JOURNAL OF GEOTECHNICAL GEOLOGY (APPLIED GEOLOGY)
Year:2009 | Volume:5 | Issue:1|Papers Count:10

This research is an evaluation of vulnerability of Khash-plain aquifer to pollution, using DRASTIC model and Geographic Information System (GIS). Seven environmental parameters have been used to represent the hydrogeological nature of the aquifer. These parameters are: depth of water table, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity. This study shows that the Khash aquifer consists of two main zones: low groundwater vulnerability risk zone (risk indexes 92-121) and moderate groundwater vulnerability risk zone (risk indexes 122-148). Areas with moderate and low risk zones comprise 75.5% and 24.5% of the studied area, respectively. Statistical analyses have been carried out using nitrate ion concentration. Two tests of sensitivity analyses were carried out: the map removal and the single-parameter sensitivity analyses. Based on the characteristics of the studied area, the results from both map removal and single-parameter sensitivity analyses showed that the net recharge parameters have the most significant impact on the vulnerability risk zones.

The Kazhdumi Formation (Albian - Cenomanian) is one of the rock units of Bangestan group that is located in the Zagros Folded Zone. In this study the Kazhdumi Formation has a thickness of 222 m. The boundary between Kazhdumi and Dariyan formations is disconfirm, which is characterized by Iron oxide and glauconite layers which shows epirogeny that is confirmed by paleontological evidences. The presence of some foraminifera such as Nezzazatinella picardi, Scandonea sp., Daxia cenomania, Choffatella sp., Pseudolituonella reicheli together with calcareous algae, such as Lithocodium aggregatum in the Sarvak Formation, represent an early Cenomanian age.The microfossils in Kazhdumi Formation are: Ammobaculites goodlandensis, Marsonella trochus, Hemicyclammina sigali, Praechrysalidina infracretacea, Orbitolina (Orbitolina) concava, Orbitolina (Conicorbitolina) conica, Orbitolina (Orbitolina) subconcava, together with calcareous algae such as: Neomeris cretacea, Salpingoporella sp., Trinocladus tripolitanus, Permocalculus irenae, Dissocladella deserta.Based on assemblage zone of foraminifera and calcareous algae, 6 different biozones were recognized, which are: Dictyoconus arabicus ass. zone;Dictyoconus arabicus ass. zone;Salpingoporella annulata concurrent zone;Hemicyclammina sigali ass. zone;Orbitolina (Orbitolina) subconcava ass. zone;Nezzazatinella picardi ass. zone;Lithocodium aggregatum ass. zone.

Baba-Ali and Galali iron deposits are located west of Hamadan, within the Sanandaj-Sirjan geo-structural zone.Mineralogy and crystal-chemistry of the ore bodies using 57 analyses on the magnetite iron ore by SEM-EDAX method lead to some interesting results. Detecting the concentration of some trace elements such as V, Co, Ni, Cu, Cr, Ti, Au, PGE (Platinum Group Elements) and some impurities of S and P in the ore bodies indicates that only primary pyrites have concentrations of Pt. Other generations of pyrite and magnetite are depleted in these trace elements. The late stage of hydrothermal fluids that leads to mineralization of pyrite in calcite-quartz veins is important for Au mineralization and therefore pyrite is the best carrier for Au. Detection of abundant phlogopite crystals and trace element concentration patterns in the Galali iron ore has strengthened the acceptance of volcanogenic magnesium skarn type hypothesis.

In the study area, the various of cap carbonates include medium to coarse (saddle dolomite) grains of dolomites, are situated uppermost of sequence of Rizu Formation. The sequence of Rizu serie contains of various lithology, quartzite sandstone, turbidities (Greywacke) with association of ore minerals (Magnetite- Hematite- Jasper), in the form of Banded iron- Formations, (BIFs).The existence of dropstones with heterogeneous grains (Diamictite) within fine matrix of carbonate are the indicators for glaciations episodes, which are located under the cao carbonate. Chemical analyses of carbonates showed that the dc13, do18 values of carbonates in area are low, ranging From- 2.65 to -6.79 per mil versus (PDB), and- 6.48 to-15.21permil (PDB), respectively, whereas the excursion wide range of 18-oxygen isotope reflect the alteration and diagenetic processes. The high concentration of iron and manganese and high index of alteration (Fe/Sr=720 or Mn/Sr=52) is associated by decreasing 13-carbon isotope. The dc13 depleted carbonates reflect climate changes from glacial (Icehouse) to greenhouse conditions that deposited during sea- level rise after retreating and deglaciation after math global glaciations snowball earth.

Bon-do-no granite located at 230 km Eastern north of Shiraz in the Center of Kuh-Sefid, anticline. Tutak metamorphic complex is a part of Sanandaj-Sirjan matamorphic zone. Field studies shows that: 1- This metamorphic complex parent rock, have between lower to upper Paleozoic age and the metamorphism casualty accured before upper Jurassic and included by paragenesis of Micaschist, Amphibolite, Marble and Greenschist.2-After this accurance Tutak complex intruded by granite intrusive and the contact metamorphic accured in a margin Rock of this intrusive mass.Field studies and labratuary research shows that this granitic intrusive mass has a various accessory minerals like Garnet, Tourmaline, Amphibole, Sphen, Zircon, Rutile, Allanite and Apatite.XRD Analysis test at a Garnet, Tourmaline and Amphibole, shows that type of Garnet is Spessartine (Mn3Al2Si3O12), Tourmaline is Schorl [Na (Fe, Mn) 3Al6B3Si6O27 (OH, F) 4] and Amphibole is Actinolite [Ca2 (Mg, Fe) 5Si8O22 (OH) 2] and Richterite [Na2Ca (Mg, Fe, Mn, Al) Si8O22 (OH, F) 4].

To study depositional environment and sequence stratigraphy of Sachun and Jahrum formations 2 stratigraphical sections have been chosen (Sarvestan, Tange Kheyare).petrographic study shows that Sachun formation consist of 5 microfacies, gypsum, dolomite, red and green marl, dolomitic limestone and stromatolite that deposited in tidal flat and lagoon.Petrographic study on Jahrum formation recognized of 11 microfacies that including pelagic bioclast mudstone, pelagic bioclast wackestone, Algal bioclast grainstone, Orbitolites bioclast grainstone, Miliolide bioclast grainstone, Miliolide bioclast wackestone, Nummulite Alveolina bioclast wackestone, Pelloidal bioclast packestone, Intraclast bioclast packestone, Dolomudstone, Mudstone with birds eyes, Stromatolite boundstone. These microfacies deposited in open marine, bar, lagoon and tidal flat. Sequence stratigraphy studies shows that Sachun formation conformed 1 depositional sequence (DS1).lower contact of Tarbur formation erosional (SB1) and upper contact with Jahrum formation transitional (SB2). TST systems tract consist of green marl interbedded of dolomite, gypsum and dolomitic limestone. HST systems tract conformed of red marl interbed of gypsum. Jahrum formation in Sarvestan and Tange Kheyare sections conformed of 1 deposional sequence (DS1).lower contact of Sachun formation transitional (SB2) and upper contact erosional (SB1).TST systems tract related to lagoon environments and HST systems tract conformed of shallowing upward parasequences and consist of dolomite and dolomitic limestone.

Choopan antimony deposit is located in the North of Lout desert, Central Iran. This area contains volcanic rocks of Early Tertiary, which are important for Sb, Pb & Zn, Ag, As, Cu and Au. Gold is below detection limit in major of these rocks. The main rocks in this area are volcanic rocks that have composite of toleoithic type, with dacite and andesite rocks. The main minerals are stibiconite, stetefeldite, bindehimite, galena, sphalerite, pyrite, arsenopyrite, sinabar, pyrolusite and chalcopyrite. The country rock in veins is dacitic porphyry rocks.The mineralization is associated by pervasive alteration of sericitization, argillitization, silicification, carbonization and propylitization. The alterations and mineralization are accompanied by faults directions, which seem to be main sources for hydrothermal circulation in these rocks. During the study 77 samples were analyzed for Cu, Pb, Zn, Au, and Ag, As, Sb, Hg, Cd and MO by AAS. Data processing showed that the Sb anomaly was developed mainly over the north and southeast area. The average of Sb content is about 4000ppm. There are good correlation between Sb and Pb and Ag. Geological, petrological, mineralogical, geochemical and fluid inclusion studies showed that the Sb mineralization in the Choopan area is a new epithermal type Antimony namely Supergen Adularia- Sericite or Sulphid Antimony-silver type.

A thick sequence of Paleozoic rocks in Central Iran with special characteristics has been investigated. This corresponds to some other regions in Iran. The aim of this research is to investigate several facies of the Paleozoic in the southern part of Central Iran containing supertidal, intertidal and lagoon facies carbonates that are found in arid climate, similar to the southern Persian Gulf and west Australian coast and sandstone, black and red shale, siltstone and conglomerate of terrigenous facies. Based on widely extended sandstone layers and the existence of dolomitic layers in the top of terrigenous sequence, we suggest the existence of a littoral environment with slow subsidence for formation of these layers. Black shales are found in the end of delta environments and small islands existing between braded channels.With increase of energy, siltstones and sandstones were formed between black shale’s layers. Red shales accompanied with siltstones and tiny to grainy sandstones indicate continental tropical weather. The conglomerate layer on the paleorelief represents an off lap stage and an orogenic phase. In the sedimentary environment of the above mentioned sequence, based on the existence of different fauna, special lithologic and sedimentary structures, there can be recognized marine facies, containing littoral, intertidal, lagoon, bioclastic bar, reef and sandy bar, and continental facies, containing braided river channels and point bar.This study demonstrates that Upper Devonian sediments were laid above the sandstone and quartzite layers, like in other regions in Central Iran, and were deposited chronologically at the Pre-Middle Frasnian.