Saline waters and residual brines in the Shiraz-Sarvistan basin,Iran     

I. Zak  J.R. Gat 《Chemical Geology》1975,16(3):179-188

Origin of saline waters in the Shiraz-Sarvistan area, Iran, is determined by a combined isotopic (¹⁸O and D) and chemical characterization. Four types are recognized: (a) fresh water of the anticlinal carbonatic aquifer; (b) fresh and brackish runoff in the synclinal basins; (c) salt springs originating through dissolution of rock salt by type (a) fresh water; and (d) residual brines formed in synclinal closed drainage basins, through evaporation of former water types and loss of the relatively less-soluble salts.  相似文献   

RbSr radiometric age of late Precambrian fossil-bearing and associated rocks from Sinai     

Aryeh E. Shimron  Douglas G. Brookins 《Earth and Planetary Science Letters》1974,24(1):136-140

Six samples of metamorphic rocks from three essentially coeval stratigraphic units, two of which contain Precambrian microfossils, have been analyzed by the Rb-Sr whole-rock radiometric method. Least-squares regression of the data yields an isochron date of 934 ± 80m.y. with initial ⁸⁷Sr/⁸⁶Sr= 0.7007 ± 0.0011. This date may reflect the approximate age of formation of these rocks or, alternately, a time of major metamorphism. Regardless, the date is significant in that it (a) is in agreement with the 900-m.y. date for rocks containing similar types of fossils from Bitter Springs, Australia, and (b) coupled with structural evidence, supports the time equivalence of these rocks with 1000-m.y. old rocks (“Kibaran cycle”) of Saudi Arabia.  相似文献   

Dating faults by fission track dating of epidotes — an attempt     

M. Bar  Y. Kolodny  Y.K. Bentor 《Earth and Planetary Science Letters》1974,22(2):157-162

An attempt was made to determine the absolute age of faulting by measuring fission track ages of epidotes from mineralization veins along fault and joint planes. The method was applied to epidotes from along faults and fissures in the Sinai Peninsula, which cut Precambrian rocks. Most samples yield Tertiary ages (32-11 m.y.) An Early Cretaceous event is also recorded (120-103 m.y.). Samples from country rocks (igneous and metamorphic) give ages older than 325 m.y. The results are compatible with previous geological information, and suggest that the method can be potentially useful for dating faults.  相似文献   

Uncertainty, inter-area tax differentials, and industrial location     

Benzion Barlev 《Geoforum》1974,5(3):37-44

Empirical investigations have demonstrated that the location effects of business taxation and of inter-area tax differentials are not of major importance. This paper attempts to explain the above results by showing that the uncertainty involved in predicting future tax rates and tax differentials nullifies their location effects. It is then shown, both theoretically as well as empirically, that reducing the uncertainty of future tax benefits has a significant effect on industrial location patterns.  相似文献   

Climatological aspects in locating settlements in arid regionsKlimatologische aspekte bei der standortwahl für neue siedlungen in ariden regionenAspects climatologiques dans l'emplacement de villages dans des régions arides     

Arieh Bitan 《Geoforum》1974,5(4):39-48

In arid and semi-arid regions it is important to pay attention to climatic factors in locating and planning new settlements. Physical factors such as large differences in elevation over short distances, proximity to a large lake or the combination of the two factors, cause improvement of the climate.The central Jordan Valley and the Dead Sea could be a suitable area for proving these assumptions. A topo-climatological research has been performed in this region to help the planners in finding the best locations for new settlements. By using a “discomfort index”, which is based on temperature and humidity, the influence of the above mentioned physical factors on local climate modification has been verified. Also, its importance in the improvement of the location of new settlements has been shown.  相似文献   

Karstic sandstone bodies in the turonian limestones of Judea,Israel     

Y. WeilerE. Sass 《Sedimentary Geology》1972

The occurrence of quartz sand in the predominantly calcareous Upper Turonian section of Judea is more widespread than was previously realised. The encountered sand or argillaceous sand bodies are classified into three types: (1) a sand or marly sand layer concordant with the calcareous sequence below and above it; (2) discordant pockets in the limestone strata filled with quartz sand; and (3) fissure filling and “matrix” in pseudobrecciated limestones. Types 2 and 3 are found below the sand layer.  相似文献   

P-T conditions of quartz-calcite boudins and vein formation within a low-angle detachment fault in Tinos Island (Aegean Sea): a fluid-inclusion study     

Ye.?VapnikEmail author  D.?Avigad 《International Journal of Earth Sciences》2004,93(4):487-499

Fluid inclusions were investigated in successive generations of quartz-calcite boudins and veins in the vicinity of, and within, the low-angle detachment fault (of Early Miocene age) exposed on Tinos Island (Cyclades, Greece). Abundant boudins, veins, tension gashes and mineral segregations were formed during various stages of ductile and brittle shear along the detachment indicating fluid flow at various crustal levels, assisted motion and slip along the detachment. Three generations of fluid inclusions were identified: (1) syn-deformation aqueous inclusions; (2) local- late-deformation H₂O-CO₂ inclusions; (3) post-slip deformation, partly decrepitated aqueous and H₂O-CO₂ inclusions. The conditions of inclusion trapping correspond to the greenschist facies, at temperatures between 300 and 450°C and pressures in the range of 1.5–4.0 kb. A gradient of pressure of about 0.5 kb from the fault zone to the rocks of upper and lower plates is suggested. The results indicate that the syn-deformation fluid was NaCl-KCl-sulfate-dominated with a salinity of about 5 wt% NaCl equiv. Downward infiltration of meteoric water is a suitable source for this fluid. During the late stage of fault activity, in the brittle field, fluid was of H₂O-CO₂ composition. Very rapid exhumation of the entire section (unrelated to motion on the investigated fault) is marked by numerous decrepitation clusters of the fluid inclusions.  相似文献   

Mechanisms of sulfur introduction chemically controlled: δS imprint     

Alon Amrani  Zeev Aizenshtat   《Organic Geochemistry》2004,35(11-12):1319

Organic sulfur in marine sediment is ³⁴S enriched relative to the co-existing pyrite. This phenomenon is still enigmatic. Timing of the sulfur incorporation, immobilization and different sulfur species involved are part of the explanations. The reduced sulfur species incorporation into organic matter (OM) is generally assumed to have negligible δ³⁴S fractionation. This assumption has never been confirmed by laboratory experimental data. The present study measures the δ³⁴S changes resulting from reduced sulfur species (sulfides and polysulfide anions) incorporation into organic model compounds in an aquatic and low temperature (25 °C) system that simulates diagenetic marine environment. In addition, we also investigate the δ³⁴S fractionation and the isotope chemical mixing in the formation of polysulfide anions produced from elemental sulfur and sulfide anions. The results showed total isotope mixing between the two species in the formation of polysulfides. Acidification of the polysulfides solution caused δ³⁴S fractionation between the released elemental sulfur and H₂S. The incorporation of polysulfides and sulfides into carbonyl groups, caused ³⁴S enrichment relative to the starting polysulfides and sulfide of 4–5‰. The ³⁴S enrichment of the sulfurized carbonyl groups showed a minimal effect by temperature (0–70 °C) and is not affected by salinity, polysulfides composition, reaction time or solubility in water. The incorporation of polysulfides and sulfides into brominated organic compounds was negligibly ³⁴S enriched. The chemical mechanisms controlling the polysulfides incorporation into OM depend mostly on the functional groups and determine the ³⁴S enrichment of the sulfurized OM. The results presented in this study can explain part of the difference between pyrite δ³⁴S and sulfurized OM δ³⁴S in natural marine sediments.  相似文献   

Controls on the chemical and isotopic compositions of urban stormwater in a semiarid zone     

L Asaf  D Shain  S Geyer 《Journal of Hydrology》2004,294(4):270-293

The temporal variations in the chemical and isotopic compositions of urban stormwater under different land uses, and their dependence on physical parameters such as precipitation intensity, stormwater discharge, cumulative stormwater volumes and the size of the drainage area, were investigated in the coastal city of Ashdod, Israel. During 2000/2001 and 2001/2002, 46 stormwater events were intensively monitored for precipitation distribution and intensity at three stations across the city, and for stormwater discharge at seven stations draining 85% of the city area. Sixty-eight and 202 precipitation samples were collected and analyzed for chemical and isotopic compositions, respectively, as were 186 stormwater samples, collected from the drains during 15 of the 46 events. Land use had only a minor effect on the concentrations of major ions and trace elements. Conversely, the concentrations and variety of volatile and semi-volatile organic compounds were significantly higher in stormwater generated in the industrial area than in that draining from residential areas. Ion and trace-metal concentrations were very low (below drinking-water standards) in 97% of the stormwater samples collected from all drains. Stormwater concentrations were higher at stations draining a larger area, thereby linking concentrations to the length of the stormwater flow paths. A first-flush effect was documented on both a seasonal and event basis for both ions and trace elements. The high concentrations of fecal coliform bacteria exceeded the drinking-water standards and displayed a random pattern. The isotopic ratios of oxygen and hydrogen in the stormwater suggest very little exposure to the atmosphere, resulting in very limited fractionation. The presence of fecal coliforms, ammonium in some samples, and specific ratios of oxygen and nitrogen isotopes, suggest that although the sewer and stormwater-collection systems are separated, wastewater, possibly from overflowing sewers, contributed to the drained stormwater.  相似文献   

The biogeochemical cycle of iron and associated elements in Lake Kinneret   总被引：2，自引：0，他引：2  

Yeala Shaked  Yigal Erel 《Geochimica et cosmochimica acta》2004,68(7):1439-1451

Iron biogeochemical cycling and distribution between particulate, reactive (colloidal + dissolved, oxine-labile, Fe(II)) fractions were studied in the seasonally stratified, mesotrophic Lake Kinneret. This article presents various aspects of the Fe budget in the lake and relates them to the chemical reactivity of various physicochemical forms of Fe.The budget of Fe in Lake Kinneret is dominated by fluvial Fe load, rather than by internal recycling of Fe from the sediment, as shown by the fact that 75 to 94% of the variance in Fe concentrations in the lake can be explained by the fluctuation in the water discharge of the Jordan River. Iron associated with phytoplankton accounts for 9-16% of the bulk particulate Fe in the lake. However, within patches of the dominate algae, the dinoflagellate Peridinium gatunense, algal Fe accounts for more than 70% of the lake’s particulate Fe. The algal Fe is predominantly intracellular, and the Fe: chlorophyll a ratios were within the range of published values for dinoflagellates and cyanobacteria. Iron associated with particles larger than 0.025 μm (20-300 nM) accounts for 80-95% of total Fe in the epilimnion of Lake Kinneret throughout the year. In contrast, this fraction of Fe is dominant in the hypolimnion only during the period of lake mixing. Iron concentration of different size fractions (<0.025 μm, <0.2 μm and >0.025 μm) in the surface water covaried throughout the research period. These covariations suggest dynamic transformations of Fe between different size fractions, either due to partial dissolution/precipitation or desorption/adsorption. Oxine-labile Fe concentrations, the Fe fraction considered chemically labile and available for phytoplankton, ranged from 15 to 75 nM. In wintertime, the oxine-labile Fe accounts for only 10-20% of the total Fe, while in other seasons most of the Fe is oxine-labile. Oxine-labile Fe concentrations always exceed the 0.025 μm-filtered Fe, implying that some of the larger particles contain oxine labile-Fe, and therefore are reactive. The fraction of reactive particles in Lake Kinneret (10-80%) is high relative to that of the marine environments, and can most likely be attributed to its fluvial source, which contains a significant proportion of reactive Fe oxide and hydrous oxide particles.The annual variability in the epilimnetic concentrations of other trace elements and nutrients, such as Al, Mn, Cd, Zn, Pb, and P were studied and grouped according to their resemblance with river water discharge, redox processes, or biological uptake and scavenging. Distribution patterns of Al, Pb and Cd resembled that of Fe, suggesting that similar processes control the concentrations of these metals, namely significant contribution from the watershed, high affinity to particulate matter and little control of biota on their fate in the lake. Other elements such as Zn and P are more affected by biological uptake, while Mn is more affected by redox cycling within the lake.  相似文献