40 research outputs found

    Osedax borings in fossil marine bird bones

    Get PDF
    The bone-eating marine annelid Osedax consumes mainly whale bones on the deep-sea floor, but recent colonization experiments with cow bones and molecular age estimates suggesting a possible Cretaceous origin of Osedax indicate that this worm might be able grow on a wider range of substrates. The suggested Cretaceous origin was thought to imply that Osedax could colonize marine reptile or fish bones, but there is currently no evidence that Osedax consumes bones other than those of mammals. We provide the first evidence that Osedax was, and most likely still is, able to consume non-mammalian bones, namely bird bones. Borings resembling those produced by living Osedax were found in bones of early Oligocene marine flightless diving birds (family Plotopteridae). The species that produced these boreholes had a branching filiform root that grew to a length of at least 3 mm, and lived in densities of up to 40 individuals per square centimeter. The inclusion of bird bones into the diet of Osedax has interesting implications for the recent suggestion of a Cretaceous origin of this worm because marine birds have existed continuously since the Cretaceous. Bird bones could have enabled this worm to survive times in the Earth’s history when large marine vertebrates other than fish were rare, specifically after the disappearance of large marine reptiles at the end-Cretaceous mass extinction event and before the rise of whales in the Eocene

    Ultramafic clasts from the South Chamorro serpentine mud volcano reveal a polyphase serpentinization history of the Mariana forearc mantle

    Get PDF
    Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Lithos 227 (2015): 1-20, doi:10.1016/j.lithos.2015.03.015.Serpentine seamounts located on the outer half of the pervasively fractured Mariana forearc provide an excellent window into the forearc devolatilization processes, which can strongly influence the cycling of volatiles and trace elements in subduction zones. Serpentinized ultramafic clasts recovered from an active mud volcano in the Mariana forearc reveal microstructures, mineral assemblages and compositions that are indicative of a complex polyphase alteration history. Petrologic phase relations and oxygen isotopes suggest that ultramafic clasts were serpentinized at temperatures below 200 °C. Several successive serpe ntinization events represented by different vein generations with distinct trace element contents can be recognized. Measured Rb/Cs ratios are fairly uniform ranging between 1 and 10, which is consistent with Cs mobilization from sediments at lower temperatures and lends further credence to the low-temperature conditions proposed in models of the thermal structure in forearc settings. Late veins show lower fluid mobile element (FME) concentrations than early veins, suggesting a deacreasing influence of fluid discharge from sediments on the composition of the serpentinizing fluids. The continuous microfabric and mineral chemical evolution observed in the ultramafic clasts may have implications as to the origin and nature of the serpentinizing fluids. We hypothesize that opal and smectite dehydration produce quartz-saturated fluids with high FME contents and Rb/Cs between 1 and 4 that cause the early pervasive serpentinization. The partially serpentinized material may then be eroded from the basal plane of the suprasubduction mantle wedge. Serpentinization continued but the interacting fluids did not carry the slab-flux signature, either because FME were no longer released from the slab, or due to an en route loss of FMEs. Late chrysotile veins that document the increased access of fluids in a now fluid-dominated regime are characterized by reduced trace element contents with a slightly increased Rb/Cs ratio near 10. This lack of geochemical slab signatures consistently displayed in all late serpentinization stages may indicate that the slab-derived fluids have been completely reset (i.e. the FME excesses were removed) by continued water-rock reaction within the subduction channel. The final stage of diapiric rise of matrix and clasts in the conduits is characterized by brucite-dominated alteration of the clasts from the clast rim inward (independent of the intra-clast fabric relations), which corresponds to re-equilibration with alkaline, low-silica activity fluids in the rising mud.This study was funded through a grant of the DFG to WB (BA 1605/5-1)

    Hochtemperatur-Lösungskalorimetrie und Leistungsdifferenzkalorimetrie zur thermodynamischen Charakterisierung von Mineralien

    Get PDF
    Kalorimetrische Untersuchungen sind ein unverzichtbares Instrument bei der Bestimmung der thermodynamischen Eigenschaften von Mineralen, um deren Gleichgewichts- und Reaktionsbeziehungen vorhersagbar zu machen.Im Rahmen dieser Arbeit wurden zwei verschiedene kalorimetrische Verfahren installiert und optimiert: zum einen die Leistungsdifferenzkalorimetrie zur Messung von Wärmekapazitäten, zum anderen die Hochtemperatur-Lösungskalorimetrie zur Bestimmung von Bildungsenthalpien. Für eine zuverlässige Bestimmung der Bildungsenthalpien wasserhaltiger Phasen wurden die seit Mitte der neunziger Jahre angewandten, speziellen Betriebsbedingungen bei der Lösungskalorimetrie eingesetzt: die Nutzung des Calvet-Kalorimeters als Einwurfkalorimeter für pelletierte Proben und die Technik einer gasgespülten Probenkammer. Auf der Grundlage dieser apparativen Voraussetzungen konnte das Verhalten der in diesem Zusammenhang kritischen Komponente H2O erstmals schlüssig auch im Rückblick auf frühere lösungskalorimetrische Arbeiten beschrieben werden. Auf dieser Basis wurden durch Verwendung mehrerer unabhängiger Berechnungszyklen, bei denen die volatile Komponente jeweils durch gänzlich unterschiedliches Verhalten berücksichtigt wird, mehrfach-konsistente Bestimmungen der Bildungsenthalpien von wasserhaltigen Phasen mit unterschiedlichen Wassergehalten verwirklicht...thesi

    Traces of the bone-eating annelid Osedax in Oligocene whale teeth and fish bones

    Get PDF
    The range of substrates that the bone-eating marine worm Osedax is able to consume has important implications for its evolutionary history, especially its potential link to the rise of whales. Once considered a whale specialist, recent work indicates that Osedax consumes a wide range of vertebrate remains, including whale soft tissue and the bones of mammals, birds and fishes. Traces resembling those produced by living Osedax have now been recognized for the first time in Oligocene whale teeth and fish bones from deep-water strata of the Makah, Pysht and Lincoln Creek formations in western Washington State, USA. The specimens were acid etched from concretions, and details of the borehole morphology were investigated using micro-computed tomography. Together with previously published Osedax traces from this area, our results show that by Oligocene time Osedax was able to colonize the same range of vertebrate remains that it consumes today and had a similar diversity of root morphologies. This supports the view that a generalist ability to exploit vertebrate bones may be an ancestral trait of Osedax

    X-ray µ-CT data reconstruction, image stack of ICPD Core ICDP5059_1_D

    No full text
    This contribution comprises true-3D volume datasets ("Digital drill cores"), acquired by a X-ray Computed Microtomography (μ-CT) survey on reference drill core material recovered from Hole 5059-1-D (354 m length to a depth of 290 m, inclined 35° from vertical) on Surtsey volcano (Vestmannaeyjar archipelago, Iceland), drilled by the SUSTAIN drilling project (Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative Concretes, see Jackson et al. 2019 for details). Thirteen reference samples (see Weisenberger et al. 2019 for preparational details) (ranging from 220.35 to 344.47 inclined depth / 180.47 to 282.12 m vertical depth, sampling roughly every 10 m) were scanned as quarter cores. The X-ray μ-CT scans were performed using the ProCon CT-ALPHA system of the Petrology of the Ocean Crust research group at the University of Bremen, Germany. This μ-CT survey has been conducted as part of the DFG SPP 1006 grant "Rates and Processes of Tephra Alteration on Surtsey: Observations and Experiments". In order to avoid imaging of void space due to the quarter core shape, and to achieve a higher magnification, the scans were performed as "out-of-area"-scans (see, e. g. Kahl et al., 2016), restricting observations to the inner regions of the samples. The reconstructed image material is of cylindrical shape with a resolution of ca. 7.5 μm/voxel, and represents virtual drill cores of ca. 15 mm diameter and 15 mm height. The μ-CT-derived image volumes comprise the true 3-D spatial arrangement of fabric compounds in the rock. In the reconstructed 16-bit greyscale volume data, areas of highly attenuating phases (e.g. magnetite, olivine) are encoded in light grey values, whereas areas of low X-ray absorption are color-coded in dark grey (e.g. clays) or black (e.g. voids, cracks). In order to facilitate straightforward access to the digital drill core image material, the volume data is provided as a zipped stack of tif images. In addition, each digital drill core is characterized by three types of visualization: (i) shaded and classical texture-based volume rendering (volren), (ii) maximum intensity projection (volren-MIP): visualization of the highest or lowest intensity in a data volume along the current line of sight, and (iii) three perpendicular virtual cutting planes (3-slices). As an added value to the non-destructive visualization procedure, the reconstructed X-ray micro-CT scans of the studied reference drill core material provide volume reconstructions which can serve as digitypes that may be studied as digital facsimile without the necessity of consulting / modifying / destructive interactions of the actual type specimens (e. g. by physical permeability tests). These image data can be used for quantitative 3D image analysis, e. g. to derive empirical relations between porosity, the extent of replacement of primary phases, and the distribution of secondary phases (and many more)

    X-ray µ-CT data reconstruction, image stack of ICPD Core ICDP5059_1_C

    No full text
    This contribution comprises true-3D volume datasets ("Digital drill cores"), acquired by a X-ray Computed Microtomography (μ-CT) survey on reference drill core material recovered from Hole 5059-1-C (192 m) on Surtsey volcano (Vestmannaeyjar archipelago, Iceland), drilled by the SUSTAIN drilling project (Surtsey Underwater volcanic System for Thermophiles, Alteration processes and INnovative Concretes, see Jackson et al. 2019 for details). Seventeen reference samples (see Weisenberger et al. 2019 for preparational details) (ranging from 22.66 to 180.65 m vertical depth, sampling roughly every 10 m) were scanned as quarter cores. The X-ray μ-CT scans were performed using the ProCon CT-ALPHA system of the Petrology of the Ocean Crust research group at the University of Bremen, Germany. This μ-CT survey has been conducted as part of the DFG SPP 1006 grant "Rates and Processes of Tephra Alteration on Surtsey: Observations and Experiments". In order to avoid imaging of void space due to the quarter core shape, and to achieve a higher magnification, the scans were performed as "out-of-area"-scans (see, e. g. Kahl et al., 2016), restricting observations to the inner regions of the samples. The reconstructed image material is of cylindrical shape with a resolution of ca. 7.5 μm/voxel, and represents virtual drill cores of ca. 15 mm diameter and 15 mm height. The μ-CT-derived image volumes comprise the true 3-D spatial arrangement of fabric compounds in the rock. In the reconstructed 16-bit greyscale volume data, areas of highly attenuating phases (e.g. magnetite, olivine) are encoded in light grey values, whereas areas of low X-ray absorption are color-coded in dark grey (e.g. clays) or black (e.g. voids, cracks). In order to facilitate straightforward access to the digital drill core image material, the volume data is provided as a zipped stack of tif images. In addition, each digital drill core is characterized by three types of visualization: (i) shaded and classical texture-based volume rendering (volren), (ii) maximum intensity projection (volren-MIP): visualization of the highest intensity in a data volume along the current line of sight, and (iii) three perpendicular virtual cutting planes (3-slices). As an added value to the non-destructive visualization procedure, the reconstructed X-ray micro-CT scans of the studied reference drill core material provide volume reconstructions which can serve as digitypes that may be studied as digital facsimile without the necessity of consulting / modifying / destructive interactions of the actual type specimens (e. g. by physical permeability tests). These image data can be used for quantitative 3D image analysis, e. g. to derive empirical relations between porosity, the extent of replacement of primary phases, and the distribution of secondary phases (and many more)
    corecore