Formation and mineral chemistry of a calcic skarn from Al-Madhiq, SW Saudi Arabia   总被引：2，自引：0，他引：2  

Zulfiqar Ahmed  Mustafa M. Hariri 《Chemie der Erde / Geochemistry》2006,66(3):187-201

A newly identified skarn occurrence is described from the Neoproterozoic rocks of the SW Arabian shield. It is exposed to the SE, E and NE of the Al-Madhiq town. The skarn attributes correspond to those typical of the calcic skarns that host W-deposits. It is characterized as an exoskarn of the proximal type, related to a granitoid contact close to an impure quartzite bed within the regional metamorphic rocks of mixed sedimentary and volcanic derivation. The skarn is localized along a shear zone parallel to the regional faults and other major shear zones. Samples from the studied area contain characteristic skarn minerals that include both the prograde (brownish red grossular, ferrosalite, aluminian titanite-grothite, albite-oligoclase, scapolite), and retrograde (epidote, quartz, hornblende, calcite) assemblages. The pyroxenes are ferrosalites, Mn-bearing, and more like those from “oxidized” skarns; although garnets indicate it to be a “reduced” type skarn. Epidote mimicks that from typical skarns, as it bears a pistacite content of 15.9–20.7%. Grossular composition reflects a largely reduced genetic environment; as it is in solid solution with 6.5–21.6% andradite, 0–0.15% uvarovite, 0–0.47% pyrope, 4.33–18.75% almandine, and 0.4–8.58% spessartine molecules. Titanite composition varies from aluminian titanite to grothite, that may be analogous to the newly described Al-rich titanite from the low-pressure calc-silicate rocks.  相似文献   

Soil Characterization Using Joint Interpretation of Remote Sensing,Resistivity and Induced Polarization Data along the Coast of the Nile Delta     

Attwa  Mohamed  El Mahmoudi  Ahmed  Elshennawey  Ahmed  Günther  Thomas  Altahrany  Ayman  Mohamed  Lamees 《Natural Resources Research》2021,30(5):3407-3428

Natural Resources Research - Soil characterization in coastal areas is essential for strategic coastal engineering implementation and for understanding the paleo-environmental conditions. However,...  相似文献   

Data-Driven Modeling Approach to Predict the Recovery Performance of Low-Salinity Waterfloods     

Kalam  Shams  Khan  Rizwan Ahmed  Khan  Shahnawaz  Faizan  Muhammad  Amin  Muhammad  Ajaib  Rameez  Abu-Khamsin  Sidqi A. 《Natural Resources Research》2021,30(2):1697-1717

Natural Resources Research - Low-salinity waterflooding (LSWF) has, in the past decade, attained a lot of attention to enhance oil recovery. In LSWF, diluted water is injected into an oil reservoir...  相似文献   

Implementation of Rock Typing on Waterflooding Process During Secondary Recovery in Oil Reservoirs: A Case Study,El Morgan Oil Field,Gulf of Suez,Egypt     

Radwan  Ahmed E.  Nabawy  Bassem S.  Kassem  Ahmed A.  Hussein  Walid S. 《Natural Resources Research》2021,30(2):1667-1696

Waterflooding is one of the most common secondary recovery methods in the oil and gas industry. Globally, this process sometimes suffers a technical failure and inefficiency. Therefore, a better understanding of geology, reservoir characteristics, rock typing and discrimination, hydraulic flow units, and production data is essential to analyze reasons and mechanisms of water injection failure in the injection wells. Water injection failure was reported in the Middle Miocene Hammam Faraun reservoir at El Morgan oil field in the Gulf of Suez, where two wells have been selected as injector’s wells. In the first well (A1), the efficiency of injection was not good, whereas in the other analog A2 well good efficiency was assigned. Therefore, it is required to assess the injection loss in the low efficiency well, where all aspects of the geological, reservoir and production data of the studied wells were integrated to get a complete vision for the reasons of injection failure. The available data include core analysis data (vertical and horizontal permeabilities, helium porosity, bulk density, and water and oil saturations), petrographical studies injection and reservoir water chemistry, reservoir geology, production, and injection history. The quality of the data was examined and a set of reliable X–Y plots between the available data were introduced and the reservoir quality in both wells was estimated using reservoir quality index, normalized porosity index, and flow zone indicator. Integration and processing of the core and reservoir engineering data indicate that heterogeneity of the studied sequence was the main reason for the waterflooding inefficiency at the El Morgan A1 well. The best reservoir quality was assigned to the topmost part of the reservoir, which caused disturbance of the flow regime of reservoir fluids. Therefore, it is clearly indicated that rock typing and inadequate injection perforation strategy that has not been aligned with accurate hydraulic flow units are the key control parameters in the waterflooding efficiency.

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Application of Tree-Based Predictive Models to Forecast Air Overpressure Induced by Mine Blasting     

Ramesh Murlidhar  Bhatawdekar  Yazdani Bejarbaneh  Behnam  Jahed Armaghani  Danial  Mohammed  Ahmed Salih  Tonnizam Mohamad  Edy 《Natural Resources Research》2021,30(2):1865-1887

Natural Resources Research - In surface mines and underground excavations, every blasting operation can have some destructive environmental impacts, among which air overpressure (AOp) is of major...  相似文献   

Holocene hydrological and vegetation changes in southern France inferred by the study of an alluvial travertine system (Saint-Guilhem-le-Désert, Hérault)     

Adam Ahmed Ali  Paul Roiron  Lucie Chabal  Paul Ambert  Jean Gasco  Joël Andr  Jean-Frdric Terral 《Comptes Rendus Geoscience》2008,340(6):356-366

A geobotanical study of the travertine system of Saint-Guilhem-le-Désert (southern France) was carried out in order to reconstruct the local Holocene environment in a region where the postglacial vegetation history is poorly documented. The travertinisation process has started at ca. 8500 cal. BP, in a landscape dominated by Pinus sylvestris type (probably Pinus nigra sub sp. salzmannii). Around 7000 cal. BP, the travertine system recorded torrential events not evidenced at the regional scale, showing the particularity of the Verdus hydrological regime. More recently, ca. 5100 cal. BP, a lake or a marsh was filled within the Verdus plain, as attested to by sand and silt particles accumulated in the sequence. The present-day vegetation dominated by Quercus ilex, on south facing slopes, was most likely established between the Bronze Age and the Gallo-Roman period correlatively to the decline of Pinus nigra and deciduous Quercus, most probably under human influence.  相似文献   

Analysis, in a free surface steady flow, of the interstitial velocity field inside a sedimentary bed     

Mustapha Kamel Mihoubi  Michel Blorgey  Ahmed Kettab 《Comptes Rendus Geoscience》2008,340(12):858-864

The objective of our study is to exploit ultrasonic Doppler velocimetry (UDV) to analyze the velocity field within a steady flow on a porous sedimentary bottom. Velocities are measured for several sedimentary beds, as well within the fluid vein as within the sediment. Our results highlight an exponential distribution of the velocities inside the sediment and a discontinuity of the velocity at the interface water–sediment, between the velocity in the free flow and the velocity within the sediment. These results highlight the need to base the analysis of sedimentary transport on the reality of the physical processes at the interface water–sediment.  相似文献   

Two forsterite-bearing FUN inclusions in the Allende meteorite     

Robert N. Clayton  Glenn J. MacPherson  Ian D. Hutcheon  Andrew M. Davis  Lawrence Grossman  Toshiko K. Mayeda  Carol Molini-Velsko  John M. Allen  Ahmed El Goresy 《Geochimica et cosmochimica acta》1984,48(3):535-548

We have discovered two FUN inclusions, CG-14 and TE, among a group of five forsterite-rich inclusions in Allende, two of which are described for the first time herein. All five consist of euhedral forsterite and spinel crystals poikilitically enclosed by fassaite. Forsterite and spinel are usually segregated from one another, sometimes into a spinel-rich mantle and a forsterite-rich core. Some inclusions contain vesicles, indicating that they were once molten. The crystallization sequence inferred from textures is: spinel, forsterite, fassaite and, finally, Mg-rich melilite. One concentrically-zoned inclusion contains melilite in its mantle whose composition lies on the opposite side of the liquidus minimum in the melilite binary from that in its core. This suggests that segregation of forsterite from spinel in all of these inclusions could be due to volatilization of MgO and SiO₂ relative to Al₂O₃ and CaO from the outsides of droplets. CG-14 is relatively uniformly enriched in refractory elements relative to Cl chondrites by a factor similar to that for Ca-, Al-rich coarse-grained inclusions except for Ca, Al and Hf which are unusually low. No Ce anomaly such as found in FUN inclusions Cl and HAL is present in CG-14. Whole-rock samples of CG-14 and TE are more strongly mass-fractionated in oxygen relative to “normal” Allende inclusions than the FUN inclusion EK 1-4-1 and less so than Cl. Relative to bulk Allende, both inclusions have strongly massfractionated magnesium and silicon and ²⁵Mg excesses or deficits of ²⁴Mg or ²⁶Mg. CG-14 has a ²⁹Si excess or a deficit of ²⁸Si or ³⁰Si. Volatilization loss cannot be responsible for the magnesium and silicon isotope fractionations, as this would require prohibitively large mass loss from these magnesium-rich inclusions. The remarkable similarity in textures between FUN and non-FUN inclusions implies similar thermal histories, arguing against different rates of evaporative loss of major elements. Sputtering alone may be insufficient to account for the magnitude and direction of oxygen isotope fractionation in FUN inclusions.  相似文献   

Momentum flux variations at lower thermospheric levels as seen from mid-latitude meteor wind observations     

P. C. S. Devara  M. I. Ahmed 《Meteorology and Atmospheric Physics》1986,35(4):236-241

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Lead isotopes and trace elements in some Miocene Red Sea galenas     

Sayed B. El-Kholy  Ahmed H. Hashad  Ezzat T. M. Selim 《Pure and Applied Geophysics》1970,81(1):135-150

Summary Lead-zinc mineralization occurs in Miocene sediments along the Egyptian Red Sea Coast in several localities. Galena samples were collected from some of these localities for isotopic and trace elements studies. The isotopic ratios²⁰⁶Pb/²⁰⁴Pb,²⁰⁷Pb/²⁰⁴Pb,²⁰⁹Pb/²⁰⁴Pb for these samples indicate that they are contaminated with radiogenic lead (J-type anomalous lead) with different degrees. The variation in the degree of contamination is significant and indicates a non-uniform source of uranium and thorium from which radiogenic lead was deriven. The highst contaminations were observed in samples collected from sediments overlying or close to acidic basement rocks. The trace element content indicates that galenas were formed at low temperature from solutions that circulated the underlying basement picking several trace elements in addition to radiogenic lead.  相似文献