Miracle-dz/UniFAR-FTUs huggingface dataset:
Snow isotope diffusion rates measured in a laboratory experiment

Abstract The diffusion of stable water isotopes in snow was measured in two controlled laboratory experiments. Two batches of snow of different isotopic composition were stacked alternately with varying layer thicknesses. The stack was stored in a freezer room at constant temperature for several months, and sampled at regular intervals to analyse the diffusion. Measured isotope profiles were fitted to a theoretical model with diffusion length as the fit parameter. In the first experiment, we observed a difference in diffusion rates between layers of different thicknesses, which is likely caused by layers of snow not being in proper contact with each other. In the second experiment we found very good agreement between measurements and model results. The measured diffusivity is compared with theory, in which we mainly focus on the temperature dependence of the ice–vapour fractionation factors. This temperature dependence is slightly different for the different isotopes of water, which leads to a difference in diffusion rates. We illustrate how our set-up can be used to measure the ratio between ice–vapour fractionation factors of oxygen-18 and deuterium, which determine the relation between the difference in diffusion and the firn temperature.
THE AMPLITUDE AND PHASE RESPONSE OF A SEISMIC VIBRATOR

The amplitude and phase response of a simple model is compared with the performance of a real vibrator working in the field. The field results show a characteristic phase response which confirms that the real drive force applied to the baseplate and its load impedance is faithfully represented by the acceleration of the reaction mass. It follows that all the parameters necessary to calculate the load impedance and the true power dissipated in the earth can be measured at the output of the vibrator. It also follows that the current method of baseplate phase compensation should be reconsidered.
Serpentinites in an Alpine convergent setting: Effects of metamorphic grade and deformation on microstructures

Alpine antigorite serpentinites associated with eclogites were investigated to determine if they can be used as indicators of the tectono-metamorphic conditions during subduction and exhumation processes. The detailed petrology of serpentinites sampled in the Monviso massif (Western Alps, Italy) was combined with a transmission electron microscopy study. Alpine serpentinites display a degree of serpentinization close to 100%. Antigorite is the main mineral present, forming non-pseudomorphic textures in the various studied samples and exhibiting a homogeneous chemical composition with limited cationic substitutions. Considering its oceanic origin, the Alpine serpentinite in the Monviso massif formed a lizardite + chrysotile assemblage that recrystallized under greenschist-facies conditions into poorly ordered antigorite, with a modulation wavelength showing significant variations at the crystal scale. Under blueschist-facies conditions, the modulation wavelength of antigorite becomes regular. Thus, periodic antigorites can be related to high-grade conditions, while poorly ordered antigorites characterize lower metamorphic grade. In the present study, we failed to observe any elimination of structural defects with increasing metamorphic grade. While around 50% of the antigorite crystals are highly ordered, it seems that this ordering is at least partly obliterated by retrogressive deformation. Antigorite displays strong evidence of deformation-sensitivity, and the observed microstructures can be directly related to the mechanical behaviour of serpentinites in subduction zones. We investigated the deformation-induced microstructures in serpentinites collected in the Erro-Tobbio eclogitic unit (Ligurian Alps, Italy), which appear to preserve prograde and retrograde structures formed during subduction. According to the microstructural evidence, shearing is accommodated by brittle and/or ductile deformation mechanisms. Collected samples were fractured at different scales (cm to nm) and have a well-developed schistosity characterized by a strong crystallographic fabric. With increasing metamorphic grade, the brittle behaviour gives way to pressure-solution, which persists up to eclogite-facies conditions. The common obliteration of high-grade microstructures in antigorite, as observed in the Monviso serpentinites, results from continuous recrystallization of this mineral during retrogressive deformation.
Sediments and structure of the Japan Trench

Seismic reflection profiles recorded east of Honshu show a fairly uniform thickness of acoustically transparent and presumably homogeneous sediment along the outer ridge and seaward slope of the Japan trench. The sediments continue to the bottom of the trench, where they abut the foot of the landward slope. In several localities the transparent sediments of the seaward slope end abruptly as a perched ledge shortly before the bottom of the trench is reached, suggesting post-depositional subsidence or extension of the sea floor near the trench axis. Seismic refraction measurements indicate that the seaward slope of the trench is a normal ocean floor that has been depressed. A succession of grabens and step faults observed along the entire seaward slope by the reflection technique suggests that the process which formed the trench is still going on. The faults are interpreted to be normal-antithetic and caused by tensional forces introduced in the convex side of the oceanic crustal plate as it is being further depressed, possibly in response to the load exerted by the weight of the island margin. Refraction profiles recorded along the upper landward slope (continental slope) show that its foundation is composed of material with seismic velocity about 5.8 km/sec; the depth to the Mohorovicic discontinuity is approximately 26 km. A tentative interpretation of one profile recorded along the lower landward slope of the trench indicates that the contact between the rocks of the island arc and the oceanic section lies west of the present topographic axis. A thick wedge of low-velocity sediment measured near the foot of the landward slope suggests that the topographic axis of the trench has been displaced seaward by outbuilding of the island margin, decreasing the maximum depth of the trench.
Recognition of the thermal effects of fluid flow in sedimentary basins

Abstract Moving fluids are capable of transporting a large amount of heat over long distances in sedimentary basins, but the effects are often ignored when modelling the thermal evolution of sedimentary basins. If significant, the passage of these heated fluids through the sediment pile will leave a thermal signature which can be measured at the present-day using palaeotemperature determinants such as vitrinite reflectance and apatite fission track analysis (AFTA™). The interpretation of palaeotemperature-depth profiles, particularly the slope of a palaeotemperature-depth profile, i.e. the palaeogeothermal gradient, allows fluid-induced temperature profiles to be distinguished from those due to simple conduction of basal heat flow. Steady-state systems, typified by large-scale lateral fluid flow in foreland basins or where low-temperature hydrothermal circulation systems occur associated with intrusions and thick volcanic piles, are characterized by dog-length geothermal gradients, with high-interval gradients near the surface, above the shallowest aquifer, and lower interval gradients beneath an aquifer. It is argued that the classic occurrence of near vertical vitrinite reflectance-depth profiles observed in many ancient foreland basins can result from this mechanism. Thermal effects of transient fluid flow are most easily observed at the present-day, where they are characterized by low or negative geothermal gradients beneath aquifers in active geothermal systems, and the same criterion enables their recognition in ancient situations. Similarly, shallow-level igneous intrusion into porous and permeable sediments can produce observable thermal signatures further from the intrusion than will result from simple conduction, but which can be readily explained by movement of fluids heated by the intrusion. Complex steady-state profiles that may be difficult to distinguish from transient profiles without additional geological data may arise where multiple aquifers are separated by aquitards. The thermal consequences of fluid flow in two of these situations, a foreland basin and igneous intrusion into porous sediments, are illustrated by examples of thermal history reconstruction from the Pliocene Papua New Guinea Fold Belt and the Canning Basin of Australia, respectively.
A New Basal Sauropodomorph Dinosaur from the Upper Elliot Formation (Lower Jurassic) of South Africa

ABSTRACT A new basal sauropodomorph dinosaur, Massospondylus kaalae sp. nov., is named on the basis of a partial skull from the upper Elliot Formation (Lower Jurassic) of the Herschel District, South Africa. It can be distinguished from Massospondylus carinatus by a combination of character states relating to the proportions of the premaxilla, the presence of a strong ridge on the dorsolateral surface of the lacrimal, and the morphology of the braincase. The description of Massospondylus kaalae further increases sauropodomorph diversity in the previously depauperate upper Elliot fauna.
Recent unrest and magma movements at Eyjafjallajokull and Katla volcanoes, Iceland

[1] Katla and Eyjafjallajokull volcanoes are situated 25 km apart at the southern tip of the Eastern Volcanic Zone in Iceland. Both have been active in historic time (last 1100 years) and have a history of simultaneous activity. The much more active Katla volcano has erupted at least 20 times, and Eyjafjallajokull's two eruptions were contemporaneous with Katla eruptions. Following a quiet period of several decades, the seismicity beneath Eyjafjallajokull was high in 1994 and again in 1999. The activity culminated in July 1999 when a flash flood occurred from the Mýrdalsjokull ice cap covering Katla, associated with changes in seismicity, bursts of volcanic tremor, and the formation and deepening of ice cauldrons. We report here results of deformation observations of these events, both by GPS geodesy and tilt measurements. The 1999 increase in seismicity at Eyjafjallajokull was associated with significant inflation of the volcano. The deformation data are modeled by a point pressure source at 3.5 km depth beneath the flank of the volcano, about 4 km south of the summit crater. Maximum uplift of the model is 0.35 m. A similar model also explains deformation associated with the 1994 seismic crisis. The deformation field of the Katla volcano is more difficult to ascertain due to the extensive glacier coverage. Movements of points on nunataks on and near the caldera rim indicate inflation and magma movements at shallow level beneath the caldera in connection with the events of July 1999.
Relationships between global precipitation and surface temperature on interannual and longer timescales (1979–2006)

[1] Associations between global and regional precipitation and surface temperature anomalies on interannual and longer timescales are explored for the period of 1979–2006 using the GPCP precipitation product and the NASA-GISS surface temperature data set. Positive (negative) correlations are generally confirmed between these two variables over tropical oceans (lands). ENSO is the dominant factor in these interannual tropical relations. Away from the tropics, particularly in the Northern Hemisphere mid-high latitudes, this correlation relationship becomes much more complicated with positive and negative values of correlation tending to appear over both ocean and land, with a strong seasonal variation in the correlation patterns. Relationships between long-term linear changes in global precipitation and surface temperature are also assessed. Most intense long-term, linear changes in annual-mean rainfall during the data record tend to be within the tropics. For surface temperature however, the strongest linear changes are observed in the Northern Hemisphere mid-high latitudes, with much weaker temperature changes in the tropical region and Southern Hemisphere. Finally, the ratios between the linear changes in zonal-mean rainfall and temperature anomalies over the period are estimated. Globally, the calculation results in a +2.3%/°C precipitation change, although the magnitude is sensitive to small errors in the precipitation data set and to the length of record used for the calculation. The long-term temperature-precipitation relations are also compared to the interannual variations of the same ratio in a zonally averaged sense and are shown to have similar profiles, except for over tropical land areas.
Evaluation of bulk carbonate δ13C data from Triassic hemipelagites and the initial composition of carbonate mud

Bulk carbonate samples of hemipelagic limestone–marl alternations from the Middle and Upper Triassic of Italy are analysed for their isotopic compositions. Middle Triassic samples are representative of the Livinallongo Formation of the Dolomites, while Upper Triassic hemipelagites were sampled in the Pignola 2 section, within the Calcari con Selce Formation of the Southern Apennines in Southern Italy. Triassic hemipelagites occur either as nodular limestones with chert nodules or as plane‐bedded limestone–marl alternations which are locally silicified. In the Middle Triassic Livinallongo Formation, diagenetic alteration primarily affected the stable isotopic composition of sediment surrounding carbonate nodules, whereas the latter show almost pristine compositions. Diagenesis lowered the carbon and oxygen isotope values of bulk carbonate and introduced a strong correlation between δ13C and δ18O values. In the Middle Triassic successions of the Dolomites, bulk carbonate of nodular limestone facies is most commonly unaltered, whereas carbonate of the plane‐bedded facies is uniformly affected by diagenetic alteration. In contrast to carbonate nodules, plane‐bedded facies often show compaction features. Although both types of pelagic carbonate rocks show very similar petrographic characteristics, scanning electron microscopy studies reveal that nodular limestone consists of micrite (< 5 μm in diameter), whereas samples of the plane‐bedded facies are composed of calcite crystals ca 10 μm in size showing pitted, polished surfaces. These observations suggest that nodular and plane‐bedded facies underwent different diagenetic pathways determined by the prevailing mineralogy of the precursor sediment, i.e. probably high‐Mg calcite in the nodular facies and aragonite in the case of the plane‐bedded facies. Similar to Middle Triassic nodular facies, Upper Triassic nodular limestones of the Lagonegro Basin are also characterized by uncorrelated δ13C and δ18O values and exhibit small, less than 5 μm size, crystals. The alternation of calcitic and aragonitic precursors in the Middle Triassic of the Dolomites is thought to mirror rapid changes in the type of carbonate production of adjacent platforms. Bioturbation and dissolution of metastable carbonate grains played a key role during early lithification of nodular limestone beds, whereby early stabilization recorded the carbon isotopic composition of sea water. The bulk carbonate δ13C values of Middle and Upper Triassic hemipelagites from Italy agree with those of Tethyan low‐Mg calcite shells of articulate brachiopods, confirming that Triassic hemipelagites retained the primary carbon isotopic composition of the bottom sea water. A trend of increasing δ13C from the Late Anisian to the Early Carnian, partly seen in the data set presented here, is also recognized in successions from tropical palaeolatitudes elsewhere. The carbon isotopic composition of Middle and Upper Triassic nodular hemipelagic limestones can thus be used for chemostratigraphic correlation and palaeoenvironmental studies.
Progress report on radio echo sounding

This report is intended to summarize activities in radio echo sounding since the introductory paper which appeared in the Polar Record four years ago (Evans, 1963 a). The field work since that time is discussed in rough chronological order, with references to the sources of more detailed information and an assessment of the principal results.
MIDDLE AND UPPER JURASSIC (CALLOVIAN TO KIMMERIDGIAN) PALYNOLOGY OF THE ONSHORE MORAY FIRTH BASIN, NORTHEAST SCOTLAND

Abstract The Brora Coal, Brora Argillaceous, Brora Arenaceous, Balintore and Kimmeridge Clay formations of the onshore Moray Firth Basin represent an important Middle to Upper Jurassic (Callovian to Lower Kimmeridgian) reference section close to hydrocarbon-rich North Sea basins. This composite succession at Brora and Balintore is c. 233 m thick; it is mudstone/siltstone-dominated and largely rich in zonal and subzonal ammonites. For example, the Callovian succession at Brora is virtually complete, with coverage of all seven ammonite zones. All the five formations examined have yielded abundant palynofloras. The lithostratigraphic units sampled, except the Brora Coal Formation, have yielded rich associations of dinoflagellate cysts. The majority of the Inverbrora Member of the Brora Coal Formation at its type section at Brora is of early Callovian age based on dinoflagellate cysts; this member yielded Meiourogonyaulax caytonensis and Mendicodinium groenlandicum and these species preclude a Bathonian age. This member has been previously attributed to the late Bathonian. Dinoflagellate cysts are diverse and abundant in the overlying Brora Argillaceous to Kimmeridge Clay formations, therefore indicating open marine conditions. The stratigraphic distributions and relative proportions of these Callovian to Lower Kimmeridgian dinoflagellate cyst floras are largely consistent with those reported elsewhere in northern Europe, and the established dinoflagellate cyst biozonations can be readily applied to the Inner Moray Firth Basin. Some taxa, such as Gonyaulacysta dentata, are of distinct Boreal affinity. Furthermore, some minor stratigraphic anomalies were noted, including the range base of Scriniodinium crystallinum being in the early Oxfordian at Balintore. In England and Germany, this bioevent occurs in the late Callovian. Some notable dinoflagellate cyst abundance phenomena were observed. An example of this is the prominence of Korystocysta spp. in the Middle Callovian. This and other quantitative phenomena are of correlative significance. Marine palynomorph diversity increased markedly during the Callovian, stabilizing in the Lower Oxfordian. A suite of characteristic dinoflagellate cysts became extinct in the Middle Oxfordian, and some typically Late Jurassic elements became more prominent at this time. The early Kimmeridgian palynofloras from Ethie are entirely typical of this interval elsewhere in Europe.
Diel and Tidal Migrations and Predator-prey Relationships of Macrobenthic Animals in Intertidal Sandy Beaches of Sendai Bay, Northern Japan

Aoba-ku,Sendai981-8555,Japan Abstract:We describe predator-prey relationships related to diel and tidal migrations based on observations of the distributions of macrobenthic animals over24hours along sandy beach slopes in two locations of Sendai Bay,northern Japan.The macrobenthic communities were largely comprised of Excirolana chiltoni (Isopoda:Cirolanidae),Haustorioides japonicus(Amphipoda:Dogielinotidae),and Archaeomysis kokuboi and A.vulgaris (Mysidacea:Gastrosaccinae). Excirolana chiltoni occurred in the swash zone at high tide and its distribution did not shift with the tidal cycle.On the other hand,H.japonicus,A.kokuboi,and A.vulgaris,loc ated in the swash zone,shifted with the tides.Their distributions overlapped with that of E . chiltoni only at high tide.Gut content analysis uggested that A.kokuboi and A.vulgaris mainly fed on co pepods at night,and that H.japonicus mainly fed on particulate detritus;E.chiltoni mainly fed on the mysidaceans,H.japonicus,and stranded carrion.These facts suggest that a food chain starts with detritus and copepods in the swash zone and the sublittoral zone,passes through H.japonicus or mysidaceans in the swash zone,and leads finally to E.chiltoni n the upper littoral zone.Judging from the fact that the overlap of the distributions ofmacrobenthic animals was formed by their tidal and diel migrations along the beach slope,it can be concluded that the predator-prey relationships insandy-beach communities are maintained by the tidal and diel migrations of macrobenthic animals.
Magmatically induced metamorphism and deformation in the Kigluaik gneiss dome, Seward Peninsula, Alaska

Field observations and U-Pb isotopic data from plutonic and high-grade metamorphic rocks within the Kigluaik gneiss dome on the Seward Peninsula, Alaska, document a Late Cretaceous age of peak metamorphism and shed light on the relationship between fundamentally mantle-derived magmatism and the development of the gneiss dome. The dome consists of upper-amphibolite-facies to granulite-facies metasedimentary rocks mantling the granitoid Kigluaik pluton. The main deformational fabric in the dome is a well-defined, moderately dipping foliation and compositional layering that contains a pervasive, east-west trending mineral-elongation lineation defined by sillimanite and hornblende. Leucosomal segregations in migmatite are boudinaged and isoclinally folded, and late-stage tension gashes are filled with melt, demonstrating that most deformation occurred at peak metamorphic temperatures. The large pluton in the core of the dome consists of a granitic cap overlying a mafic to intermediate root. Mafic pillows with crenulate margins and spectacular magma mingling textures indicate that the two magmas were coeval. The Kigluaik pluton is largely undeformed and discordant, although some dikes possess a weak deformational fabric. The lack of quench textures at the margins of the pluton and very limited alteration in adjacent wall rock suggest that the pluton was emplaced while country rocks were still at high temperatures. U-Pb analyses of three fractions of zircon from a highly strained and concordant garnet-bearing granite orthogneiss yield an intrusive age of 105 Ma; therefore significant deformation in the dome must have occurred after 105 Ma. Several U-Pb analyses of monazite from metapelite and pegmatite (derived from partial melting of metapelite) yield an age of 91 ± 1 Ma for high-temperature metamorphism and deformation. U-Pb analysis of eight fractions of zircon from the Kigluaik pluton shows that it crystallized at 92 ± 2 Ma. Thus there is both field and geochronologic evidence for coeval magmatism, metamorphism, and deformation at about 92 Ma, which may represent the latest stages of a more protracted tectonic event. We present a model for gneiss dome development wherein a large, silicic to intermediate magmatic diapir with its mantling gneisses ascended from ∼35 km to ∼15 km during an event associated with crustal extension in northern Alaska. We emphasize the close link between plutonism and gneiss dome development and the fundamentally mafic character of this plutonism.