Miracle-dz/UniFAR-FTUs huggingface dataset:
The Barremian-Aptian Evolution of The Eastern Arabian Carbonate Platform Margin (Northern Oman)

ABSTRACT Carbonate platform margins are sensitive recorders of changes in sea level and climate and can reveal the relative importance of global and regional controls on platform evolution. This paper focuses on the Barremian to Aptian interval (mid Cretaceous), which is known for climatic and environmental changes towards more intensified greenhouse conditions. The study area in the northern Oman mountains offers one of the very few locations where the Cretaceous carbonate margin of the Arabian Plate can be studied along continuous outcrops. Our detailed sedimentological and sequence stratigraphic model of the platform margin demonstrates how major environmental and ecological changes controlled the stratigraphic architecture. The Early Cretaceous platform margin shows high rates of progradation in Berriasian to Hauterivian times followed by lower rates and some aggradation in the Late Hauterivian to Barremian. High-energy bioclastic and oolitic sands were the dominant deposits at the margin. Turbidites were deposited at the slope and in the basin. The Early Aptian platform margin shows a marked change to purely aggradational geometries and a welldeveloped platform barrier that was formed mainly by microbial buildups. The sudden dominance in microbial activity led to cementation and stabilization of the margin and slope and, therefore, a decrease of downslope sediment transport by turbidites. In the Late Aptian, large parts of the Arabian craton were subaerially exposed and a fringing carbonate platform formed. Seven Barremian to Early Albian large-scale depositional sequences reflecting relative sea-level changes are identified on the basis of time lines constrained by physical correlation and biostratigraphy. The reconstruction of the margin geometries suggests that tectonic activity played an important role in the Early Aptian. This was most likely related to global plate reorganization that was accompanied by increased volcanic activity in many parts of the world. Along the northeastern Arabian platform the associated global changes in atmospheric and oceanic circulation are recorded with a change in platform-margin ecology from an ooid-bioclast dominated to a microbial dominated margin. Time-equivalent argillaceous deposits suggest an increase in rainfall and elevated input of nutrients onto the platform. This process contributed to the strongly diminished carbonate production by other organisms and favored microbial activity. The platform margin may thus represent a shallow-marine response to the Early Aptian global changes, commonly associated with an oceanic anoxic event in basinal environments.
Oligocene uplift of the Western Greater Caucasus: an effect of initial Arabia–Eurasia collision

The Greater Caucasus is Europe's largest mountain belt. Significant uncertainties remain over the evolution of the range, largely due to a lack of primary field data. This work demonstrates that depositional systems within the Oligocene–Early Miocene Maykop Series on either side of the Western Greater Caucasus (WGC) display a similar provenance and divergent palaeocurrents away from the range, constraining a minimum age for the subaerial uplift of the range as early Early Oligocene. An Eocene–Oligocene hiatus, basal Oligocene olistostromes and a marked increase in nannofossil reworking also point to initial deformation in the earliest Oligocene. The initial uplift of the WGC occurred during the final assembly of the Tethysides to its south. Uplift commenced after the Late Eocene final suturing of northern Neotethys and during the initial collision of Arabia with the southern accreted margin of Eurasia. This suggests that compressional deformation was rapidly transferred across the collision zone from the indenting Arabian plate to its northern margin.
Migration of petroleum into Brent Group reservoirs: some observations from the Gullfaks field, Tampen Spur area North Sea

Abstract Whereas the processes of petroleum generation and primary migration are beginning to be understood from a quantitative viewpoint, the process of secondary migration is still incompletely quantitatively understood. We estimate that typically the carrier systems feeding Brent Group reservoirs contain an average of around 3% residual oil saturation, the petroleum flowing in high saturation petroleum rivers through the most permeable carrier bed zones. Most of the carrier porosity contains no petroleum. The filling of the Brent Group reservoir in the Gullfaks field (Tampen Spur) is elucidated by petroleum geochemistry and this study indicates that the field has filled from more than one source basin and has been biodegraded post oil-emplacement. The complex filling and degradation history suggests that geochemical study of reservoir petroleum columns is a useful exercise providing information on the fillpoints of these complex reservoir systems and potentially information on the palacohydrogeology of the area.
Monazite-huttonite solid-solutions from the Vico Volcanic Complex, Latium, Italy Monazite-huttonite solid-solutions from the Vico Volcanic Complex, Latium, Italy

Abstract The crystal-chemical relationships occurring within a single grain of monazite-(Ce) from Vetralla, Vico Volcanic Complex, north of Rome, are outlined. The sample is from a miarolitic cavity in a holocrystalline ejectum consisting of K-feldspar plus minor plagioclase, mica and Fe-oxides, collected from a pyroclastic explosive level. The Gandolfi film (Cu-Kα radiation) can be indexed in space group P21 /n with a = 6.816(4); b = 6.976(4); c = 6.471(3) Å ,β = 103.63(3)° :V = 299.0(6) Å3. Electron-probe microanalyses plot within the field of monazite along the huttonite-monazite edge of the huttonite-monazite-brabantite triangle. Despite patchy and irregular zoning, the grain shows a clear enrichment towards pure monazite at the outer rim. A constant Th:Si ratio of 1:1 indicates the existence of a simple solid-solution between huttonite and monazite. The substitution can be written as Th4+ + Si4+ → REE3+ + P5+ without requiring any electrostatic compensation by divalent cations, or by anionic groups. The REE distribution pattern is compatible with that of monazites from syenitic rocks.
Two‐ and three‐dimensional electrical resistivity imaging at a heterogeneous remediation site

Geometrically complex heterogeneities at a decommissioned sour gas plant could not be adequately characterized with drilling and 2D electrical resistivity surveys alone. In addition, 2D electrical resistivity imaging profiles produced misleading images as a result of out‐of‐plane resistivity anomalies and violation of the 2D assumption. Accurate amplitude and positioning of electrical conductivity anomalies associated with the subsurface geochemical distribution were required to effectively analyze remediation alternatives. Forward and inverse modeling and field examples demonstrated that 3D resistivity images were needed to properly reconstruct the amplitude and geometry of the complex resistivity anomalies. Problematic 3D artifacts in 2D images led to poor inversion fits and spurious conductivity values in the images at depths close to the horizontal offset of the off‐line anomaly. Three‐dimensional surveys were conducted with orthogonal sets of Wenner and dipole–dipole 2D resistivity survey lines. The .
An Analysis of Beach Pebble Abrasion and Transportation

On the west shore of Lake Michigan between Racine, Wisconsin, and Waukegan, Illinois, beach pebbles derived entirely from a cliff of glacial till at Racine travel southward. The pebbles in the till are angular. At a point seven miles south the pebbles are spheroidal. From this point southward the beach pebbles are progressively flatter. This difference in shape is attributed to two processes, namely, wear and selective transportation. It is proved that angular pebbles become round, and round pebbles become flat. By laboratory experiments it is shown that flat pebbles travel more readily by wave action than round pebbles because of differences in behavior due to differences in shape, and to the fact that round pebbles seek deeper water and are consequently more readily buried.
Simultaneous spectroradiometry: A study of solar UV irradiance at two altitudes

Spectrally resolved measurements of solar ultraviolet (UV) radiation were made at adjacent mountain top and valley sites, vertically separated by 1 km. Data was collected over a period of 4 days in August 1993 providing simultaneously measured spectra for a range of zenith angles with both sites in direct sunlight and less than 2 octas of cloud cover. As there was no snow cover the local albedo was similar at both sites. Irradiances at the mountain site were 9% higher than the valley at 370 nm, increasing gradually to 11% at 320 nm. Across the UVB waveband the altitude effect increased dramatically to 24% at 300 nm. The magnitude of the altitude effect was independent of zenith angle, within the measurement accuracy, for the range z = 30°–70°. These measured differences between the mountain and valley station can be interpreted by model calculations using the corresponding differences in air pressure, column ozone and aerosol content.
On the Roles of Tropical and Midlatitude SSTs in Forcing Interannual to Interdecadal Variability in the Winter Northern Hemisphere Circulation

Abstract Three numerical experiments have been conducted to explore the relative roles of midlatitude and tropical SSTs in producing atmospheric variability. In these experiments, anomalous observed SSTs were prescribed in 1) the tropical oceans only, 2) the midlatitude oceans only, and 3) globally. These simulations were conducted with the same atmospheric model and covered the period 1970–88. Although each simulation reproduced some aspects of the observed circulation variability, the results from the two experiments including tropical SSTs performed best by most measure particularly in showing temporal signals that agreed with those seen in the observations. The results indicate that the response of the observed atmospheric circulation to North Pacific SST anomalies is much smaller and much less systematic than the response to tropical SSTs. It is suggested that the apparent links between North Pacific SSTs and the observed winter circulation am due primarily to the effects on oceanic forcing by the re.
Experimental observations of pressure oscillations and flow regimes in an analogue volcanic system.

Gas-liquid flows, designed to be analogous to those in volcanic conduits, are generated in the laboratory using organic gas-gum rosin mixtures expanding in a vertically mounted tube. The expanding fluid shows a range of both flow and pressure oscillation behaviors. Weakly supersaturated source liquids produce a low Reynolds number flow with foam expanding from the top surface of a liquid that exhibits zero fluid velocity at the tube wall; i.e., the conventional “no-slip” boundary condition. Pressure oscillations, often with strong long-period characteristics and consistent with longitudinal and radial resonant oscillation modes, are detected in these fluids. Strongly supersaturated source liquids generate more energetic flows that display a number of flow regimes. These regimes include a static liquid source, viscous flow, detached flow (comprising gas-pockets-at-wall and foam-in-gas annular flow, therefore demonstrating strong radial heterogeneity), and a fully turbulent transonic fragmented or mist flow. Each of these flow regimes displays characteristic pressure oscillations that can be related to resonance of flow features or wall impact phenomena. The pressure oscillations are produced by the degassing processes without the need of elastic coupling to the confining medium or flow restrictors and valvelike features. The oscillatory behavior of the experimental flows is compared to seismoacoustic data from a range of volcanoes where resonant oscillation of the fluid within the conduit is also often invoked as controlling the observed oscillation frequencies. On the basis of the experimental data we postulate on the nature of seismic signals that may be measured during large-scale explosive activity.
Tectonic assembly of inverted metamorphic sequences

Inverted metamorphic sequences are characterized by peak metamorphic temperatures that increase structurally upward, with isograds that are typically parallel to associated thrust faults. A fully coupled thermal-mechanical model for convergent orogens shows how an inverted sequence can be tectonically assembled in a crustal-scale ductile shear zone at moderate to high rates of synorogenic erosion. Model inverted sequences form by tectonic juxtaposition of points with widely differing initial positions that reach peak temperatures at different times and in different places within the model orogen, and thus do not represent metamorphic or thermal gradients. Inverted crustal isotherms are not required to produce model inverted isograds. Model results agree well with metamorphic pressure-temperature data from the Main Central Thrust zone of the central Nepal Himalayas.
Effect of grain size on the distribution and transport of deep‐seated fluids and melts

Because permeability increases with the square of the grain size for a given fluid fraction, it is commonly assumed that porous flow of fluids and melts is more effective in coarse‐grained domains of deep‐seated rocks. This relative behavior is accurate, however, only as a description of two systems operating in isolation. We demonstrate that if coarse‐ and fine‐grained domains are in chemical communication, then equilization of pore‐wall curvature across the system results in concentration of fluid or melt in domains of finer grain size. Because of this localization of fluid, the permeability of the finer‐grained domains will match or exceed that of domains with coarser grains. Fluid focussing due to differences in grain size has potentially important implications for grain‐scale transport of metamorphic fluids — including those released from subducting slabs into the sheared mantle wedge — and also for partial melts in the mantle and deep crust.
Field measurements of the suspended sand concentration profiles and fluxes and of the resuspension coefficient γ0 over a rippled bed

Measurements of the acoustic backscatter from suspended sand over a rippled bed and of currents were made near the crest of a ridge-and-runnel beach on the macrotidal North Norfolk coast of the United Kingdom. Two 12-min records were taken close to high water in a depth of 1.7±0.2 m. Visual inspection of the data shows that sand was intermittently suspended to heights of 20–30 cm but that these events were not always correlated with strong wave-induced currents: the structure of some of the suspension events suggest that they are due to vortex shedding from a rippled bed. The observed time-averaged concentration profiles were compared with predictions generated using Glenn and Grant's (1987) combined-flow model. The nondimensionalised concentrations showed good correspondence in the first 8 to 10 cm above the wave boundary layer, supporting the use of a value of 0.74, drawn from atmospheric data, for the constant of proportionality between sediment and momentum diffusivity. Above this height, observed values of the proportionality constant tended to approach 1.0, which may have been due to a decrease in sediment settling velocity with height (which is consistent with finer sand being suspended higher in the flow), or alternatively to nonuniform turbulence in the vicinity of the wave ripples. Absolute concentrations measured 2 cm above the bed were consistent with values of O(10−4) for the empirical constant γ0 in Smith and McLean's (1977) pickup function. Concentrations within the wave boundary layer were observed to decrease much more rapidly than predicted by the model. Sand transport fluxes were computed for both the cross-shore and alongshore components of the flow using a current profile based on the combined-flow model of Glenn and Grant (1987). For the two records, vertically integrated fluxes of 1.5-mg/s/cm width and 0.89-mg/s/cm width directed towards the shore were calculated for the wave oscillatory component of the transport; the mean flow produced shoreward vertically integrated fluxes of 5.1- and 10.5-mg/s/cm width. The uncertainty associated with these estimates is considerable (±50%). The vertical profile of the total flux (wave oscillatory and mean) for both records showed a strong shoreward transport close to the bed, an offshore transport between 5 and 15 cm above the bed, and a further weak onshore flux above this, demonstrating the necessity for measurements of the whole concentration profile (rather than a few point samples) for the calculation of sand transport over a rippled bed in a wave-dominated environment.
Classification of Schubert Galois groups in Gr(4,9)

We classify Schubert problems in the Grassmannian of 4-planes in 9-dimensional space by their Galois groups. Of the 31,806 essential Schubert problems in this Grassmannian, only 149 have Galois group that does not contain the alternating group. We identify the Galois groups of these 149---each is an imprimitive permutation group. These 149 fall into two families according to their geometry. This study suggests a possible classification of Schubert problems whose Galois group is not the full symmetric group, and it begins to establish the inverse Galois problem for Schubert calculus.
Daytime vertical and zonal velocities from 150‐km echoes: Their relevance to F‐region dynamics

As it was suggested by Kudeki and Fawcett [1993] , and later shown by Woodman and Villanueva [1995] , vertical Doppler velocities of daytime 150‐km echoes represent the vertical E × B drift velocities at F region altitudes. Recently a special experiment was conducted to compare not only the vertical but also the zonal velocities from 150‐km echoes with those from an incoherent scatter radar (ISR) mode perpendicular to the magnetic field. The vertical velocity comparisons show that (1) there is a very good agreement between 150‐km velocity and the mean F‐region E × B drift, and (2) much better agreement is found with the extrapolated values from the ISR altitudinal profiles. On the other hand poor‐to‐good agreement is found between their zonal components. Our preliminary zonal velocity results, indicate that there is a poor agreement before noontime, while better agreement is found in the afternoon.
Soil density evaluated by spectral reflectance as an evidence of compaction effects

Soil compaction, reflected by high bulk density, is an environmental degradation process and new technologies are being developed for its detection. Despite the proven efficiency of remote sensing, it has not been widely used for soil density. Our objective was to evaluate the density of two soils: a Typic Quartzpisament (TQ) and a Rhodic Paleudalf (RP), using spectral reflectance obtained by a laboratory spectroradiometer between 450 and 2500 nm. Undisturbed samples were taken at two depths (0–20 and 60–80 cm), and were artificially compacted. Spectral data, obtained before and after compaction, were compared for both wet and dried compacted samples. Results demonstrated that soil density was greater in RP than in TQ at both depths due to its clayey texture. Spectral data detected high density (compacted) from low density (non-compacted) clayey soils under both wet and dry conditions. The detection of density in sandy soils by spectral reflectance was not possible. The intensity of spectral reflectance of high soil bulk density (compacted) samples was higher than for low density (non-compacted) soils due to changes in soil structure and porosity. Dry samples with high bulk density showed differences in the spectral intensity, but not in the absorption features. Wet samples in equal condition had statistically higher reflectance intensity than that of the low soil bulk density (non-compacted), and absorption differences at 1920 nm, which was due to the altered position of the water molecules. Soil line and spectral reflectance used together could detect soil bulk density variations for the clay soil. This technique could assist in the detection of high soil density in the laboratory by providing new soil information.
Mollusks as indicators of historical changes in an estuarine-lagoonal system (Cananéia-Iguape, SE Brazil)

Mollusks recovered from three cores taken from the Cananéia-Iguape estuarine-lagoonal system (São Paulo State, Brazil) were studied. The sampled sediments cover a period beginning approximately two centuries ago and end at the present, including a period when the system suffered significant changes of anthropogenic origin – that is, the construction of an artificial channel connecting the lagoon with a nearby river and with the resulting input of fresh water and contaminants generated from mining activity upstream. The mollusk composition reflects these changes. The more abrupt changes in this composition coincide with the opening of the Valo Grande artificial channel in 1852. Another significant but minor change event was verified for around 1977± one year in areas that were not previously affected, perhaps showing the effect of the closing and reopening of the channel.
In Situ Comparison of Three Dielectric Soil Moisture Sensors in Drip Irrigated Sandy Soils

The number of different sensors available for measuring soil water content has increased since the introduction of time domain reflectometry (TDR). In this study the performances of the CS616 (Campbell Scientific, Ltd., Shepshed, UK) sensor and the Aquaflex (Streat Instruments., Ltd, Christchurch, NZ) sensor were compared with TDR using both vertically and horizontally installed sensors. It was found that the CS616 manufacturer's standard calibration needed to be linearly transformed, y = 0.59x + 0.01 (m3 m−3), to obtain accurate measurements in a sandy soil with horizontally installed probes. In two different soils the standard calibration performed better, and smaller corrections were found, y = 0.87x − 0.01 for a sandy loam and y = 0.96x − 0.001 (m3 m−3) for a sandy loam with a larger clay content, respectively. The CS616 sensor was most likely affected by electrical conductivity at 1.6 dS m−1 in the soil solution when measuring in drip‐fertigated potatoes (Solanum tuberosum L.). In the period of fertigation, the sensor overestimated the soil water content in the sandy soil by 0.01 to 0.11 m3 m−3 compared with TDR measurements. The dynamic response of the vertically installed sensor to changes in soil water content was shown to be good, and the sensor may be useful for assessing threshold values in water content for the start and end of irrigation. The performance of the Aquaflex sensor was investigated in the sandy soil only, and the sensor was found to reflect the dynamics of soil water content well. However, the manufacturer's standard calibration underestimated the soil water content in the order of 0.10 m3 m−3 and even showed negative values.
Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes: Does Marine Isotope Stage 11 stand out?

Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes: Does Marine Isotope Stage 11 stand out? A. H. L. Voelker, T. Rodrigues, R. Stein, J. Hefter, K. Billups, D. Oppo, J. McManus, and J. O. Grimalt Dept. Geologia Marinha, Laboratorio Nacional de Energia e Geologia (LNEG; ex-INETI), Estrada da Portela, Zambujal, 2721-866 Alfragide, Portugal CIMAR Associate Laboratory, Rua dos Bragas 289, 4050–123 Porto, Portugal Alfred-Wegener-Institute for Polar and Marine Research, Columbusstrasse, 27568 Bremerhaven, Germany College of Marine and Earth Studies, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA