Browse

1 - 10 of 761 items :

  • Geosciences, other x
Clear All
Lamprophyric rock locations in Greece

Abstract

Twenty-four areas with lamprophyric formations have been located through a bibliographic search in Macedonia, Thrace, the islands and Attica. Most lamprophyre types have been identified including rare “alkali minette”. In most localities the dikes/sills appear to be late mantle products associated with deep faulting following extensional activity in granitoids.

Open access
Synthesis and characterization of cadmium chlorapatite Cd5(PO4)3Cl

Abstract

One of the most effective methods for the immobilization of toxic metals involves the use of minerals from the apatite supergroup. The formation of cadmium chlorapatite may lead to successful entrapping of cadmium; thus, it is important to examine the solubility constant to determine the stability of cadmium in the the apatite structure. Cadmium chlorapatite was synthetized and characterized by X-ray diffraction, infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy. The solubility constant (log) Ksp of cadmium chlorapatite was -65.58. The Gibbs free energy of formation of cadmium chlorapatite reached -3950.48 kJ mol−1. The solubility constant turned out to be low but was enough for cadmium chlorapatiteto be considered a very stable compound..

Open access
3D Interpretation of Resistivity Data for Groundwater Potential Assessment of Pakhli Plain, Mansehra District, Pakistan

Abstract

The present research describes a method of combining geostatistical analysis with geophysical inversion of electrical resistivity data conducted in Pakhli Plain, northwestern Himalayas, Pakistan. The raw data has been collected from the Technical Report VII-I on Ground Water Resources in Pakhli Plain, Mansehra District. Subsequently, the data has been deciphered and broadened from one dimensional resistivity data into a 2D model that can be entirely visualized and deduced in a spatial sense. Interpretation and calibration of the electrical resistivity curves with the lithologies and geophysical logs of boreholes suggests possible identification of distinctive sedimentary accumulations occurring within the Pakhli Plain. The 2D and 3D gridding and visualization is imperative to map the extents of the alluvial deposits within the Pakhli Plain formed during the periods of extreme tectonic activity. The coarser sediments are associated with lower levels of resistivity as measured in the electrical surveys, whereas the finer sediments exhibit characteristically lower resistivities. Therefore, the zones of low and high resistivity values are indicative of particles associated with coarser and finer sediments, respectively. It has been mentioned that the Pakhli Plain has remained a lacustrine zone during some time in the geological past as indicated by low resistivities representing finer sediments in the middle of the Plain. Consequently, the overall transmissivity of the sediments is low, which imply poor conditions for commercial groundwater production in the Pakhli Plain. Moreover, high resistivity zones of coarse material could be further investigated for groundwater potential areas. In particular, the prime objectives of the present study include 3D modeling of underground resistivity and its exploration in terms of groundwater potential on the basis of distribution of low resistivity zones.

Open access
Biostratigraphic constraints for a Lutetian age of the Harrersdorf Unit (Rhenodanubian Zone): Implication for basement structure of the northern Vienna Basin (Austria)

Abstract

The formations underlying the Neogene infill of the Vienna Basin are still poorly documented. Until now correlation of subsurface lithostratigraphic units with those of the Rhenodanubian nappe system and the Magura nappe system, outcropping at the basin margins, has been based on extrapolations. A recent drilling campaign in the Bernhardsthal oil field of the northern Vienna Basin in Austria reached the pre-Neogene basement and provided cuttings for biostratigraphic and paleoecological analyses. Based on these data, acquired by using detailed micro- and nanno-paleontological analyses, a Lutetian age (middle Eocene) and a bathyal depositional environment for the Flysch of the Harrersdorf Unit was documented. The lithological similarity of the drilling with the Steinberg Flysch Formation of the Greifenstein Nappe and its Lutetian age suggests, that the middle Eocene part of the Harrersdorf Unit represents a continuation of the Greifenstein Nappe of the Rhenodanubian Flysch, rather than a frontal part of the Rača Nappe of the Magura Flysch as previously thought.

Open access
Deep gravity data interpretation using seismic reflection and well data: A case study of the West Gharib-Bakr area, Eastern Desert, Egypt

Abstract

A rigorous processing and analysis of the gravity data with seismic reflection and borehole information enabled a general view of the deep-seated regional structures in the West Gharib-Bakr area, Eastern Desert, Egypt. In this context, several interpretational techniques were applied to learn more about the supra-basement structures and intra-basement sources. The interpretation started with a review of the seismic data to clarify the structural elements on top of the Miocene strata, where a number of isochronous reflection maps were constructed and had migrated into depth maps. The Bouguer anomaly map was processed using Fast Fourier Transform filtering based on spectral analysis to separate the gravity anomalies into its components. Gravity stripping was also performed under the seismic isopachs and density controls. The gravity effect of each rock unit was calculated and progressively removed from the original data to obtain a new gravity map on top of the Pre-Miocene. To ensure more reliable results, further filtering and analytical processes were applied to the stripped map. The results of seismic analysis show simple structural configurations at the Miocene level, with a significant increase of evaporite thickness along the Gulf of Suez coast. In contrast, analysis of the stripped gravity map reveals a more intricate structure at the Pre-Miocene level, with increasing numbers/lengths of faults on the basement surface. Lineament analysis shows two major peaks trending N0–20°W and N50–70°E, produced by two main forces in NNW–SSE (compression) and ENE–WSW (tension) directions. The models confirmed a rough and ruptured basement surface, with no evidence of any magmatic intrusions penetrating the sediments. The basement relief map delineates five basins/sub-basins in the area which are separated from each other by ridges/saddles.

Open access
Geophysical and geological interpretation of the Vienna Basin pre-Neogene basement (Slovak part of the Vienna Basin)

Abstract

The Vienna Basin is situated at the contact of the Bohemian Massif, Western Carpathians, and Eastern Alps. Deep borehole data and an existing magnetotelluric profile were used in density modelling of the pre-Neogene basement in the Slovak part of the Vienna Basin. Density modelling was carried out along a profile oriented in a NW–SE direction, across the expected contacts of the main geological structures. From bottom to top, four structural floors have been defined. Bohemian Massif crystalline basement with the autochthonous Mesozoic sedimentary cover sequence. The accretionary sedimentary wedge of the Flysch Belt above the Bohemian Massif rocks sequences. The Mesozoic sediments considered to be part of the Carpathian Klippen Belt together with Mesozoic cover nappes of Alpine and Carpathian provenance are thrust over the Flysch Belt creating the third structural floor. The Neogene sediments form the highest structural floor overlying tectonic contacts of the Flysch sediments and Klippen Belt as well as the Klippen Belt and the Alpine/Carpathians nappe structures.

Open access
Mineralogical and physico–chemical properties of bentonites from the Jastrabá Formation (Kremnické vrchy Mts., Western Carpathians)

Abstract

In the past years an increasing demand for bentonites resulted in the opening of new bentonite deposits in the Jastrabá Formation. The shortage of information, in particular analytical data, on the bentonites from the newly opened Jastrabá Fm. deposits was the motivation for the current study. Smectite is the predominant mineral in all bulk bentonites from the new deposits. Its amount varied between 43 and 90 wt. %. The bulk bentonites also contain variable amounts (10–57 wt. %) of mineral admixtures such as feldspars, mica, opal-CT, kaolinite, quartz and sometimes goethite. The smectite mineral comprising the studied bentonites was montmorillonite. The octahedral Al in the structure of montmorillonite was partially substituted by Mg, and to a lesser extent by Fe. The interlayer space of montmorillonite is occupied predominantly by divalent exchangeable cations (Ca2+ and Mg2+). The dehydroxylation temperature of smectites (>600 °C) determined on the DTG curves indicates the presence of the cis-vacant variety of montmorillonites. The mean crystallite thicknesses of smectites (TMEAN) calculated by BWA analyses ranges from 7.2 to 11.5 nm. The shape of the crystallite thickness distributions (CTDs) for smectites is lognormal in all cases. Cation exchange capacity (CEC) and total specific surface area (TSSA) increases with increasing amount of smectite. The CEC of 101 meq/100g and TSSA of 616 m2/g correspond to bulk bentonite from the Stará Kremnička III deposit containing 89 wt. % of smectite.

Open access
New 40Ar/39Ar, fission track and sedimentological data on a middle Miocene tuff occurring in the Vienna Basin: Implications for the north-western Central Paratethys region

Abstract

The Kuchyňa tuff is found on the Eastern margin of the Vienna Basin and was formed by felsic volcanism. The Ar/Ar single grain sanidine method was applied and resulted in an age of 15.23±0.04 Ma, which can be interpreted as the age of the eruption. The obtained numerical age is in accordance with the subtropical climate inferred by the presence of fossil leaves that originated in an evergreen broadleaved forest. Furthermore, the described volcanism was connected with the syn-rift stage of the back-arc Pannonian Basin system. The sedimentological data from the underlying sandy mudstones indicate alluvial environment what confirms terrestrial conditions during deposition. Moreover, the tuff deposition probably occurred shortly before the Badenian transgression of the Central Paratethys Sea.

Open access
Aeromagnetic Mapping of Iwo Region of Southwestern Nigeria for Lithostructural Delineation

Abstract

The IGRF filtered Aeromagnetic data over Iwo, southwestern part of Nigeria within the basement complex was subjected to reduction to magnetic equator filtering, residual filtering, upward and downward continuation filtering, automatic gain control filtering, tilt angle derivative, second vertical derivative, analytical signal and Euler deconvolution. This reveals the geologic information such as structural trend. Based on the result of the total magnetic intensity map, reduction to equator map, analytical signal map and residual magnetic intensity map, it can be concluded that; The rocks in the study area have a trend of approximately northeast-southwest direction as seen on the upward continuation map. Most of the delineated lineaments found within the study area strike mostly in NNE-SSW, NE-SW and NW-SE with minor trend of E-W and ENE-WSW direction. Structural lineament orientation suggested that they were products of Pan-African orogeny (NE-SW, NW-SE and NNE-SSW trends) and pre-Pan-African orogeny (NNW-SSE and E-W trend). The interpretation of the aeromagnetic dataset gave an insight into the regional geology and structural trends of the area.

Open access
Provenance of the Early Cambrian Abbottabad Formation in the Hazara region, Pakistan

Abstract

The early Cambrian Abbottabad Formation mainly comprises of dolomite, sandstone, shale and conglomerates at Khote-di-Qabar section, Hazara region, Pakistan. The formation makes lower contact with Hazara Formation and upper contact with Hazira Formation. The formation is comprehensively studied during the field and lab work to interpret its provenance. Five distinguishable sedimentary units including 1) Tanaki boulder bed; 2) Sanghargali siltstone/shale; 3) Mohammdagali Dolomite/quartzite; 4) Mirpur sandstone; 5) Sirban dolomite can be identified in the field that indicate variable depositional strata of the formation under various depositional setting. Additionally, petrographic analysis of Sanghargali siltstone/shale unit and Mirpur sandstone unit of the formation indicate the main lithologies of these units are litharenite and sublitharenite respectively. Moreover, the provenance of these sandstone units of the formation most probably belong to Aravali and Malani Ranges located in the South of the study area.

Open access