Miracle-dz/UniFAR-FTUs huggingface dataset:
Axial Intrusion Zone beneath the Median Valley of the Mid‐Atlantic Ridge at 37°N Detected by Explosion Seismology

Summary. Four seismic refraction lines, three of which had shots every 250 m, were shot across, along and parallel to the median valley of the Mid-Atlantic Ridge at 37° N. A method has been developed for calculating the effect on the travel times of the rough sea-floor relief beneath the profiles and has been used to correct all the travel times for this effect. Most arrivals were from a main refractor of apparent velocity 5·4 to 6·3 km s−1; only beyond 35 km were faster arrivals observed from an 8·09 ± 36 km s−1 refractor. The main refractor corresponds in depth, at least approximately, to the top of Layer 3 of the ocean basins but its velocity is significantly less than normal for Layer 3, perhaps due to dip. A study of time residuals along two profiles across the median valley indicates the presence of a 2 to 3 km wide low velocity zone (about 3·2 km s−1) beneath the median valley floor. This zone extends over the upper 2·5 km of the crust and is believed to represent a zone of intrusion through which magma passes on its way to the sea floor.
A deep‐ocean Kelvin‐Helmholtz billow train

Detailed overturning is observed between 0.5 and 50 m above the sloping side of Great Meteor Seamount, Canary Basin, using 100 moored temperature sensors, 1 mK accurate, sampling at 1‐Hz. While previously reported frontal bores of 40‐m amplitude can form with vigorous near‐bottom motions and sediment resuspension at the beginning of the upslope phase of large, e.g., tidal, carrier waves, the downslope phase presented here is more “permanently” turbulent away from the bottom. This turbulence is inferred from high‐resolution temperature space‐time series, which reveal ubiquitous “finger‐like” structures. It occurs during the clear‐water tidal phase, with low amounts of acoustic scatterers. The high‐frequency finger‐like motions σ ≫ N, N the buoyancy frequency, are observed simultaneously with local mode‐2 near‐N inertio‐gravity waves and overall shear ∣S∣ ≈ N. They show large temperature variations, 5–10 m vertical amplitudes and occasionally develop Kelvin‐Helmholtz billows. The typical (Eulerian) period of these firstly observed deep‐ocean billows amounts 50 ± 10 s.
Volcaniclastic Sequences With Continental Affinities Within the Late Jurassic‐Early Cretaceous Guerrero Intra‐Oceanic Arc Terrane (Western Mexico)

The Guerrero terrane in western Mexico consists of upper Jurassic‐lower Cretaceous volcano‐plutonic and volcano‐sedimentary arc sequences developed in an intra‐oceanic setting and accreted to North America late in the Early Cretaceous. The Playa Azul sequence belongs to the southern Pacific Province of the Guerrero terrane (PPGT), which extends along the Pacific coast from Puerto Vallarta to Acapulco. This sequence is composed of pyroclastic rocks and rare lava flows interlayered with red detrital rocks and coastal calcarenites. The red beds yielded Early Cretaceous dinosaur footprints. The whole sequence is capped by Albian to Cenomanian reefal limestones. The rare basalts are olivine‐phyric and include altered amphibole‐bearing cumulates. The most common facies are amphibole‐biotitephyric andesites and dacites. The welded, or not, tuffs have K‐feldspar, quartz, and plagioclase phenocrysts, while their groundmass includes biotite and zircon. Amphibole ranges in composition from pargasitic hornblende to edenite similar to volcanic rocks of islands arcs and continental margins. The mafic rocks are Ti‐, Ta‐, and Nb‐depleted and belong to mild tholeiitic and calc‐alkaline suites. They show transitional geochemical characteristics between lavas from oceanic island arc and active continental margins. The felsic rocks belong to calc‐alkaline suites. The Playa Azul rocks exhibit a wide range of εNd ratios, but the basalts have εNd ratios that range from +9 to +2. The predominance of hornblende‐biotite‐phyric felsic rocks in the Playa Azul sequence suggest that it was built on a thick basement. The low εNd ratios of some mafic rocks imply that the sediments played a key role in the genesis of some basalts. A basement formed of continental crust is highly unlikely because the felsic rocks do not show continental contamination. Thus, the Playa Azul sequence was probably built on an oceanic crust thickened by sediments such as the Arteaga complex. Compared to the neighboring arc sequences along the Pacific coast, the Playa Azul sequence differs by its subaerial environment, the predominance of hornblende‐biotite felsic rocks, and a wide diversity of the rock facies. However, like all the other igneous rocks of the Guerrero terrane, the Playa Azul lavas derived from a mantle source that was little affected by crustal components. A geodynamic model of the PPGT is proposed based on these differences and similarities.
SOLUTIONS FOR A HYPERBOLIC MODEL OF MULTI-PHASE FLOW

We discuss a model for the ow of an inviscid uid admitting liquid and vapor phases, as well as a mixture of them. The ow is modeled in one spatial dimension; the state variables are the specic volume, the velocity and the mass density fraction of vapor in the uid. The equation governing the time evolution of contains a source term, which enables metastable states and drives the uid towards stable pure phases. We rst discuss, for the homogeneous system, the BV stability of Riemann solutions generated by large initial data and check the validity of several sucient conditions that are known in the literature. Then, we review some recent results about the existence of solutions, which are globally dened in time, for close either to 0 or to 1 (corresponding to almost pure phases). These solutions possibly contain large shocks. Finally, in the relaxation limit, solutions are proved to satisfy a reduced system and the related entropy condition. R
CHEMICAL COMPOSITION OF SANDSTONES

The author has collected 168 chemical analyses from the literature. All analyses with less than 5 per cent Al 2 O 3 (“quartzite” clan) were removed. The remaining analyses were divided on a tectonic basis into three clans; taphrogeosynclinal, eugeosynclinal, and others (mainly exogeosynclinal). Histograms for the seven major oxides and variation diagrams for K 2 O/Na 2 O and alkalies/Al 2 O 3 indicate that the tectonic associations group together clans of chemical analyses which differ significantly from each other. The eugeosynclinal graywackes especially differ from other sandstones by their low K 2 O/Na 2 O ratio, which is correlated with the presence of basic volcanic detritus. Arithmetic and geometric means for the seven major oxides for the four clans are as follows (given to two significant figures):
U-Pb detrital zircon geochronological constraints on the Early Silurian collision of Ganderia and Laurentia along the Dog Bay Line: The terminal Iapetan suture in the Newfoundland Appalachians

The Dog Bay Line is a major Silurian terrane boundary in the Exploits Subzone of the Newfoundland Appalachians. Late Ordovician-Early Silurian rocks northwest of the Dog Bay Line, the Badger and Botwood groups, contain detritus sourced exclusively from Laurentia. These rocks were deposited upon peri-Gondwanan volcanic arc terranes that were accreted to Laurentia in the Middle Ordovician. The Davidsville and Indian Islands groups southeast of the Dog Bay Line have stratigraphic links to peri-Gondwanan terranes and were deposited during the Late Ordovician-Early Silurian upon the peri-Gondwanan margin of Iapetus and were then accreted to Laurentia in the Early Silurian. A change from Paleozoic-dominated (Badger Group) to Meso- and Neoproterozoic-dominated (Botwood Group) detritus in sequences northwest of the Dog Bay Line is attributed to the Middle Ordovician collision and exhumation of peri-Laurentian arc terranes of the Notre Dame Subzone with Laurentia. Unroofing and erosion of these accreted arc terranes re-exposed Laurentian basement and deposited detritus from the latter into the Botwood Group. Salinic orogenesis resulting from the collision of Ganderia with Laurentia resulted in obduction and erosion of the accreted Victoria and Exploits arcs and deposition of the detritus into a forearc basin on Laurentia. The absence of zircons in the 510 to 550 Ma and 1520 to 1600 Ma age range northwest of the Dog Bay Line and no 1600 to 1700 Ma zircons southeast of the Dog Bay Line suggests the presence of a Silurian arm of the Iapetus Ocean (Tetagouche-Exploits basin) that separated Laurentia from peri-Gondwanan microcontinents of Ganderia and Avalonia. The change in Late Ordovician deep marine turbidites to Early Silurian stable-shelf rocks and non-marine, subaerial sediments east of the Dog Bay Line parallels that on the Laurentian margin and indicates the destruction and subsequent closure of Iapetus. The upper sequences of the Botwood Group (Rogerson Lake Formation) contain 700 to 800 Ma zircons that are atypical of Laurentia, but are common in peri-Gondwanan terranes, and suggest that the youngest rocks of the Botwood Group may post-date closure of the Dog Bay Line and transgress the suture as an overlap sequence. The presence of Silurian orogenesis on both the Laurentian and peri-Gondwanan margins of Iapetus is consistent with the closure of the Tetagouche-Exploits basin and Iapetus Ocean by the Late Silurian. Laurentia and the Ganderian microcontinent were involved in a continent-continent collision suggesting that rocks along the Dog Bay Line represent the last known occurrence of Iapetus in the Newfoundland Appalachians.
Relationship between Shortwave Cloud Radiative Forcing and Local Meteorological Variables Compared in Observations and Several Global Climate Models

Abstract The relations between local monthly mean shortwave cloud radiative forcing and aspects of the resolved-scale meteorological fields are investigated in hindcast simulations performed with 12 of the global coupled models included in the model intercomparison conducted as part of the preparation for Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). In particular, the connection of the cloud forcing over tropical and subtropical ocean areas with resolved midtropospheric vertical velocity and with lower-level relative humidity are investigated and compared among the models. The model results are also compared with observational determinations of the same relationships using satellite data for the cloud forcing and global reanalysis products for the vertical velocity and humidity fields. In the analysis the geographical variability in the long-term mean among all grid points and the interannual variability of the monthly mean at each grid point are considered separately.
Lateritic paleoweathering profiles in French Massif Central: Paleomagnetic datings

[1] Geological records of the history of ancient land surfaces are scarce and often fragmented by unconformities. Determining the age of these surfaces has long been the limiting factor in correlating continental paleosurfaces with marine basin deposits. Age determination of the weathering product of continental paleosurfaces as well as weathered material within the crystalline basement, is of prime importance for geodynamic reconstruction in general and more so for assessing differential dynamics between basin and basement areas, erosion rates, etc. In this paper, we examine layers of ferruginous kaolinitic paleoweathering products overlying the basement rocks of the French Massif Central. These layers, which are mainly formed in situ and are azoic (devoid of fossils), have been classically related to the "siderolithic" (Eocene-Oligocene) period because of their geographic ties with Tertiary deposits. The paleomagnetic ages of these paleoweathered surfaces have been obtained by comparing their acquired remanent magnetization, converted into paleomagnetic poles, with the APWP (apparent polar wander path) of the Eurasian plate. Recovered ages indicate late Jurassic to early Cretaceous ages (140-160 Ma with a confidence limit of 10 Ma) which are much older than the previously assumed Tertiary age. The ages obtained in this study considerably alter the present knowledge of the geodynamic evolution of the French Massif Central. Our results suggest a lack of sedimentary cover at the Jurassic-Cretaceous boundary. This implies that at the time of deposition of the siderolithic formations, the basement was cropping out and devoid of any Mesozoic cover. Furthermore, the profiles are not compacted, indicating that they have never been buried beneath a significant sedimentary cover. The obtained ages point to a great stability of French Massif Central throughout the Mesozoic, with very low ablation-erosion, while neighbouring basins (Aquitaine and Paris) were subsiding about 2000 m.
Hydrological flowpaths and nitrate removal rates within a riparian floodplain along a fourth‐order stream in Brittany (France)

Three main reservoirs were identified that contribute to the shallow subsurface flow regime of a valley drained by a fourth‐order stream in Brittany (western France). (i) An upland flow that supplied a wetland area, mainly during the high‐water period. It has high N‐NO3− and average Cl− concentrations. (ii) A deep confined aquifer characterized by low nitrate and low chloride concentrations that supplied the floodplain via flow upwelling. (iii) An unconfined aquifer under the riparian zone with high Cl− and low N‐NO3− concentrations where biological processes removed groundwater nitrate. This aquifer collected the upland flow and supplied a relict channel that controlled drainage from the whole riparian zone. Patterns of N‐NO3− and Cl− concentrations along riparian transects, together with calculated high nitrate removal, indicate that removal occurred mainly at the hillslope–riparian zone interface (i.e. first few metres of wetland), whereas dilution occurred in lower parts of the transects, especially during low‐water periods and at the beginning of recharge periods. Stream flow was modelled as a mixture of water from the three reservoirs. An estimation of these contributions revealed that the deep aquifer contribution to stream flow averaged 37% throughout the study period, while the contribution of the unconfined reservoir below the riparian zone and hillslope flow was more variable (from ca 6 to 85%) relative to rainfall events and the level of the riparian water table. At the entire riparian zone scale, NO3− removal (probably from denitrification) appeared most effective in winter, despite higher estimated upland NO3− fluxes entering the riparian zone during this period. Copyright © 2003 John Wiley & Sons, Ltd.
Rainfall-Runoff Modeling Using Artificial Neural Networks

An Artificial Neural Network (ANN) methodology was employed to forecast daily runoff as a function of daily precipitation, temperature, and snowmelt for the Little Patuxent River watershed in Maryland. The sensitivity of the prediction accuracy to the content and length of training data was investigated. The ANN rainfall-runoff model compared favorably with results obtained using existing techniques including statistical regression and a simple conceptual model. The ANN model provides a more systematic approach, reduces the length of calibration data, and shortens the time spent in calibration of the models. At the same time, it represents an improvement upon the prediction accuracy and flexibility of current methods.
Aerosol measurements at four background sites

Atmospheric monitoring stations are operated at Barrow, Alaska; Mauna Loa, Hawaii; American Samoa; and South Pole by the Geophysical Monitoring for Climatic Change program to measure the characteristics of gaseous and aerosol species under background conditions. A nearly continuous record of light-scattering coefficient and condensation nuclei concentration measurements is available for Barrow since 1971, Mauna Loa since 1974, Samoa since 1977, and South Pole since 1974. The Barrow light-scattering data exhibit a strong annual cycle with a maximum in winter and spring (the Arctic haze) and a minimum in summer. The Barrow condensation nuclei data exhibit a strong semiannual cycle with a maximum coinciding with that of light scattering and an additional maximum about August. The Mauna Loa light-scattering data show a strong annual cycle with a maximum in April or May caused by long-range transport of Asian desert dust. The Mauna Loa condensation nuclei data show no significant annual cycle. The Samoa light-scattering and condensation nuclei data are representative of a clean marine atmosphere and exhibit no significant annual or diurnal cycle. The South Pole light-scattering data show a complicated annual cycle with a maximum in the austral summer and a minimum about April. The austral winter is dominated by events most likely caused by the transport of sea salt in the troposphere from the coastal regions to the interior of the Antarctic continent. The South Pole condensation nuclei data show a repeatable annual cycle with a maximum in the austral summer and a minimum in the austral winter. Linear least squares trend analyses show no significant trend compared to the standard error about the regression line at any station.
Superimposed folding and oblique structures in the palaeomargin-derived units of the Central Betics (SW Spain)

The Subbetic units consist of a deformed wedge of sedimentary rocks deriving from the South Iberian palaeomargin, in the westernmost segment of the Alpine–Mediterranean orogenic belt. In the central Betics, shortening produced folding, thrusting and nappe-stacking. The structural trend is NE–SW to ENE–WSW, and the internal structure of the thrust sheets, which shows no preferred vergence, is strongly controlled by the rheology of the décollement level, a viscous layer of Triassic evaporites, and of the overlying carbonate rock sequence. The relationships of piggyback basin Miocene sediments with the main structures show that the latter developed during the Aquitanian–Burdigalian transition. Superimposed folding is described for the first time in the study area. The origin of the interference cannot be determined at present, but may be related to initially oblique structures refolded during progressive deformation. A revision of previously published palaeomagnetic data in the light of the data presented in this paper, in conjunction with a model of the structural evolution of the Subbetic units of the western Betics, permits us to establish milestones of the tectonic evolution of the external zones in the northern branch of the Gibraltar Arc.
Midlatitude Frontal Clouds: GCM-Scale Modeling Implications

The importance of subgrid-scale processes for the simulation of midlatitude frontal clouds by global models is investigated. The case chosen is a frontal cloud associated with a cool change crossing the southern Australian coastline between 17 and 19 November 1984. The Commonwealth Scientific and Industrial Research Organisation limited-area model, Division of Atmospheric Research Limited-Area Model, was run at horizontal resolutions of 30 and 300 km, and the results of the 30-km simulation were then averaged to 300-km resolution. Comparisons and evaluations of the simulations showed that the 300-km simulation failed to develop the frontal clouds. Comparison with the 30-km simulation averaged to 300 km showed the importance of the subgrid-scale vertical motions for this cloud development. In particular, it is found that the covariance of the subgrid-scale terms, although of smaller magnitude when compared with the larger-scale terms, needs to be parameterized to capture correctly the frontal cloud development. It is suggested that parameterization of the subgrid-scale dynamical forcing is important for the correct cloud development in general circulation models.
Variations in the surface texture of suspended quartz grains in the Loire River: an SEM study

Statistical size distribution and scanning electron microscopic studies of suspended sand grains in the Loire River at Montjean, France were carried out over a period of a year (hydrological cycle) to discern seasonal variations. The sand fraction in suspension is better sorted during winter (average mean = 0.69 mm, median = 0.65–0.95 mm, sorting value, σ= 1.1–1.35) and is dominated by quartzo-feldspathic minerals. During summer, on the contrary, this fraction is rich in mica minerals and is poorly sorted (average mean = 1.21 mm, median = 0.33–0.95 mm, sorting value, σ= 1.4–2.0). The grain size of the coarser fraction shows a tendency to increase with river discharge up to an optimum discharge of about 1000 m3 s-1 and thereafter decreases. Scanning electron photomicroscopy of quartz grains from the suspended sand population indicates that both mechanical and chemical features occur. The former (conchoidal fractures, mechanical fractures and breakage) dominate in the samples collected near the water surface during winter floods and the latter (solution pits, vermicular features, silica flowers, neogene silica and diatoms) in the samples from the bottom during low summer flows. During summer, chemical action takes place on sediments prior to or upon their deposition. Sediments that are resuspended during winter floods undergo mainly physical processes (attrition/abrasion). Mixed surface features are, therefore, observed during average and low river discharge. Inheritance of these surface features from the source area is, however, not completely excluded. Thus, the history of quartz grains in suspension can be reconstructed from SEM exoscopic studies: therefore, it can be proposed that the fluvial quartz grain surface textures result from a combination of alternating chemical and physical processes.
Investigating peat hydrological properties using field and laboratory methods: application to the Lanoraie peatland complex (southern Quebec, Canada)

Flow dynamics within a peatland are governed by hydraulic parameters such as hydraulic conductivity, dispersivity and specific yield, as well as by anisotropy and heterogeneity. The aim of this study is to investigate hydraulic parameters variability in peat through the use of different field and laboratory methods. An experimental site located in the Lanoraie peatland complex (southern Quebec, Canada) was used to test the different approaches. Slug and bail tests were performed in piezometer standpipes to investigate catotelm hydraulic conductivity. Combined Darcy tests and tracer experiments were conducted on cubic samples using the modified cube method (MCM) to assess catotelm hydraulic conductivity, anisotropy and dispersivity. A new laboratory method is proposed for assessing acrotelm hydraulic conductivity and gravity drainage using a laboratory experimental tank. Most of slug tests' recovery curves were characteristic of compressible media, and important variability was observed depending on the initial head difference. The Darcy experiments on cubic samples provided reproducible results, and anisotropy (Kh > Kv) was observed for most of samples. All tracer experiments displayed asymmetrical breakthrough curves, suggesting the presence of retardation and/or dual porosity. Hydraulic conductivity estimates performed using the experimental tank showed K variations over a factor of 44 within the upper 40 cm of the acrotelm. The results demonstrate that the intrinsic variability associated with the different field and laboratory methods is small compared with the spatial variability of hydraulic parameters. It is suggested that a comprehensive assessment of peat hydrological properties can be obtained through the combined use of complementary field and laboratory investigations. Copyright © 2007 John Wiley & Sons, Ltd.