Meteoritic iron from the Libyan glass area,southwestern Egypt

Abstract— A fragment of a weathered iron meteorite was collected from the Libyan Desert glass area of southwestern Egypt in 1991 May. The specimen is of irregular shape, measuring 5 × 3.5 × 2 cm and weighing 110 g. It is covered by a shiny black layer of magnetite ～1 mm thick. The interior is brownish-black in color owing to terrestrial oxidation. An unetched polished surface shows some areas still having remnants of kamacite and taenite. Remnants of the lamellar octahedral structure have been detected. The kamacite bandwidth ranges from 0.2 mm to 0.8 mm. Chemical analysis shows that the meteorite contains 3.4% Ni, 0.24% Co, 85 ppm Cu, 4 ppm As, 132 ppm Au and 2530 ppm Ir. The meteorite was discovered after the discovery of two different chondritic meteorites in the same area; so, it will be named Great Sand Sea 003.     

Estimating hydraulic conductivity from specific capacity for Hawaii aquifers,USA

Site-specific relationships between specific capacity and hydraulic parameters (transmissivity and hydraulic conductivity) were investigated for volcanic rocks in Maui, Hawaii, USA. Details about well construction were commonly ignored in previous studies. To improve on such efforts, specific-capacity values were normalized by the open interval of the well. Correcting specific capacity for turbulent head losses using step-drawdown tests and including aquifer penetration length improved the correlation between specific capacity and hydraulic conductivity and reduced uncertainty in the prediction of hydraulic parameters. The relationships provide estimates of aquifer parameters with correlation coefficients between 0.81 and 0.99. The relationships for Maui can probably be extended to other Hawaii islands, given the similarity of aquifer formations and a reasonable fit to step-drawdown data from Oahu. Hydraulic conductivity was estimated from 1,257 specific-capacity values in the Hawaii’s well database. Hydraulic-conductivity estimates for dike-free volcanic rocks are consistent on different islands. For all islands, the estimates range from 3 to 8,200 m/d, with a geometric-mean and median value of 272 and 291 m/d, respectively. A geostatistical approach was applied to Maui and Oahu to generate island-wide hydraulic-conductivity maps to facilitate groundwater management efforts.     

The hydrochemical characteristics and evolution of groundwater and surface water in the western part of the River Nile, El Minia district, Upper Egypt

A combination of major and trace elements have been used to characterize surface- and groundwater in El Minia district, Egypt. Surface water versus groundwater chemistry data enabled geographical zonation and chemical types to be differentiated. The main target of this research is to investigate the groundwater quality and hydrochemical evaluation. The situation is further complicated by contamination with lithogenic and anthropogenic (agricultural and sewage wastewaters) sources and low plan exploitation techniques. The investigated Pleistocene aquifer is composed of sand and gravel of different sizes, with some clay intercalation. The semi-confined condition was around the River Nile shifted to unconfine outside the floodplain. The groundwater flow generally from south to north and locally diverts towards the western part from the River Nile. Fifty-six, 11, five, and two water samples were collected from the Pleistocene aquifer, River Nile, Ibrahimia canal, and Al Moheet drain, respectively. The collected water samples were analyzed for major and trace elements. The toxic metal concentrations of Al Moheet drain are higher than those in the River Nile and the Ibrahimia canal. Cr, Hg, As, and Cd concentrations in the River Nile and Ibrahimia canal are fluctuated above and below the WHO drinking standards. Se concentration in River Nile and Ibrahimia canal is below WHO drinking and irrigation guidelines. Total dissolved solid content in groundwater is generally low, but it is increased due to the western part of the study area. The geographic position of the River Nile, Ibrahimia canal, and Al Moheet drain impact on the groundwater quality. The PHREEQC confirm the high mixing proportions from the River Nile into the groundwater and decline away from it. In addition to the thicknesses of the Pleistocene, aquifer and aquitard layer enhance the River Nile and agricultural wastewaters intrusion into the aquifer system. The toxic metal concentrations (Pb, Cd, Cr, PO₄, Se, Mn, As, Hg, Ni, Al, Fe, and SIO₂) in groundwater were increased mainly in the northwestern and southeastern part (far from the River Nile). It is attributed to anthropogenic, high vulnerability rate (unconfined), and partially to lithogenic. In most localities, the groundwater are unsuitable for drinking and irrigation purposes with respect to Se concentration, while they are unsuitable for dinking according Mn, As, and Hg contents. There are some Cd and Pb anomalies concentrations, which cause severe restriction if used in irrigation. The results suggested that significant changes are urgently needed in water use strategy to achieve sustainable development.     

Groundwater source assessment program for the state of Hawaii, USA: methodology and example application

The 1996 reauthorization of the Safe Drinking Water Act required that each state in the US addresses the protection of public drinking water sources, including the development and implementation of a source-water assessment program. Such a program includes delineating source-water assessment areas, inventorying potential contaminant sources within this area, and determining the water system's susceptibility to contamination. The public was also involved in various phases of the program. Hawaii’s groundwater source assessment program is presented, along with an approach for implementation, which is consistent with federal requirements. The approach integrates groundwater models, aquifer databases, and a geographic information system. Source assessment areas were delineated by using numerical groundwater-flow models that used site-specific data to their fullest availability. The proposed approach is flexible enough to allow easy future updates as more sources are identified or as new information becomes available. The final product includes numerical scores that quantify the relative source susceptibility to contamination. Aquifer models developed in this study are potentially useful for future site-specific protection efforts or for other modeling purposes.     

NETPATH-WIN: An interactive user version of the mass-balance model, NETPATH

NETPATH‐WIN is an interactive user version of NETPATH, an inverse geochemical modeling code used to find mass‐balance reaction models that are consistent with the observed chemical and isotopic composition of waters from aquatic systems. NETPATH‐WIN was constructed to migrate NETPATH applications into the Microsoft WINDOWS® environment. The new version facilitates model utilization by eliminating difficulties in data preparation and results analysis of the DOS version of NETPATH, while preserving all of the capabilities of the original version. Through example applications, the note describes some of the features of NETPATH‐WIN as applied to adjustment of radiocarbon data for geochemical reactions in groundwater systems.     

Taphonomic and diagenetic aspects of the Late Cretaceous Libycoceras ismaeli (Zittel) from Northern Jordan

Taphonomy and diagenesis of the ammonoid Libycoceras ismaeli (Zittel) have been approached in order to interpret the post-mortem depositional history during the Late Cretaceous of Jordan based on the comparative analysis of composition and taphonomy. The Campanian–Maastrichtian Al-Hisa Phosphorite Formation is exposed in northwestern and central Jordan is rich in cephalopods. It consists of alternating thin-bedded limestone, more or less silicified or calcified phosphorite layers, thick- and cross-bedded oyster lumachells, and lenses and layers of minable phosphate. The sphenodiscid ammonite L. ismaeli (Zittel) predominantly occurs in the middle part of this formation. L. ismaeli is associated with different nautiloid and baculitid species. The mode of occurrence of the studied ammonoids suggesting that they are best interpreted to been nektobenthic, not nektoplanktic. Taphonomic and diagenetic studies of transversely sliced specimens were carried out by means of polarizing and scanning electron microscope.     

Transpressive Structures in the Ghadir Shear Belt,Eastern Desert,Egypt: Evidence for Partitioning of Oblique Convergence in the Arabian‐Nubian Shield during Gondwana Agglutination

Transpressional deformation has played an important role in the late Neoproterozoic evolution of the ArabianNubian Shield including the Central Eastern Desert of Egypt. The Ghadir Shear Belt is a 35 km-long, NW-oriented brittleductile shear zone that underwent overall sinistral transpression during the Late Neoproterozoic. Within this shear belt, strain is highly partitioned into shortening, oblique, extensional and strike-slip structures at multiple scales. Moreover, strain partitioning is heterogeneous along-strike giving rise to three distinct structural domains. In the East Ghadir and Ambaut shear belts, the strain is pure-shear dominated whereas the narrow sectors parallel to the shear walls in the West Ghadir Shear Zone are simple-shear dominated. These domains are comparable to splay-dominated and thrust-dominated strike-slip shear zones. The kinematic transition along the Ghadir shear belt is consistent with separate strike-slip and thrustsense shear zones. The earlier fabric(S1), is locally recognized in low strain areas and SW-ward thrusts. S2 is associated with a shallowly plunging stretching lineation(L2), and defines ～NW-SE major upright macroscopic folds in the East Ghadir shear belt. F2 folds are superimposed by ～NNW–SSE tight-minor and major F3 folds that are kinematically compatible with sinistral transpressional deformation along the West Ghadir Shear Zone and may represent strain partitioning during deformation. F2 and F3 folds are superimposed by ENE–WSW gentle F4 folds in the Ambaut shear belt. The sub-parallelism of F3 and F4 fold axes with the shear zones may have resulted from strain partitioning associated with simple shear deformation along narrow mylonite zones and pure shear-dominant deformation in fold zones. Dextral ENEstriking shear zones were subsequently active at ca. 595 Ma, coeval with sinistral shearing along NW-to NNW-striking shear zones. The occurrence of upright folds and folds with vertical axes suggests that transpression plays a significant role in the tectonic evolution of the Ghadir shear belt. Oblique convergence may have been provoked by the buckling of the Hafafit gneiss-cored domes and relative rotations between its segments. Upright folds, fold with vertical axes and sinistral strike-slip shear zones developed in response to strain partitioning. The West Ghadir Shear Zone contains thrusts and strikeslip shear zones that resulted from lateral escape tectonics associated with lateral imbrication and transpression in response to oblique squeezing of the Arabian-Nubian Shield during agglutination of East and West Gondwana.