Miracle-dz/UniFAR-FTUs huggingface dataset:
Influence de la végétation forestière sur la formation de dépôts sédimentaires en terrains marneux/ Influence of forest vegetation on sediment delivery in marly terrain

Resume La maitrise de l'erosion par la vegetation forestiere, pour la prevention et la lutte contre les risques torrentiels et l'envasement des retenues hydroelectriques, reste une preoccupation importante des amenageurs dans les Alpes francaises du Sud. Les etudes en cours, menees sur plusieurs sites des Alpes-de-Haute-Provence, visent a mieux comprendre l'influence de la vegetation forestiere sur la production sedimentaire de terrains marneux, a differentes echelles spatiales : celles du versant de ravine, de la ravine elementaire et du bassin versant. Il en ressort que la vegetation forestiere joue non seulement un role de protection des sols par couverture et fixation, mais egalement un role de piegeage et de fixation des sediments a l'amont des barrieres qu'elle constitue. Les resultats montrent, de ce fait, l'importance de la distribution spatiale de la vegetation forestiere sur une ravine, notamment des strates herbacees et buissonnantes, pour une reduction significative de la production de sediments a son exutoire. L'interet de ces resultats reside dans leur application a la gestion du risque torrentiel et au controle de l'erosion, dans un objectif d'optimisation des travaux de genie ecologique, ainsi qu'a la cartographie du risque torrentiel.
Revisions to the stratigraphy and volcanology of the post‐0.5 Ma units and the volcanic section of VC‐1 core hole, Valles Caldera, New Mexico

Reexamination of the Continental Scientific Drilling Project VC-1 core, new field data, and new isotopic ages necessitate revision of the previously described geology of the youngest eruptive units from the Valles caldera. The Banco Bonito rhyolite lava flow and minor attendant pyroclastic, autoclastic, and reworked deposits about 0.9 km3 dense rock equivalent volume (DRE), are recognized as the product of the youngest eruption from the caldera. The best estimate of the age of this event is 170–240 ka (1σ). A slightly earlier eruption produced the El Cajete pumice fall deposit, followed by the Battleship Rock ignimbrite and the VC-1 Rhyolite, totalling about 1.8 km3 DRE. We suggest that the VC-1 Tuffs, ignimbrites recognized only in the VC-1 core hole, are not a separate unit as previously proposed but are, in fact, the Battleship Rock ignimbrite. A complex volcaniclastic breccia dating from about the time of the South Mountain Rhyolite lava flow (529 ka) is the lowermost volcanic unit in the VC-1 core. The young, post-500 ka eruption products from the SW part of the Valles caldera are all composed of very similar low-silica rhyolite and are thus distinct from earlier, postcaldera high-silica rhyolites included in the Valles Rhyolite Formation. This distinction marks a major change in the magmatic evolution of the Valles caldera. We propose that recognition of this change necessitates revisions to the stratigraphy of the upper part of the Tewa Group.
Theoretical model of optimal drainage networks

A simulation model of drainage network optimization is presented in which channels shift to minimize total stream power pgQS within the network. The simulation model starts from an arbitrary initial stream network developed on a square matrix, such as produced by random headward growth. Discrete stream capture then is simulated within the network, occurring wherever a new stream linkage would produce a steeper course than the original. Such capture produces a network with minimum power optimization but flow directions constrained to eight directions. Individual segment end points are then allowed to migrate by iterative relaxation with a direction and rapidity of motion governed by the gradient of stream power at the node. This valley migration is subject to the constraint that the sources and outlet remain fixed. The resulting networks are visually and morphometrically more similar to natural stream networks than the original networks produced by the random headward growth model.
FOSSIL BISON AND ASSOCIATED ARTIFACTS FROM PLAINVIEW, TEXAS

A quarry containing fossil bison and associated artifacts was discovered on the High Plains of northwest Texas in 1944 and excavated in 1945. The bone bed, ranging in thickness from a few inches to 1½ feet, is in a former stream channel at the base of valley fill. At the top of the bone bed the bones are more or less broken while at lower levels and at the bottom the bones are usually complete and often in articulation. Whole skeletons are preserved but are difficult or impossible to separate from associated skeletons. Excavation of 62 running feet (about 500 square feet) of the bone bed yielded parts of skeletons of 100 bison (estimated), together with 26 artifacts. The associated projectile points bear some resemblance to Folsom and Yuma types but are distinctive from both and have been described as Plainview points. The bison is notably larger than the largest individuals of the modern species and is referred to Bison taylori. The only other vertebrate fossil found in the bone bed is a wolf, but near-by localities in the same horizon have yielded Parelephas columbi and Equus sp. Fresh-water in vertebrates of several species are abundant in the bison bone bed and in the same horizon at other exposures in the vicinity.
Finding a Way: Modeling Landscape Prerequisites for Roman and Early‐Medieval Routes in the Netherlands

This study focuses on reconstructing landscape prerequisites for Roman and early‐medieval routes in the Netherlands. We applied spatial modeling to modern and paleogeographical landscape data in order to determine geographical obstacles for possible translocation in ca. A.D. 100 and 800 via land and water. Network‐friction values were calculated to produce a spatial model of possible movement corridors and to enable the integration of archaeological data. Results show that in geographically dynamic lowland regions such as the current Netherlands, landscape units such as water, peat, and levees must have had a high impact on route orientation. The lower parts of the western Netherlands were almost inaccessible by land, implying that its inhabitants largely must have depended on rivers and streams for transportation. In Dutch coastal and river areas, the landscape changed drastically between A.D. 100 and 800, the largest changes occurring along the coast.
The Geochemistry of the Arabian Lithospheric Mantle—a Source for Intraplate Volcanism?

DANISH LITHOSPHERE CENTRE, STER VOLDGADE 10, COPENHAGEN, 1350K, DENMARK DEPARTMENT OF GEOLOGY, ROYAL HOLLOWAY UNIVERSITY OF LONDON, EGHAM TW20 0EX, UK SCHOOL OF EARTH SCIENCES, VICTORIA UNIVERSITY OF WELLINGTON, PO BOX 600, WELLINGTON, NEW ZEALAND DEPARTMENT OF EARTH SCIENCES, OREGON STATE UNIVERSITY, CORVALLIS, OR97331-5506, USA DEPARTMENT OF EARTH AND ENVIRONMENTAL SCIENCES, HASHEMITE UNIVERSITY OF JORDAN, ZARQA, JORDAN
Chemistry and Mineralogy of Earth’s Mantle. Experimental determination of melting in the systems enstatite-magnesite and magnesite-calcite from 15 to 80 GPa

Abstract Pressure-temperature melting curves in two carbonate-bearing systems of relevance to Earth’s mantle have been determined using the laser-heated diamond-anvil cell (LH-DAC). The solidus along the MgSiO3-MgCO3 join in the MgO-SiO2-CO2 system (MS-CO2) was defined from 15 to 80 GPa using in situ melting criteria, reaching a maximum temperature of ~2340 K at 80 GPa. The occurrence of melting has been confirmed with ex-situ textural and chemical analysis of recovered samples. The melting curve has a negative dT/dP slope at pressures between ~15 and 23 GPa resulting from the subsolidus phase transition of ilmenite- to perovskite-structured MgSiO3. The shallow slope of the melting curve at pressures higher than this transition indicate that for plausible mantle geotherms carbonate-bearing silicate lithologies will melt throughout the lower mantle. The solidus of a mixture along the MgCO3-CaCO3 join was determined as a proxy for alkali-free carbonate lithologies. Melting temperatures increase from 1860 K at 16 GPa to ~2100 K above 35 GPa, where the melting curve flattens. The melting reaction magnesite + post-aragonite (high-pressure CaCO3) = melt was confirmed using an in situ experiment. We conclude that crystalline Mg and Ca carbonate mixtures are unstable with respect to molten carbonate at conditions of the convective lower mantle. The flat melting curves at high pressures in both systems suggests that subducted carbonates will undergo melting at lower mantle conditions, a process that may be important for superdeep diamond formation and carbon storage in the deep mantle.
A Review of the Enigmatic Microalga Tetranguladinium Yu et al. 1983 ex Chen et al. 1988; Palaeoecology, Stratigraphy and Palaeogeographical Distribution

The probable zygnematacean zygospore Tetranguladinium is recorded in Mesozoic strata from southern Scandinavia for the first time. Tetranguladinium, which exhibits morphological similarities to the extant filamentous green alga Mougeotia, occurs in Jurassic-Cretaceous (J/K) boundary (latest Tithonian-Early Berriasian) assemblages from the Vomb Trough, southern Sweden and on the Danish island of Bornholm. The J/K boundary strata of southern Scandinavia were deposited in marginal marine settings, varying from freshwater marshes, lakes and flood plains, to lagoons, shoreface, and shallow marine to fully marine environments. The assemblages containing Tetranguladinium are diverse, consisting of spores and pollen, the colonial green alga Botryococcus, various other zygnematacean zygospores e.g. Ovoidites, Schizosporis and Tetraporina, and rare marine dinoflagellate cysts. A review of published fossil occurrences of Tetranguladinium reveals that its stratigraphical range extends at least from the Late Guadalupian (Mid Permian) to the Holocene. It has been recorded from Africa (Tanzania), Asia (China, Korea), Australia, northwest Europe (Denmark, Great Britain, Sweden), North America (Canada, USA), and South America (Argentina). Depositional and palaeoclimatological data for the known localities of Tetranguladinium confirm a preference for freshwater settings in a humid warm temperate to subtropical-tropical climate, often with a pronounced dry season. The palaeogeographical positions of all the known Tetranguladinium localities indicate that it is has stayed restricted within narrow belts between 30–40° south and 30–60° north of the palaeoequator since the Late Jurassic.
Magnetostratigraphy of the Dali Basin in Yunnan and implications for late Neogene rotation of the southeast margin of the Tibetan Plateau

The rotation pattern and fault activity in the southeast margin of the Tibetan Plateau (SEMTP) provide meaningful constraints on the geodynamic evolution of the plateau. However, the lack of Cenozoic paleomagnetic studies and accurate age constraints on Neogene sediments prevents a better understanding of the late Cenozoic tectonic activity in this area. To clarify the tectonic rotation pattern and deformation history of the SEMTP, we report new magnetostratigraphic data from a late Neogene sedimentary sequence in the Dali Basin, northwestern Yunnan Province, China. Rock magnetic analyses indicate that both magnetite and hematite are the main carriers of the characteristic remanent magnetizations (ChRMs). Magnetostratigraphic results show that the sedimentary profile spans from Chron C4n.1r to Chron C2n. The age of the sedimentary sequence in the Dali Basin can thus be paleomagnetically constrained to an interval from late Miocene to early Pleistocene. The basal age of the sediments is ~7.6 Ma, which indicates that the unroofing of Diancang Shan and activation of the Dali fault system were initiated at this time. The appearance of conglomerates and syntectonic sediments suggests the reactivation of the Dali fault system at ~2.5 Ma. Moreover, the overall mean ChRM direction suggests that the Dali Basin experienced significant (4.4 ± 2.5°), but minor post–late Miocene rotation. This indicates that most of the clockwise rotation demonstrated by previous paleomagnetic studies in the SEMTP occurred prior to late Miocene and may be concentrated between Eocene and Miocene, which is contemporaneous with the sinistral slip of the Ailao Shan‐Red River fault.
Attenuation of multiple ScS in various parts of the world

SUMMARY A waveform and amplitude matching scheme is used to study regional variations of Qscs at low-frequency band between 0.02 and 0.1 Hz for paths across various parts of the world. The scheme estimates attenuation by convolving the first well-recorded, clear SCS, phase with multiples of trial t* operators until the phases so derived match the amplitude decay-rates and waveform characteristics of the observed later multiples. Thirty-five intermediate-to-deep focus earthquakes recorded at seismographic stations throughout the world were used in this study. The regions sampled are the tectonic and shield areas of Eurasia, tectonic regions of North America, shield regions of South America, and tectonic portions of NW, SW and E Pacific Ocean. In general, the regional differentials in t* between successive multiples of ScS are similar to those reported in earlier studies (Nakanishi 1979; Spikin & Jordan 1980). For the tectonic regions of Eurasia, tgcs are 5.0 f 1.1 s for a double passage through the mantle, whereas for the shield areas, they are around 2.8 f 0.4 s. For the tectonic regions of North America, our estimates of t& are 4.8 f 1.6 s. A mean t& of 6.3 f 0.9 s has been obtained for paths across the E Pacific while the NW and SE Pacific are characterized by moderate attenuation with average t& values of 4.4 f 0.7 and 4.2 f 0.8 s respectively. For central South America, the estimated tics is 2.7 f 0.7 s. Assuming that the lateral variations in Q observed using the ScS data are confined to a 200-300 km thick layer in the upper mantle, where the lateral velocity variations are also the most pronounced, these results imply lateral variations in shear wave Q of about an order of magnitude. The lateral variations of mantle Q in the upper mantle derived from these analyses of long-period ScS phases correlate well with mantle Q estimates from short period data. It is therefore unlikely that Q(f) appropriate to various types of upper-mantle structures converge at low frequencies of 0.02 to 0.1 Hz as required by the ‘absorption-band shift’ models.
Aftershock distribution of the 1994 Sanriku-oki earthquake (Mw 7.7) revealed by ocean bottom seismographic observation

The 1994 Sanriku-oki earthquake (Mw 7.7) ruptured the entire seismogenic zone of the Pacific plate subduction beneath northeastern Japan arc. We deployed 18 ocean bottom seismographs and recorded its aftershocks, which span the whole seismogenic zone, with unprecedented accuracy. We calculate hypocenters and mechanisms to improve our understanding of the plate subduction geometry and plate coupling. The rupture of the mainshock initiated at the updip end of the seismogenic zone defined as the trenchward limit of the aftershock and background seismicity. The rupture continued to slip along a shallow dipping (<10°) interface for ∼60 km, and then slipped across an asperity where the dip angle starts to increase at ∼143°E. Here aftershocks are few, suggesting complete release of strain. The rupture continued another 100 km or so to the downdip end beneath the coastline, where the plate dip angle reaches 30° to smoothly connect to the dip angle of the Wadati-Benioff zone. Coseismic slips are larger westward of 143°E, where the mantle wedge comes into contact with the subducting plate. The stress redistribution due to the mainshock seems to have caused aftershocks with normal faultings to occur offset above and below the plate boundary.
Influence of Rainfall Scenario Construction Methods on Runoff Projections

Abstract The future rainfall series used to drive hydrological models in most climate change impact studies is informed by global climate models (GCMs). This paper compares future runoff projections in ∼11 000 0.25° grid cells across Australia from a daily rainfall–runoff model driven with future daily rainfall series obtained using three simple scaling methods, informed by 14 GCMs. In the constant scaling and daily scaling methods, the historical daily rainfall series is scaled by the relative difference between GCM simulations for the future and historical climates. The constant scaling method scales all the daily rainfall by the same factor, and the daily scaling method takes into account changes in the daily rainfall distribution by scaling the different daily rainfall amounts differently. In the daily translation method, the GCM future daily rainfall series is translated to a 0.25° gridcell rainfall series using the relationship established between the historical GCM-scale rainfall and 0.25° gridcell.
Pans of the southern Kalahari, Botswana

The pans, or small dry or ephemeral lakes, of the southern Kalahari in Botswana are contained in shallow, sub-circular to sub-elliptical, enclosed depressions in the surface sands which mantle the region. The depressions, of probable deflation origin, are concentrated in a well defined belt along the Okwa, Nosop-Molopo watershed. Two crescentic dunes on the southern side of the pans represent material defiated from the depressions, which are floored by calcareous and saline clays and sandy clays, laid down in the period between the formation of the outer and inner dunes, when the depressions held permanent or seasonal lakes up to three times the area of the present pans. The origins and development of the pans are seen as reflecting the fluctuating climates in the region during the late Quaternary.
Lake Surface Height Calibration of Jason-1 and Jason-2 Over the Great Lakes

This study presents results of Jason-1 (J1) and Jason-2 (J2) radar altimetry absolute calibration (cal/val) over the Marblehead lake water level gauge, with an aid of a GPS buoy, in Lake Erie, the Great Lakes, in North America. The altimeter bias is estimated using the height difference between the altimeter lake surface height and the in situ data in each altimeter 10-day repeat cycle. The altimeter bias estimates for J1 are 81 ± 2 and 70 ± 2 mm for Geophysical Data Record (GDR) Versions ‘B’ and ‘C’, respectively, and 148 ± 5 mm (GDR) and 147 ± 7 mm (IGDR) for J2, respectively. The bias estimates are slightly smaller compared with estimates at other dedicated calibration sites such as the Harvest Platform, the Corsica Site, and the Bass Strait site due in part to the effect of the sea state bias. The J2-to-J1 relative bias determined in the tandem mode over Lake Erie is 84 ± 28 mm, which agrees well with the results from the global analysis and the dedicated sites aforementioned.
Multifractal Analysis of Pore Size Distributions as Affected by Simulated Rainfall

Rainfall changes the physical state, pore system geometry, and structure of soils. Characterization of the soil pore system provides a realistic base to understand the retention and movement of water in soil. The objective of this work was to estimate multifractal parameters from Hg injection porosimetry data on the uppermost soil surface layer as affected by simulated rainfall. Soil aggregates were sampled at the 0‐ to 2‐cm depth in a loamy soil, both on a recently tilled soil surface and on its disturbed counterpart after 260‐mm cumulative rainfall. Pore size distributions (PSDs) were determined by Hg intrusion porosimetry from 0.005‐ to about 100‐μm pore diameters on 10 samples per surface stage. The rainfall reduced aggregate pore volume, showing significant differences between the pore space of the reference and the disturbed soil surfaces. A multifractal analysis was performed by means of scaling of the moments ranging from −10 < q < 10 for all PSDs. Mean values of the entropy dimension, D1, and correlation dimension, D2, in the aggregate set sampled after rain disturbance were lower than those of the reference stage; however, mean values of the difference Δ(D1 − D2), the Hölder exponent of order zero, α0, and widths of the left (α0 − αq+) and right (αq− − α0) hand sides of the singularity spectra f(α) after rainfall action were higher than those of the initial soil surface. Entropy dimension, D1, and the width of the left (α0 − αq+) hand side of the f(α) spectra best discriminated between PSDs of the reference initial soil surface vs. soil surface disturbed by rain.
Environmental Risk Assessment of Agrochemicals — A Critical Appraisal of Current Approaches

This chapter provides insights into the difficulties and challenges of performing risk evaluations of agrochemicals. It is a critical review of the current methodologies used in ecological risk assessment of these chemicals, not their risks to humans. After an introduction to the topic, the current framework for ecological risk assessment is outlined. Two types of assessments are typically carried out depending on the purpose: i) regulatory assessments for registration of a chemical product; and ii) ecological assessments, for the protection of both terrestrial and aquatic ecosystems, which are usually site-specific. Although the general framework is well established, the methodologies used in each of the steps of the assessment are fraught with a number of shortcomings. Notwithstanding the subjectivity implicit in the evaluation of risks, there is scepticism in scientific circles about the appropriateness of the current methodologies because, after so many years of evaluations, we are still incapable of foreseeing the negative consequences that some agrochemicals have in the environ‐ ment. A critical appraisal of such methodologies is imperative if we are to improve the current assessment process and fix the problems we face today. The chapter reviews first the toxicity assessment methods, pointing to the gaps in knowledge about this essential part of the process and suggesting avenues for further improve‐ ment. Deficiencies in the current regulations regarding toxicity testing are discussed, in particular the effect of the time factor on toxicity and the issue of complex mixtures. Other matters of concern are the extrapolation of toxicity data from the individual to the population and community levels, and the sub-lethal effects. The exposure assessment methods are dealt with in a second place. These rely on modelling and actual measurements of chemical residues in the environment. Various techniques employed to determine to exposure and bioavailability of agrochemicals to the various organisms in both aquatic and terrestrial ecosystems are reviewed. Again, the shortcomings and gaps in knowledge are addressed and suggestions for improvement are pointed out. Then, the process of putting together the information from the toxicity and exposure assessments to evaluate risks is discussed. Tiers I and II of the risk assessment are reviewed. The challenge here is to keep objectivity in the evaluations; this may require the introduction of new methods of risk assessment. Finally, the risk assessment implies establishing a management strategy that aims at reducing or minimising the impacts of agrochemicals under normal agricultural scenarios. Recommendations are often case-specific and need to be based on sound science as well as common sense principles. The chapter concludes with a summary of issues that need to be considered for improving risk assessments of agrochemicals.