New paleomagnetic results from the northern margin of the Kohistan Island Arc

Different phases of remanent magnetizations have been identified in the Cretaceous–Tertiary rocks collected from the northern margin of the Kohistan Island Arc, northern Pakistan. Among them, a magnetite-related component is recognized as the most useful one because of its relatively stable behaviour and widespread presence in the volcanics and red beds. Calculation of mean direction for this component reveal two visible groupings in terms of paleomagnetic directions (Yasin + Baris Group: D?=?341.6º, I?=?10.6º, α ₉₅?=?23.3 º, k?=?11.7, N?=?5; Sandhi Group: D?=?28.4º, I?=??27.4º, α ₉₅?=?32.5 º, k?=?8.96, N?=?4). The fold tests applied to both these groups are inconclusive, indicating a syn-folding to post-folding origin for this component. A set of inclinations from this study provide new insight into post-collision northward displacement of the Kohistan Arc with respect to its surrounding terranes. Reliability of the paleomagnetic declinations from this study is not fully guaranteed, but when compared with previously reported paleomagnetic directions, a systematic increase in counter-clockwise deflections towards west has been detected along this paleo-island arc. This trend of declinations is well matched with the extrusion model of Asia, where counter-clockwise rotation has been suggested for the tectonic terranes around Western Himalaya. Another important observation is a divergence in paleomagnetic declinations across the rivers, which may indicate the presence of faulted zones under the cover of flowing water. This aspect can be compared to recent geological interpretations that Kohistan may not have acted as a rigid block following its collision with India but may have been deformed through localized shears and faults.     

Assessment of Relationship Between Grouted Values and Calculated Values in the Bazoft Dam Site

Seepage through foundation and abutments of a dam can potentially result in a waste of the water stored in dam reservoir, erosion of foundation materials, and development of uplift pressure in dam foundation which, consequently, threatens the long-term stability of the dam. In this study, the grout volume is estimated based on parameters such as joint aperture, the maximum penetration length of the grout, and calculated grout take in Bazoft dam site. Bazoft Dam is a hydroelectric supply and double-curvature arch dam with a height of 211 m located in Chaharmahal and Bakhtiari Province of Iran. The bedrock of Bazoft dam site consists of Asemari Formation (limy marl and marly lime), in the middle and upper parts of left abutment, and Jahrom Formation (limestone and dolomite) in the right abutment, river bed, and lower part of left abutment. The joint apertures were calculated based on the permeability and the joint spacing. Next, the maximum penetration length of the grout and grout volume were calculated. Using a statistical analysis, the relationship of the joint aperture, maximum penetration length, and the calculated grout volume with real grout take was also investigated. The results show that the grout take can be predicted with appropriate accuracy based on the calculated grout volume.     

Origin of groundwater salinity in the Fasa Plain,southern Iran,hydrogeochemical and isotopic approaches

The study area, the Fasa Plain, is situated in the semiarid region of Fars Province in the south of Iran. The Salloo diapir is a salt dome that crops out in the northwest of the study area. Isotopic and hydrochemical analyses were used to examine the water and how the origin of salinity and the diapir affect the quality of the groundwater quality in the study area. Groundwater was sampled from 31 representative pumping wells in alluvial aquifer and five springs in order to measure their stable isotope compositions, bromide ion concentration, and physical and chemical parameters. The alluvial aquifer was organized into two main groups based on the chemistry, with Group 1 consisting of low-salinity well samples (544–1744 µS/cm) with water type Ca–Mg–HCO₃–SO₄ which were taken in the center and north of the area, and Group 2 consisting of high-salinity samples (2550–4620 µS/cm) with water type Ca–Mg–Cl–SO₄ which were taken from the wells in the south and southwest of the area. A saline spring near the salt dome with an EC of 10,280 µS/cm has water type Na–Cl, while the compositions of the water in the other karstic springs is comparable to the fresh groundwater samples. All groundwater samples are undersaturated with respect to gypsum, anhydrite, and halite and are supersaturated with respect to calcite and dolomite. Stable isotopes (δ¹⁸O and δ²H) differentiated four water types: saline springs, freshwater spring, fresh groundwater, and saline groundwater. The results indicate that meteoric water is the main origin of these water resources. Halite dissolution from the salt dome was identified as the origin of salinity. The Na/Cl and Cl/Br ratios confirmed the results. Groundwater compositions in the southwestern part of the area are affected by the intrusion of saltwater from the salt dome. The average saltwater fraction in the some water wells is about 0.2%. In the south and southwestern part of the area, the saltwater fraction is positive in mixed freshwater/saltwater (Group 2). Different processes interact together to change the hydrochemical properties of Fasa’s alluvial aquifer. The main processes that occur in the aquifer are mixing, gypsum dissolution, and calcite precipitation.     

Abundance of sulfur in Eocene coal beds from Bapung, Northeast India

At 625°C the percentage of sulfur in the non-volatile portion of the Bapung coal beds ranges from 1.08 to 3.10 wt.%, with the pyritic sulfur ranging from 0.02 to 0.32 wt.%, the sulfate sulfur ranges from 0.02 to 0.30 wt.%, and the organic sulfur from 0.88 to 2.49 wt.%. The total sulfur in the Bapung coal ranges from 2.50 to 12.44%. Organic sulfur appears to be more abundant among the different sulfur species. However, the pyritic sulfur increases quickly as the total sulfur content increases at 925°C, the percentage of sulfur in non-volatile portion ranges from 1.27 to 2.54 wt.%, with pyritic sulfur ranging from 0.02 to 0.56 wt.%, sulfate sulfur ranges from 0.04 to 0.16 wt.%, and the organic sulfur from 1.15 to 2.03 wt.%.     

Zur Bedeutung der methodischen Probennahme für genetische Untersuchungen von Bauxit-Lagerstätten am Beispiel der Oberkreide-Bauxite der Parnass-Kiona-Zone Griechenlands

Zusammenfassung Die Diskussionen über die Diaspor-Boehmit-Genese in Bauxit-Lagerstätten stützten sich im wesentlichen auf die Untersuchung einzelner Profile. Bei der Bearbeitung griechischer Bauxitvorkommen der Parnass-Kiona-Zone ergab sich jedoch, daß die Frage der Diaspor-Boehmit-Verteilung nur durch eine flächenhafte, netzartige Probenentnahme mit Dezimeter-Abständen geklärt werden kann. Diese Untersuchungsmethodik ist von entscheidender Bedeutung für das Studium der Diaspor-Boehmit-Genese. Es gelang, im Gelände makroskopisch Diaspor- von Boehmit-Bauxiten zu unterscheiden. Es zeigte sich, daß die Lage von Diaspor und Boehmit im Profil nicht konstant ist. Somit erscheint es unumgänglich, die bisherigen Vorstellungen über die Diaspor-Boehmit-Genese zu überprüfen.

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The discussions on the diaspore and boehmite genesis in bauxite deposits so far have been based mainly on investigations of single profiles and their comparisons. Our investigations on Greek bauxites of the Parnass-Kiona-Zone showed clearly that the distribution of these two minerals within the bauxites can be found out only by grid-like taken samples at intervals of decimeters. This method is of greatest importance to studies of the boehmite and diaspore genesis. We are able to distinguish in the field macroscopically between diaspore and boehmite bauxites. The distribution of these two minerals is not the same within different profiles. It seems necessary to revise again the present opinions on the formation of diaspore and boehmite in the bauxite deposits.

     

Biological copper extraction from melting furnaces dust of Sarcheshmeh copper mine

This paper deals with bacterial leaching of copper dust emanating from furnaces at Sarcheshmeh copper complex. Regarding the considerable amount of acid leachable copper, a sulphuric acid leaching process was performed prior to bacterial leaching. Some shake flask and then bioreactor tests were conducted using a mixed culture of Acidithiobacilli and the effect of significant parameters such as culture medium, pulp density and bacterial inoculation rate were investigated. By increasing the pulp density because of higher toxicity and shear stress much more microorganisms and richer nutrient medium were needed. Favoured conditions that governed the agitated bioreactors caused a remarkable promotion in metal dissolution rate in comparison with shake flask. Copper recovery by bacterial leaching in shaking flasks and chemical leaching after 22 d were 87% and 38%, respectively. At the same condition, the maximum copper recovery in bioreactor was 91% within 6.5 d.     

Persistence of road runoff generation in a logged catchment in Peninsular Malaysia

Measurements of saturated hydraulic conductivity (K_s) and diagnostic model simulations show that all types of logging road/trail in the 14·4 ha Bukit Tarek Experimental Catchment 3 (BTEC3) generate substantial Horton overland flow (HOF) during most storms, regardless of design and level of trafficking. Near‐surface K_s(0–0·05 m) on the main logging road, skid trails and newly constructed logging terraces was less than 1, 2 and 34 mm h^?1, respectively. Near‐surface K_s on an abandoned skid trail in an adjacent basin was higher (62 mm h^?1), owing to the development of a thin organic‐rich layer on the running surface over the past 40 years. Saturated hydraulic conductivity measured at 0·25 m below the surface of all roads was not different (all <6 mm h^?1) and corresponded to the K_s of the adjacent hillslope subsoil, as most roads were excavated into the regolith more than 0·5–1 m. After 40 years, only limited recovery in near‐surface K_s occurred on the abandoned skid trail. This road generated HOF after the storage capacity of the upper near‐surface layer was exceeded during events larger than about 20 mm. Thus, excavation into low‐K_s substrate had a greater influence on the persistence of surface runoff production than did surface compaction by machinery during construction and subsequent use during logging operations. Overland flow on BTEC3 roads was also augmented by the interception of shallow subsurface flow traveling along the soil–saprolite/bedrock interface and return flow emerging from the cutbank through shallow biogenic pipes. The most feasible strategy for reducing long‐term road‐related impacts in BTEC3 is limiting the depth of excavation and designing a more efficient road network, including minimizing the length and connectivity of roads and skid trails. Copyright © 2007 John Wiley & Sons, Ltd.