GEOCHEMISTRY
Year:2013 | Volume:1 | Issue:4|Papers Count:7

Governance of arid and semiarid climates in a vast area of country and demand growth for water in the various uses require the study of water resources status for water supply. Geographical information system is applied in different subjects including classification of groundwater quality. Zirrah plain, is located in the northeast of Dashtestan city in Bushehr province. In order to assess the hydrogeochemistry of groundwater in this area 19 groundwater samples were taken. According to maps and diagrams, the water quality in the north and central parts of this plain is unacceptable for drinking use, and other existing wells have temporary drinkable quality. In terms of irrigation water quality, most groundwater samples are plotted in C4S4 class on the basis of Wilcox's classification. Also the groundwater near the villages of Siah Mansur, Sar-e-Qanat, Nazar Aqai, Tall-e-Sar-e-Kuh can destroy soil physical structure. The quality of these water resources are shell depositing in terms of industrial use.

Shahkhairollah volcano lies at the Southeastern part of urumieh-Dokhtar belt (West of Sarcheshmeh copper mine) with Neogene age. This volcano contains pyroclastic, lava and subvolcanic intrusions which have located on Eocene basaltic rocks. Based on petrographic studies, Shahkhairollah volcano is composed of three types of rocks, including dacite, trachy dacite and trachy andesite. Mineralogically, they consist of plagioclase, quartzes, biotites and hornblendes; also, porphyritic is the rocks main texture. Plagioclas phenocrysts show evidences of disequilibrium textures such as sieve texture and zoning. These features can be formed by P H2O variations and decompression (as magma rises to the surface). The geochemical studies show that primitive magma has been calc-alkaline. Also, these data show enrichment of LREE and depletion of HREE. primitive mantle and chondrite normalized spider diagrams indicate the differentiation process and crust contamination on the primitive magma. AFC processes has been effective on the magmatic changes of Shahkhairollah volcanic rocks that it is understood by the mineralogical and geochemical evidences. LILE and Pb enrichments indicate crustal contamination. Moreover, typical negative anomaly of Ti and Nb can be shown that this volcano is composed in a volcanic arc environment and it is considered as an active continental margin volcano.

In south Tabriz, which is considered as a part of western Alborz-Azarbaijan magmatic belt, the volcanic and pyroclastic rocks of Sahand volcano cover the vast areas. The volcanic rocks include andesite, dacite, rhyodacite and rhyolites and pyroclastic rocks largely occur as widespread ignimbritic outcrops. Based on the high LILE/HFSE and LREE/HREE ratios and their similar composition to subduction volcanic rock suites; it is supposed that they have been formed in a subduction zone. The subduction process has effected on the concentration of Zr, Ta, Hf, Sm, Tb, Nd, Eu and Y elements, while it has strong influence on concentration of Th, U and La elements. Concentration of elements such as K, Pb, P, Zr, Sr, Ba, Rb shows that these rocks belong to the calc-alkaline series. Comparison of these rocks shows a considerable similarity with the calc-alkaline rocks from Turkey and it can be concluded that these rocks belong to post-collisional arcs. In this tectonic setting, magma ascent is controlled by strike-slip faulting and associated pull-apart extensional tectonics. This post-collisional magmatism may have been occurred due to the Arabian-Iranian collision events.

Numerous mafic dike swarms are crosscutting the Band-e-Hezarchah granitoid pluton (SE shahrood) Their host rocks consist of late Neoproterozoic-early Cambrian metaplitic, metapsammitic and gneissic rocks. These dykes crosscut Upper Triassic-Lower Jurassic conglomerates, sandstones and shales (equivalent to the Shemshak formation) and they don’t cut younger rocks such as lower Cretaceous (Neocomian) limestones. Based on geochemical characteristics, these rocks have alkaline to calk alkaline nature and their magma have been formed by 8-20% partial melting of spinel lherzolite sources. Thes rocks have formed in a continental arc setting to back arc basin related to Neotethys oceanic lithosphere subduction beneath Central Iran microcontinent. The formation of these rocks is a result of magmatism related to the middle Cimmerian orogeny phase. Pb positive anomaly and Ba, Ce and K high values show crustal contamination of basic magma during rising and emplacement.

The study area is located in the south of Rayen, 100 km from southeast of Kerman city, in northeast of Sardouiyeh geological map. This area is located in Urmia-Dokhtar Volcanic Belt (Sardouiyeh-Dehaj belt). Geological units of this area have calc-alkaline and K-rich calc-alkaline to shoshonitic nature. Geochemical analysis resulted from analyzing samples of Copper and associated elements (Ag, As, Mo, Pb, Zn) showed high enrichment of this element and Arsenic. Histograms of elements silver, molybdenum, lead and zinc show negative skewness and depletion; for Cu and As show a positive skewness which indicates their enrichment in samples. Correlation of copper with silver and zinc elements is too high, while the elements arsenic, molybdenum, and lead show low to moderate correlations with other elements. Average values for Cu in samples was 6219.5 ppm with the highest value in the sample EH-11 (33973 ppm).

In this study organic geochemical characteristics of probable source rocks including Kazhdumi, Gurpi and Pabdeh formations in Parsi Oilfield was evaluated using Rock-Eval pyrolysis and burial history modeling. Hydrocarbon potential of Kazhdumi, Gurpi, and Pabdeh formations were suggested to be very good, poor, and good to very good, respectively. Based on the values of TOC and S2. The Kazhdumi, Gurpi, and Pabdeh formations were generally plotted in an area of Type III kerogen, mixed Type II/III kerogen, and Type II, respectively, whereby these formations were derived from plant materials of terrigenous, mixed, and marine source materials, respectively. Thus considered to be generating mainly gas-prone and oil/gas-prone, and oil-prone, respectively. Based on the values of Tmax, Gurpi and Pabdeh samples are located in early maturation for hydrocarbon generation, while Kazhdumi Formation is in the peak maturation stage. Burial history model indicates that that Kazhdumi, Gurpi, and Pabdeh formations entered the mature stage for hydrocarbon generation.

Sari Gunay epithermal gold deposit, located in Kordestan Province, is one of the most important discovered gold deposits of Iran in the world class. This is a low sulfidation epithermal gold deposit. In this paper, positioning of gold mineralization has been modeled in this deposit using soil media geochemical data and through four classification methods including Bayes, k-Nearest Neighbor, Parzen Window and Naïve-Bayes classifiers based on Bayes decision theory. The productivity index parameter has been defined for surface cells with 25×25 in meters.65 percent of data are used as train data and the rest 35 percent as test data. The results indicate that Bayes classifier with accuracy of %72.6 and Parzen Window classifier with accuracy of %70.4 have functioned better than the two other classifiers. Besides, their gold mineralization models have been predicated the shape and their extent of hope-giving gold mineralization. Some other areas have also been recommended for further drilling in these models.