Societal application of geophysics as an aid to a rescue operation at Jaipur

Geophysical techniques are normally employed to explore the subsurface and determine the anomalies but they are always much larger in dimension. However, a very precise measurement was needed to pin point a misaligned horizontal tunnel made at 47 m depth to intercept an old bore well and rescue a four year child fallen accidently on 9^th November at Jagatpura village in Jaipur, India. Due to the greater depth and presence of iron casing, electric power, etc., no equipment could work to determine the orientation of the tunnel that has lost its direction. The dimension of the site and many other constrains didn’t allow conventional geophysical methods to be used. An innovative method was then designed and successfully applied, which determined 1.92 m deviation of the tunnel end point to the east from the old bore well. The digging was redirected accordingly and the bore well was intercepted. This paper describes the theoretical background, forward simulations and the field experiment of the newly designed geophysical method.     

Assessment of water quality and identification of pollution sources of three lakes in Kashmir, India, using multivariate analysis

Multivariate statistical techniques, such as cluster analysis, principal component analysis (PCA) and factor analysis (FA) were applied to evaluate and interpret the water quality data set for 13 parameters at 10 different sites of the three lakes in Kashmir, India. Physicochemical parameters varied significantly (p?<?0.05) among the sampling sites. Hierarchical cluster analysis grouped 10 sampling sites into three clusters of less polluted, moderately polluted and highly polluted sites, based on similarity of water quality characteristics. FA/PCA applied to data sets resulted in three principal components accounting for a cumulative variance of 69.84, 65.05 and 71.76% for Anchar Lake, Khushalsar Lake and Dal Lake, respectively. Factor analysis obtained from principal components (PCs) indicated that factors responsible for accelerated eutrophication of the three lakes are domestic waste waters, agricultural runoff and to some extent catchment geology. This study assesses water quality of three lakes through multivariate statistical analysis of data sets for effective management of these lakes.     

Hydrochemistry and thermal activity of damt region,Yemen

The aim of this study was to identify the complex hydrogeological and hydrochemistry conditions of Damt region, through determining hydrochemical properties of groundwater in the study area. According to the results of hydrochemical analyses, sampled waters can be divided into three groups: cold, thermal, and mixed waters. Thermal waters in the area are characterized by Na–HCO₃, while the cold waters by CaHCO₃ facies. HCO₃ indiscriminate cation and/or Na-indiscriminate anion are present in many places in the region and indicate generally mixing water. Only three villages with dental fluorosis observed using water elevated in F⁻ for drinking. Agricultural and liquid waste disposal are the main sources of pollution, leads to increase of Na, Cl, NO₃, Cd, and Iron. The groundwater flow is from north, northwest, and northeast to the south. Within this regional trend, structural controlling groundwater flow along Wadis and it flows from upper reaches of tributaries toward the main channel, then downward to the south of the study area. The similarity of TDS and Cl concentration at Qa’a Al Haql and Al Nadirah between aquifers indicates hydraulic continuity between alluvial and the underlying volcanic, while at Damt no hydraulic continuity found between alluvial, volcanic and Sandstone aquifers. The temporal variation shows slight decrease in the concentration of nitrate and sulfate of thermal water indicating previously high gas content of nitrogen, hydrogen sulfide in the thermal active region. The developed conceptual model of water circulation indicates flood waters infiltrate slowly through the wadi bottoms in the East where Sandstone aquifer outcrops. These waters flow westward, following the westerly dip of the Sandstone through the effects of gravity, gains heat and dissolve materials as it comes in contact with the numerous dykes, which are the feeders to the overlying volcanoes and sputter cones. All thermal water samples from Damt region fall into immature water field in NA–K–Mg diagram. Therefore, the results obtained from the cation geothermometers should be taken into account as doubtful.     

Mesozoic deltaic system along the western margin of the Indian plate: lithofacies and depositional setting of Datta Formation,North Pakistan

Over 1 km thick Mesozoic sedimentary sequence is exposed over a wide area in the Upper Indus basin of north Pakistan along the western margin of the Indian Plate. The Mesozoic sequence is comprised of clastic facies in the lower part, while carbonate facies are dominant in the upper part. About 200 m thick mixed sequence of interbedded sandstone, siltstone, clay, and carbonaceous shale represents the lower Jurassic Datta Formation in the Salt and Trans Indus Ranges in North Pakistan. The Datta Formation constitutes important reservoir horizons in a number of oil fields in the western Himalayan foreland basins where it is encountered at a depth of about 4 km in various wells. The Datta Formation is described from different parts of the range front to understand the internal architecture of various sedimentary facies and their depositional system. The thickness and lithofacies assemblages of the Datta Formation change in different parts of the range front as well as in subsurface of the Upper Indus basin. The Datta Formation represents a coarsening upward deltaic sequence in most parts of the basin. On the basis of lithological variations and sedimentary structures, a number of depositional facies have been recognized which include channel belt facies, floodplain/abandoned channel facies, swamp facies, and lagoonal facies. Further north, in the Kalachitta and Hazara regions, the siliciclastic facies change to more complex assemblages of interbedded bauxite, silcrete, marl, and some limestone. These sediments represent deposition in a delta-plain setting of a fluvial-dominated delta with northwestward flowing channels.     

Lithostratigraphy and standard microfacies types of the Neogene carbonates of Rabigh and Ubhur areas, Red Sea coastal plain of Saudi Arabia

The Neogene carbonate rocks have relatively small exposure relative to the siliciclastic and evaporite rocks in Rabigh and Ubhur areas, north Jeddah, Red Sea coastal plain of Saudi Arabia. The Miocene carbonates form small hills in both areas, which conformably overlie the siliciclastics, whereas the Pleistocene coral reefs form terraces facing the Red Sea in Rabigh area. The Neogene carbonates are represented by the following microfacies types: (1) dolomitic, oolitic, foraminiferal packstone; (2) sandy, dolomitic, intraclastic, foraminiferal packstone; (3) dolomitic and oolitic wackestone; (4) dolomitic, foraminiferal, intraclastic wackestone; (5) dolomitic mudstone; (6) coral boundstone; and (7) grainstone. The diagenetic processes affecting these carbonates are compaction, dissolution, aggrading neomorphism, and replacement that took place during deposition, shallow burial, and uplift. Pervasive dolomitization by the seepage reflux mechanism is responsible for the mimic replacement of the calcite of the original component of the limestone with dolomite. Sediments, biota, and lithofacies characteristics of the studied carbonate rocks of Rabigh and Ubhur areas indicate the presence of three facies zones; these are (1) FZ 5 platform margin reefs, (2) FZ 6 (platform margin sand shoals), and (3) FZ 7 platform interior-normal marine. The standard microfacies types are represented by (1) SMF 12, limestone with shell concentration; (2) SMF 15, oolitic wackestone and packstone; and (3) SMF 18, bioclastic grainstone and packstone with abundant benthic foraminifera.     

Isotopic variations of oxygen and hydrogen in groundwater of carbonate aquifer in an arid environment

The stable isotopic characteristics were used together with the total chloride to assess changes in groundwater from recharge zones into the carbonate aquifer in an arid environment. The aquifer under study represents a major source of groundwater and thermal springs in Al-Ain city, which are located at the northern part of Jabal Hafit in the United Arab Emirates (UAE). The relationship between oxygen and hydrogen isotopic composition of groundwater is established and is described by δD?=?2.2δ¹⁸O???9.96. The lower slope and y-intercept of groundwater samples relative to the local meteoric waterline suggests that the isotopic enrichment is due to the evaporation of shallow groundwater after recharge occurs. The majority of the shallow groundwater samples have a negative deuterium excess (d-excess) which might be ascribed to high a degree of evaporation, while most of the groundwater samples from deep wells, have a positive value of d-excess which may be related to a low degree of evaporation. The δ¹⁸O values of the thermal waters suggest enrichment towards δ¹⁸O of the carbonate rocks because of the exchange with oxygen at higher temperatures. A possible mixing between thermal or hot water and shallow groundwater is evident in some samples as reflected by δD vs. Cl and d-excess vs. δ¹⁸O plots.     

Probabilistic tsunami hazard assessment along Oman coast from submarine earthquakes in the Makran subduction zone

The Sultanate of Oman is among the Indian Ocean countries that were subjected to at least two confirmed tsunamis during the twentieth and twenty-first centuries: the 1945 tsunami due to an earthquake in the Makran subduction zone in the Sea of Oman (near-regional field tsunami) and the Indian Ocean tsunami in 2004, caused by an earthquake from the Andaman Sumatra subduction zone (far - field tsunami). In this paper, we present a probabilistic tsunami hazard assessment for the entire coast of Oman from tectonic sources generated along the Makran subduction zone. The tsunami hazard is assessed taking into account the contribution of small- and large-event magnitudes. Results of the earthquake recurrence rate studies and the tsunami numerical modeling for different magnitudes were used through a logic-tree to estimate the tsunami hazard probabilities. We derive probability hazard exceedance maps for the Omani coast considering the exposure times of 100, 250, 500, and 1000 years. The hazard maps consist of computing the likelihood that tsunami waves exceed a specific amplitude. We find that the probability that a maximum wave amplitude exceeds 1 m somewhere along the coast of Oman reaches, respectively, 0.7 and 0.85 for 100 and 250 exposure times, and it is up to 1 for 500 and 1000 years of exposure times. These probability values decrease significantly toward the southern coast of Oman where the tsunami impact, from the earthquakes generated at Makran subduction zone, is low.     

Performance evaluation of artificial neural networks for planimetric coordinate transformation—a case study,Ghana

Two national horizontal geodetic datums, namely, the Accra and Leigon datum, have been the only available datum used in Ghana. These two datums are non-geocentric and were established based on astro-geodetic observations. Relating these different geodetic datums mostly involves the use of conformal transformation techniques which could produce results that are not very often satisfactory for certain geodetic, surveying and mapping purposes. This has been ascribed to the incapability of the conformal models to absorb more of the heterogeneous and local character of deformations existing within the local geodetic networks. Presently, application of new approaches such as artificial neural network (ANN) is highly recommended. Whereas the ANN has been gaining much popularity to solving coordinate transformation-related problems in recent times, the existing researches carried out in Ghana have shown that only three-dimensional conformal transformation methods have been utilized. To the best of our knowledge, plane coordinate transformation between the two local geodetic datums in Ghana has not been investigated. In this paper, an attempt has been made to explore the plane coordinate transformation performance of two different ANN approaches (backpropagation neural network (BPNN) and radial basis function neural network (RBFNN)) compared with two different traditional techniques (six- and four-parameter models) in the Ghana national geodetic reference network. The results revealed that transforming plane coordinates from Leigon to Accra datum, the RBFNN was better than the BPNN and traditional techniques. Transforming from Accra to Leigon datum, both the BPNN and RBFNN produced closely related results and were better than the traditional methods. Therefore, this study will create the opportunity for Ghana to recognize the significance and strength of the ANN technology in solving coordinate transformation problems.     

The vein-type barite mineralization of the Draïssa ore field,Ougarta; SW- Algeria: mineralogy,trace elements and halogens

The Draïssa barite vein system in the Ougarta district is located in southwestern Algeria. It is the principal mineral deposit of economic interest of the area. The mineralization is hosted by Cambrian sedimentary rocks that unconformably overlie Precambrian formations. The mineralized structures consist mostly of barite and quartz with minor sulfide minerals and trend dominantly NE-SW, NW-SE, and E-W. Siliceous alteration zones are associated with the vein system. Samples of barite ore are characterized by low total REE contents ranging from 9 to 50 ppm and positive Eu (2–2.15 ppm) and Y (1.2–11.1 ppm) anomalies, indicating hydrothermal activity during mineralization. Halogen data of the barite show that the Cl/Br molar ratio is 189:571 and the Na/Br ratio is 34:376, indicating that the sulfur was derived from seawater. The Ba-enrichment trend in the volcanic rocks of Draïssa is interpreted as possible probable source of the Ba (424–3039 ppm Ba). It appears that the barite-quartz deposits were formed in two stages. Endogenous fluids deposited the primary vein materials, consisting of quartz associated with copper sulfides. Exogenous fluids (cold seawater) became heated during ascendant fluid movement. Mineralization was governed by convective motions and the barite and galena fillings were deposited in openings created by normal faulting.