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Harald Furnes - One of the best experts on this subject based on the ideXlab platform.
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characterization of alteration textures in cretaceous oceanic crust Pillow Lava from the n atlantic dsdp hole 418a by spatially resolved spectroscopy
Geochimica et Cosmochimica Acta, 2012Co-Authors: Hubert Staudigel, Karlis Muehlenbachs, Daniel Fliegel, Emily Knowles, Richard Wirth, Alexis S Templeton, Harald FurnesAbstract:Abstract The habit, mineralogy, crystallography, and Fe speciation of tubular and granular alteration textures in basaltic glass recovered from DSDP Hole 418A, which have previously been associated with biologically mediated alteration, were investigated using an integrated suite of microscopic and spectroscopic approaches in order to shine light on their formation and mineralization history. Two different analytical approaches were used: (1) micro scale investigations with conventional petrographic optical microcopy and microscale X-ray fluorescence mapping and X-ray absorption spectroscopy, and (2) nano scale analyses with FIB (focused ion beam milling) to prepare cross-sections for TEM (transmission electron microscopy), EELS (electron energy loss spectroscopy), and STXM (scanning transmission electron microscopy) analyses. The integrated data show that tubular and granular textures are similar in chemical, mineralogical and structural habit. Both granular and tubular alteration textures show a marked transition from ferrous iron in the glass matrix to ferric iron in the textures. Granular and tubular textures are filled with sheet silicates of similar chemistry, and both exhibit thin amorphous alteration rims ∼10–20 nm wide. The alteration rims are typically depleted in Ca and Fe. Ca is enriched at the contact between the secondary mineralization and the alteration rims, whereas Fe is enriched throughout the alteration features and is mainly present as Fe III in contrast to Fe II in the host glass. Carbon is enriched only in a few areas, and could possibly be of organic origin but is not bound in carbonate. The mineralization of the features follows the sequence: dissolution of the glass; formation of a leached amorphous rim; mineralizing the cavities by smectide type clays and subsequently congruent growing of the texture diameter by diffusing of the elements through the alteration layer. None of the features could be linked solely to a biogenic origin and hence the biogenicity of the textures can neither be refuted nor supported by this micro- and nano-scale data set.
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the origin of large varioles in flow banded Pillow Lava from the hooggenoeg complex barberton greenstone belt south africa
Contributions to Mineralogy and Petrology, 2011Co-Authors: Nils Rune Sandsta, Harald Furnes, Brian Robins, Maarten J. De WitAbstract:Exceptionally well-preserved Pillowed and massive phenocryst-free metabasaltic Lava flows in the uppermost part of the Palaeoarchaean Hooggenoeg Complex of the Barberton Greenstone Belt exhibit both flow banding and large leucocratic varioles. The flow banding is defined by blebs and bands of pale and dark green metabasalt and was the result of mingling of two types of basalt (Robins et al. in Bull Volcanol 72:579–592, 2010a). Varioles occur exclusively in the dark chlorite-, MgO- and FeO-rich metabasalt. Varioles are absent in the outermost rinds of Pillows and increase in both abundance and size towards the centres of Pillows. In the central parts of some Pillows, they impinge to form homogeneous pale patches, bands or almost homogenous cores. Individual varioles consist essentially of radially orientated or outwardly branching dendritic crystals of albite. Many varioles exhibit concentric zones and finer-grained rims. Some varioles seem to have grown around tiny vesicles and vesicles appear to have been trapped in others between a core and a finer-grained rim. The matrix surrounding the ocelli contains acicular pseudomorphs of actinolite and chlorite after chain-like, skeletal Ca-rich pyroxenes that are partly overgrown by the margins of varioles. Varioles are enriched in the chemical constituents of feldspar but contain concentrations of immobile TiO2, Cr, Zr and REE that are similar to the host metabasalts. The shape, distribution, texture and composition of the varioles exclude liquid immiscibility and support an origin by spherulitic crystallisation of plagioclase from severely undercooled basalt melt and glass. Nucleation of plagioclase was strongly inhibited and took place on vesicles, on the bases of drainage cavities and along early fractures. Eruption in deep water and retention of relatively high concentrations of volatiles in the melt may be the principal cause of spherulitic crystallisation in the interiors of Pillows rather than only in their margins as in younger submarine flows.
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Septate-tubular textures in 2.0-Ga Pillow Lavas from the Pechenga Greenstone Belt: a nano-spectroscopic approach to investigate their biogenicity.
Geobiology, 2010Co-Authors: Daniel Fliegel, Hubert Staudigel, Harald Furnes, Richard Wirth, Antonio Simonetti, E. Hanski, Karlis MuehlenbachsAbstract:ABSTRACT Pillow Lava rims and interPillow hyaloclastites from the upper part of the Pechenga Greenstone Belt, KolaPeninsula, N-Russia contain rare tubular textures 15–20 lm in diameter and up to several hundred lmlonginprehnite–pumpellyite to lower greenschist facies meta-volcanic glass. The textures are septate with regularcompartments5–20 lmacross andexhibitbranching,stoppingand nointersectingfeatures.Synchrotronmicro-energy dispersive X-ray was used to image elemental distributions; scanning transmission X-ray microscopy, FeL-edgeandC K-edgewereusedtoidentifyiron and carbonspeciation at interfacesbetweenthetubulartexturesand the host rock. In situ U–Pb radiometric dating by LA-MC-ICP-MS (laser ablation multicollector inductivelycoupled plasma mass spectrometry) of titanite from Pillow Lavas yielded a metamorphic age of 1790 ± 89 Ma.Focused ion-beam milling combined with transmission electron microscopy was used to analyze the textures inthree dimensions. Electron diffraction showed that the textures are mineralized by orientated pumpellyite. Onthe margins of the tubes, an interface between mica or chlorite and the pumpellyite shows evidence of dissolu-tion reactions where the pumpellyite is replaced by mica⁄chlorite. A thin poorly crystalline Fe-phase, probablyprecipitated out of solution, occurs at the interface between pumpellyite and mica⁄chlorite. This sequence ofphasesleadstothehypothesisthatthetubeswereinitiallyhollow,compartmentalizedstructuresinvolcanicglassthatwere mineralized by pumpellyite during low-grade metamorphism. Later, a Fe-bearing fluid mineralized thecompartments between the pumpellyite and lastly the pumpellyite was partially dissolved and replaced bychloriteduringgreenschistmetamorphism.Themostplausibleoriginforaseptate-tubulartextureisaprogressiveetching of the host matrix by several generations of microbes and subsequently these tubes were filled byauthigenic mineral precipitates. This preserves the textures in the rock record over geological time. The microtextures reported here thus represent a pumpellyite-mineralized trace fossil that records a Paleoproterozoicsub-seafloorbiosphere.Received4September2009;accepted16May2010Correspondingauthor:DanielFliegel.Tel.:+4755583038;fax:+4755583660;e-mail:d.j.fliegel@gmail.com
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Comparing petrographic signatures of bioalteration in recent to Mesoarchean Pillow Lavas: Tracing subsurface life in oceanic igneous rocks
Precambrian Research, 2007Co-Authors: Harald Furnes, Hubert Staudigel, Nicola Mcloughlin, Neil R. Banerjee, Karlis Muehlenbachs, Maarten J. De Wit, Martin J. Van KranendonkAbstract:Abstract Bioalteration of basaltic glass in Pillow Lava rims and glassy volcanic breccias (hyaloclastites) produces several distinctive traces including conspicuous petrographic textures. These biologically generated textures include granular and tubular morphologies that form during glass dissolution by microbes and subsequent precipitation of amorphous material. Such bioalteration textures have been described from upper, in situ oceanic crust spanning the youngest to the oldest oceanic basins (0–170 Ma). The granular type consists of individual and/or coalescing spherical bodies with diameters typically around 0.4 μm. These are by far the most abundant, having been traced up to ∼550 m depths in the oceanic crust. The tubular type is defined by distinct, straight to irregular tubes with diameters most commonly around 1–2 μm and lengths exceeding 100 μm. The tubes are most abundant between ∼50 m and 250 m into the volcanic basement. We advance a model for the production of these bioalteration textures and propose criteria for testing the biogenicity and antiquity of ancient examples. Similar bioalteration textures have also been found in hyaloclastites and well-preserved Pillow Lava margins of Phanerozoic to Proterozoic ophiolites and Archean greenstone belts. The latter include Pillow Lavas and hyaloclastites from the Mesoarchean Barberton Greenstone Belt of South Africa and the East Pilbara Terrane of the Pilbara Craton, Western Australia, where conspicuous titanite-mineralized tubes, have been found. Petrographic relationships and age data confirm that these structures developed in the Archean. Thus, these biologically generated textures may provide an important tool for mapping the deep oceanic biosphere and for tracing some of the earliest biological processes on Earth and perhaps other planetary surfaces.
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Early Life Recorded in Archean Pillow Lavas
Science (New York N.Y.), 2004Co-Authors: Harald Furnes, Hubert Staudigel, Neil R. Banerjee, Karlis Muehlenbachs, Maarten J. De WitAbstract:Pillow Lava rims from the Mesoarchean Barberton Greenstone Belt in South Africa contain micrometer-scale mineralized tubes that provide evidence of submarine microbial activity during the early history of Earth. The tubes formed during microbial etching of glass along fractures, as seen in Pillow Lavas from recent oceanic crust. The margins of the tubes contain organic carbon, and many of the Pillow rims exhibit isotopically light bulk-rock carbonate δ 13 C values, supporting their biogenic origin. Overlapping metamorphic and magmatic dates from the Pillow Lavas suggest that microbial life colonized these subaqueous volcanic rocks soon after their eruption almost 3.5 billion years ago.
Hubert Staudigel - One of the best experts on this subject based on the ideXlab platform.
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characterization of alteration textures in cretaceous oceanic crust Pillow Lava from the n atlantic dsdp hole 418a by spatially resolved spectroscopy
Geochimica et Cosmochimica Acta, 2012Co-Authors: Hubert Staudigel, Karlis Muehlenbachs, Daniel Fliegel, Emily Knowles, Richard Wirth, Alexis S Templeton, Harald FurnesAbstract:Abstract The habit, mineralogy, crystallography, and Fe speciation of tubular and granular alteration textures in basaltic glass recovered from DSDP Hole 418A, which have previously been associated with biologically mediated alteration, were investigated using an integrated suite of microscopic and spectroscopic approaches in order to shine light on their formation and mineralization history. Two different analytical approaches were used: (1) micro scale investigations with conventional petrographic optical microcopy and microscale X-ray fluorescence mapping and X-ray absorption spectroscopy, and (2) nano scale analyses with FIB (focused ion beam milling) to prepare cross-sections for TEM (transmission electron microscopy), EELS (electron energy loss spectroscopy), and STXM (scanning transmission electron microscopy) analyses. The integrated data show that tubular and granular textures are similar in chemical, mineralogical and structural habit. Both granular and tubular alteration textures show a marked transition from ferrous iron in the glass matrix to ferric iron in the textures. Granular and tubular textures are filled with sheet silicates of similar chemistry, and both exhibit thin amorphous alteration rims ∼10–20 nm wide. The alteration rims are typically depleted in Ca and Fe. Ca is enriched at the contact between the secondary mineralization and the alteration rims, whereas Fe is enriched throughout the alteration features and is mainly present as Fe III in contrast to Fe II in the host glass. Carbon is enriched only in a few areas, and could possibly be of organic origin but is not bound in carbonate. The mineralization of the features follows the sequence: dissolution of the glass; formation of a leached amorphous rim; mineralizing the cavities by smectide type clays and subsequently congruent growing of the texture diameter by diffusing of the elements through the alteration layer. None of the features could be linked solely to a biogenic origin and hence the biogenicity of the textures can neither be refuted nor supported by this micro- and nano-scale data set.
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Septate-tubular textures in 2.0-Ga Pillow Lavas from the Pechenga Greenstone Belt: a nano-spectroscopic approach to investigate their biogenicity.
Geobiology, 2010Co-Authors: Daniel Fliegel, Hubert Staudigel, Harald Furnes, Richard Wirth, Antonio Simonetti, E. Hanski, Karlis MuehlenbachsAbstract:ABSTRACT Pillow Lava rims and interPillow hyaloclastites from the upper part of the Pechenga Greenstone Belt, KolaPeninsula, N-Russia contain rare tubular textures 15–20 lm in diameter and up to several hundred lmlonginprehnite–pumpellyite to lower greenschist facies meta-volcanic glass. The textures are septate with regularcompartments5–20 lmacross andexhibitbranching,stoppingand nointersectingfeatures.Synchrotronmicro-energy dispersive X-ray was used to image elemental distributions; scanning transmission X-ray microscopy, FeL-edgeandC K-edgewereusedtoidentifyiron and carbonspeciation at interfacesbetweenthetubulartexturesand the host rock. In situ U–Pb radiometric dating by LA-MC-ICP-MS (laser ablation multicollector inductivelycoupled plasma mass spectrometry) of titanite from Pillow Lavas yielded a metamorphic age of 1790 ± 89 Ma.Focused ion-beam milling combined with transmission electron microscopy was used to analyze the textures inthree dimensions. Electron diffraction showed that the textures are mineralized by orientated pumpellyite. Onthe margins of the tubes, an interface between mica or chlorite and the pumpellyite shows evidence of dissolu-tion reactions where the pumpellyite is replaced by mica⁄chlorite. A thin poorly crystalline Fe-phase, probablyprecipitated out of solution, occurs at the interface between pumpellyite and mica⁄chlorite. This sequence ofphasesleadstothehypothesisthatthetubeswereinitiallyhollow,compartmentalizedstructuresinvolcanicglassthatwere mineralized by pumpellyite during low-grade metamorphism. Later, a Fe-bearing fluid mineralized thecompartments between the pumpellyite and lastly the pumpellyite was partially dissolved and replaced bychloriteduringgreenschistmetamorphism.Themostplausibleoriginforaseptate-tubulartextureisaprogressiveetching of the host matrix by several generations of microbes and subsequently these tubes were filled byauthigenic mineral precipitates. This preserves the textures in the rock record over geological time. The microtextures reported here thus represent a pumpellyite-mineralized trace fossil that records a Paleoproterozoicsub-seafloorbiosphere.Received4September2009;accepted16May2010Correspondingauthor:DanielFliegel.Tel.:+4755583038;fax:+4755583660;e-mail:d.j.fliegel@gmail.com
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Comparing petrographic signatures of bioalteration in recent to Mesoarchean Pillow Lavas: Tracing subsurface life in oceanic igneous rocks
Precambrian Research, 2007Co-Authors: Harald Furnes, Hubert Staudigel, Nicola Mcloughlin, Neil R. Banerjee, Karlis Muehlenbachs, Maarten J. De Wit, Martin J. Van KranendonkAbstract:Abstract Bioalteration of basaltic glass in Pillow Lava rims and glassy volcanic breccias (hyaloclastites) produces several distinctive traces including conspicuous petrographic textures. These biologically generated textures include granular and tubular morphologies that form during glass dissolution by microbes and subsequent precipitation of amorphous material. Such bioalteration textures have been described from upper, in situ oceanic crust spanning the youngest to the oldest oceanic basins (0–170 Ma). The granular type consists of individual and/or coalescing spherical bodies with diameters typically around 0.4 μm. These are by far the most abundant, having been traced up to ∼550 m depths in the oceanic crust. The tubular type is defined by distinct, straight to irregular tubes with diameters most commonly around 1–2 μm and lengths exceeding 100 μm. The tubes are most abundant between ∼50 m and 250 m into the volcanic basement. We advance a model for the production of these bioalteration textures and propose criteria for testing the biogenicity and antiquity of ancient examples. Similar bioalteration textures have also been found in hyaloclastites and well-preserved Pillow Lava margins of Phanerozoic to Proterozoic ophiolites and Archean greenstone belts. The latter include Pillow Lavas and hyaloclastites from the Mesoarchean Barberton Greenstone Belt of South Africa and the East Pilbara Terrane of the Pilbara Craton, Western Australia, where conspicuous titanite-mineralized tubes, have been found. Petrographic relationships and age data confirm that these structures developed in the Archean. Thus, these biologically generated textures may provide an important tool for mapping the deep oceanic biosphere and for tracing some of the earliest biological processes on Earth and perhaps other planetary surfaces.
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Early Life Recorded in Archean Pillow Lavas
Science (New York N.Y.), 2004Co-Authors: Harald Furnes, Hubert Staudigel, Neil R. Banerjee, Karlis Muehlenbachs, Maarten J. De WitAbstract:Pillow Lava rims from the Mesoarchean Barberton Greenstone Belt in South Africa contain micrometer-scale mineralized tubes that provide evidence of submarine microbial activity during the early history of Earth. The tubes formed during microbial etching of glass along fractures, as seen in Pillow Lavas from recent oceanic crust. The margins of the tubes contain organic carbon, and many of the Pillow rims exhibit isotopically light bulk-rock carbonate δ 13 C values, supporting their biogenic origin. Overlapping metamorphic and magmatic dates from the Pillow Lavas suggest that microbial life colonized these subaqueous volcanic rocks soon after their eruption almost 3.5 billion years ago.
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BIOLOGICAL MEDIATION IN OCEAN CRUST ALTERATION : HOW DEEP IS THE DEEP BIOSPHERE?
Earth and Planetary Science Letters, 1999Co-Authors: Harald Furnes, Hubert StaudigelAbstract:Abstract Biological mediation has been suggested as a control of the chemical exchange between the oceanic crust and seawater, but very little is known about its distribution within the oceanic crust and the relative importance of biotic and abiotic processes. Alteration textures in glassy Pillow Lava margins record the proportions of biotic and abiotic alteration, and the fraction of biotic alteration may be determined by point counting methods. We used this method at DSDP/ODP Sites 417D and 418A (110 Ma crust south of Bermuda Rise) and Holes 504B and 896A (5.9 Ma Costa Rica Rift). Biotic alteration dominates glass alteration in the upper 250 m of the oceanic crust (60–85% of the total glass alteration) and steadily declines in importance down to 10–20% at 500 m. The consistency of data between two crustal sections of very different age and tectonic setting suggest that microbially mediated glass alteration may be largely confined to the upper oceanic crust. However, both sites studied are sealed by thick sedimentary layers and, thus, are typical for ocean crust underlying the oceanic basins, rather than crust at mid-ocean ridges with possibly deep and rapid hydrothermal circulation. Down-hole temperature measurements at the Costa Rica Rift suggest that glass-altering microbes are hyperthermophilic and thrive at least up to temperatures of about 90°C. Microbial activity does occur at higher temperatures (up to about 110°C) but with reduced apparent abundance.
Karlis Muehlenbachs - One of the best experts on this subject based on the ideXlab platform.
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characterization of alteration textures in cretaceous oceanic crust Pillow Lava from the n atlantic dsdp hole 418a by spatially resolved spectroscopy
Geochimica et Cosmochimica Acta, 2012Co-Authors: Hubert Staudigel, Karlis Muehlenbachs, Daniel Fliegel, Emily Knowles, Richard Wirth, Alexis S Templeton, Harald FurnesAbstract:Abstract The habit, mineralogy, crystallography, and Fe speciation of tubular and granular alteration textures in basaltic glass recovered from DSDP Hole 418A, which have previously been associated with biologically mediated alteration, were investigated using an integrated suite of microscopic and spectroscopic approaches in order to shine light on their formation and mineralization history. Two different analytical approaches were used: (1) micro scale investigations with conventional petrographic optical microcopy and microscale X-ray fluorescence mapping and X-ray absorption spectroscopy, and (2) nano scale analyses with FIB (focused ion beam milling) to prepare cross-sections for TEM (transmission electron microscopy), EELS (electron energy loss spectroscopy), and STXM (scanning transmission electron microscopy) analyses. The integrated data show that tubular and granular textures are similar in chemical, mineralogical and structural habit. Both granular and tubular alteration textures show a marked transition from ferrous iron in the glass matrix to ferric iron in the textures. Granular and tubular textures are filled with sheet silicates of similar chemistry, and both exhibit thin amorphous alteration rims ∼10–20 nm wide. The alteration rims are typically depleted in Ca and Fe. Ca is enriched at the contact between the secondary mineralization and the alteration rims, whereas Fe is enriched throughout the alteration features and is mainly present as Fe III in contrast to Fe II in the host glass. Carbon is enriched only in a few areas, and could possibly be of organic origin but is not bound in carbonate. The mineralization of the features follows the sequence: dissolution of the glass; formation of a leached amorphous rim; mineralizing the cavities by smectide type clays and subsequently congruent growing of the texture diameter by diffusing of the elements through the alteration layer. None of the features could be linked solely to a biogenic origin and hence the biogenicity of the textures can neither be refuted nor supported by this micro- and nano-scale data set.
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Septate-tubular textures in 2.0-Ga Pillow Lavas from the Pechenga Greenstone Belt: a nano-spectroscopic approach to investigate their biogenicity.
Geobiology, 2010Co-Authors: Daniel Fliegel, Hubert Staudigel, Harald Furnes, Richard Wirth, Antonio Simonetti, E. Hanski, Karlis MuehlenbachsAbstract:ABSTRACT Pillow Lava rims and interPillow hyaloclastites from the upper part of the Pechenga Greenstone Belt, KolaPeninsula, N-Russia contain rare tubular textures 15–20 lm in diameter and up to several hundred lmlonginprehnite–pumpellyite to lower greenschist facies meta-volcanic glass. The textures are septate with regularcompartments5–20 lmacross andexhibitbranching,stoppingand nointersectingfeatures.Synchrotronmicro-energy dispersive X-ray was used to image elemental distributions; scanning transmission X-ray microscopy, FeL-edgeandC K-edgewereusedtoidentifyiron and carbonspeciation at interfacesbetweenthetubulartexturesand the host rock. In situ U–Pb radiometric dating by LA-MC-ICP-MS (laser ablation multicollector inductivelycoupled plasma mass spectrometry) of titanite from Pillow Lavas yielded a metamorphic age of 1790 ± 89 Ma.Focused ion-beam milling combined with transmission electron microscopy was used to analyze the textures inthree dimensions. Electron diffraction showed that the textures are mineralized by orientated pumpellyite. Onthe margins of the tubes, an interface between mica or chlorite and the pumpellyite shows evidence of dissolu-tion reactions where the pumpellyite is replaced by mica⁄chlorite. A thin poorly crystalline Fe-phase, probablyprecipitated out of solution, occurs at the interface between pumpellyite and mica⁄chlorite. This sequence ofphasesleadstothehypothesisthatthetubeswereinitiallyhollow,compartmentalizedstructuresinvolcanicglassthatwere mineralized by pumpellyite during low-grade metamorphism. Later, a Fe-bearing fluid mineralized thecompartments between the pumpellyite and lastly the pumpellyite was partially dissolved and replaced bychloriteduringgreenschistmetamorphism.Themostplausibleoriginforaseptate-tubulartextureisaprogressiveetching of the host matrix by several generations of microbes and subsequently these tubes were filled byauthigenic mineral precipitates. This preserves the textures in the rock record over geological time. The microtextures reported here thus represent a pumpellyite-mineralized trace fossil that records a Paleoproterozoicsub-seafloorbiosphere.Received4September2009;accepted16May2010Correspondingauthor:DanielFliegel.Tel.:+4755583038;fax:+4755583660;e-mail:d.j.fliegel@gmail.com
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Comparing petrographic signatures of bioalteration in recent to Mesoarchean Pillow Lavas: Tracing subsurface life in oceanic igneous rocks
Precambrian Research, 2007Co-Authors: Harald Furnes, Hubert Staudigel, Nicola Mcloughlin, Neil R. Banerjee, Karlis Muehlenbachs, Maarten J. De Wit, Martin J. Van KranendonkAbstract:Abstract Bioalteration of basaltic glass in Pillow Lava rims and glassy volcanic breccias (hyaloclastites) produces several distinctive traces including conspicuous petrographic textures. These biologically generated textures include granular and tubular morphologies that form during glass dissolution by microbes and subsequent precipitation of amorphous material. Such bioalteration textures have been described from upper, in situ oceanic crust spanning the youngest to the oldest oceanic basins (0–170 Ma). The granular type consists of individual and/or coalescing spherical bodies with diameters typically around 0.4 μm. These are by far the most abundant, having been traced up to ∼550 m depths in the oceanic crust. The tubular type is defined by distinct, straight to irregular tubes with diameters most commonly around 1–2 μm and lengths exceeding 100 μm. The tubes are most abundant between ∼50 m and 250 m into the volcanic basement. We advance a model for the production of these bioalteration textures and propose criteria for testing the biogenicity and antiquity of ancient examples. Similar bioalteration textures have also been found in hyaloclastites and well-preserved Pillow Lava margins of Phanerozoic to Proterozoic ophiolites and Archean greenstone belts. The latter include Pillow Lavas and hyaloclastites from the Mesoarchean Barberton Greenstone Belt of South Africa and the East Pilbara Terrane of the Pilbara Craton, Western Australia, where conspicuous titanite-mineralized tubes, have been found. Petrographic relationships and age data confirm that these structures developed in the Archean. Thus, these biologically generated textures may provide an important tool for mapping the deep oceanic biosphere and for tracing some of the earliest biological processes on Earth and perhaps other planetary surfaces.
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Early Life Recorded in Archean Pillow Lavas
Science (New York N.Y.), 2004Co-Authors: Harald Furnes, Hubert Staudigel, Neil R. Banerjee, Karlis Muehlenbachs, Maarten J. De WitAbstract:Pillow Lava rims from the Mesoarchean Barberton Greenstone Belt in South Africa contain micrometer-scale mineralized tubes that provide evidence of submarine microbial activity during the early history of Earth. The tubes formed during microbial etching of glass along fractures, as seen in Pillow Lavas from recent oceanic crust. The margins of the tubes contain organic carbon, and many of the Pillow rims exhibit isotopically light bulk-rock carbonate δ 13 C values, supporting their biogenic origin. Overlapping metamorphic and magmatic dates from the Pillow Lavas suggest that microbial life colonized these subaqueous volcanic rocks soon after their eruption almost 3.5 billion years ago.
Daniel Fliegel - One of the best experts on this subject based on the ideXlab platform.
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characterization of alteration textures in cretaceous oceanic crust Pillow Lava from the n atlantic dsdp hole 418a by spatially resolved spectroscopy
Geochimica et Cosmochimica Acta, 2012Co-Authors: Hubert Staudigel, Karlis Muehlenbachs, Daniel Fliegel, Emily Knowles, Richard Wirth, Alexis S Templeton, Harald FurnesAbstract:Abstract The habit, mineralogy, crystallography, and Fe speciation of tubular and granular alteration textures in basaltic glass recovered from DSDP Hole 418A, which have previously been associated with biologically mediated alteration, were investigated using an integrated suite of microscopic and spectroscopic approaches in order to shine light on their formation and mineralization history. Two different analytical approaches were used: (1) micro scale investigations with conventional petrographic optical microcopy and microscale X-ray fluorescence mapping and X-ray absorption spectroscopy, and (2) nano scale analyses with FIB (focused ion beam milling) to prepare cross-sections for TEM (transmission electron microscopy), EELS (electron energy loss spectroscopy), and STXM (scanning transmission electron microscopy) analyses. The integrated data show that tubular and granular textures are similar in chemical, mineralogical and structural habit. Both granular and tubular alteration textures show a marked transition from ferrous iron in the glass matrix to ferric iron in the textures. Granular and tubular textures are filled with sheet silicates of similar chemistry, and both exhibit thin amorphous alteration rims ∼10–20 nm wide. The alteration rims are typically depleted in Ca and Fe. Ca is enriched at the contact between the secondary mineralization and the alteration rims, whereas Fe is enriched throughout the alteration features and is mainly present as Fe III in contrast to Fe II in the host glass. Carbon is enriched only in a few areas, and could possibly be of organic origin but is not bound in carbonate. The mineralization of the features follows the sequence: dissolution of the glass; formation of a leached amorphous rim; mineralizing the cavities by smectide type clays and subsequently congruent growing of the texture diameter by diffusing of the elements through the alteration layer. None of the features could be linked solely to a biogenic origin and hence the biogenicity of the textures can neither be refuted nor supported by this micro- and nano-scale data set.
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Septate-tubular textures in 2.0-Ga Pillow Lavas from the Pechenga Greenstone Belt: a nano-spectroscopic approach to investigate their biogenicity.
Geobiology, 2010Co-Authors: Daniel Fliegel, Hubert Staudigel, Harald Furnes, Richard Wirth, Antonio Simonetti, E. Hanski, Karlis MuehlenbachsAbstract:ABSTRACT Pillow Lava rims and interPillow hyaloclastites from the upper part of the Pechenga Greenstone Belt, KolaPeninsula, N-Russia contain rare tubular textures 15–20 lm in diameter and up to several hundred lmlonginprehnite–pumpellyite to lower greenschist facies meta-volcanic glass. The textures are septate with regularcompartments5–20 lmacross andexhibitbranching,stoppingand nointersectingfeatures.Synchrotronmicro-energy dispersive X-ray was used to image elemental distributions; scanning transmission X-ray microscopy, FeL-edgeandC K-edgewereusedtoidentifyiron and carbonspeciation at interfacesbetweenthetubulartexturesand the host rock. In situ U–Pb radiometric dating by LA-MC-ICP-MS (laser ablation multicollector inductivelycoupled plasma mass spectrometry) of titanite from Pillow Lavas yielded a metamorphic age of 1790 ± 89 Ma.Focused ion-beam milling combined with transmission electron microscopy was used to analyze the textures inthree dimensions. Electron diffraction showed that the textures are mineralized by orientated pumpellyite. Onthe margins of the tubes, an interface between mica or chlorite and the pumpellyite shows evidence of dissolu-tion reactions where the pumpellyite is replaced by mica⁄chlorite. A thin poorly crystalline Fe-phase, probablyprecipitated out of solution, occurs at the interface between pumpellyite and mica⁄chlorite. This sequence ofphasesleadstothehypothesisthatthetubeswereinitiallyhollow,compartmentalizedstructuresinvolcanicglassthatwere mineralized by pumpellyite during low-grade metamorphism. Later, a Fe-bearing fluid mineralized thecompartments between the pumpellyite and lastly the pumpellyite was partially dissolved and replaced bychloriteduringgreenschistmetamorphism.Themostplausibleoriginforaseptate-tubulartextureisaprogressiveetching of the host matrix by several generations of microbes and subsequently these tubes were filled byauthigenic mineral precipitates. This preserves the textures in the rock record over geological time. The microtextures reported here thus represent a pumpellyite-mineralized trace fossil that records a Paleoproterozoicsub-seafloorbiosphere.Received4September2009;accepted16May2010Correspondingauthor:DanielFliegel.Tel.:+4755583038;fax:+4755583660;e-mail:d.j.fliegel@gmail.com
George P L Walker - One of the best experts on this subject based on the ideXlab platform.
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Morphometric study of Pillow-size spectrum among Pillow Lavas
Bulletin of Volcanology, 1992Co-Authors: George P L WalkerAbstract:Measurements of H and V (dimensions in the horizontal and vertical directions of Pillows exposed in vertical cross-section) were made on 19 Pillow Lavas from the Azores, Cyprus, Iceland, New Zealand, Tasmania, the western USA and Wales. The median values of H and V plot on a straight line that defines a spectrum of Pillow sizes, having linear dimensions five times greater at one end than at the other, basaltic toward the small-size end and andesitic toward the large-size end. The Pillow median size is interpreted to reflect a control exercised by Lava viscosity. Pillows erupted on a steep flow-foot slope in Lava deltas can, however, have a significantly smaller size than Pillows in tabular Pillowed flows (inferred to have been erupted on a small depositonal slope), indicating that the slope angle also exercised a control. Pipe vesicles, generally abundant in the tabular Pillowed flows and absent from the flow-foot Pillows, have potential as a paleoslope indicator. Pillows toward the small-size end of the spectrum are smooth-surfaced and grew mainly by stretching of their skin, whereas disruption of the skin and spreading were important toward the large-size end. Disruption involved increasing skin thicknesses with increasing Pillow size, and Pillows toward the large-size end are more analogous with toothpaste Lava than with pahoehoe and are inferred from their thick multiple selvages to have taken hours to grow. Pseudo-Pillow structure is also locally developed. An example of endogenous Pillow-Lava growth, that formed intrusive Pillows between ‘normal’ Pillows, is described from Sicily. Isolated Pillow-like bodies in certain andesitic breccias described from Iceland were previously interpreted to be Pillows but have anomalously small sizes for their compositions; it is now proposed that they may lack an essential attribute of Pillows, namely, the development of bulbous forms by the inflation of a chilled skin, and are hence not true Pillows. Para-Pillow Lava is a common Lava type in the flow-foot breccias. It forms irregular flow-sheets that are locally less than 5 cm thick, and failed to be inflated to Pillows perhaps because of an inadequate Lava-supply rate or too high a flow velocity.