Miracle-dz/UniFAR-FTUs huggingface dataset:
Rare earth elements distribution in seawater and suspended particulate of the Central Mediterranean Sea

Rare earth element (REE) content in suspended and dissolved phases from the Strait of Sicily (Central Mediterranean Sea) has been measured. Vertical profiles of several dissolved REEs along the water column reflect the 3-D oceanographic features of the studied area and identifies the different water masses present there. Shale-normalized REE distribution patterns and derived parameters calculated for the suspended particulate show different atmospheric dust-surface inputs and their interactions with seawater. Finally, combined information from [La/Yb]N, ratios, REE/La ratios and Eu anomalies measured in the suspended particulate suggest an important contribution of volcanic materials from the Etna volcano and Saharan dust to the lithogenic fraction of the suspended particulate.
A flume study on the development and equilibrium morphology of current ripples in very fine sand

An empirical model is constructed for the development and equilibrium dimensions of small scale, unidirectional bedforms in sand with a median grain size of 0·095 mm, based on a series of steady flow experiments in a flume. Current ripples always attain a linguoid plan morphology with constant average height (13·1 mm) and wavelength (115·7 mm), provided that sufficient time is allowed for their formation. The development pattern of these ripples on a flat bed is independent of flow velocity, and involves four stages: (1) incipient ripples; (2) straight and sinuous ripples; (3) non-equilibrium linguoid ripples, and (4) equilibrium linguoid ripples. Straight and sinuous ripples are non-equilibrium bedforms at all flow velocities. The time needed to reach equilibrium dimensions is related to the inverse power of flow velocity and ranges from several minutes to more than hundreds of hours. At flow velocities where washed ripples are stable, the equilibrium wavelength is similar to that of equilibrium linguoid ripples, but the equilibrium height rapidly decreases from 13·1 mm to zero towards upper stage plane bed conditions. The results of the flume experiments correspond reasonably well with those of previous studies, provided that various complicating factors, such as different experimental methods, different sediment characteristics, shallow flow depths and non-equilibrium runs, are accounted for.
Biogenic silica accumulation and paleoproductivity in the northern basin of Lake Baikal during the Holocene

The effects of the Holocene climatic amelioration, productivity, and preservation on biogenic silica accumulation in the northern basin of Lake Baikal are evaluated by analyzing biogenic silica, organic carbon, nitrogen, and the stable carbon isotopic composition of organic matter in a 4 m piston core and a companion box core. In the early Holocene (11,000-8500 yr B.P.), biogenic silica accumulation was low because of low productivity, strong oligotrophy, and the influx of nutrient-limited alpine glacial meltwater. In the middle Holocene, productivity increased significantly during 8500-7000 yr B.P., but little biogenic silica accumulated in sediments because the dominant primary producer was not diatom flora and because of the relatively higher productivity caused by enhanced terrestrial nutrient influx. The highest accumulation rates of biogenic silica were those between 7000 and 4500 yr B.P., when aquatic productivity increased, limnological stratification occurred, a mature diatom flora developed. In the late Holocene (the past 4500 yr), biogenic silica accumulation decreased because of enhanced recycling and regeneration of silica and a low sedimentation rate.
New radiometric dates for precolumbian (2000–700 b.p.) earthworks in western Amazonia, Brazil

Abstract In this paper we present new data on the precolumbian geometric ditched enclosures identified in Acre State, western Amazonia, Brazil. Remote sensing and ground survey have revealed 281 earthworks, located mainly on the edges of high plateaus overlooking the river valleys drained by the southeastern tributaries of the Upper Purus River. Excavations have shown that the few existing cultural materials are concentrated on the slopes and in the bottoms of the ditches, as well as on small mounds that were likely remains of houses, whereas the central, flat enclosed areas lack major archaeological features. New radiocarbon dates place the initial stage of earthwork construction as early as ca. 2000 b.p. We suggest that the building of these geometric earthworks may have been a regionally shared phenomenon, especially among the Arawak and the Tacana peoples, who used them for special gatherings, religious activities, and, in some cases, as village sites.
Formation of Wulong Mafic Dikes via Mixing of Enriched Lithospheric Mantle-Derived and Crustal Magmas, Eastern North China Craton

Zircon U-Pb age and geochemical data are reported for the Wulong dike swarms from the Liaodong Peninsula, NE China. The studied dikes include diorite, lamprophyre, and dolerite. Together with previous dating, the diverse rocks have a peak age of ca. 120–125 Ma. They are marked by inversely zoned phenocrysts with Mg- and Cr-rich rims, and they exhibit mantle-like signatures (i.e., high Mg-Cr-Ni) associated with prominent subduction-type element enrichments. The early diorites have relatively radiogenic Sr (–0.7143) and less radiogenic Nd ( to −11.0) isotopes coupled with high and variable MgO (Cr, Ni) contents, indicating that they were mainly derived from ancient lower crust with subordinate contributions of enriched lithospheric mantle. The transitional lamprophyres are characterized by high Rb/Sr ratios (0.22–0.54) but low initial 87Sr/86Sr ratios (0.7069–0.7093), moderate negative ϵNd(t) values (−14.4 to −12.6), and low promantle elements (such as Mg-Cr-Ni), reflecting that juvenile lower crustal components with a short residence time were significantly added to their source as well. The late dolerites possess extremely high Mg, Cr, and Ni concentrations, less radiogenic Sr (–0.7082) and much radiogenic Nd ( to −2.4) isotopes, suggesting that they mainly originated from an enriched mantle source with minor involvement of old lower crustal materials. Petrographic and chemical evidence points to an origin of these rocks by mixing of enriched mantle-derived and lower crustal magmas. The rapid progressive change of source compositions first indicates a complex, multistage hybridization process, and second, it shows an extensional tectonic regime during magma generation.
Soil-water characteristic curve and consolidation behavior for a compacted silt

Measurement of the soil-water characteristic curve (SWCC) in the laboratory is commonly conducted under zero confining pressure. However, in the field, the soil is under a confining stress. Therefore, it is important to study the effects of the confining stress on SWCC. In addition, the consolidation curve is normally generated under saturated conditions. However, the soil above the water table is usually unsaturated. Hence, it is also necessary to investigate the effects of matric suction on the characteristics of the consolidation curves. This paper presents the SWCCs under different net confining stresses and the isotropic consolidation curves under different matric suctions that describe the volume change characteristics of unsaturated soils with respect to stress state variables, net normal stress, and matric suction. A series of SWCCs was determined for statically compacted silt specimens in a triaxial cell apparatus under different net confining stresses. Isotropic consolidation tests under differe.
A New Bayesian Chronology for Postclassic and Colonial Occupation at Xaltocan, Mexico

This article proposes a new four-phase chronology for Postclassic and colonial occupation at Xaltocan, Mexico, using Bayesian statistical modeling of a suite of 54 radiometric dates. Of these, 46 samples come from recent extensive excavations of sealed, stratified household deposits, facilitating improved understanding of sample context and resulting in a more accurate chronology. The timing of the adoption of major ceramic wares at the site and intrasite level is outlined and contextualized within broad, regional phases. These results are particularly valuable given recent research that repudiates a uniform chronological framework for the Basin of Mexico in the Postclassic period, and indicates instead a significant amount of chronological overlap and regional variation in the use of distinct ceramic types.
Consolidation of a soil layer subsequent to cessation of deposition

It is necessary in certain cases to estimate the progress of consolidation in a soil layer that has ceased increasing in thickness over time. In this paper, the existing excess pore pressures for two timethickness relations are used as the "initial" pore pressures for analysing the consolidation of soil subsequent to the cessation of deposition. Average degrees of consolidation of the soil layer are presented for one-way drainage and two-way drainage boundary conditions. The average degrees of consolidation are compared with those for uniform and triangular initial excess pore pressure distributions. It is found that the average degree of consolidation for one-way drainage boundaries can be estimated using the value for the triangular distribution. The average degree of consolidation for two-way drainage boundaries is bound by the averages for both the uniform and the triangular initial excess pore pressure distributions.Key words: consolidation, deposition, drainage, settlement, soil.
Age and spreading history of the Cayman Trough as determined from depth, heat flow, and magnetic anomalies

The opening of the Cayman Trough records aspects of relative motion between the North American and Caribbean plates essential to accurate reconstruction of Caribbean evolution. Assessment of opening rates based upon basement subsidence analysis as well as magnetic anomaly interpretation shows that the trough may have opened at one third to one half previously proposed rates. Depths to basement show that the crust has subsided away from the present axis in two stages: a younger stage characterized by substantial and asymmetric (greater to the east) subsidence, preceded by an older stage of slight increases of depth with distance. Depth to age relations calculated from subsidence curves which accommodate lateral as well as vertical cooling of the accreting slab indicate that the trough has opened at an overall rate of less than 15 mm/yr since 25–30 Ma and at 20–30 mm/yr prior to 30 Ma. Marine magnetic anomalies show lineations perpendicular to the trough, including a distinct central anomaly, but the pattern is neither well defined nor symmetrical about the present axis. However, partial anomaly sequences can be identified on both sides of the axis, and the distribution of these sequences indicates that spreading may have involved frequent short ridge jumps, mostly eastward. The overall rate of opening as indicated by this interpretation of the magnetics is about 15 and 30 mm/yr since and prior to 26 Ma. Both subsidence and magnetics indicate that the trough opened by at least 45–50 Ma.
Field evaluation of crushed glass-dredged material blends

Based on the laboratory results reported in a companion paper, three crushed glass–dredged material (CG–DM) blends were prepared and evaluated in the field to explore the feasibility of using CG–DM blends in general, embankment and structural fill applications. A trailer-mounted pugmill successfully prepared 20∕80 , 50∕50 , and 80∕20 CG–DM blends (dry weight percent CG content reported first) within a tolerance of ±5 dry % by weight of the targeted percentages. Blending criteria were routinely met at pugmill throughputs up to 1,500 m3 ∕day . The constructed 20∕80 CG–DM embankment was compacted to a minimum of 90% modified Proctor compaction, whereas the 50∕50 and 80∕20 CG–DM embankments were constructed to a minimum of 95% modified Proctor compaction. Twenty to 80% CG addition to DM resulted in 1.5–5.5 kN∕ m3 increases in field dry densities above 100% DM, densities not achievable with other DM stabilization techniques such as Portland cement, fly ash, and/or lime (PC/FA/lime) addition. CG substantially i.
Validation of the Earth radiation budget as simulated by the Max Planck Institute for Meteorology general circulation model ECHAM4 using satellite observations of the Earth Radiation Budget Experiment

In this study, the Earth radiation budget as simulated by the latest version of the ECHAM general circulation model (ECHAM4) is documented. The Earth radiation budget obtained from the model is evaluated through comparison with Earth Radiation Budget Experiment (ERBE) data. The model simulations generally agree with the satellite-observed spatial distribution and seasonal variation of the radiation budget. The interannual variabilities of the simulated radiative quantities in the tropics are also comparable to the observed data. There are, however, biases in the details. The longitudinal structure of the radiation fields in the tropics is not exactly reproduced. The slight differences in the geographical location of the various radiation quantities are related to the errors in the simulation of the tropical east-west longitudinal circulation and associated cloud fields. The most significant bias in the radiation budget is the simulated shortwave radiative effect from cloud. Consistent underestimation in the shortwave cloud radiative forcing is found over the midlatitude oceans in summer. This bias is due to an underestimation in the total cloud amount. In the tropics the simulated shortwave cloud radiative forcing is persistently larger than that derived from ERBE data. The systematic overestimation in the shortwave cloud radiative forcing at various values of the longwave cloud radiative forcing suggests that this problem is related to the neglect of sub-grid-scale cloud water content variability and its effect on the grid-averaged shortwave radiative flux. Although the tropical interannual variability of cloud radiative forcing is reasonably well reproduced by the model, the major contribution for the simulated anomalies is from the cloud water anomalies, while observations suggest the dominant factor is the total cloud cover anomalies. Lack of observations for various cloud parameters limits the attempt of further validation.
Interhemispheric differences in springtime production of HCl and ClONO2 in the polar vortices

UARS observations of O3 and ClO (Microwave Limb Sounder), ClONO2 and HNO3 (Cryogenic Array Etalon Spectrometer), NO, NO2, and HCl (Halogen Occultation Experiment), and model calculations are used to produce an exposition of the different processes through which the reservoir gases ClONO2 and HCl are reformed at the end of the polar winter. Comparison of the observations within the polar vortices shows that HCl increases more rapidly in the Antarctic vortex in spring than in the Arctic vortex. Model analysis shows that this occurs because the O3 concentrations in the southern vortex fall well below those in the northern vortex. The Cl/ClO fraction calculated for the southern hemisphere is therefore up to 30 times higher, leading to rapid HCl formation by Cl + CH4. The concentrations of NO observed by HALOE are substantially lower for the northern hemisphere than for the southern hemisphere, even for similar values of the concentration of HNO3 and the production of NOX from HNO3 through photolysis and reaction with OH. This is consistent with the dependence of the NO/NOX ratio on the O3 concentration, i.e., the daytime production rate of NO2 via NO + O3 is reduced, leading to higher NO in the southern hemisphere. This higher concentration of NO also contributes to the rapid HCl increase as Cl production from ClO + NO is enhanced.
The influence of structure on the pre-failure behaviour of a natural clay

Results are presented of an extensive laboratory and field investigation of a Pleistocene stiff clay in its natural and reconstituted states, including constant rate of strain oedometer and triaxial tests over a wide stress range, scanning electron microscopy and chemical micro-analysis. The relationships between the structure of the clay, its geological history and its mechanical response are demonstrated. The structure of the clay is strongly influenced by bonding, apparently largely due to a film of amorphous calcite which developed in situ at the end of normal consolidation. The effects of structure on the stiffness of the clay are identified, with sensitivity as the parameter quantifying the mechanical effects of structure. A frictional flow rule is found generally to be applicable over a wide strain range, including yield, even when strong bonding is present, although its form is influenced by structure. A new normalization shows that the gross yield surface is isotropically hardening in terms of bo.
The basaltic shergottite Northwest Africa 856: Petrology and chemistry

Abstract— We report on the discovery of a new shergottite from South Morocco. This single stone weighing 320 g is referenced as Northwest Africa (NWA) 856 with Djel Ibone as a synonymous name. It is a fresh, fine‐grained basaltic rock consisting mainly of two pyroxenes (total ˜68 vol%: 45% pigeonite, En61‐16Wo9–22Fs26–68; 23% augite, En46‐26Wo34‐29Fs21–43) and plagioclase converted to maskelynite (˜23 vol%, Ab43–57Or1–5An54‐36). Accessory minerals include merrillite, Cl‐apatite, pyrrhotite, ilmenite, ulvöspinel, silica (stishovite and glass), amorphous K‐feldspar and baddeleyite. Amorphous mixtures of maskelynite and silica occur most commonly as median layers inside maskelynite laths. In addition, melt pockets (˜2 vol%) were recognized with relics of maskelynite, pyroxene and both dense silica glass and stishovite occurring as both grains and submicrometer needles. The compositions of the melt pockets are consistent with mixtures of maskelynite and pyroxenes with an average of ˜50 vol% maskelynite. The meteorite is highly fractured at all scales.
A new specimen of Guaibasaurus candelariensis (basal Saurischia) from the Late Triassic Caturrita Formation of southern Brazil

The comparison of the anatomy of a second incomplete skeleton of Guaibasaurus candelariensis to that of basal Saurischia suggests that the origin of the “Prosauropoda” was from unknown basal saurischians, after separating from theropods (except herrerasaurids). Guaibasaurus and Saturnalia are part of this early dichotomy, and they bear mixed characters-states of basal theropods and “prosauropods” type. The Late Triassic age of both Guaibasaurus and Saturnalia (the latter is older) predates the ‘dominance’ of basal sauropodomorphs as well as the appearance of the basal theropod Zupaysaurus, both recorded from the upper Los Colorados Formation of Argentina.
Cooling and inferred exhumation history of the Ryoke metamorphic belt in the Yanai district, south‐west Japan: Constraints from Rb–Sr and fission‐track ages of gneissose granitoid and numerical modeling

Abstract The Ryoke metamorphic belt in south‐west Japan consists mainly of I‐type granitoids and associated low‐pressure/high‐temperature metamorphic rocks. In the Yanai district, it has been divided into three structural units: northern, central and southern units. In this study, we measured the Rb–Sr whole‐rock–mineral isochron ages and fission‐track ages of the gneissose granodiorite in the central structural unit. Four Rb–Sr ages fall in a range of ca 89–87 Ma. The fission‐track ages of zircon and apatite are 68.9 ± 2.6 Ma and 57.4 ± 2.5 Ma (1σ error), respectively. Combining the newly obtained ages with previously reported (Th–)U–Pb ages from the same unit, thermochronologic study revealed two distinctive cooling stages; 1) a rapid cooling (> 40°C/Myr) for a period (~7 Myr) soon after the peak metamorphism (~ 95 Ma) and 2) the subsequent slow cooling stage (~ 5°C/Myr) after ca 88 Ma. The first rapid cooling stage corresponds to thermal relaxation of the intruded granodiorite magma and its associated metamorphic rocks, and to the uplift by a displacement along low‐angle faults which initiated soon after the intrusion of the magma. Uplift by the later stage deformation having formed large‐scale upright folds resulted in progress of the exhumation during the first stage. The average exhumation velocity of the stage is ≥ 2 mm/yr. During the second stage, the rocks were not accompanied by ductile deformation and were exhumed with the rate of 0.1–0.2 mm/yr. The difference in the exhumation velocity between the first and second cooling stages resulted from the difference in the thickness of the crust and in the activity of ductile deformation between the early and later stages of the orogenesis.
African transform continental margins: Examples from Guinea, the Ivory Coast and Mozambique

Marine Studies of selected sheared-type margins have been undertaken along both West and East African coastal regions in order to determine the geological structure and the evolution of this specific type of passive margin. Geological and geophysical data have been obtained in the coastal waters off Guinea, Ivory Coast, and Ghana (Western Equatorial Africa) and off Mozambique (Eastern Africa). The continental margin off the Guinea coastline can be divided into three distinct sectors. To the Northwest, the observed seismic stratigraphy and structures are typical of a rifted Central Atlantic margin of Jurassic age. To the south, several features such as steep scarps, basement ridges, volcanic piles, magnetic and gravity lineaments, etc., are interpreted in relation to a transcurrent motion. A southwestern marginal area contains lower tectonized sequences of Early Cretaceous age covered by post-Albian detrital sediments. The overall structure is interpreted as a Jurassic rifted margin reactivated by shearing during the Lower Cretaceous. Off shore from the Ivory Coast and Ghana, two main marginal areas are also distinguished. To the east, south of Ghana, the upper margin is fractured by dissymetric and sedimented grabens, with the continental slope representing the unsedimented truncated African craton. South of the Ivory Coast, thick sedimentary basins, containing a Lower Cretaceous tectonized sequence developed between the continent and the Ivory Coast–Ghana Ridge, correspond to a composite feature consisting of deformed sedimentary wedges and basement structures. Off the Mozambique coast, the strike-slip motion of Madagascar with respect to Africa, during the Upper Jurassic, has generated a series of en echelon structures. The Davie Ridge includes a series of sedimentary shear folds and basement structures. Later, in Cretaceous times. throughout the Cenozoic, and since Miocene times, the continental margin has been submitted to different tectonic stresses generating diversely-trending extensional features. When shearing commences between two continental margins, it seems to generate either tensional features (e.g. Ivory Coast) or transpressive features (e.g. Mozambique) depending on the area. Later on, basement-involved structures and sedimentary wedges develop at the boundary between a thinned continental crust and a thick continental crust before connecting laterally with a typical oceanic fracture zone. The southern Guinea margin represents an unusual example where a rifted margin has been reactivated by transcurrent motion.