Study of a rockfall in a limy conglomerate canyon (Covarrubias, Burgos, N. Spain)

In this paper, a rockfall of some tenths of cubic metres of rock, occurred in a conglomerate canyon in the northern Castilian plateau (N-Central Spain), is described in detail. This includes the basic data (geology, mapping, meteorological data and rock involved), the mechanical mechanism of the instability, the propagation and reach of the fallen rock boulders and the final location of the pieces. The study is based on detailed geological, aerial photography and geotechnical studies and advance topographical measurements. Geological engineering techniques are used to analyze the instability initiation and rockfall propagation. This study contributes to a better understanding of the geological processes leading to the occurrence of calcareous canyons and cliffs in the drainage network of the upper Castilian plateau. It is also helpful to improve our knowledge on natural rockfall phenomena for risk engineering purposes aiming to quantify, control and mitigate associated hazards.     

Potential for localized groundwater contamination in a porous pavement parking lot setting in Rhode Island

The control of polluted surface runoff and the assessment of possible impacts on groundwater is a concern at the local and regional scale. On this background, a study investigates possible impacts of organic and inorganic pollutants (including bacteria) originating from a permeable asphalt parking lot on the water quality immediately beneath it. The functioning of the permeable pavement, including clogging and restricted vertical percolation, was also evaluated. Four nested sample ports (shallow and deep) were installed below low- and high-traffic areas, including one port outside the parking lot. At least initially there was a good hydraulic connection between the parking surface and the shallow sample ports. The presence of a geotextile layer at the base of the parking lot structure, however, was identified in lab tests as one factor restricting vertical percolation to the deeper ports. Clogging of the permeable surface was most pronounced in heavy traffic areas and below snow pile storage areas. Corroborated by high electric conductivity and chloride measurements, sand brought in by cars during winter was the principal cause for clogging. No bacteria or BOD were found in percolating water. Polycyclic aromatic hydrocarbons (PAH) were present at concentrations near minimum detection limit. Nutrients (nitrate and phosphate) were being leached into the ground via the permeable parking lot surface at annual flux rates of 0.45–0.84 g/m²/year. A multi-species tracer test demonstrated a retention capacity of the permeable parking lot structure of >90% for metals and 27% for nutrients, respectively.     

Direct and Indirect Validation of Potential Fishing Zone Advisory off the Coast of Uttara Kannada,Karnataka

The technique of predicting Potential Fishing Zone using satellite derived sea surface temperature and chlorophyll is becoming an important aspect for the fishermen. In the present study an attempt has been made to compare fish density/catch per unit effort in the areas predicted by Satellite imagery and available to fishermen via electronic display boards at the fish landing centers of Uttara Kannada district, Karnataka with those of non predicted areas. Direct and Indirect validation was done. Direct method means comparing the catch using fishing vessels simultaneously in the notified region with that of catch from non notified region. And in indirect method by comparing catch data from landing centers on notified days with that of non notified days. Direct validation off Karwar showed that catch was significantly higher in notified (PFZ) area with high densities as compared to non notified (non PFZ) regions. When comparisons of landing center data of Karwar, Tadadi and Bhatkal are done it is evident that in all the centers during the period under study, higher catches were observed on notified days than non notified days except in Bhatkal centre in 2009–10. There by validating the accuracy of PFZ predictions and economic gains to fishermen.     

Stratigraphic relations and habitat of the Bende fish teeth,southeastern Nigeria

The age and habitat of the Bende fish fossils have remained a matter of controversy with interpretations ranging between the Paleocene Imo Formation and the Eocene Ameki Formation. Outcrop-based sequence stratigraphic analysis presented in this work shows that the Imo and Ameki Formations together include three laterally extensive estuarine central basin/offshore mud rock units that are associated with the 59.7, 58.1, and the 56.8 ma maximum flooding surfaces, respectively. Field evidence and stratigraphic analysis show that the Bende fossil bones are hosted by the mud rock unit containing the 58.1 ma maximum flooding surface, while the Ameke bone fossils are contained within the condensed section associated with the 56.8 ma maximum flooding surface. Apart from highlighting the relevance of sequence stratigraphy in paleobiological interpretations, this study shows that the Bende fish fauna which Arua first assigned to the Eocene Ameki Formation indeed belongs to the Paleocene Imo Formation.     

Spatial and temporal variability of mesozooplankton and tintinnid ciliates in a seasonally hypersaline estuary

The zooplankton community of Mission Bay, San Diego, California, was monitored over two years, to study spatial and temporal patterns and the response of zooplankton species composition to environmental variation. Data were collected every two weeks from six stations and included hydrographic parameters, dissolved nutrient concentrations, and phytoplankton and zooplankton species composition. Hydrography varied seasonally, along a spatial gradient from the mouth to the back of the bay, and between the two years around the influence of rainfall. Spatially, Mission Bay could be divided into three regions during this study based on hydrography and zooplankton species composition. Zooplankton species composition followed a predictable seasonal progression, with different groups of species being characteristic to particular times of the year. Variability in zooplankton species composition was also evident between years, as certain species were more common in one or the other year of the study. Spatial patterns were more consistent than temporal ones, and related to distance from the mouth of the bay during much of the year and distance from freshwater inlets during the relatively short rainy season. Multivariate analysis revealed that variation in zooplankton species composition was best related to measured abiotic factors (temperature, salinity, rainfall, and tidal velocity).     

The Alleret maar (Massif Central, France): A new lacustrine sequence of the early Middle Pleistocene in western Europe

The Alleret maar (Massif Central, France) provides a long lacustrine sequence (40.6 m) attributed to the early Middle Pleistocene. Sediment, pollen and diatoms analysis of its upper part (AL2 core, 14.6 m) indicates two temperate phases marked by high lake levels, forest development and vegetation expansion. They are separated by a cold period during which lake level drops, coarse sediment input increases and steppic and xerophilous plants develop. Pollen data suggests that this sequence belongs to the upper part of the Cromerian complex. These results are in agreement with the 557 ± 3 ka (±12 ka, including all errors) ⁴⁰Ar/³⁹Ar age obtained from an interbedded tephra layer emitted by the Mont-Dore/Sancy strato-volcano and establish that this sequence probably covers the MIS 15 substages.     

Olivine in ultramafic lamprophyres: chemistry,crystallisation, and melt sources of Siberian Pre- and post-trap aillikites

We studied olivines from the Devonian pre-trap (the Ilbokich occurrence) and the Triassic post-trap (the Chadobets occurrence) carbonate-rich ultramafic lamprophyres (UMLs) in the southwestern portion of the Siberian craton. On the basis of detailed investigations of major, minor, and trace-element distributions, we have reconstructed the main processes that control the origins of these olivines. These include fractional crystallisation from melt, assimilation, and fractional crystallisation processes with orthopyroxene assimilation, melt-reaction diffusive re-equilibration, alkali enrichment, and CO₂ degassing of the melt. Furthermore, we inferred the composition of the sources of the primary UML melt and their possible correlations with proto-kimberlitic melts, as well as the influence of the Triassic Siberian plume on the composition of the lithospheric mantle. The main differences between olivines from the Ilbokich and the Chadobets aillikites were that the olivines from the former had more magnesium-rich cores (Mg# = 89.2?±?0.2), had Mg- and Cr-rich transition zones (Mg# = 89.7?±?0.2 and 300–500 ppm Cr), had lower Ni (up to 3100 ppm) and Li (1.4–1.5 ppm), and had higher B (0.8–2.6 ppm) contents, all at higher Fo values (90–86), relative to the olivines from the latter (Mg# = 88–75; 200–300 ppm Cr; up to 3400 ppm Ni; 1.4–2.4 ppm Li; 0.4–2.2 ppm B). The Siberian aillikite sources contained a significant amount of metasomatic material. Phlogopite-rich MARID-type veins provided the likely metasomatic component in the pre-trap Devonian Ilbokich aillikite source, whereas the Triassic Chadobets aillikitic post-trap melts were derived from a source with a significant carbonate component. A comparison of UML olivines with olivines from the pre-trap and post-trap Siberian kimberlites shows a striking similarity. This suggests that the carbonate component in the aillikitic source could have been produced by evolved kimberlite melts. The differences in the lithospheric metasomatic component that contributed to pre-trap and post-trap aillikitic melts can be interpreted as reflections of the thermal impact of the Siberian Traps, which reduced phlogopite-bearing metasomes within the southwestern Siberian sub-continental lithospheric mantle.     

Flow and transport predictions during multi-borehole tests in fractured chalk using discrete fracture network models

Multi-borehole pumping and tracer tests on the 10 to 100-m scale were conducted in a fractured chalk aquitard in the Negev Desert, Israel. Outcrop and core fracture surveys, as well as slug tests in packed-off intervals, were carried out at this site to obtain the parameters needed for construction of a stochastic discrete fracture network (DFN). Calibration of stochastic DFNs directly to the multiple borehole test data was inadequate. Instead, two equivalent deterministic DFN flow models were used: the vertical-fractures (VF) model, consisting of only vertical fractures, and the fractures’ intersections (INT) model, consisting of vertical and horizontal fractures with enhanced transmissivity at their intersections. Both models were calibrated against the multi-borehole response of one pumping test and their predictions were tested against three other independent pumping tests. The average accuracies of all transient drawdown predictions of the VF and INT models were 65 and 66%, respectively. In contrast to this equality in average drawdown predictions of both models, the INT model predicted better important breakthrough curve features (e.g., first and peak arrival times), than the VF model. This result is in line with previously assumed channeled flow, derived from analytical analysis of these pumping and tracer tests. Ronit Nativ, deceased, may her memory be blessed.     

Numerical simulation of physical and dynamical characteristics associated with the severe thunderstorm on April 5, 2015 at Kushtia and Jhenaidah

The paper deals with the study of the physical and dynamical characteristics of a severe thunderstorm, which had occurred on April 5, 2015, at about 2100 UTC in the southwestern Bangladesh with location around 23.3–23.7N and 89.0–89.4E within the upazilas (sub-districts) of Kumarkhali and Shailkupa under the districts of Kushtia and Jhenaidah, respectively. The thunderstorm was associated with numerous hails of large size. More than 5000 birds which used to live in the bird sanctuary at Shailkupa and 22,011 birds in Chhaglapara Bird Sanctuary of Kumarkhali died as they were hit by the hails. Large hails also damaged crops, houses and forests over the thunderstorm hit areas. The evolution of the thunderstorm is studied by the WRF model, which is initialized using the National Centers for Environmental Prediction Final reanalysis data of 0000 UTC of April 5, 2015. The simulated results provide a basis to study the physical and dynamical characteristics of the thunderstorm, which are generally not identified by the meteorological observations which are too sparse. The model has captured a micro-low over Kumarkhali and its neighborhood, which favored the occurrence of the severe thunderstorm. The model simulated rainfall is about 26 mm near the place of occurrence, which matches well with the area where the reflectivity of hydrometeor is maximum. The convective available potential energy is found to be 1600 J kg^?1 at 1730 UTC near the place of occurrence of the thunderstorm; this indicates high atmospheric instability over the thunderstorm location for the formation of the thunderstorm. The vertical velocity, convergence, cloud water mixing ratio and the ice water mixing ratio and their vertical extensions are found to be satisfactory and responsible for the occurrence of large hails associated with the thunderstorm.     

Geochemical Characteristics of Gold Polymetallic Deposits as Exemplified by the Laozuoshan Deposit,Heilong jiang,China

From the studies of ore deposit geologic settings,sulfur isotopes,lead isotopes,carbon isotopes and oxygen isotopes,fluid inclusions and petrochemistry in this paper,the authors have drawn a conclusion that the ore-forming hydrothermal solutions are the high-temperature magmatic hydrothermal solutions for the gold ore deposit,and at the same time,the involvemety of crustal materials can not be ruled out .It is the first time that the authors have proposed that the Laozuoshan gold-ploymetallic ore deposit in Heilongjiang Province was formed in the calc-alkaline series environment at the margin of an active continent.