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Heteroconchia Cardiomorphi bivalves from Silurian and Devonian beds of the Central Andean Basin of Western Gondwana are herein presented. This paper is not only a systematic updated revision of three Heteroconchia Cardiomorphi genera, but it also includes the description of new findings and first reports of some taxa in the basin. They were collected in nine scattered outcrops in the Interandean and Subandean regions of Bolivia. A total of 22 specimens, well- to regularly-preserved was studied. The genus Pleurodapis, is reported for the first time from Ludlow-pridoli successions of Alarache, southern Subandean as Pleurodapis sp. A. The cosmopolitan genus Paracyclas is reported in the Central Andean Basin for the first time, from the Middle Devonian of Subandean as Paracyclas? sp. The species Pleurodapis multicincta and Cardiomorpha oblonga, are described from the central Subandean and the Interandean regions for the first time in the basin. This research is also a contribution to understand the distribution and the richness of Silurian and Devonian bivalves in Central Andean Basin and their relations with the surrounding basins of Gondwana. [ABSTRACT FROM AUTHOR]

Blasting and drilling methods are mainly used in basalt rock quarries as blasting-digging methods. The purpose of this study is to argue the validity of using a jackhammer as a rock removal method in Gabricar quarry, based on knowing the geomechanical parameters of rocks as well as the technicaleconomic indicators for exploitation. Gravimetric, saturation, hydrostatic weighing, pycnometric and axial loads methods were used to obtain physical-mechanical properties of the rocks and geological survey, volumetric joint count, and strength coefficient were used to establish crack elements, block size, and rock mass quality, respectively. 4.75% humidity; 2.39 % porosity; 5.73 g/cm3 volumetric mass; density of 26.44 g/cm3 and axial compressive strength of 173.53 Mpa as average values of physical-mechanical properties were obtained. Four families of cracks with spacing of 0.4 m, 0.6 m; 0.3 m and 0.2 m and 18 mm openings; 13 mm; 3 mm and 9 mm, respectively were established. Blocks are small and the rocky massif is of good quality. The technical-economic analysis showed the efficiency of the jackhammer as a blasting-based digging method in Gabricar quarry. [ABSTRACT FROM AUTHOR]

Basalt is an extrusive igneous rock derived from Lava and spread over different localities in Jordan. It can be used in industrial applications, and as construction materials. Before using basalt, it is essential to determine its dry density, porosity, uniaxial compressive strength, and Brazilian tensile strength. The testing procedure and sample preparation used to determine the engineering properties are time-consuming and need expertise. Hence, the ultrasonic pulse velocity (UPV) test, a quick and non-destructive evaluation method, was used to determine the engineering properties. Empirical relationships for determination of dry density, porosity, uniaxial compressive strength, Brazilian tensile strength, and tangent modulus of elasticity were deduced. Good correlation coefficients (R2 = 0.832-0.929) were obtained between UPV and dry density, porosity, uniaxial compressive strength, Brazilian tensile strength and modulus of elasticity. These correlations were limited to intact basalt with UPV ≥ 4000 m/s. [ABSTRACT FROM AUTHOR]

The Archean spherule layers (SLs) of the Barberton Greenstone Belt (BGB, South Africa) and Pilbara Craton (Australia) are the only known evidence of early, large impact events on Earth. Spherules in these layers have been, alternatively, interpreted as molten impact ejecta, condensation products from an impact vapor cloud, or ejecta from impact craters melted during atmospheric re-entry. Recently, a new exploration drill core (CT3) from the northern BGB revealed 17 SL intersections. Spherules are densely packed, sand-sized, and variably rounded or deformed. The CT3 SLs are intercalated with black and brown shale, and laminated chert. The determination of the original number of impact events that are represented by these multiple SLs is central to the present paper. A comprehensive study of the sedimentary and petrographic characteristics of these SLs involved the determination of the size, shape and types of individual spherules, as well as their mineralogy. CT3 SLs consist of K-feldspar, phyllosilicate, siderite, dolomite, quartz, Ti- and Fe-oxides, as well as apatite. In addition, small amounts of carbonaceous, presumably organic material are observed in several spherules at 145 and 149 m depth. Only Ni-rich Cr-spinel (up to 11 wt% NiO) crystals, rare zircon grains, and alloys of platinum group elements ± Fe or Ni represent primary phases in these thoroughly altered strata. The 0.3 to 2.6-mm-sized spherules can be classified into four types: 1. Spherules crystallized completely with secondary K-feldspar (subtype 1A) or phyllosilicate (subtype 1B); spherules completely filled with Ti- and Fe-oxides (subtype 1C); spherules containing disordered or radially oriented, fibrous and lath-shaped K-feldspar textures (subtype 1D); or subtype 1B spherules that contain significant Cr-spinel (subtype 1E); 2. zoned compositions with these types 1A and/or 1B minerals (subtype 2A); spherules that contain central or marginal vesicles (subtype 2B); subtype 1B spherules whose rims consist of Ti and Fe-oxides (subtype 2C); 3. deformed spherules (subtype 3A) - of all types; (B) subtype 1B spherules are assimilated into groundmass; (C) open spherules or spherules with collapsed rims; and 4. interconnected spherules of type 1A. A few spherules show botryoidal devitrification textures interpreted to result from rapid cooling/devitrification of former melt droplets. SL 15 at a depth of 145 m is unique in being the only grain-size sorted SL; this bed may have been deposited by fallout through a water column. The SL and their host rocks can be easily distinguished by their significant differences in micro-XRF elemental distribution maps. Depending on which aspects of the SLs are primarily considered (such as similar geochemistry, similar layering, SL occurrences abundant at three different depth intervals), the 17 CT3 SLs can be assigned to three or up to 13 individual impact events. Uncertainty about the actual number of impact events represented remains, however, due to the complex folding deformation observed throughout the drill core. [ABSTRACT FROM AUTHOR]

A 1251 m thick succession of Deccan lava flows has been recovered by scientific drilling in the Koyna region, western part of the Deccan Volcanic Province (DVP). Forty-six lava flows, starting with the first flow overlying the granitic basement in the region, have been identified through mesoscopic studies of cores obtained from a 1500 m deep borehole KBH7 in Panchgani village of Patan sub-division. Mesoscopic observations supported by petrographic studies bring out the characteristics of the basaltic pile. The salient findings are as follows. The thickness of Deccan trap in the Panchgani area is 1251.20 m, comprising a succession of 40 simple lava flows and 6 compound lava flows. The contact with the underlying granitic basement occurs over a short span of 90 cm. Infra-trappean sediments are absent. Overall, ∼74% of the basaltic pile is constituted of massive basalt and ∼24% vesicular/amygdaloidal basalt. Red bole horizons are observed in 7 flows. Nine giant plagioclase basalt (GPB) flows are identified in the single vertical section. The long basalt core may serve as a model Deccan trap section for correlation with the flows exposed at the surface in the Koyna and surrounding region and support detailed investigations to constrain the duration of Deccan volcanism. [ABSTRACT FROM AUTHOR]

This paper gives an account of the petrophysical characteristics and the petrographical descriptions of Tertiary vesicular and amygdaloidal olivine basalt flows from Wadi Wizr in the central Eastern Desert of Egypt. The petrographical studies indicated that the studied vesicular basalts are rich in calcic-plagioclase, augite and olivine in addition to numerous amounts of fine opaque minerals and vesicles filled with carbonate and quartz amygdales. The degree of oxidation and alteration of magnetite and ilmenite are discussed in detail. Petrophysically, the studied samples can be grouped into two main groups; the first group includes amygdaloidal basalts and the second group consists of vesicular basalts. The vesicular group (the permeable one) is characterized by fair to very good porosity (∅), good permeability (k), very low true formation resistivity factor (F) and contain micro to ultra micropores. On the other hand, the amygdaloidal basalt group (impermeable group) is characterized by very low storage capacity properties, fair porosity, negligible permeability, medium to high true formation resistivity factor and ultra micropores. The mercury injection capillary pressure technique (MICP) indicates that the pore throats of the studied vesicular samples have a binomial distribution (rank IV), while that of the amygdaloidal samples have a trinomial distribution (rank V). It has been found in this study that the petrophysical behavior of basalts is dependent on the degree of oxidation and alteration; and in particular on the rate of cooling and oxidation of the opaque minerals which caused filling in the primarily produced vesicles by low temperature secondary minerals. [ABSTRACT FROM AUTHOR]

We used annual re-surveys of two populations of channel heads affected by a severe wildfire in 2012 to monitor changes in channel head location with time following disturbance. Relative to channel heads in surrounding unburned areas, the median contributing drainage area of burned channel heads decreased by two orders of magnitude immediately after the fire, but then returned to values comparable to unburned areas within four years. We distinguish three types of channel heads. Permanent channel heads, which constitute 4% of the total population, occur in well-developed swales in association with stable features such as bedrock outcrops: these channel heads appear to have been unaffected by the fire. Persistent channel heads, which are 40% of the total population, also occur within hillslope concavities, but the exact location of the channel head moves upslope and downslope through time in response to varying inputs of water and sediment. Transient channel heads form on straight and convex slopes immediately following disturbance, but disappear as regrowth of ground cover limits overland flow and sediment movement. The majority of the position changes for persistent and transient channel heads occurred abruptly when viewed as annual time steps. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper reports the laboratory measurement of compression and shear waves in Basalt rock. Compression or primary waves were produced using a standard ultrasonic pulse velocity tester. However, it is well accepted that the production of pure shear waves in rock is difficult because of which suitable assumptions are made in the testing. Since bender elements have traditionally been used to produce pure shear at very small strains in soft materials, their use has been extended in this study to Basalt rock. The fabrication and setup of bender element tests is first discussed. The transducers were accommodated in pre-drilled slots at the two flat ends of the samples, the effect of which was carefully investigated using experimental and numerical studies. For 10–12 mm long piezoceramic plates, the shear wave velocity was found to reduce by about 5% because of the slots. The shear wave velocity was estimated using the first arrival method after removing the near field and the crosstalk effects from the output signal. The shear wave velocity ranged between 1.15 and 3.31 km/s and was nearly equal to one-half of the primary wave velocity. The results also show that the ratio of the shear wave velocity and the compression wave velocity was independent of the density and porosity of the Basalt rock. Because most of the rock was unweathered and compact and, its cavities filled with secondary minerals such as zeolites, calcites and silicates, it is unlikely that the high overburden pressures would affect the observed wave velocities. [ABSTRACT FROM AUTHOR]

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The Lessini Mountains carbonate plateau (Venetian Prealps, Italy) is one of the most important karst areas in Italy. Along with alpine-type caves and well-developed karst landscapes, palaeokarst features are also common. In most cases, palaeokarst is represented by caves and fissures filled by limonitic-haematitic palaeosols (ochres) in which fossiliferous arenite layers are sometimes embedded. These features developed and fossilised during a late Eocene-middle Miocene phase of emersion. Between the Palaeocene and the Oligocene, over a time span partially overlapping the development of palaeokarst, basaltic volcanism took place in the Lessini Mountains. Along with ochre fills, cave passages that were intruded by basalt provide further evidence that a well developed karst network existed in the Lessini Mountains area in the middle-late Palaeogene. Moreover, basalt intrusions provide the only available data for the dating of palaeokarst in the central Lessini Mountains, where fossiliferous layers in ochre beds have not been found. we have started a new survey on palaeokarst in the Lessini plateau, with the aim of identifying ancient features on the basis of unusual fills (namely, ochre and basalt) and morphologies. New instances of basalt intrusions in three caves, Spigola di Canova, Covoli di Velo, and Covolo della Croce, have been recognised; evidence of pre-existing karst features filled by basalt in a previously studied cave (Grotta A Veja) has been identified, and an unusual basalt outcrop that might relate to palaeokarst has also been observed. This paper aims to document the new findings and to discuss previous ones. At the same time, we would like to point out some cautionary observations to prevent a "basalt = palaeokarst" misunderstanding. [ABSTRACT FROM AUTHOR]

At the southernmost part of Tierra del Fuego a few outcrops and erratic boulders of alkali basaltic rocks with ultramafic enclaves have been studied. Alkali basalt plugs or pipes hitherto identified are scarce, and host rocks are constituted by slates that belong to Mesozoic deposition. The petrography, texture and composition of the basalt and xenoliths were investigated by petrographic microscope and electron microprobe analysis. Xenocrysts of amphibole and alkali feldspar, phenocrysts of nepheline, olivine, spinel, phlogopite and Fe-Ti minerals (10 %) and a diversity of xenoliths, mainly lherzolitic, pyroxenite and wehrlitic nodules (15 %), but also from metamorphic rocks provenance, are contained in the basalt groundmass (75 %). This finer-grained material is made up of laths or needles of plagioclase, pyroxene, opaque minerals, apatite and glass, with intersertal, hyalopilitic and pilotaxitic. Locally, rock has an even granoblastic texture. Former amygdules are filled by analcite, zeolites, sodalite and calcite. The normative classification, based on nepheline content, conclude that this rock is an alkali basalt. The chemical classification, considering immobile elements as Zr/TiO versus Nb/Y indicate an alkali basalt too and plots over the TAS diagram fall in the foidite (Na-rich or nephelinite) and basanite fields. The REE patterns are fractionated (La/Yb primitive mantle normalized is approximately 30). The K-Ar isotopic technique on individual macrocrysts gave ages of 146 ± 5 Ma (amphibole) and 127 ± 4 Ma (alkali feldspar); and K-Ar whole rock datum reported 8.3 ± 0.3 Ma. Nevertheless, fertile samples show geochemical features typical of deep derived material thus, based on the position in the actual tectonic setting, indicate that the basalt is older than its isotopic age. [ABSTRACT FROM AUTHOR]

A detailed facies and depositional analysis of the Miocene-Pliocene siliciclastic-dominated sequence (ranges from 10 to 35 m thick) of siliciclastic succession below the basalt rocks have been carried out to interpret the depositional pattern, facies and sedimentary depositional environments. This siliciclastic-dominated succession, underlying Harrat Rahat, belonging to the Miocene-Pliocene is exposed at Al-Rehaili area, North Jeddah. Three main depositional units from bottom to top: Unit I, II and III are identified and correlated. These units comprise of gravels/conglomerates, sandstones, siltstones and mudstones. Sandstones below the basaltic rocks of Harrat Rahat generally contain about 30-70 % quartz, 10-50 % rock fragments, 10-20 % feldspar, 15-40 % detrital clay, 2-8 % iron oxides, and minor amounts of other components. Siltstones are distinguished from sandstones by their finer grain sizes of the quartz silt (45-70 % quart and higher proportion of clay (30-55% detrital clay minerals). Mudstones contain about 25-50 % quartz, 40-60 and detrital clay minerals, 2-8 iron oxides, and minor amounts of other components. Based on petrography, components, textures, fabrics, contacts nature, sedimentary structures, stratal geometry, and stratigraphic relationships, ten facies, covering the three depositional units are distinguished representing fluvial to lacustrine depositional conditions. [ABSTRACT FROM AUTHOR]

Researchers have long debated whether a transient knickzone, accompanied by a wave of high incision, has migrated through the Grand Canyon in the geologically recent past or if, instead, canyon incision rate has been constant during the past several million years. Resolution of this debate has been hindered until recently by the absence of incision rate data for central Grand Canyon and the short duration (since 385 ka) of the eastern Grand Canyon rate history derived directly from river terraces. Here we constrain incision rate histories since ca. 500 ka at eastern Grand Canyon's Hermit Creek (river mile 96) and at river mile 159 in central Grand Canyon. At Hermit Creek, U/Th ages of travertine- cemented river terrace fill and other surficial deposits reveal an average incision rate of 519 +55 -58 m/m.y. since 506 ± 33 ka and a maximum rate of 210 +42 -49 m/m.y. since 394 ± 32 ka. These data require an incision rate of 1-4 km/m.y. between ca. 500 and 400 ka followed by at least a fivefold decrease after 400 ka. We attribute this decrease to the migration of a transient knickzone past Hermit Creek between 500 and 400 ka. These same deposits also record a 600-800 m/m.y. retreat rate for the Redwall-Muav escarpment since 500 ka. At river mile 159, we analyze the relative age relationship between intrusion of the basaltic "159-Mile Dikes" and cutting of the Muav Gorge. We conclude that the dikes intruded prior to cutting of the gorge, which requires an average river incision rate of 763 m/m.y. since ca. 520 ka. We interpret this rapid rate (compared to ~100-160 m/m.y. over shorter time scales) as independent evidence of knickzone passage through central and eastern Grand Canyon at ca. 500-400 ka. [ABSTRACT FROM AUTHOR]

The Mars Science Laboratory rover, “Curiosity” landed near the base of a 5 km-high mound of layered material in Gale crater. Mounted on the rover mast, the ChemCam instrument is designed to remotely determine the composition of soils and rocks located a few meters from the rover, using a Laser-Induced Breakdown Spectrometer (LIBS) coupled to a Remote Micro-Imager (RMI). We provide an overview of the diverse imaging investigations that were carried out by ChemCam’s RMI during the first year of operation on Mars. 1182 individual panchromatic RMI images were acquired from Sol 10 to Sol 360 to document the ChemCam LIBS measurements and to characterize soils, rocks and rover hardware. We show several types of derived imaging products, including mosaics of images taken before and after laser shots, difference images to enhance the most subtle laser pits, merges with color Mastcam-100 images, micro-topography using the Z-stack technique, and time lapse movies. The very high spatial resolution of RMI is able to resolve rock textures at sub-mm scales, which provides clues regarding the origin (igneous versus sedimentary) of rocks, and to reveal information about their diagenetic and weathering evolution. In addition to its scientific value over the range accessible by LIBS (1–7 m), we also show that RMI can also serve as a powerful long distance reconnaissance tool to characterize the landscape at distances up to several kilometers from the rover. [ABSTRACT FROM AUTHOR]

Surface compositional features on rocks such as coatings and weathering rinds provide important information about past aqueous environments and water–rock interactions. The search for these features represents an important aspect of the Curiosity rover mission. With its unique ability to do fine-scale chemical depth profiling, the ChemCam laser-induced breakdown spectroscopy instrument (LIBS) onboard Curiosity can be used to both identify and analyze rock surface alteration features. In this study we analyze a terrestrial manganese-rich rock varnish coating on a basalt rock in the laboratory with the ChemCam engineering model to determine the LIBS signature of a natural rock coating. Results show that there is a systematic decrease in peak heights for elements such as Mn that are abundant in the coating but not the rock. There is significant spatial variation in the relative abundance of coating elements detected by LIBS depending on where on the rock surface sampled; this is due to the variability in thickness and spatial discontinuities in the coating. Similar trends have been identified in some martian rock targets in ChemCam data, suggesting that these rocks may have coatings or weathering rinds on their surfaces. [ABSTRACT FROM AUTHOR]

The ChemCam instrument onboard the Curiosity rover provides for the first time an opportunity to study martian soils at a sub-millimeter resolution. In this work, we analyzed 24 soil targets probed by ChemCam during the first 250 sols on Mars. Using the depth profile capability of the ChemCam LIBS (Laser-Induced Breakdown Spectroscopy) technique, we found that 45% of the soils contained coarse grains (>500 μm). Three distinct clusters have been detected: Cluster 1 shows a low SiO 2 content; Cluster 2 corresponds to coarse grains with a felsic composition, whereas Cluster 3 presents a typical basaltic composition. Coarse grains from Cluster 2 have been mostly observed exposed in the vicinity of the landing site, whereas coarse grains from Clusters 1 and 3 have been detected mostly buried, and were found all along the rover traverse. The possible origin of these coarse grains was investigated. Felsic (Cluster 2) coarse grains have the same origin as the felsic rocks encountered near the landing site, whereas the origin of the coarse grains from Clusters 1 and 3 seems to be more global. Fine-grained soils (particle size < laser beam diameter which is between 300 and 500 μm) show a homogeneous composition all along the traverse, different from the composition of the rocks encountered at Gale. Although they contain a certain amount of hydrated amorphous component depleted in SiO 2 , possibly present as a surface coating, their overall chemical homogeneity and their close-to-basaltic composition suggest limited, or isochemical alteration, and a limited interaction with liquid water. Fine particles and coarse grains from Cluster 1 have a similar composition, and the former could derive from weathering of the latter. Overall martian soils have a bulk composition between that of fine particles and coarse grains. This work shows that the ChemCam instrument provides a means to study the variability of soil composition at a scale not achievable by bulk chemical analyses. [ABSTRACT FROM AUTHOR]

The WR-2 watershed is located in the Deccan trap basaltic terrain of Maharashtra State, India. The watershed area incorporates a rich orange orchard belt that requires a huge quantity of water for irrigation. This requirement is mostly met through groundwater, extracted from the shallow aquifers of the WR-2 watershed. However, over the years, excess withdrawal of groundwater from these aquifers has resulted in depletion of groundwater level. The declining trends of groundwater level, both long term and short term, have had a negative impact on the groundwater quality of the study area. This effect can be gauged through the rising electrical conductivity (EC) of groundwater in the shallow aquifers (dug wells) of the WR-2 watershed. It is observed that the long term declining trend of groundwater level, during 1977-2010, varied from 0.03 to 0.04 m per year, whereas the corresponding trend of rising EC varied from 1.90 to 2.94 μS/cm per year. During 2007-2010, about 56% dug wells showed a positive correlation between depleting groundwater level and rising EC values. The groundwater level depletion during this period ranged from 0.03 to 0.67 m per year, whereas the corresponding trend of rising EC ranged from 0.52 to 46.91 μS/cm per year. Moreover, the water quality studies reveal that groundwater from more than 50% of the dug wells of the WR-2 watershed is not suitable for drinking purpose. The groundwater, though mostly suitable for irrigation purpose, is corrosive and saturated with respect to mineral equilibrium and shows a tendency towards chemical scale formation. [ABSTRACT FROM AUTHOR]

The aim of our study was to identify the most important ecological factors influencing the breeding density of chukar partridges (Alectoris chukar) in Southeastern Bulgaria. Identified habitats were divided into two categories: 1) natural habitats with an extant population of the species, and 2) habitats in which it was absent. In each habitat, annual precipitation, lowest elevation in the habitat, Paliurus cover, grazing livestock per 100 ha, shrub height, shrub density, bedrock type, percentage of pastures, percentage of agriculture, percentage of wetlands, percentage of rocks, presence/absence of buildings, presence/absence of highways, plant species composition, plant layer coverage, and chukar breeding pairs were measured. We have found several habitat variables that probably affect the density of nesting chukar partridge. These are: 1) grazing intensity, 2) percentage of rock outcrops, 3) percentage of grasslands, 4) shrub cover, and 5) elevation. Grazing intensity and rock outcrop presence, together with the elevation gradient, influence the breeding pair distribution and abundance most significantly. Our study has confirmed only three types of habitats that the chukar currently prefers to nest in. Unknown factors probably changed the other sites in a way that they are no longer suitable for the species' existence and reproduction. [ABSTRACT FROM AUTHOR]

Abstract: In the western L'Aquila basin (Italy), six seismic stations of the Italian Strong Motion Network, which were used on both soil and rock outcrops, recorded a huge amount of weak- and strong-motion data near an active fault during the 2009 L'Aquila seismic sequence. This paper analyzes the ground motion records of events with magnitudes ranging between 1.6 and 6.3 and compares the observed peak accelerations and the H/V and V/H spectral ratios with those revealed from numerical simulations. The finite element method is considered herein to perform 2D dynamic modeling on a geologic cross-section of the upper Aterno River Valley, which is 1000m wide and 50m deep, based on the reviewed geologic, geotechnical and geophysical investigations that were performed in previous studies. The Martin–Finn–Seed's pore-water pressure model is used in the simulations. The observed peak accelerations, the frequencies and the levels of maximum amplification are correctly estimated using the FEM simulations. The consistency between the computed and the experimental results shows a seismic response that is sensitive to the level of earthquake magnitude and mainly depends on the rock and soil elastic and dynamic properties, the intensity and the depth of the seismic impedance contrast, the water table depth, the two-dimensional irregular configuration, the dip angle of strata, the shape and the frequency content of the input motion record. The seismic motion amplification is usually higher at station AQV, which is located near the valley center, where a peak acceleration value of 0.66g was recorded. Both the PGA amplification factor and the maximum amplification frequency of the horizontal component decrease when the earthquake magnitude level increases, which shows a nonlinear seismic response at the stations AQG (on fractured and weathered rock), AQA and AQV (on alluvium). The simulation of the 2009 M w =6.3 L'Aquila earthquake confirms the observed nonlinear effective stress behavior and allows us to relate it to the generation of excess pore-water pressure, which ranges between 50 and 300kPa. [Copyright &y& Elsevier]

Lebanon is a country that is relatively rich in water resources, as compared to its neighboring states in the Middle East. Several water sources are issuing on the surface or subsurface, including nonconventional water sources as the geothermal groundwater. This aspect of water sources exists in Lebanon in several localities, as springs or in deep boreholes. To the present little attention has been given to these resources and their geological setting is still unidentified. The preliminary geological field surveys revealed that they mainly occur in the vicinity of the basalt outcrops. Therefore, understanding their geological controls will help in exploring their origin, and thus giving insights into their economical exploitation. This can be investigated by applying advanced detection techniques, field surveys along with detailed geochemical analysis. This study aims at assessing the geographic distribution of the geothermal water in Lebanon with respect to the different geological settings and controls that govern their hydrogeologic regimes. It will introduce an approach for an integrated water resources management which became of utmost significance for the country. [ABSTRACT FROM AUTHOR]

Abstract: The solubilities of volatiles (H2O, CO2, S, F, and Cl) in basaltic melts are dependent on variables such as temperature, pressure, melt composition, and redox state. Accordingly, volatile concentrations can change dramatically during the various stages of a magma's existence: from generation, to ascent through the mantle and crust, to final eruption at the Earth's surface. Olivine-hosted melt inclusions have the potential to preserve volatile concentrations at the time of entrapment due to the protection afforded by the host olivine against decompression and changes to the oxidation state of the external magma. Recent studies, however, have demonstrated that rapid diffusive re-equilibration of H2O and oxygen fugacity ( ) can occur within olivine-hosted melt inclusions. Here we present volatile, hydrogen isotope, and major element data from dehydration experiments and a quantitative model that assesses proposed mechanisms for diffusive re-equilibration of H2O and in olivine-hosted melt inclusions. Our comprehensive set of data for the behavior of common magmatic volatiles (H2O, CO2, F, Cl, and S) demonstrates that post-entrapment modification of CO2, and to a lesser extent S, can also occur. We show that the CO2 and S concentrations within an included melt decrease with progressive diffusive H2O loss, and propose that this occurs due to dehydration-induced changes to the internal pressure of the inclusion. Therefore, deriving accurate estimates for pre-eruptive CO2 and S concentrations from olivine-hosted melt inclusions requires accounting for the amount of CO2 and S hosted in vapor bubbles. We find, however, that Cl and F concentrations in olivine-hosted melt inclusions are not affected by diffusive re-equilibration through the host olivine nor by dehydration-induced pressure changes within the melt inclusion. Our results indicate that measured H2O, CO2 and S concentrations and Fe3+/ΣFe ratios of included melts are not necessarily representative of the melt at the time of entrapment and thus are not reliable proxies for upper mantle conditions. [Copyright &y& Elsevier]

The Elie Ness diatreme (Fife, Scotland) is an ideal place to study the internal architecture and emplacement processes of diatremes. Elie Ness is one of approximately 100 alkali basaltic diatremes and intrusions in the East Fife area, emplaced during Upper Carboniferous to Early Permian times into an extensive rift system in the northern Variscan foreland. Within the diatreme, seven lithofacies and three lithofacies associations (LFAs 1-3) are recognised. Field, petrographic and geochemical studies demonstrate that the diatreme experienced a protracted history of eruption and infill, initially driven by volatile expansion and later by magma-water interaction. Massive lapilli tuffs of LFA 1 contain abundant highly vesicular juvenile scoria and magma-coated clasts, which are best explained by a magmatic origin for the early explosive eruptions. On a large-scale, the tuffs are well mixed and locally exhibit small-scale degassing structures attributed to fluidisation processes occurring within the diatreme fill. The occurrence of abundant volcaniclastic autoliths and megablocks within LFA 1 can be explained by subsidence of volcaniclastic strata from the maar crater and upper diatreme during emplacement. Pyroclastic density current deposits of LFA 2 form a series of continuous sheets across the diatreme, some of which may have originated from phreatomagmatic explosions in a neighbouring vent. We attribute the overall bedding pattern to a combination of primary volcanic processes and post-depositional folding related to movement along an adjacent fault. Minor steeply inclined breccias and tuffs of LFA 3 cross-cut the LFA 2 succession and are interpreted as late-stage volcaniclastic dykes and conduits, signalling the final phase of eruptive activity at Elie Ness. The study offers new insights into the volcanic evolution of diatremes fed by low viscosity, alkali-rich magmas. [ABSTRACT FROM AUTHOR]

Dabbahu is a composite volcano at the north end of the active Manda-Hararo segment of the Afar Rift in northern Ethiopia. We present 93 new whole-rock analyses, mineral analyses from 65 samples, and 9 new 40Ar-39Ar dates for rocks ranging in composition from mildly alkaline basalt through trachy andesite to peralkaline rhyolite (comendite and pantellerite) erupted from Dabbahu. These data, supplemented by a new geological map, are used to provide insights into the evolution of the volcano. We show that Dabbahu has been active for over 67 k.y., but an apparent hiatus occurred between the eruption of comendite (29 ka) and pantellerite (ca. 8 ka) lavas. Mineral data for olivine, clinopyroxene, plagioclase, and alkali feldspar show a remarkably extensive range of solid solution across the rock suite consistent with protracted fractionation from basalt to rhyolite. The parental basalt is compositionally similar to recent riftrelated basalts in the Manda-Hararo rift, with low initial H2O contents (<1 wt%). Closedsystem fractionation increased H2O contents of residual liquids sufficiently for some rhyolites to erupt both explosively and effusively. The diverse magma types were erupted from a relatively closely spaced network of vents and fissures. Field evidence indicates that magmas were not erupted in a simple fractionation sequence. Some mixing occurred between magmas of less-evolved compositions and more-evolved compositions shortly prior to, or during, eruption. The differentiation of basalt to rhyolite must have occurred on time scales that were relatively short compared to the lifetime of the volcano, probably due to the small volumes of basalt intruded into the crust and consequently enhanced cooling and crystallization rates. A network of stacked sills or closely spaced dikes in the shallow to midcrust represents the most plausible configuration of the subvolcanic plumbing system. Input of new magma batches into such a system may serve as a key eruption trigger at Dabbahu. [ABSTRACT FROM AUTHOR]

Abstract: Headlands, rock outcrops and engineering structures impact beach and nearshore dynamics of coastal embayments, inducing boundary effects that constrain the lateral and vertical beach variability. This study analyses morphological change in six embayed beaches with diverse levels of exposure to wave action and various degrees of geological control in the mesotidal coast of southwestern Portugal. The aim is to identify whether geological boundaries constrain the morphological behaviour of embayed beaches and assess whether their effects can be decoupled from datasets of morphological change. Topographic data, obtained over a two-year period on each of the six embayments, were analysed using empirical orthogonal functions (EOF) to decompose temporal and spatial variability in the datasets. First and second mode eigenfunctions were explored using time-variable linear correlation analysis with several nearshore parameters that include hydrodynamic variables, sedimentary and geometric characteristics of each embayment in order to derive forcing–response relationships. Our results demonstrate that natural geological boundaries constrain the morphological behaviour of embayed beaches, producing conspicuous alongshore variability in all embayments. Localised responses induced by lateral and vertical boundary interference with beach and nearshore dynamics include beach rotation, topographically-controlled rip circulation and restrained profile fluctuation. Spatial decoupling in cross- and longshore responses is accompanied by a temporal decoupling in response times, both of which are slower in more constrained embayments (from 1day in exposed embayments to 1week or more in the most sheltered ones). Normalised wave power was correlated at the 99% confidence level with the primary mode of morphological variability at most embayments, which represent 67% to 94% of the variance in the datasets. This correlation stresses the importance of combined parameterization of wave and tide forcing in process–response relations between hydrodynamics and morphological change for mesotidal coastal environments. Lateral and vertical geological boundaries exert their effects fundamentally by restraining longshore sediment transport, inducing cellular surf zone circulation and by impacting cross-shore sediment transport. It is postulated that decreasing sediment abundance and substrate depth intensify vertical boundary effects, while higher indentation and wave obliquity enhance the effects of lateral boundaries. [Copyright &y& Elsevier]

Abstract: The Koras Group is a bimodal metavolcanic suite on the western margin of the Archean Kaapvaal Craton at its contact with the poly-deformed and highly metamorphosed Proterozoic Namaqua Sector of the Namaqua-Natal Province of southern Africa. It is composed of two temporally distinct but lithologically similar volcanosedimentary successions, the lower at ∼1.17Ga and the upper at ∼1.1Ga. Both successions are characterised by basaltic andesites and rhyolites sandwiched between immature siliciclastic metasediments. The subalkaline basalt to basaltic andesites are tholeiitic, magnesian, and calcic to calc-alkalic. Their trace element concentrations are enriched in the large ion lithophile (LIL) elements (Cs, Rb, Sr, Ba, K and Pb), along with Th and U relative to primitive mantle (PM), and show depletions in P and Ti, with a Nb–Ta ‘trough’ relative to the LILE and light rare earth elements (LREE). The basaltic andesites were extruded in a continental rift setting, but with low Nb contents (7.8–10.9ppm), along with La/Nb ratios of 2.3–3.1, have a subduction-related signature for both successions. The rhyolitic porphyries of both successions are peraluminous, magnesian and alkali-calcic to alkalic. They have similar trace element patterns to the basaltic andesites, but are strongly enriched in the LILE and LREE relative to PM, and have strong depletions in P, Ti and Sr and a prominent Nb–Ta ‘trough’. The rhyolitic porphyries were emplaced in a within-plate tectonic setting and are characterized by high Zr+Nb+Ce+Y contents (>350ppm) and Ga/Al ratios (10,000Ga/Al>2.6), typical of A-type granitoids. The upper volcanic succession, in particular, shows many similarities, both in terms of whole rock geochemistry, as well as age, to the late- to post-tectonic granitoids of the Keimoes Suite, an extensive granitoid suite that ‘stitches’ accretionary terranes together on the eastern margin of the Namaqua Sector. Chondrite-normalized REE patterns of the bimodal volcanism are characterised by LREE enrichment [(La/Sm)CN =2.7–4.96], slight HREE depletion [(Gd/Yb)CN =1.09–2.46] and negative Eu anomalies which become more pronounced from the basaltic andesites (Eu/Eu*=0.69–0.86) to the rhyolitic porphyries (Eu/Eu*=0.57–0.66). The overall coherence of both major and trace element trends, as well as the positive correlation between incompatible element contents favours a co-magmatic origin for the basaltic and rhyolitic rocks with fractional crystallization processes dominant giving rise to A-type magmas. The magmas were emplaced during trans-tensional periods on the western margin of the Kaapvaal Craton that followed two collisional events due to decompression melting of the subduction-related subcontinental lithospheric mantle following slab detachment in an area of previously thickened crust, which then incorporated varying degrees of continental crustal material. This is supported by ɛ Nd(t) values ranging from positive for some rhyolitic porphyries through to dominantly negative, variable T DM ages of >1.5Ga, and low Nb/La and Ta/Th ratios. The Koras Group represents an example of A-type bimodal volcanism at 1.1Ga which finds regional correlatives in similar Mesoproterozoic successions in southern Namibia and northwestern Botswana associated with accretionary collisional events. [Copyright &y& Elsevier]

Most typical rock outcrop plants of the eastern United States occur either on calcareous or on non-calcareous outcrops, but not both. Often this is because their growth is inhibited in soil from the non-native substrate, as shown in this study for the granite outcrop endemic sedge Cyperus granitophilus when grown on limestone soil. For those rock outcrop species that can exploit both calcareous and non-calcareous substrates, it might be expected that they would do so by substrate specialization, with each population growing better on its native substrate than the other substrate. However, in most previously tested species, populations from both substrates grow well on the same substrate and both are inhibited on the second substrate. Populations found on the second substrate, though inhibited, are nevertheless able to maintain good health and grow sufficiently to maintain themselves there. In this study we show that the widespread sedge Cyperus aristatus (=C. inflexus), a regular component of limestone, sandstone, granite, chert, and serpentine rock outcrop communities in the eastern United States, exploits both calcareous and non-calcareous substrates by substrate specialization, something previously shown in only one other eastern United States rock outcrop species. [ABSTRACT FROM AUTHOR]

Transitional-composition pillow basalts from the toe of the Hilo Ridge, collected from outcrop by submersible, have yielded the oldest ages known from the Island of Hawaii: 1138 ± 34 to 1159 ± 33 ka. Hilo Ridge has long been interpreted as a submarine rift zone of Mauna Kea, but the new ages validate proposals that it is the distal east rift zone of Kohala, the oldest subaerial volcano on the island. These ages constrain the inception of tholeiitic volcanism at Kohala, provide the first measured duration of tholeiitic shield building (≥870 k.y.) for any Hawaiian volcano, and show that this 125-km-long rift zone developed to near-total length during early growth of Kohala. Long eastern-trending rift zones of Hawaiian volcanoes may follow fractures in oceanic crust activated by arching of the Hawaiian Swell in front of the propagating hotspot. [ABSTRACT FROM AUTHOR]

Chromite is a mineral with low solubility and is thus resistant to dissolution. The exception is when manganese oxides are available, since they are the only known naturally occurring oxidants for chromite. In the presence of Mn(IV) oxides, Cr(III) will oxidise to Cr(VI), which is more soluble than Cr(III), and thus easier to be removed. Here we report of chromite phenocrysts that are replaced by rhodochrosite (Mn(II) carbonate) in subseafloor basalts from the Koko Seamount, Pacific Ocean, that were drilled and collected during the Ocean Drilling Program (ODP) Leg 197. The mineral succession chromite-rhodochrosite-saponite in the phenocrysts is interpreted as the result of chromite oxidation by manganese oxides. Putative fossilized microorganisms are abundant in the rhodochrosite and we suggest that the oxidation of chromite has been mediated by microbial activity. It has previously been shown in soils and in laboratory experiments that chromium oxidation is indirectly mediated by microbial formation of manganese oxides. Here we suggest a similar process in subseafloor basalts. [ABSTRACT FROM AUTHOR]

The subsurface imaging using conventional seismic reflection technique is challenging in areas where high velocity rocks such as basalts are underlain by low velocity rocks. The seismic image quality worsens in the presence of intercalated sediments within the basaltic layers. In the recent years, the multicomponent seismic exploration technique has drawn great attention because it reduces the ambiguity in seismic imaging, enlarges the S-wave information, and improves the prediction and identification of reservoir fluids. Improvements in sub-basalt imaging techniques could hold highly significant geologic implications such as resource exploration and identifying permanent geochemical trapping potential (such as for carbon sequestration studies). In this article, we examine the possibility of utilizing mode-converted (P-SV) waves for sub-basalt imaging as well as likely complicacies one may expect in such processes. [ABSTRACT FROM AUTHOR]

We report and describe two new small diamictite outcrops on Isla Marambio (Seymour Island), Antarctic Peninsula. These rocks rest on an erosional unconformity on top of the Eocene La Meseta Formation and are unconformably covered by glaciomarine rocks of the ?Pliocene-Pleistocene Weddell Sea Formation. The lithology, fossil content and isotopic ages obtained strongly suggest that the rocks belong to the Hobbs Glacier Formation and support a Late Miocene age for this unit. Additionally, the dated basalt clast provides the oldest age (12.4 Ma) for the James Ross Island Volcanic Group recorded up to now. The here described diamictite cannot be confidently correlated with a glaciomarine unit previously assigned to the Late Eocene-Lower Oligocene taken as proof that initial expansion of ice on Antarctica encompassed the entire continent synchronously in the earliest Oligocene. However, it is now evident that there are likely to be more, short but important, stratigraphic sequences of key regional and Antarctic wide interest preserved on the plateau of Isla Marambio. [ABSTRACT FROM AUTHOR]

Paleovalleys and their infilling successions are described from outcrops and drill cores of the Cantabrian Range (northern Spain). A Hirnantia fauna and associated diamictites with striated lonestones indicate that the paleovalleys are related to the Hirnantian (latest Ordovician) glacial event. Based on overall geometry, depositional facies, and associated deformation structures, the paleovalleys are interpreted as subglacial tunnel valleys. They were most likely related to the North Gondwana ice sheet. The ice sheet therefore reached the Ibero-Armorican domain that was still attached to the Gondwana landmass at least until the latest Ordovician. [ABSTRACT FROM AUTHOR]

The aim of this study to demonstrate that how, and in which form sea caves develop in structurally different basaltic lavas and pyroclastites of these kinds. Also influenced by marine erosion, the dimensions and morphology of sea caves principally depend on the structural behaviour of the enclosing basaltic lavas and pyroclastics. In basalt volcanic areas sea caves can form in columnar and irregularly jointed basaltic lava; through opening up and further shaping of primarily existing caverns; in lava deltas; by the excavation of embedded volcanic agglomerate or slack structured aa lava from between thick and primarily existing caverns; in pillow lava; in basaltic dyke; along the border of a basaltic dyke and thick hydrovolcanic tuff and in basaltic tuff. The aim of this study is to demonstrate that how and in which form sea caves develop in structurally different basaltic lavas and pyroclastics. [ABSTRACT FROM AUTHOR]

The Rümker region, located in the northern Oceanus Procellarum, is the candidate landing region for China's Chang'E‐5 lunar sample‐return mission. The area is geologically complex and known for its volcanic activity. To understand the volcanism of the Rümker region, we investigate the 3D crustal density structure of this region using Bouguer gravity data from the Gravity Recovery and Interior Laboratory mission. We applied derivative filters and a 3D density inversion to resolve both the shallow and deep structures in the subsurface. Results indicate that the Rümker region exhibits different modes of emplacement. The Mons Rümker volcanic complex is fed by an intrusion‐like structure at a depth of ~6–18 km and contains high‐density basaltic materials of >3,000 kg/m3. A quasi‐circular mass anomaly that was identified in a previous study with high gravity amplitude (~130 mGal) and high density (> 3,000 kg/m3) was also documented in the study region. The quasi‐circular mass anomaly feature represents deeper and thicker buried mare basalts with a bowl‐shaped geometry formed by an impact event. Based on our geophysical analysis, we propose four landing site candidates for the Chang'E‐5 mission that satisfy the geological and geophysical criteria for maximum scientific return. Plain language Summary: The Mons Rümker region on the Moon features evidence for multiple volcanic episodes, including some of the youngest lunar mare basalts known to date. To better understand the volcanic activity, we analyzed gravity data from the Gravity Recovery and Interior Laboratory mission with a high resolution of 4.5 km. We used geophysical tools to study both shallow and deep subsurface structures. Our results suggest that the Mons Rümker region features multiple small and large high‐density underground bodies, some of which breach the surface. In particular, there could be a large magmatic body at a depth of ~6–18 km that fed the surface volcanoes. Our analyses also revealed another circular feature at ~7‐ to 17‐km depth with high‐density values. As China prepares to send the Chang'E‐5 mission to collect drill‐hole samples, we combine the results from this study with remote sensing and geological analyses to propose four candidate landing sites that would possibly maximize the scientific return of the mission. Key Points: The Rümker region is characterized by various subsurface basaltic bodies formed by multiple volcanic episodesHigh‐density bodies beneath the Mons Rümker and quasi‐circular mass anomaly are located in midcrustFour landing site candidates consistent with spectral and geological analysis for Chang'E‐5 mission are proposed [ABSTRACT FROM AUTHOR]