Provenance implications of Th–U–Pb electron microprobe ages from detrital monazite in the Carboniferous Upper Silesia Coal Basin, Poland

This paper reports the results of CHIME (chemical Th–U–Pb isochron method) dating of detrital monazites from Carboniferous sandstones in the Upper Silesia Coal Basin (USCB). A total of 4739 spots on 863 monazite grains were analyzed from samples of sandstone derived from six stratigraphic units in the sedimentary sequence. Age distributions were identified in detrital monazites from the USCB sequence and correlated with specific dated domains in potential source areas. Most monazites in all samples yielded ca. 300–320 Ma (Variscan) ages; however, eo-Variscan, Caledonian and Cadomian ages were also obtained. The predominant ages are comparable to reported ages of certain tectonostratigraphic domains in the polyorogenic Bohemian Massif (BM), which suggests that various crystalline lithologies in the BM were the dominant sources of USCB sediments.     

The beach placer iron deposit of Portman Bay,Murcia, SE Spain: the result of 33 years of tailings disposal (1957–1990) to the Mediterranean seaside

Between 1957 and 1990, the Peñarroya Mining and Metallurgical Company (SMMPE) disposed about 60 million tonnes of tailings materials directly to the Mediterranean Sea. A substantial part of it (12.5 Mt) was dragged back by the sea currents progressively infilling the Portman Bay (Murcia, SE Spain), thus making the shoreline advance between 500 and 600 m seaward. The Roberto froth flotation plant processed mineral from manto-type deposits belonging to the Sierra de Cartagena-La Unión lead-zinc district. One of the mineral assemblages present in these deposits comprises greenalite, magnetite, sulfides, carbonates, and silica. Despite that magnetite recovery was undertaken by SMMPE between 1959 and 1967, we estimate that magnetite contained in the tailings hosts a substantial resource that could be as large as 2.3 Mt of iron ore. The ore contains magnetite ± hematite ± siderite. Tidal waves and sea currents led to gravimetric classification of the tailings material, with concentration of the dense iron oxides in the sandy fractions, eventually forming a coastal placer iron deposit. A major problem for magnetic separation is the intimate intergrowth between magnetite, hematite, and siderite. Besides, the sands contain large concentrations of Pb (0.27 %), Zn (0.72 %), and As (559 ppm).     

Magnetic susceptibility of volcanic rocks in geothermal areas: application potential in geothermal exploration studies for identification of rocks and zones of hydrothermal alteration

Magnetic susceptibility and petrographic studies of drilled rock cuttings from two geothermal wells (Az-26 and Az-49) of the important electricity-generating geothermal system, Los Azufres, Mexico, were carried out to determine the relation between the magnetic susceptibility of rocks, the concentration of magnetic minerals and hydrothermal alteration. For this purpose, low-frequency magnetic susceptibility (χ _lf) was measured and compared its distribution trends with those of magnetic and Fe–Mg silicate minerals, and with the extent of hydrothermal alteration in rocks of the two geothermal wells. The study indicates a decrease in χ _lf values with depth in the two geothermal wells corresponding with: (1) an increase in the reservoir temperature and hydrothermal alteration; and (2) a decrease in the concentrations of Fe–Mg silicates and opaque minerals. The data suggest that ferromagnesian minerals and opaque minerals like ilmenite are the main contributors to the χ _lf of rocks. The decrease in χ _lf, ilmenite, and Fe–Mg mineral contents with an increase in the hydrothermal alteration degree, pyrite and haematite contents suggests the hydrothermal alteration of ilmenite and Fe–Mg minerals (characteristic of high χ _lf values) to pyrite, haematite and other opaque minerals (with low χ _lf values). The interaction of hydrothermal fluids with rocks results in the hydrothermal alteration of primary minerals. In a geothermal area, an anomaly of low magnetic susceptibility values of rocks in a homogenous litho unit characterized by high magnetic susceptibility may suggest hydrothermal alteration. Magnetic susceptibility can be a useful parameter, during the initial stages of geothermal exploration, in identifying hydrothermally altered rocks and zones of hydrothermal alteration both at the surface and from drilled wells in geothermal systems.     

Analysis of the effect of trees on block propagation using a DEM model: implications for rockfall modelling

The objective of this research was to use numerical models based on mechanical approaches to improve the integration of the protective role of forests against rockfall into block propagation models. A model based on the discrete element method (DEM) was developed to take into account the complex mechanical processes involved during the impact of a block on a tree. This modelling approach requires the definition of many input parameters and cannot be directly integrated into block propagation models. A global sensitivity analysis identified the leading parameters of the block kinematics after impact (i.e. block energy reduction, trajectory changes, and rotational velocity): the impact velocity, the tree diameter, and the impact point horizontal location (i.e. eccentricity). Comparisons with the previous experimental and numerical studies of block impacts on trees demonstrated the applicability of the DEM model and showed some of the limitations of earlier approaches. Our sensitivity analysis highlights the significant influence of the impact velocity on the reduction of the block’s kinetic energy. Previous approaches usually also focus on parameters such as impact height, impact vertical incidence, and tree species, whose importance is only minor according to the present results. This suggests that the integration of forest effects into block propagation models could be both improved and simplified. The DEM model can also be used as an alternative to classical approaches for the integration of forest effects by directly coupling it with block propagation models. This direct coupling only requires the additional definition of the location and the diameter of each tree. Indeed, the input parameters related to the mechanical properties of the stem and the block/stem interaction in the DEM model can be set to average values because they are not leading parameters. The other input parameters are already defined or calculated in the block propagation model.     

A long-necked pterosaur (Pterodactyloidea,Azhdarchidae) from the Upper Cretaceous of Valencia,Spain

Fragmentary remains, including cervical vertebrae and limb bones, of a large pterosaur from the Upper Cretaceous of Tous, province of Valencia (Spain), are described. The material was recovered from lacustrine beds in the upper part of the Calizas y Margas de Sierra Perenchiza Formation, which is probably Maastrichtian in age. Six fragments of vertebrae allow a reconstruction of the anatomy of the mid-series cervicals of the animal. The general morphology of the cervical vertebrae is closely similar to that of the long-necked Azhdarchidae. Compared to other azhdarchids, the Valencia pterosaur shows minor differences from the genera Azhdarcho and Quetzalcoatlus, and is here provisionally referred to as Azhdarchidae indet. A wingspan of about 5.5 m is calculated by comparison with other known azhdarchids. This is the second azhdarchid pterosaur described from the Iberian peninsula. It confirms the wide distribution of this group of large pterosaurs at the end of the Cretaceous.     

MERLIN: a flood hazard forecasting system for coastal river reaches

Natural Hazards - This study presents MERLIN, an innovative flood hazard forecasting system for predicting discharges and water levels at flood prone areas of coastal catchments. Discharge...     

Waste dump erosional landform stability – a critical issue for mountain mining

Mining is the largest producer of solid wastes which, when released to land or into waterways, can cause harmful environmental impacts. This is mostly due to fluvial erosion, which is highly increased in mountain areas, due to abrupt slopes. We have analysed this situation at a mountain watershed (192 ha), where steep mined sites and their waste dumps are the main source of sediment in a Natural Park. This problem was tackled by building gabion check dams downstream from the mined sites. We used the DEM of Differences (DoD) method to quantify erosion and sediment yield from three waste dumps (5 ha). Their topography and substrate properties were analysed to understand the erosion problem. The sediment trapped by the check dams was quantified by electrical resistivity tomography (ERT). The rainfall characteristics triggering an episode that filled the check dams with sediment in the winter 2009–2010, were studied to confirm whether it was a case of extreme precipitation conditions. The waste dumps sediment yield (353 ± 95 Mg ha^?1 yr^?1) suggests severe landform instability. Analysis of topographic and substrate properties confirmed long, steep slopes combined with highly erodible materials. The check dams proved to be inefficient in controlling sediment loads, as they had only functioned for four years of 31 of existence, having trapped 13 000 ± 660 m³ of sediment, whereas we estimated that the waste dumps have yielded approximately three times more sediment for the same period. Rainfall analyses showed that neither intense nor extreme conditions (return period of 25 to 35 years) triggered the mobilization of 37 ± 2 Mg ha^?1 in a month. This study highlights the fact that mining operations in similar mountainous settings, with equivalent waste dump construction and reclamation practices, are currently unfeasible. We conclude that landform stability cannot be achieved at this site without landform changes. Copyright © 2017 John Wiley & Sons, Ltd.     

San Quirce (Palencia,Spain): new chronologies for the Lower to Middle Palaeolithic transition of south-west Europe

San Quirce is an open-air archaeological site situated on a fluvial terrace in the Duero basin (Palencia, northern Iberia). This paper presents new and consistent chronologies obtained for the sedimentary sequence using post-infrared infrared stimulated luminescence (pIR-IR) dating of K-feldspars and single-grain thermally transferred optically stimulated luminescence (TT-OSL) dating of quartz. The new dating results indicate that the sequence is older than ~200 000 years and place San Quirce Level III within marine isotope stages (MIS) 8 and 7, between 274 ± 13 ka and 238 ± 13 ka. The main lithic assemblage at San Quirce comes from Level III. The predominant tool types found in this level are hammerstones, manuports and flakes, with a small proportion of cores and a significant presence of denticulates. Adaptation to local environmental conditions resulted in distinctive cultural habits, which were embedded in the cultural tradition of hominins occupying the site during the final third of the Middle Pleistocene. San Quirce preserves a simple cultural tradition that was employed by local hominins to engage in a diverse array of activities, and highlights the cultural diversity that appears to have been a characteristic feature of the Lower to Middle Palaeolithic transition 300–200 ka.