refereed)
    Abstract [en]

    Garnets from disparate geographical environments and origins such as oxidized soils and river sediments in Thailand host intricate systems of microsized tunnels that significantly decrease the quality and value of the garnets as gems. The origin of such tunneling has previously been attributed to abiotic processes. Here we present physical and chemical remains of endolithic microorganisms within the tunnels and discuss a probable biological origin of the tunnels. Extensive investigations with synchrotron-radiation X-ray tomographic microscopy (SRXTM) reveal morphological indications of biogenicity that further support a euendolithic interpretation. We suggest that the production of the tunnels was initiated by a combination of abiotic and biological processes, and that at later stages biological processes came to dominate. In environments such as river sediments and oxidized soils garnets are among the few remaining sources of bio-available Fe2+, thus it is likely that microbially mediated boring of the garnets has trophic reasons. Whatever the reason for garnet boring, the tunnel system represents a new endolithic habitat in a hard silicate mineral otherwise known to be resistant to abrasion and chemical attack.

  • 44. Jackson, Marie
    et al.
    Couper, Samantha
    Stan, S
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Czabaj, M
    Tamura, N
    Parkinson, D
    Miyagi, L.M.
    Moore, James
    Authigenic mineral textures in submarine 1979 basalt drill core, Surtsey volcano, Iceland2019In: Geochemistry Geophysics Geosystems, E-ISSN 1525-2027, Vol. 20, no 7, p. 3751-3773Article in journal (Refereed)
    Abstract [en]

    Micrometer‐scale maps of authigenic microstructures in submarine basaltic tuff from a 1979 Surtsey volcano, Iceland, drill core acquired 15 years after eruptions terminated describe the initial alteration of oceanic basalt in a low‐temperature hydrothermal system. An integrative investigative approach uses synchrotron source X‐ray microdiffraction, microfluoresence, micro‐computed tomography, and scanning transmission electron microscopy coupled with Raman spectroscopy to create finely resolved spatial frameworks that record a continuum of alteration in glass and olivine. Microanalytical maps of vesicular and fractured lapilli in specimens from 157.1‐, 137.9‐, and 102.6‐m depths and borehole temperatures of 83, 93.9, and 141.3 °C measured in 1980, respectively, describe the production of nanocrystalline clay mineral, zeolites, and Al‐tobermorite in diverse microenvironments. Irregular alteration fronts at 157.1‐m depth resemble microchannels associated with biological activity in older basalts. By contrast, linear microstructures with little resemblance to previously described alteration features have nanocrystalline clay mineral (nontronite) and zeolite (amicite) texture. The crystallographic preferred orientation rotates around an axis parallel to the linear feature. Raman spectra indicating degraded and poorly ordered carbonaceous matter of possible biological origin are associated with nanocrystalline clay mineral in a crystallographically oriented linear microstructure in altered olivine at 102.6 m and with subcircular nanoscale cavities in altered glass at 137.9‐m depth. Although evidence for biotic processes is inconclusive, the integrated analyses describe the complex organization of previously unrecognized mineral texture in very young basalt. They provide a foundational mineralogical reference for longitudinal, time‐lapse characterizations of palagonitized basalt in oceanic environments.

  • 45. Jackson, Marie
    et al.
    Gudmundson, Magnus
    Bach, Wolfgang
    Cappeletti, P
    Coleman, Nicole
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Jonasson, K
    Jörgensen, Steffen
    Marteinson, M.L.
    McPhie, V.
    Moore, James
    Nielson, Daniel
    Rhodes, J.
    Rispoli, C
    Schiffman, Peter
    Stefansson, Andri
    Turke, Andreas
    Vanorio, T
    Weisenberg, T.B.
    White, James
    Zierenberg, R.
    Zimanowski, B
    Time-lapse characterization of hydrothermal seawater and microbial interactions with basaltic tephra at Surtsey volcano2015In: Scientific Drilling, ISSN 1816-8957, E-ISSN 1816-3459, Vol. 20, p. 51-58Article in journal (Refereed)
    Abstract [en]

    A new International Continental Drilling Program (ICDP) project will drill through the 50-yearold edifice of Surtsey Volcano, the youngest of the Vestmannaeyjar Islands along the south coast of Iceland, to perform interdisciplinary time-lapse investigations of hydrothermal and microbial interactions with basaltic tephra. The volcano, created in 1963–1967 by submarine and subaerial basaltic eruptions, was first drilled in 1979. In October 2014, a workshop funded by the ICDP convened 24 scientists from 10 countries for 3 and a half days on Heimaey Island to develop scientific objectives, site the drill holes, and organize logistical support. Representatives of the Surtsey Research Society and Environment Agency of Iceland also participated. Scientific themes focus on further determinations of the structure and eruptive processes of the type locality of Surtseyan volcanism, descriptions of changes in fluid geochemistry and microbial colonization of the subterrestrial deposits since drilling 35 years ago, and monitoring the evolution of hydrothermal and biological processes within the tephra deposits far into the future through the installation of a Surtsey subsurface observatory. The tephra deposits provide a geologic analog for developing specialty concretes with pyroclastic rock and evaluating their long-term performance under diverse hydrothermal conditions.

  • 46.
    Lima-Zaloumis, Jon
    et al.
    Arizona State University, School of Earth and Space Exploration, PO Box 871404, Tempe, 85287-1404, AZ, USA.
    Neubeck, Anna
    Uppsala University, Department of Palaeobiology Geocentrum, Villavägen 16, 752 36, Uppsala, Sweden.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Bose, Maitrayee
    Arizona State University, School of Earth and Space Exploration, PO Box 871404, Tempe, 85287-1404, AZ, USA.
    Greenberger, Rebecca
    Caltech Division of Geological and Planetary Sciences, 1200 E. California Blvd., Pasadena, 91125, CA, USA.
    Templeton, Alexis S.
    University of Colorado, Department of Geological Sciences, UCB 399, Boulder, 80309, CO, USA.
    Czaja, Andrew D.
    University of Cincinnati, Department of Geology, 500 Geology-Physics, Cincinnati, 45221-0013, OH, USA.
    Kelemen, Peter B.
    Columbia University Lamont-Doherty Earth Observatory, 211 Comer, 61 Route 9W – PO Box 1000, Palisades, 10964, NY, USA.
    Edvinsson, Tomas
    Uppsala University, Department of Materials Science and Engineering, Ångströmlaboratoriet, Lägerhyddsvägen 1, Box 35, 751 03, Uppsala, Sweden.
    Microbial biosignature preservation in carbonated serpentine from the Samail Ophiolite, Oman2022In: Communications Earth & Environment, E-ISSN 2662-4435, Vol. 3, no 1, article id 231Article in journal (Refereed)
    Abstract [en]

    Serpentinization is a geological process involving the interaction of water and ultramafic rock, the chemical byproducts of which can serve as an energy source for microbial communities. Although serpentinite systems are known to host active microbial life, it is unclear to what extent fossil evidence of these communities may be preserved over time. Here we report the detection of biosignatures preserved in a mineralized fracture within drill cores from the Samail Ophiolite in Oman. Two varieties of filamentous structures were identified in association with iron oxide precipitates. The first type are interpreted as likely microbial remains, while the second type are recognized as potentially microbiological dubiofossils. Additionally, laminated structures composed of carbon and nitrogen rich material were identified and interpreted as having a microbially-associated origin. Our observations affirm the potential to detect subsurface microbial communities within serpentinizing environments and highlight a unique taphonomic window to preserve evidence of rock-hosted life.

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  • 47.
    Little, Crispin T. S.
    et al.
    School of Earth and Environment University of Leeds Leeds UK.
    Johannessen, Karen C.
    Department of Earth Science University of Bergen Bergen Norway.
    Bengtson, Stefan
    Swedish Museum of Natural History, Department of Paleobiology.
    Chan, Clara S.
    Department of Earth Sciences University of Delaware Newark USA.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Slack, John F.
    U.S. Geological Survey (Emeritus), National Center Reston USA.
    Broman, Curt
    Department of Geological Sciences Stockholm University Stockholm Sweden.
    Thorseth, Ingunn H.
    Department of Earth Science University of Bergen Bergen Norway.
    Grenne, Tor
    Geological Survey of Norway Trondheim Norway.
    Rouxel, Olivier J.
    Marine Geosciences Research Unit IFREMER Plouzané France.
    Bekker, Andrey
    Department of Earth and Planetary Sciences University of California Riverside USA;Department of Geology University of Johannesburg Johannesburg South Africa.
    A late Paleoproterozoic (1.74 Ga) deep-sea, low-temperature, iron-oxidizing microbial hydrothermal vent community from Arizona, USA2021In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 19, no 3, p. 228-249Article in journal (Refereed)
    Abstract [en]

    Modern marine hydrothermal vents occur in a wide variety of tectonic settings and are characterized by seafloor emission of fluids rich in dissolved chemicals and rapid mineral precipitation. Some hydrothermal systems vent only low-temperature Fe-rich fluids, which precipitate deposits dominated by iron oxyhydroxides, in places together with Mn-oxyhydroxides and amorphous silica. While a proportion of this mineralization is abiogenic, most is the result of the metabolic activities of benthic, Fe-oxidizing bacteria (FeOB), principally belonging to the Zetaproteobacteria. These micro-organisms secrete micrometer-scale stalks, sheaths, and tubes with a variety of morphologies, composed largely of ferrihydrite that act as sacrificial structures, preventing encrustation of the cells that produce them. Cultivated marine FeOB generally require neutral pH and microaerobic conditions to grow. Here, we describe the morphology and mineralogy of filamentous microstructures from a late Paleoproterozoic (1.74 Ga) jasper (Fe-oxide- silica) deposit from the Jerome area of the Verde mining district in central Arizona, USA, that resemble the branching tubes formed by some modern marine FeOB. On the basis of this comparison, we interpret the Jerome area filaments as having formed by FeOB on the deep seafloor, at the interface of weakly oxygenated seawater and low-temperature Fe-rich hydrothermal fluids. We compare the Jerome area filaments with other purported examples of Precambrian FeOB and discuss the implications of their presence for existing redox models of Paleoproterozoic oceans during the “Boring Billion.”

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  • 48. McMahon, Sean
    et al.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    A new frontier for palaeobiology: Earth's vast deep biosphere2019In: Bioessays, ISSN 0265-9247, E-ISSN 1521-1878, Vol. 41, no 8, article id 1900052Article in journal (Refereed)
    Abstract [en]

    Diverse micro‐organisms populate a global deep biosphere hosted by rocks and sediments beneath land and sea, containing more biomass than any other biome except forests. This paper reviews an emerging palaeobiological archive of these dark habitats: microfossils preserved in ancient pores and fractures in the crust. This archive, seemingly dominated by mineralized filaments (although rods and coccoids are also reported), is presently far too sparsely sampled and poorly understood to reveal trends in the abundance, distribution, or diversity of deep life through time. New research is called for to establish the nature and extent of the fossil record of Earth's deep biosphere by combining systematic exploration, rigorous microanalysis, and experimental studies of both microbial preservation and the formation of abiotic pseudofossils within the crust. It is concluded that the fossil record of Earth's largest microbial habitat may still have much to tell us about the history of life, the evolution of biogeochemical cycles, and the search for life on Mars.

  • 49.
    McMahon, Sean
    et al.
    UK Centre for Astrobiology School of Physics and Astronomy University of Edinburgh Edinburgh UK;School of Geosciences Grant Institute University of Edinburgh Edinburgh UK.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology. Department of Paleobiology Swedish Museum of Natural History Stockholm Sweden.
    Wacey, David
    Centre for Microscopy Characterisation and Analysis The University of Western Australia Perth WA Australia.
    Saunders, Martin
    Centre for Microscopy Characterisation and Analysis The University of Western Australia Perth WA Australia.
    Belivanova, Veneta
    Swedish Museum of Natural History, Department of Paleobiology. Department of Paleobiology Swedish Museum of Natural History Stockholm Sweden.
    Muirhead, David
    School of Geosciences King's College University of Aberdeen Aberdeen UK.
    Knoll, Pamela
    Department of Chemistry and Biochemistry Florida State University Tallahassee FL USA.
    Steinbock, Oliver
    Department of Chemistry and Biochemistry Florida State University Tallahassee FL USA.
    Frost, Daniel A.
    Department of Earth &amp; Planetary Science University of California Berkeley CA USA.
    Dubiofossils from a Mars‐analogue subsurface palaeoenvironment: The limits of biogenicity criteria2021In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Vol. 19, no 5, p. 473-488Article in journal (Refereed)
    Abstract [en]

    The search for a fossil record of Earth's deep biosphere, partly motivated by potential analogies with subsurface habitats on Mars, has uncovered numerous assemblages of inorganic microfilaments and tubules inside ancient pores and fractures. Although these enigmatic objects are morphologically similar to mineralized microorganisms (and some contain organic carbon), they also resemble some abiotic structures. Palaeobiologists have responded to this ambiguity by evaluating problematic filaments against checklists of “biogenicity criteria”. Here, we describe material that tests the limits of this approach. We sampled Jurassic calcite veins formed through subseafloor serpentinization, a water–rock reaction that can fuel the deep biosphere and is known to have occurred widely on Mars. At two localities ~4 km apart, veins contained curving, branched microfilaments composed of Mg-silicate and Fe-oxide minerals. Using a wide range of analytical techniques including synchrotron X-ray microtomography and scanning transmission electron microscopy, we show that these features meet many published criteria for biogenicity and are comparable to fossilized cryptoendolithic fungi or bacteria. However, we argue that abiotic processes driven by serpentinization could account for the same set of lifelike features, and report a chemical garden experiment that supports this view. These filaments are, therefore, most objectively described as dubiofossils, a designation we here defend from criticism and recommend over alternative approaches, but which nevertheless signifies an impasse. Similar impasses can be anticipated in the future exploration of subsurface palaeo-habitats on Earth and Mars. To avoid them, further studies are required in biomimetic geochemical self-organization, microbial taphonomy and micro-analytical techniques, with a focus on subsurface habitats.

  • 50.
    McMahon, Sean
    et al.
    UK Centre for Astrobiology School of Physics and Astronomy University of Edinburgh Edinburgh UK;School of Geosciences Grant Institute University of Edinburgh Edinburgh UK.
    Ivarsson, Magnus
    Swedish Museum of Natural History, Department of Paleobiology.
    Wacey, David
    Centre for Microscopy Characterisation and Analysis The University of Western Australia Perth WA Australia.
    Saunders, Martin
    Centre for Microscopy Characterisation and Analysis The University of Western Australia Perth WA Australia.
    Belivanova, Veneta
    Department of Paleobiology Swedish Museum of Natural History Stockholm Sweden.
    Muirhead, David
    School of Geosciences King's College University of Aberdeen Aberdeen UK.
    Knoll, Pamela
    Department of Chemistry and Biochemistry Florida State University Tallahassee FL USA.
    Steinbock, Oliver
    Department of Chemistry and Biochemistry Florida State University Tallahassee FL USA.
    Frost, Daniel A.
    Department of Earth &amp; Planetary Science University of California Berkeley CA USA.
    Dubiofossils from a Mars‐analogue subsurface palaeoenvironment: The limits of biogenicity criteria2021In: Geobiology, ISSN 1472-4677, E-ISSN 1472-4669, Geobiology, Vol. 19, no 5, p. 473-488Article in journal (Refereed)
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