Chemostratigraphy of the Cenomanian-Turonian shallow-water carbonate: new correlation for the rudist levels from north Sinai,Egypt

The present study aims to provide carbon-isotope curves for the Cenomanian to Turonian rudist-dominated successions in north Sinai. The high-resolution carbon-isotope curves obtained from north Sinai sections provide new insight for calibrating the age of rudists as well as for evaluating the effects of the oceanic anoxic event 2 (OAE2) on rudist communities. The primary goals are (1) to provide a high-resolution sequence stratigraphic framework for the Cenomanian-Turonian succession, (2) to use rudist and ammonite biostratigraphic data to distinguish the stratigraphic levels of the rudist species, and (3) to integrate the chemostratigraphic (δ¹³C) profile and the rudist levels to improve the biostratigraphy based on the rudist distributions and the carbon-isotope data. The recognition of three ammonite zones through the Cenomanian-Turonian succession was utilized to identify four temporally significant rudist levels indicative of the Lower Cenomanian, Middle Cenomanian, Upper Cenomanian, and Middle Turonian, respectively. Most of the rudists occur in the highstand deposits of medium-scale sequences. Carbon- and oxygen-isotopic analyses were carried out on both rudists and surrounding carbonate units. Based on the variations in the carbon-isotope signals, 12 chronostratigraphic segments were identified in the studied sections. The Cenomanian carbon-isotope segments (C23–C30) were obtained from the Halal Formation at Gabal Yelleg and Gabal Maaza sections, while the Turonian segments (C30–C34) were measured from the Wata Formation at Gabal Yelleg section. The carbon-isotope record from the studied sections is consistent with the trends documented in previous studies of the Tethyan realm. The Cenomanian-Turonian boundary is placed at the onset of falling carbon-isotope values (δ¹³C) from 2.61 to ?0.25‰ in the upper part of OAE2 with the carbon-isotope segment C30 at Gabal Yelleg. The negative shift in δ¹³C values (C33) occurred in the Middle Turonian lowstand deposits characterizing the global sea level fall during this interval.     

Detailed surface photometry of the cD galaxies NGC 4839 and NGC 4874

We present a detailed photometric study of the cD galaxies NGC 4839 and NGC 4874 based on the technique of surface photometry by fitting ellipses to the isophotes of the galaxies in the u, g, r, i, and z bands using Data Release 7 (DR7) of the Sloan Digital Sky Survey (SDSS). The motivation of this paper is to study the properties (e.g. break radius and surface brightness, color gradient, etc.) of the extended envelope of the two cD galaxies. The surface brightness profile in each band is obtained and fitted to the de Vaucouleurs r ^1/4 model. A deviation of the observed profile brighter than the fitted r ^1/4 model is noticed especially in the outer part of each galaxy. The profiles of ellipticity, position angle, B4 and shifts with respect to the center of each isophote are also obtained. The color index profiles, u-g, g-r, r-i, and i-z are also obtained and no significant color gradients are noticed except in the outer parts of the two galaxies. The integrated magnitude in each band and color indices are obtained and found to be in good agreement with the published ones.     

Geochemical mobilization of some heavy metals in water resources and their impact on human health in Sohag Governorate,Egypt

Geochemical mobilization of heavy metals in water has been cited as an important factor in many diseases of Sohag Governorate, Egypt. Forty-two groundwater samples were collected from the Quaternary aquifer and eight samples from surface water of Sohag governorate. The results recorded high contamination with cadmium and lead. Besides, about 50 % of samples are contaminated with iron and manganese at an alert level. All the metals under study exhibited an asymmetric statistical distribution in the investigated area. The study identified positive relationship between contaminated water (surface and groundwater) of Sohag with Cd (r _s?=?0.43) as well as Pb (r _s?=?0.21) and renal failure rate (R.F.R.?=?26 patients/10⁵ capita). The spatial distribution of these two metals (Cd and Pb) showed that they accumulated in the southern part of Sohag Governorate around Albalina District and in the northwestern part at Gehina District, which have the highest R.F.R. This study highlighted the need for more detailed research to assess the different pollutants and their relation to chronic diseases.     

Investigating the time dynamics of monthly rainfall time series observed in northern Lebanon by means of the detrended fluctuation analysis and the Fisher-Shannon method

We investigate the time dynamics of monthly rainfall series intermittently recorded on seven climatic stations in northern Lebanon from 1939 to 2010 using the detrending fluctuation analysis (DFA) and the Fisher-Shannon (FS) method. The DFA is employed to study the scaling properties of the series, while the FS method to analyze their order/organization structure. The obtained results indicate that most all the stations show a significant persistent behavior, suggesting that the dynamics of the rainfall series is governed by positive feedback mechanisms. Furthermore, we found that the Fisher Information Measure (the Shannon entropy power) seems to decrease (increase) with the height of the rain gauge; this indicates that the rainfall series appear less organized and less regular for higher-located stations. Such findings could be useful for a better comprehension of the climatic regimes governing northern Lebanon.     

Analysis of long-term fluctuations in stream flow time series: An application to Litani River, Lebanon

Litani River is the largest river in Lebanon and has been affected by several physical and anthropogenic factors that influenced its flow dynamics. By means of the Singular Spectrum Analysis (SSA), the time dynamics of the stream flow of seven sites along the course of Litani River was investigated, extracting for each site the long-term trend. A clear decreasing trend characterizes all the long-term trends of the stream flow. Furthermore, several peaks were identified, consistent with the rainfall rate and snow cover variability.     

Use of remote sensing and GIS to determine recharge potential zones: the case of Occidental Lebanon

Water recharge from land surfaces into subsurface media is an essential element in the hydrologic cycle. For a small-scale assessment, experimental approaches are usually followed, however, on a regional scale, this assessment needs to be made into a comprehensive picture where spatial data of the different contributing factors are treated. The case of Occidental Lebanon, with an area of around 5,000 km², was studied by the integration of all factors influencing this hydrologic process. Contributing factors are: lineaments and drainage frequency density, lithologic character, karstic domains and land cover/land use. The determination of these factors was carried out mainly by the application of remote sensing. Satellite images (Landsat 7 ETM &; SPOT) and aerial photos were subjected to several treatment processes using a miscellany of software, mainly ERDAS Imagine and ESRI’s Arc View software. Furthermore, exogenetic data, such as topographic and geologic maps, were utilized. The extracted information for these factors was plotted on maps. The integration of the maps in a GIS allowed deciding their interactive effects. However, each factor had its own degree of effect, i.e., weight, which was also determined in this study. This study is an approach to better estimate and provide qualitative assessments of recharge potential (RP). The resultant map shows the highest recharge potentials towards the elevated regions where karstification is well development. It was found that around 57% of the study area is terrain with very high to high recharge rate values, which a considerable amount of precipitated water is allowed to percolate into subsurface rocks.     

Sequence Stratigraphy and Rudist Facies Development of the Upper Barremian‐Lower Cenomanian Platform,Northern Sinai,Egypt

The Lower Cretaceous sections in northern Sinai are composed of the Risan Aneiza (upper Barremian-middle Albian) and the Halal (middle Albian-lower Cenomanian) formations. The facies reflect subtle paleobathymetry from inner to outer ramp facies. The inner ramp facies are peritidal, protected to open marine lagoons, shoals and rudist biostrome facies. The inner ramp facies grade northward into outer ramp deposits. The upper Barremian-lower Cenomanian succession is subdivided into nine depositional sequences correlated with those recognized in the neighbouring Tethyan areas. These sequences are subdivided into 19 medium-scale sequences based on the facies evolution, the recorded hardgrounds and flooding surfaces, interpreted as the result of eustatic sea level changes and local tectonic activities of the early Syrian Arc rifting stage. Each sequence contains a lower retrogradational parasequence set that constituted the transgressive systems tracts and an upper progradational parasequence set that formed the highstand systems tracts. Nine rudist levels are recorded in the upper Barremian through lower Cenomanian succession at Gabal Raghawi. At Gabal Yelleg two rudist levels are found in the Albian. The rudist levels are associated with the highstand systems tract deposits because of the suitability of the trophic conditions in the rudist-dominated ramp.     

Real-time prediction of shield moving trajectory during tunnelling

Acta Geotechnica - This paper presents a novel deep learning model for real-time prediction of shield moving trajectory during tunnelling. The proposed model incorporates a wavelet transform (WT)...     

Control of Cambrian evaporites on fracturing in fault-related anticlines in the Zagros fold-and-thrust belt

Orientation and distribution of fractures in the Oligocene–Early Miocene Asmari Formation (a major reservoir rock of the Zagros petroleum system) were investigated in two anticlines of the Zagros fold-and-thrust belt. The Sim and Kuh-e-Asmari anticlines developed in the areas of the Zagros characterized by the occurrence and absence of Cambrian evaporites at the bottom of the stratigraphic pile, respectively. The aim was to outline major differences in terms of fracture spacing and saturation. Organic matter maturity and clay minerals-based geothermometers suggest that the depth of deformation for the top of the Asmari Formation in the Kuh-e-Asmari anticline was in the range of 1.5–2.7 km assuming a geothermal gradient of 22.5 °C/km. The Asmari Formation in the Sim anticline probably experienced a slightly deeper sedimentary burial (maximum 3 km) with a geothermal gradient of 20 °C/km. The spacing of fractures is generally 2–3 times larger (i.e., strain accommodated by fracturing is smaller) in the Sim anticline than in the Kuh-e-Asmari anticline. This is consistent with regional geological studies, analogue, and numerical models that suggest that thrust faults geometry and related folds are markedly different in the absence or presence of a weak decòllement (evaporites). The larger spacing in the Sim anticline is also consistent with higher temperature predicted for the Asmari Formation in this area. By contrast, the orientation of fractures with respect to the fold axes is the same in both anticlines. The fracture systems are rather immature in both anticlines. The amount and density of fractures in the twofolds are controlled by regional (occurrence/absence of salt and probably different burial), rather than local features (fold geometry).     

Geologic controls of submarine groundwater discharge: application of remote sensing to north Lebanon

Typical of Mediterranean countries, the Lebanese shoreline is well known for its littoral and offshore groundwater discharges, the so-called submarine springs. The tectonic framework of the terrain explains its interruption by dense geologic structures, i.e., fracturing, faulting, karstic routes, as well as acute dips of rock strata seaward. All of these structures serve as hydrologic agents transporting groundwater to the sea. The study aims to locate these groundwater discharges, and to interpret their geologic controls on land. For this purpose, two major lines of approach were followed. The first is an airborne thermal infrared (TIR) survey using radiometers to identify thermal anomalies, thereby determining the exact location of submarine groundwater discharges (SGDs). The second line of approach is the analysis of satellite images (Landsat 7ETM⁺) to delineate the geologic features that govern the mechanism of water flow, thereby determining their sources on land. Twenty-seven major SGDs were identified, 10 of these being offshore springs, the others littoral springs. The springs show a large variety of discharge configurations and extents, mainly parallel or perpendicular to the shoreline or rounded. Three major structural controls were identified to contribute to the transport of groundwater to the sea. These are karstic galleries, faults, and tilted rock strata, their contributions being 48, 37, and 15%, respectively. The SGDs associated with linear passageways, i.e., karstic galleries and faults, are connected with land aquifer formations several kilometers away from the shoreline. Moreover, the presence of impervious rock formations at many localities along the coastline results in a confined hydrologic system, promoting the flow of SGDs into the sea.