Journal of Geological Research The latest articles from Hindawi © 2018 , Hindawi Limited . All rights reserved. Methane at the NW of Weddell Sea, Antarctica Mon, 13 Feb 2017 00:00:00 +0000 The presence of gaseous hydrocarbons (from methane to n-pentane) in the seabed sediments and the bubbling of methane may suggest the presence of gas accumulations in the substrate of the NW Weddell Sea, Antarctica. The release of methane from the frozen ocean substrate adjacent to Seymour Island would be linked to climate instability during Late Cenozoic, when vast areas of the Antarctic continental shelf were flooded during the marine transgression that occurred . 18,000 years ago, after the Last Glacial Maximum (LGM). As the ice melted, the sea again occupied the regions which it had abandoned. As the transgression was relatively rapid, the sub-air relief was not destroyed but was submerged and the ground had frozen (permafrost) along with it. Thus, the heat flow from the sea to the marine substrate, now flooded, would have destabilized frozen gas accumulations, which were originally formed into terrestrial permafrost during the LGM, similarly to what would have happened in the Arctic. R. A. del Valle, E. Yermolin, J. Chiarandini, A. Sanchez Granel, and J. C. Lusky Copyright © 2017 R. A. del Valle et al. All rights reserved. Combining Resistivity and Aeromagnetic Geophysical Surveys for Groundwater Exploration in the Maghnia Plain of Algeria Wed, 18 Jan 2017 10:12:45 +0000 The Maghnia plain in western Algeria is filled by Plio-Quaternary and Miocene sediments that rest unconformably on a basement of Jurassic rocks. Electrical sounding (VES), magnetic data, well information, and hydrogeological data have been used to explore for groundwater potential in the Maghnia plain. The interpretation of Schlumberger sounding data was first calibrated with the lithology of available nearby wells. Four geoelectrical layers were identified within the study area. They are a thin near surface topsoil layer with variable resistivities, a moderate resistive aquifer (15–30 ohm-m), a resistive aquifer (40–70 ohm-m), and a conductive clay layer (1–10 ohm-m). Near Sidi Mbarek, the geoelectric section is reduced to three layers: a topsoil layer, a conductive layer corresponding to the Miocene marls, and a deep resistive layer that correlates with the Oxfordian sandstones. The interpretation of VES data and the enhancement techniques of magnetic data enabled the identification of a number of unmapped faults that occur near recharge zones close to adjacent mountains. This study enabled us to study the extension of the known Plio-Quaternary aquifer of the Maghnia plain and to explore the possible existence of a second deep groundwater aquifer in Oxfordian sandstones. Djamel Boubaya Copyright © 2017 Djamel Boubaya. All rights reserved. Depth Estimation Using the Tilt Angle of Gravity Field due to the Semi-Infinite Vertical Cylindrical Source Mon, 09 Jan 2017 13:25:49 +0000 Tilt angle filter is an interpretation method that is used to determine the source borders locations from potential fields data. Moreover, the tilt angle is applied for estimation of the anomaly source depth, such as contact-depth method and tilt-depth method. In this paper an application of the tilt angle technique obtained from the first vertical and horizontal gradients of the gravity anomaly from semi-infinite vertical cylindrical source is described. The technique is based on the tilt angle and derivatives ratio. In this approach the depth estimates are proportional to the computed tilt angles and their distances from the cross section center of the anomaly cause on the surface. This new method is termed the tilt-distance-depth (TDD). The method is demonstrated using synthetic gravity data, with and without random noise, and real gravity data from Iran. The results are also compared with the solutions from Euler deconvolution technique and inverse modelling using Modelvision software. Ata Eshaghzadeh Copyright © 2017 Ata Eshaghzadeh. All rights reserved. Lidar-Based Detection and Interpretation of Glaciotectonic Features of the Morainic Topography of Finland Sun, 06 Nov 2016 13:58:20 +0000 In Finland’s digital elevation model, marks of glaciotectonics as an important formation process of glacial geomorphology can be seen. This is a new finding to this extent regarding central parts of the former ice sheets. Deformational processes produced fragmented till surfaces probably mostly by brittle fracture of frozen till. Good signs of deformational effect to the till surfaces are the plucked edges or steps and semilinear or fan-like quarry edges in topography, which are often oblique compared with the main direction of the flow of the glacier. Plucked fractured steps of blocks of till can be so tight that they construct horizontal-like diamond patterned surfaces. Sometimes punctate proximal endings of fan-like hollows of transported rafts can be seen. Within main ice lobes or streams the glaciated terrain is often divided into longitudinal smooth looking drumlin terrain and into rough erosional slightly lower level situated zones, where the erosion has happened firstly by glaciotectonism and then by glaciofluvial streams. The eskers and different kind of hummocky moraines are often located in same zones. Among them deformational hummocky moraines and ribbed moraines are common. The abundance of glaciotectonic and plucking related features indicates that the base of the receding ice sheet was cold based in places or from time to time. Matti Veli Juhani Seppälä Copyright © 2016 Matti Veli Juhani Seppälä. All rights reserved. Caspian Sea Tidal Modelling Using Coastal Tide Gauge Data Tue, 26 Jul 2016 12:04:31 +0000 The purpose of this paper is to model tidal conditions in the Caspian Sea using data from coastal tide gauges of Anzali, Noshahr, and Neka Ports. Harmonic analysis method was used to identify and examine 40 tidal components. The results illustrate that the annual (Sa) and semiannual solar (Ssa) components on all of the ports listed have the highest range in comparison with the other components which are, respectively, 16 cm, 18 cm, and 15 cm for annual components and 2.8 cm, 5.4 cm, and 3.7 cm for semiannual components. Mahmoud Pirooznia, Seyyed Rouhollah Emadi, and Mehdi Najafi Alamdari Copyright © 2016 Mahmoud Pirooznia et al. All rights reserved. Structural Overview and Morphotectonic Evolution of a Strike-Slip Fault in the Zone of North Almora Thrust, Central Kumaun Himalaya, India Sun, 07 Feb 2016 13:44:09 +0000 The aim of the present research is to provide the base line details of the NNW-SSE trending Raintoli fault (RF) which is running parallel to the North Almora Thrust (NAT) along the Saryu valley from Seraghat-Naichun to Seri in the central sector of the Uttarakhand Himalaya, India. The RF is characterized as dextral strike slip fault and behaves as a ductile shear zone within the zone of NAT. The dextral sense of shear movement of RF is delineated by the fabric of the shear zone rocks including microscopically observed indicators such as sigma and delta porphyroclasts, quartz c-axis, and the field structural data. Additionally, in the quaternary period the dextral strike slip fault is reactivated with oblique slip component as characterized by various geomorphic indicators, for example, triangular facets, abandoned river channels, unpaired fluvial terraces, and V-shaped valleys with recurrent seismicity. Further, the morphometric parameters including Valley Floor Width to Valley Height (), asymmetry factor (AF), and gradient index (GI) further prove active nature of RF as suggested by low values of hypsometric integration, V-shaped valley, higher gradient index, and tilting of Saryu basin. Lalit M. Joshi, Pitamber D. Pant, Bahadur S. Kotlia, Girish C. Kothyari, Khayingshing Luirei, and Anoop K. Singh Copyright © 2016 Lalit M. Joshi et al. All rights reserved. Tunnel Probabilistic Structural Analysis Using the FORM Wed, 12 Aug 2015 11:43:04 +0000 In this paper tunnel probabilistic structural analysis (TuPSA) was performed using the first order reliability method (FORM). In TuPSA, a tunnel performance function is defined according to the boundary between the structural stability and instability. Then the performance function is transformed from original space into the standard normal variable space to obtain the design point, reliability index, and also the probability of tunnel failure. In this method, it is possible to consider the design factors as the dependent or independent random parameters with arbitrary probability distributions. A software code is developed to perform the tunnel probabilistic structural analysis (TuPSA) using the FORM. For validation and verification of TuPSA, a typical tunnel example with random joints orientations as well as mechanical properties has been studied. The results of TuPSA were compared with those obtained from Monte-Carlo simulation. The results show, in spite of deterministic analysis which indicates that the rock blocks are stable, that TuPSA resulted in key-blocks failure with certain probabilities. Comparison between probabilistic and deterministic analyses results indicates that probabilistic results, including the design point and probability of failure, are more rational than deterministic factor of safety. Yousef Mirzaeian, Kourosh Shahriar, and Mostafa Sharifzadeh Copyright © 2015 Yousef Mirzaeian et al. All rights reserved. A Study on Preventing Spontaneous Combustion of Residual Coal in a Coal Mine Goaf Tue, 31 Mar 2015 10:10:18 +0000 The effectiveness of grouting scheme has been simulated to prevent the coal spontaneous combustion at a goaf in Haizi Colliery, China. The colliery has been operated for long period over 27 years and has a complex ventilation network including airflow leakages which could possibly lead to the spontaneous combustion of coal at goafs. Firstly, the mine ventilation simulator MIVENA was used to analyze the mine ventilation network airflows to control airflows in and out of working faces and goafs. As the second approach, numerical simulations were carried by the simulator FLUENT in order to predict spontaneous combustion of residual coal with leakage flow in the #3205 goaf. It was cleared that the goaf can be divided into three zones based on oxygen concentration in the goaf area. Finally, the numerical simulation results show that the slurry grouting method is able to be an effective and economical method by reducing porosity in the goaf area to prevent spontaneous combustion of residual coal. Yongjun Wang, Xiaoming Zhang, Yuichi Sugai, and Kyuro Sasaki Copyright © 2015 Yongjun Wang et al. All rights reserved. Comparative Analysis between Biogas Flow in Landfill and Electrical Resistivity Tomography in Rio Claro City, Brazil Wed, 26 Nov 2014 12:55:32 +0000 The biogas originated from anaerobic degradation of organic matter in landfills consists basically in CH4, CO2, and H2O. The landfills represent an important depository of organic matter with high energetic potential in Brazil, although with inexpressive use in the present. The estimation of production of the productive rate of biogas represents one of the major difficulties of technical order to the planning of capture system for rational consumption of this resource. The applied geophysics consists in a set of methods and techniques with wide use in environmental and hydrogeological studies. The DC resistivity method is largely applied in environmental diagnosis of the contamination in soil and groundwater, due to the contrast of electrical properties frequent between contaminated areas and the natural environment. This paper aims to evaluate eventual relationships between biogas flows quantified in drains located in the landfill, with characteristic patterns of electrical resistivity in depth. The drain of higher flow (117 m3/h) in depth was characterized for values between 8000 Ω·m and 100.000 Ω·m, in contrast with values below 2000 Ω·m, which characterize in subsurface the drain with less flow (37 m3/h), besides intermediary flow and electrical resistivity values, attributed to the predominance of areas with accumulation or generation of biogas. César Moreira, Marcus Castro, Ana Gonsalez, Fernanda Cavallari, Thais Munhoz, and Alice Pereira Copyright © 2014 César Moreira et al. All rights reserved. The Influence of Sewage System on the Functioning and Quality of Krakow’s Watercourses Tue, 18 Nov 2014 09:57:17 +0000 The content of heavy metals, pH, Eh, and EC were measured for the Vistula River and its two tributaries, Prądnik-Białucha and Wilga, functioning as rainwater collectors for Krakow. Water sediments were collected from several inlets of the rainwater canals into the Prądnik-Białucha and Wilga. The Vistula was examined to catch the change of water environment quality of those two tributaries as well as storm overflow systems installed on both its left and right bank. In this last case the research was based on the bottom sediments of the storm overflow system, from its inlets into the Vistula River, and from the inside of the waste water collector. Also, samples of suspension and water were collected where the bridges are located and also near Dębnicki bridge bottom sediments. The sampling was conducted in 2004-2005 but because of financial constraints after ten years the tests were not repeated, but it was decided to publish the results. The attention was paid to the Cd and Pb content in the sediments of sanitary catch basins from the Wilga and the Prądnik, in Vistula sediments from storm overflow system, in the siphon, in the suspension of Vistula waters, and in fine-grain river silts. Marta Wardas-Lasoń Copyright © 2014 Marta Wardas-Lasoń. All rights reserved. Geochemistry, Paragenesis, and Wall-Rock Alteration of the Qatruyeh Iron Deposits, Southwest of Iran: Implications for a Hydrothermal-Metasomatic Genetic Model Wed, 22 Oct 2014 11:02:32 +0000 The Qatruyeh iron deposits, located on the eastern border of the NW-SE trending Sanandaj-Sirjan metamorphic zone, southwest of Iran, are hosted by a late Proterozoic to early Paleozoic sequence dominated by metamorphosed carbonate rocks. The magnetite ores occurred as layered to massive bodies, with lesser amounts of disseminated magnetite and hematite-bearing veins. Textural evidences, along with geochemical analyses of the high field strengths (HFSEs), large ion lithophiles (LILEs), and rare earth elements (REEs), indicate that the main mineralization stage occurred as low-grade layered magnetite ores due to high-temperature hydrothermal fluids accompanied by Na-Ca alteration. Most of the main ore-stage minerals precipitated from an aqueous-carbonic fluid (3.5–15 wt.% NaCl equiv.) at temperatures ranging between 300° and 410°C during fluid mixing process, CO2 effervescence, cooling, and increasing of pH. Low-temperature hydrothermal activity subsequently produced hematite ores associated with propylitic alteration. The metacarbonate host rocks are LILE-depleted and HFSE-enriched due to metasomatic alteration. Sina Asadi and Mohammad Ali Rajabzadeh Copyright © 2014 Sina Asadi and Mohammad Ali Rajabzadeh. All rights reserved. Mineralogical and Geochemical Characterization of Gold Bearing Quartz Veins and Soils in Parts of Maru Schist Belt Area, Northwestern Nigeria Mon, 14 Jul 2014 00:00:00 +0000 Epigenetic, N-S, NNE-SSW quartz veins crosscut metapelites and metagabbro in Maru area. The objectives of this work were to study field, mineralogy, and geochemical characteristics of gold bearing quartz veins and soils. Euhedral and polygonal magnetite with hematite constituted the major ore minerals. Quartz occurred as main gangue phase with appreciable sericite and chlorite. The mineralogy of soil retrieved from twelve minor gold fields examined with X-ray diffraction is quartz ± albite ± microcline ± muscovite ± hornblende ± magnetite ± illite ± kaolinite ± halloysite ± smectite ± goethite ± vermiculite ± chlorite. The concentration of gold in quartz vein varies from 10.0 to 6280.0 ppb with appreciable Pb (3.5–157.0 ppm) and ΣREE (3.6 to 82.9 ppm). Gold content in soil varies from < to 5700.0 ppb. The soil is characterized by As ± Sb gold’s pathfinder geochemical association. Multidata set analysis revealed most favourable areas for gold. Possibility of magmatic fluids as part of ore constituents is feasible due to presence of several intrusions close to quartz veins. Based on field, mineralogical, and geochemical evidences, ore fluids may have been derived from fracturing, metamorphic dewatering, crustal devolatilization of sedimentary, gabbroic protoliths, and emplaced in an orogenic setting. Samson Adeleke Oke, Akinlolu Festus Abimbola, and Dieter Rammlmair Copyright © 2014 Samson Adeleke Oke et al. All rights reserved. Crustal Evolution of a Paleozoic Intra-oceanic Island-Arc-Back-Arc Basin System Constrained by the Geochemistry and Geochronology of the Yakuno Ophiolite, Southwest Japan Wed, 28 May 2014 08:09:05 +0000 The Yakuno ophiolite in southwest Japan is considered to have been obducted by the collision between an intra-oceanic island-arc-back-arc basin (intra-OIA-BAB) system and the East Asian continent during the late Paleozoic. New SIMS (SHRIMP) zircon U-Pb determinations for amphibolite and metagabbro of BAB origin within the Yakuno ophiolite yield ages of 293.4 ± 9.5 Ma and 288 ± 13 Ma, respectively. These ages are slightly older (however, overlapping within analytical errors) than the magmatic age of arc granitoids (ca. 285–282 Ma) that intruded into the mafic rocks of BAB origin. Results from geochronological and geochemical data of the Yakuno ophiolite give rise to the following tentative geotectonic model for the Paleozoic intra-OIA-BAB system: the initial stage of BAB rifting (ca. 293–288 Ma) formed the BAB crust with island-arc basalt (IAB) signatures, which was brought to the OIA setting, and generated the arc granitoids (ca. 285–282 Ma) by anatexis of the BAB crust. A later stage of BAB rifting (<ca. 285 Ma) formed the BAB crust with IAB to MORB signatures, on which the Permian sediments were conformably deposited. These components collided with the eastern margin of the East Asian continent during the early Mesozoic. Yoshimitsu Suda, Yasutaka Hayasaka, and Kosuke Kimura Copyright © 2014 Yoshimitsu Suda et al. All rights reserved. Determination of Specific Surface of Rock Grains by 2D Imaging Thu, 17 Apr 2014 14:00:36 +0000 Specific surface is an important parameter for predicting permeability of porous rocks. Many digital methods have been invented to extract the rock properties via imaging such as Micro-CT. With utilizing 3D volume data, this helps in precise investigation; however, it is neither economically efficient nor can be applied for different situations. In this study, a new approach is developed to estimate rock specific surface using 2D thin section images with micron resolution. One specific conclusion of this study is that there is specific ratio between the specific perimeter of 2D images and the specific surface in the 3D real rock structure. To further investigate this ratio several 3D blocks of rock volume data have been virtually cut in every possible angle and the value of specific perimeter calculated for each obtained 2D thin section. Finally, the predicted value of specific surface for 6 rock types is compared with the real values calculated from the original 3D data. Result indicates acceptable precision of this approach for sandstone rocks whereas not applicable for carbonate rocks. Arash Rabbani, Saeid Jamshidi, and Saeed Salehi Copyright © 2014 Arash Rabbani et al. All rights reserved. A Petrographic Study of the Three Forks Formation (Upper Devonian), Williston Basin, North Dakota: Based on Thin Section Analysis, XRD and SEM Thu, 17 Apr 2014 07:00:54 +0000 Deeply buried below 8,000 ft, the Three Forks Formation in North Dakota displays a variety of interesting diagenetic characteristics including dolomitization and hematite precipitation. Samples from three lithofacies are analyzed by thin section and SEM petrography and combined bulk and clay XRD analyses. Key aspects controlling the porosity and permeability of this formation are revealed by focusing on the detail mineralogy, rock type and diagenetic mineral distribution, and overall reservoir quality. Results prove that the Three Forks mineralogy is dominated by dolomite, along with substantial hematite, monocrystalline quartz, and mica flakes with trace feldspar, calcite, and pyrite. Clays mainly consist of illite together with minor chlorite and kaolinite and are associated with the scattered clasts. The reservoir quality is controlled by intercrystalline, rare microvuggy, and microporosity types that result from diagenetic and depositional events. Three stages of the dolomitization process are identified and discussed. Our hypothesis is that dolomitization commenced soon after deposition and was pervasive as no original carbonate texture is detectable. Richard Ashu Copyright © 2014 Richard Ashu. All rights reserved. Assessment of Slope Instability and Risk Analysis of Road Cut Slopes in Lashotor Pass, Iran Thu, 10 Apr 2014 12:36:59 +0000 Assessment of the stability of natural and artificial rock slopes is an important topic in the rock mechanics sciences. One of the most widely used methods for this purpose is the classification of the slope rock mass. In the recent decades, several rock slope classification systems are presented by many researchers. Each one of these rock mass classification systems uses different parameters and rating systems. These differences are due to the diversity of affecting parameters and the degree of influence on the rock slope stability. Another important point in rock slope stability is appraisal hazard and risk analysis. In the risk analysis, the degree of danger of rock slope instability is determined. The Lashotor pass is located in the Shiraz-Isfahan highway in Iran. Field surveys indicate that there are high potentialities of instability in the road cut slopes of the Lashotor pass. In the current paper, the stability of the rock slopes in the Lashotor pass is studied comprehensively with different classification methods. For risk analyses, we estimated dangerous area by use of the RocFall software. Furthermore, the dangers of falling rocks for the vehicles passing the Lashotor pass are estimated according to rockfall hazard rating system. Mohammad Hossein Taherynia, Mojtaba Mohammadi, and Rasoul Ajalloeian Copyright © 2014 Mohammad Hossein Taherynia et al. All rights reserved. Indications for the Occurrence of Gas Hydrates in the Fram Strait from Heat Flow and Multichannel Seismic Reflection Data Sun, 09 Feb 2014 06:41:19 +0000 The distribution of gas hydrates recently raised increased attention, especially along glaciated continental margins, due to its potential importance for slope stability and global climate. We present new heat flow data together with multichannel reflection seismic data from the central Fram Strait in-between Northeast Greenland and Svalbard. This area is only accessible by icebreaking vessels, and, therefore, knowledge about this area is still sparse. The new heat flow data concur with previous measurements in the region. High temperature gradients of >200 mK/m were recorded along the active spreading zone in the Fram Strait, and gradients of 75 mK/m along the western slope of Yermak Plateau. Along the Northeast Greenland slope, the measured gradients reach 54 mK/m at maximum. Seismic data image bottom-simulating reflections proofing that the known gas-hydrate province spreads much further north along the western slope of the Yermak Plateau than previously known. Existing slide scars indicate that there might be a causal relationship between the occurrence of gas hydrates and slope instability in that area. Along the Northeast Greenland continental margin and in the adjacent abyssal plain, strong indications for the occurrence of gas within the sedimentary basins and for its migration along fault zones and chimney-like structures are found. W. H. Geissler, P. V. Pulm, W. Jokat, and A. C. Gebhardt Copyright © 2014 W. H. Geissler et al. All rights reserved. Arctic Ocean Gas Hydrate Stability in a Changing Climate Thu, 19 Dec 2013 08:18:16 +0000 Recent estimations suggest that vast amounts of methane are locked in the Arctic Ocean bottom sediments in various forms of gas hydrates. A potential feedback from a continued warming of the Arctic region is therefore the release of methane to the atmosphere. This study addresses the relationship between a warming of the Arctic ocean and gas hydrate stability. We apply a theoretical model that estimates the base of the gas hydrate stability zone in the Arctic Ocean considering different bottom water warming and sea level scenarios. We model the present day conditions adopting two different geothermal gradient values: 30 and 40°C/km. For each geothermal gradient value, we simulate a rise and a decrease in seafloor temperature equal to 2°C and in sea level equal to 10 m. The results show that shallow gas hydrates present in water depths less than 500 m would be strongly affected by a future rise in seafloor temperature potentially resulting in large amounts of gas released to the water column due to their dissociation. We estimate that the area, where there could be complete gas hydrate dissociation, is about 4% of the area where there are the conditions for gas hydrates stability. Michela Giustiniani, Umberta Tinivella, Martin Jakobsson, and Michele Rebesco Copyright © 2013 Michela Giustiniani et al. All rights reserved. Formation of Gas Hydrates at Deep Interior of the Earth and Their Dissipation to Near Surface Horizon Tue, 10 Dec 2013 17:37:51 +0000 Methane hydrates occur in diverse geological settings and their origin is puzzling, owing to package of more than 160 times of equivalent volume of methane in ice cage at standard temperature pressure indicating formation at high pressure state. At the core mantle boundary of the Earth, high dense supercritical fluids of Fe with significant amount of O, Ti, Nb, C, H, and other elements exist. Geophysical studies reveal that at the core mantle boundary of the Earth at 2900 km depth, temperature exceeds 4000°C, pressure ranges around 135 GPa and the material present possesses high molar volume 8.8 gm/cm3. Sudden release of pressure causes opening of vents and supercritical fluid/plasma phase of CH4 exsolves as finely divided plasma bubbles and rapidly rises up through weak planes. The potential energy of these bubbles is so high; the velocity of ascending bubbles steadily increases with super adiabatic state with minimum frictional energy loss. The rapidly ascending CH4 plasma bubbles quench with outer skins of H2 or H2O while passing through the permafrost or near surface horizons. Again, some bubbles burst into numerous tiny droplets of dense methane into cold seawater near seafloor. The water layer surrounding the tiny bubble is formed as ice-cage on hydrophobic methane, by absorbing or releasing sufficient latent heat energy from freezing water for endothermic formation of methane hydrate. The water envelops as ice cage around CH4 near surface conditions at ambient temperature and pressure conditions. Numerical analyses of specific heats J/mole for CH4 and H2O reveal that such plasma bubbles could form even from upper mantle horizons ~100 km depth but with less potentiality. The charged particles inside the plasma bubble are highly influenced by magnetic and electric fields. Hence most bubbles drive through deep interconnecting fractures towards continental margins of polar region where earth’s electromagnetic and gravity intensities are relatively high. Ramachandran Ramasamy, Subramanian Subramanian, and Ranganathan Sundaravadivelu Copyright © 2013 Ramachandran Ramasamy et al. All rights reserved. Petrogenesis of Quaternary Shoshonitic Volcanism in NE Iran (Ardabil): Implication for Postcollisional Magmatism Sat, 07 Dec 2013 11:08:19 +0000 Trachyandesites, trachytes, andesites, and pyrocalstic rocks, with shoshonitic signature, are the main Quaternary volcanic rocks in the Sabalan region (Ardabil). Plagiocalse, K-feldspar, biotite associated with clinopyroxene, and glass are the main constituents of these lavas. Plagioclases are andesine to labradorite while clinopyroxenes have augitic composition. The Sabalan volcanic rocks show enrichment in LREEs (relative to HREEs) and are characterized by enrichment in LILEs and depletion in HFSEs. Petrological observations, along with rare earth and trace elements geochemistry, suggest shoshonitic signature for Sabalan lavas. This signature highlights derivation from a subduction-related source. The Sabalan volcanic rocks are isotopically characterized by derivation from an enriched mantle source with a tendency to plot in the fields defined by island-arc basalts (IAB) and OIBs (in εNd versus 87Sr/86Sr diagram). The geochemical and isotopic characteristics of the Sabalan lavas suggest that their magma has been issued via low degree partial melting of a subduction-metasomatized continental lithospheric mantle. The formation of these lavas is related to slab steepening and breakoff in a postcollisional regime. Habib Shahbazi Shiran Copyright © 2013 Habib Shahbazi Shiran. All rights reserved. Surface Morphology of Basalt Columns at Svartifoss, VatnajökulsÞjóðgarður, Southern Iceland Tue, 03 Dec 2013 13:42:19 +0000 A spectacular example of columnar-jointed basalt occurs at Svartifoss in the Vatnajökull National Park of southern Iceland. The columns are notable for a variety of features on the vertical joint surfaces and the horizontal parting surfaces. The jointed surfaces of the columns display horizontal striations at a spacing of centimeters to decimeters. The individual striations exhibit crescentic hackles with a plumose pattern, the orientation of which varies between adjacent striations. Also present are gently dipping, millimeter-scale laminations not previously described. Horizontal parting surfaces of the columns display a circular ring that inscribes most of the diameter column. The ring features alternately positive or negative relief against the perimeter of the column and exhibits a radiating pattern of hackles originating at the center of the ring. Petrographic examination reveals that the basalt contains an interlocking network of plagioclase laths preferentially aligned perpendicular to the column axes. The circular features have been described previously and attributed to late-stage melt migration driven by a load-induced pressure gradient. The striations were formed from stepwise, downward propagation of the polygonal fracture system, and the plumose structures were formed from tensile stresses during fracture propagation. The small-scale laminations may result from preferential grain alignment of plagioclase laths. Lawrence H. Tanner Copyright © 2013 Lawrence H. Tanner. All rights reserved. Remote Sensing and Geographic Information System for Fault Segments Mapping a Study from Taiz Area, Yemen Mon, 11 Nov 2013 14:24:06 +0000 GIS and remote sensing data for allowing detection of structural features, such as faults, offer opportunities for improving mapping and identifying the areas that are likely to be locations of faulting areas. Landsat ETM-7 satellite data images were used and band-5 was found as the most suitable band for lineament delineation, based on the ability to identify geological features. Four contributing factors, namely, drainage patterns, faults (previously mapped), lineaments, and lithological contacts layers, were parameters used in this study to produce a fault potential prediction map using the overlay model techniques. The potential map (fault susceptibility map) classifies the study area into five potential zones, namely, very low, low, moderate, high, and very high potential. The areas covered by moderate to the highest potential zones were considered as fault segments (fault lines) in the area. The comparison of the potential map and the published fault map by using GIS matching techniques shows that 75 fault segments (fault lines) in the potential map were not properly identified in the study area. The correlation between fault segments and faults data collected from field work stations shows that there were 39 fault segments which may represent new faults in the area being identified. The presence of these faults is not known from the literature; this leads to updating and revising of existing geological map of the study area. Anwar Abdullah, Shawki Nassr, and Abdoh Ghaleeb Copyright © 2013 Anwar Abdullah et al. All rights reserved. Application of 2D Electrical Resistivity Tomography in Landfill Site: A Case Study of Iku, Ikare Akoko, Southwestern Nigeria Mon, 28 Oct 2013 08:31:19 +0000 2D resistivity tomography was used in , , and directions to delineate the extent of leachate plumes around a solid waste landfill in Ikare Akoko, Ondo State, behind the secretariat. I access the geometry and depth contamination extent of the landfill repository using dipole-dipole method and Global positioning system to ascertain the image of the subsurface and the position at the earth surface. The study area is underlain by Precambrian basement rocks. Quantitative interpretation of pseudosection results shows that in traverse 1, stations 7, 8, and 9 form a conductive path at the depth of 1–10 m and penetrate to depth of 25 m; the second traverse shows a layer of highly conductive structure extending diagonally across the study area, while the third traverse is partly conductive and largely resistive due to its closeness to fresh basement rocks. The 2D structure has shown various conductive path ways via fractures and openings, thus, contaminating the groundwater. I recommend that further geochemical analysis of the water should be done to ascertain the level of contamination. Cyril Chibueze Okpoli Copyright © 2013 Cyril Chibueze Okpoli. All rights reserved. Study on p-Wave Attenuation in Hydrate-Bearing Sediments Based on BISQ Model Wed, 09 Oct 2013 18:46:35 +0000 In hydrate-bearing sediments, the elastic wave attenuation characteristics depend on the elastic properties of the sediments themselves on the one hand, and on the other hand, they also depend on the hydrate occurrence state and hydrate saturation. Since the hydrate-bearing sediments always have high porosity, so they show significant porous medium characteristics. Based on the BISQ porous medium model which is the most widely used model to study the attenuation characteristics in the porous media, we focused on p-wave attenuation in hydrate-bearing sediments in Shenhu Area, South China Sea, especially in specific seismic frequency range, which lays a foundation for the identification of gas hydrates by using seismic wave attenuation in Shenhu Area, South China Sea. Our results depict that seismic wave attenuation is an effective attribute to identify gas hydrates. Chuanhui Li, Kai Feng, and Xuewei Liu Copyright © 2013 Chuanhui Li et al. All rights reserved. Biostratigraphy and Sequence Stratigraphy of Paleogene Deposits in Central Kopet-Dagh Basin (NE of Iran) Sun, 15 Sep 2013 15:13:28 +0000 In this paper, the biostratigraphy and sequence stratigraphy of marine Paleogene deposits from the Kopet-Dagh basin (NE of Iran) are described. Particularly the absence of Morozovella genus is discussed. In addition, the Paleocene/Eocene boundary has been studied in detail using the record of planktonic and larger benthic foraminifera. This boundary is located probably within a thin red horizon (~10–15 cm) representing a paleosoil. Close to this boundary is located the base of the calcareous test dissolution interval, with the dominance of agglutinated benthic foraminifera and with a sudden decrease in the richness of benthic foraminiferal species. Biostratigraphic studies led to the identification of 33 genera of larger benthic foraminifera and 5 genera of planktonic foraminifera. Petrographical studies indicate that these sediments, consisting of four carbonate lithofacies (15 subfacies), may have been deposited on a shallow carbonate platform (ramp type). These lithofacies have been deposited in open marine, shoal, lagoon, and tidal flat environmental conditions. Sequence stratigraphic analysis led to the identification of four third-order depositional sequences. The interpreted sea-level curve in the Kopet-Dagh basin can be correlated with Paleocene-Eocene global curves, with a sea-level fall in the latest Paleocene, followed by a sea-level rise in the earliest Eocene. Batool Rivandi, Mohammad Vahidinia, Mehdi Nadjafi, Asadollah Mahboubi, and Abbas Sadeghi Copyright © 2013 Batool Rivandi et al. All rights reserved. Fluoride in the Serra Geral Aquifer System: Source Evaluation Using Stable Isotopes and Principal Component Analysis Thu, 29 Aug 2013 11:10:15 +0000 Groundwater with anomalous fluoride content and water mixture patterns were studied in the fractured Serra Geral Aquifer System, a basaltic to rhyolitic geological unit, using a principal component analysis interpretation of groundwater chemical data from 309 deep wells distributed in the Rio Grande do Sul State, Southern Brazil. A four-component model that explains 81% of the total variance in the Principal Component Analysis is suggested. Six hydrochemical groups were identified. δ18O and δ2H were analyzed in 28 Serra Geral Aquifer System samples in order to identify stable isotopes patterns and make comparisons with data from the Guarani Aquifer System and meteoric waters. The results demonstrated a complex water mixture between the Serra Geral Aquifer System and the Guarani Aquifer System, with meteoric recharge and ascending water infiltration through an intensive tectonic fracturing. Arthur Schmidt Nanni, Ari Roisenberg, Maria Helena Bezerra Maia de Hollanda, Maria Paula Casagrande Marimon, Antonio Pedro Viero, and Luiz Fernando Scheibe Copyright © 2013 Arthur Schmidt Nanni et al. All rights reserved. Multiscale Erosion Surfaces of the Organic-Rich Barnett Shale, Fort Worth Basin, USA Mon, 24 Jun 2013 13:49:43 +0000 The high frequency and diversity of erosion surfaces throughout the Barnett Shale give a unique view into the short-duration stratigraphic intervals that were previously much more difficult to detect in such fine-grained rocks. The erosion surfaces in Barnett Shale exhibit variable relief (5.08–61 mm) which commonly consists of shelly laminae, shale rip-up clasts, reworked mud intraclasts, phosphatic pellets, and/or diagenetic minerals (dolomite and pyrite) mostly with clay-rich mudstone groundmass. Several factors control this lithological variation, including the energy conditions, rate of relative sea-level fluctuation, rate of sedimentation, sediment influx, and the lithofacies type of the underlying as well as the overlying beds. The erosional features and their associated surfaces make them serve at least in part as boundaries between different genetic types of deposits but with different scales according to their dependence on base level and/or sediment supply. Accordingly, the studied erosion surfaces of the Barnett Shale can be grouped into three different scales of sequence stratigraphic surfaces: sequence-scale surfaces, parasequence-scale surfaces, and within trend-scale surfaces. Mohamed O. Abouelresh Copyright © 2013 Mohamed O. Abouelresh. All rights reserved. Multiphase Alkaline Basalts of Central Al-Haruj Al-Abyad of Libya: Petrological and Geochemical Aspects Tue, 18 Jun 2013 16:46:37 +0000 Al-Haruj basalts that represent the largest volcanic province in Libya consist of four lava flow phases of varying thicknesses, extensions, and dating. Their eruption is generally controlled by the larger Afro-Arabian rift system. The flow phases range from olivine rich and/or olivine dolerites to olivine and/or normal basalts that consist mainly of variable olivine, clinopyroxene, plagioclase, and glass. Olivine, plagioclase, and clinopyroxene form abundant porphyritic crystals. In olivine-rich basalt and olivine basalt, these minerals occur as glomerophyric or seriate clusters of an individual mineral or group of minerals. Groundmass textures are variably intergranular, intersertal, vitrophyric, and flow. The pyroclastic, clastogenic flows and/or ejecta of the volcanic cones show porphyritic, vitrophric, pilotaxitic, and vesicular textures. They are classified into tholeiite, alkaline, and olivine basalts. Three main groups are recorded. Basalts of phase 1 are generated from tholeiitic to alkaline magma, while those of phases 3 and 4 are derived from alkaline magma. It is proposed that the tholeiitic basalts represent prerift stage magma generated by higher degree of partial melting (2.0–3.5%) of garnet-peridotite asthenospheric mantle source, at shallow depth, whereas the dominant alkaline basalts may represent the rift stage magma formed by low degree of partial melting (0.7–1.5%) and high fractionation of the same source, at greater depth in an intra-continental plate with OIB affinity. The melt generation could be also attributed to lithosphere extension associated with passive rise of variable enriched mantle. Abdel-Aal M. Abdel-Karim, El-Nuri M. Ramadan, and Mohamed R. Embashi Copyright © 2013 Abdel-Aal M. Abdel-Karim et al. All rights reserved. Magmatism in the Asunción-Sapucai-Villarrica Graben (Eastern Paraguay) Revisited: Petrological, Geophysical, Geochemical, and Geodynamic Inferences Thu, 16 May 2013 08:29:09 +0000 The Asunción-Sapucai-Villarrica graben (ASV) in Eastern Paraguay at the westernmost part of the Paraná Basin was the site of intense magmatic activity in Mesozoic and Tertiary times. Geological, petrological, mineralogical, and geochemical results indicate that the following magmatic events are dominant in the area: (1) tholeiitic basalt and basaltic andesites, flows and sills of low- and high-titanium types; (2) K-alkaline magmatism, where two suites are distinguished, that is, basanite to phonolite and alkali basalt to trachyte and their intrusive analogues; (3) ankaratrite to phonolite with strong Na-alkaline affinity, where mantle xenoliths in ultramafic rocks are high- and low-potassium suites, respectively. The structural and geophysical data show extensional characteristics for ASV. On the whole, the geochemical features imply different mantle sources, consistently with Sr-Nd isotopes that are Rb-Nd enriched and depleted for the potassic and sodic rocks, respectively. Nd model ages suggest that some notional distinct “metasomatic events” may have occurred during Paleoproterozoic to Neoproterozoic times as precursor to the alkaline and tholeiitic magmas. It seems, therefore, that the genesis of the ASV magmatism is dominated by a lithospheric mantle, characterized by small-scale heterogeneity. Piero Comin-Chiaramonti, Angelo De Min, Aldo Cundari, Vicente A. V. Girardi, Marcia Ernesto, Celso B. Gomes, and Claudio Riccomini Copyright © 2013 Piero Comin-Chiaramonti et al. All rights reserved. Recycling of Badger/Fox Burrows in Late Pleistocene Loess by Hyenas at the Den Site Bad Wildungen-Biedensteg (NW, Germany): Woolly Rhinoceros Killers and Scavengers in a Mammoth Steppe Environment of Europe Tue, 30 Apr 2013 14:51:32 +0000 The Late Pleistocene (MIS 5c-d) Ice Age spotted hyena open air den and bone accumulation site Bad Wildungen-Biedensteg (Hesse, NW, Germany) represents the first open air loess fox/badger den site in Europe, which must have been recycled by Crocuta crocuta spelaea (Goldfuss, 1823) as a birthing den. Badger and fox remains, plus remains of their prey (mainly hare), have been found within the loess. Hyena remains from that site include parts of cub skeletons which represent 10% of the megafauna bones. Also a commuting den area existed, which was well marked by hyena faecal pellets. Most of the hyena prey bones expose crack, bite, and nibbling marks, especially the most common bones, the woolly rhinoceros Coelodonta antiquitatis (NISP  =  32%). The large amount of woolly rhinoceros bones indicate hunting/scavenging specializing on this large prey by hyenas. Other important mammoth steppe hyena prey remains are from Mammuthus primigenius, Equus caballus przewalskii, Bison/Bos, Megaloceros giganteus, Cervus elaphus, and Rangifer tarandus. The few damaged bone remains of a scavenged cave bear Ursus spelaeus subsp. are unique for an open air situation. Abundant micromammal, frog, and some fish remains were concentrated in “pellets” that contain mainly mammoth steppe micromammals and also frog and fish remains that seem to originate from the nearby river/lake. Cajus Diedrich Copyright © 2013 Cajus Diedrich. All rights reserved.