Search

The gabbro-diorite complex of the Um Balad prospect hosts lode gold mineralization. The complex is dated at 723 ± 4 Ma using the LA-ICP-MS U-Pb zircon method and is correlated with the late Tonian-early Cryogenian subduction-related magmatic stage during the evolution of the Arabian-Nubian Shield. The gabbro-diorite complex evolved through the crystallization of a calc-alkaline magma and the subduction signature of this magma is verified by primitive mantle-normalized trace element patterns that show enrichment in large ion lithophile elements, U, and Th relative to high field strength elements as well as negative Nb and Ti anomalies. The high La/Ybcn (3.1–9.4) and Ta/Yb (0.12–0.41) ratios are consistent with a continental arc rather than an oceanic arc system. Amphibole chemistry indicates that this complex might have crystallized under a moderately oxidizing condition from a hydrous magma (>6 wt% water content) at temperature and pressure estimates of about 800°C and 3 kbar, respectively. Gold mineralization in the Um Balad prospect is confined to structurally controlled massive quartz±carbonate veins and surrounding alteration halos. Alteration in the prospect is represented by localized sericitization and carbonation as well as pervasive chlorite-sericite alteration. The alteration halos are characterized by enrichment in K and Rb and depletion in Ca and Sr compared to their host rocks. The veins of the prospect are related to lower order extensional fractures associated with the regional first order transpressional Najd Fault System. The high Fe contents of the gabbro-diorite complex represent a suitable chemical trap for gold through sulfidation of the host rocks. Supergene alteration resulted in the formation of goethite in association with atacamite and chrysocolla. Free mill gold is associated with these supergene phases, which were deposited in near neutral to slightly alkaline conditions. [ABSTRACT FROM AUTHOR]

Although ancient Egypt has a firmly established record of mining and metallurgy of gold and copper, iron production in ancient Egypt is less well documented. Evidence of ancient iron manufacture in Egypt is to be found in the burnt plant remains, slag fragments, and a furnace‐like structure discovered in the Hamama workshop in the Eastern Desert of Egypt. The iron ore required for iron production was delivered from the nearby specular hematite mines of the Abu Gerida area. This Egyptian specularite is geochemically distinguished from other Mediterranean varieties of specularite such as those in Elba, Tuscany, and Seriphos Island. The bloomery iron smelting process in the Hamama workshop produced two types of slags: furnace slags and tapping slags. These two types show different petrographic features and geochemical signatures. Some of the geochemical signatures of the slags, such as their high calcium contents, were derived from charcoal, while others were related to the ore used during the smelting process. Radiocarbon dating of the charred plant remains from the Hamama workshop suggests that the iron smelting activities took place in the early Ptolemaic era. Iron production was seasonal and was conducted by locals who most likely had dynamic socioeconomic ties with the urban centers of the Nile valley. [ABSTRACT FROM AUTHOR]

The Makran complex in southeast Iran provides a spectacular subduction-related accretionary complex to understand the mechanism of oceanic accretion and the evolution of subduction zones. In this paper, we present new major and trace element data as well as isotopic compositions of mafic volcanic blocks from the Makran ophiolitic mélange complex (OMC). Our aim is to assess the genesis of these rocks and discuss their implications on the evolution of Neotethys Ocean. These volcanic blocks are composed mainly of basalts with minor trachytes. The Makran lavas are occasionally interlayered with tuff layers. Zircons from these tuffs give U-Pb ages of 95 Ma, which is well in accordance with the reposted microfossil data for the interlayered pelagic limestones with pillow lavas. Makran basalts can be geochemically subdivided into four groups; normal to transitional MORB, enriched-MORB, Plume-type MORB and alkaline (-OIB-like) basalts. The OIB-like pillow lavas are represented by high values of Th/Tb (6.3–7.4) which are higher than other basalts (group 1 = 0.3–0.8; groups 2 = 0.7–1.6; group 3 = 1.58–1.36).143Nd/144Nd(t) ratios for basalts ranges from 0.51247 to 0.51292, whereas 87Sr/86Sr(t) isotopic composition of the OMC lavas varies from 0.704433 to 0.709466. The Pb isotopic composition of the lavas are quite high, ranging from 15.49–15.66 for 207Pb/204Pb(t), 18.09–19.12 for 206Pb/204Pb(t) and 37.80–39.23 for 208Pb/204Pb(t). The chemistry of these rocks suggests that they were formed most likely in an oceanic setting with clear plume-ridge interaction. These rocks can form from partial melting of a highly heterogeneous mantle source, which is extensively metasomatized with deep mantle OIB-type components. We suggest these rocks have been generated in an oceanic ridge with plume-ridge interaction, similar to the Iceland-Reykjanes Ridge, before being fragmented and accreted into the Makran accretionary complex. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to construct and evaluate the performance of a hydroponic unit for intensive barley green fodder production. The constructed hydroponic system included lighting unit to provide plants with its lighting requirement, cooling and air conditioning unit to conserve the appropriate microclimate conditions to propagate a healthy plants and aeration and CO2 proportioning unit to enhance the root-zone media with its air balance to achieve the plant stress. The performance of the constructed hydroponic unit was studied under some different technical parameters (growing period, aeration rate, with and without nutrient solution addition and with and without CO2 injection). The performance of the constructed hydroponic unit was evaluated in terms of total yield, yield quality, water use efficiency, energy requirements, operational cost and net profit. The experimental results reveal that total yield (4646.4 kg/period), plant moisture content (92.13%), water use efficiency (156.028 g/l) and net profit (8256 LE/period) were in the optimum region under conditions of 8.0 days growing period, 2 hr./day aeration rate, with both nutrient solution addition and CO2 injection. While the protein percentage (18.29%) was optimum under conditions of 5.0 days growing period, 1 hr./day aeration rate, with both nutrient solution addition and CO2 injection. Meanwhile dry matter (21.12%) was optimum under conditions of 5.0 days growing period, 2 hr./day aeration rate, without neither nutrient solution addition nor CO2 injection. [ABSTRACT FROM AUTHOR]