GEOCHEMISTRY
Year:2012 | Volume:1 | Issue:2|Papers Count:7

The Quaternary basaltic rocks of north Siriz, located in the northwest of Zarand, are part of the volcanic rocks of Central Iran structural zone. Mineralogically, they consist of olivine, clinopyroxene and plagioclase phenocrysts and porphyritic is the main texture. Furthermore, they are characterized by microlitic-porphyritic, gelomero porphyritic, trachytic, intergranular, intersertal and amygdaloidal textures. Based on the electron probe microanalysis (EPMA), the olivine, clinopyroxene and plagio-clase phenocrysts are chrysolite, augite and anorthite in composition, respectively. Also, changes of chemical composition of magma are insignificant during crystallization of the phenocrysts, as MgO contents of olivine phenocrysts are slightly decreased from core to the rim. However, TiO2, and MgO and SiO2 contents of clinopyroxene phenocrysts show increasing and decreasing trends toward the rim, respectively. Based on thermometric studies, the temperatures between 1212 to 1283oC are estimated for the formation of clinopyroxene crystals.

The Gorgan plain with 11594 square kilometers surface area is located in the South East of Caspian Sea. In this region, groundwater is the main source of domestic, industrial and agricultural uses thus it is necessary to investigate the variation of hydrochemical quality of groundwater to protect it against the pollutant impacts. In this study, 189 samples have been collected from the deep wells of alluvial aquifer. However, the hydrochemical quality of groundwater has been evaluated by analyzing major cations (Ca2+, Mg2+, Na+, k+) and anions (HCO32-, Cl-, SO42-, CO32-) and also measurement of pH, Electrical Conductivity (EC), and total dissolved solids. The spatial analysis of data has been carried out using ArcGIS 9.3 software. According to the Piper diagram, samples are in Ca2+- Mg2+ - Cl- - SO42- and Ca2+ - Mg2+ - HCO3- groups and the qualitative trend in central, northeast and southwest regions of the plain are toward the salinization and sulfate increase which is due to contaminant leakage and salt water intrusion. Based on the Wilcox diagram, 71.43% of the samples are in C3-S1 group, indicating high salinity and low sodium content. As a result, the quality of drinking water is acceptable to good, and also it is desirable for irrigation.

River are main water resources for human communities. There are numerous long rivers and streams, froe of contamination, which are major factor in the sustainability, growth, and development of societies. The Shour Rivers watershed is located in the north of Khuzestan province southwest of Iran. This river has many tributaries and its main tributary discharges from Zanglab and Kynow Mountains. In this research, the chemical quality of the rivers in the whole watershed has been assessed, using AQqa software. All surface waters were sampled during both dry and wet seasons. The results show the significant effect of geological environment on the surface water quality in the study area. The evidence of dissolution of gypsum, halite and carbonate rocks were observed in course of rivers. Gachsaran formation outcrop in area is the main cause of Shour Rivers water quality degradation.

Increasing population and shortage of water resources savings have resulted in concerns regarding food supply that caused many nations towards the use of unconventional water resources for irrigation and food production. Among the saline and unconventional waters that are comonly used for agri-culture are sulfur springs. This research carried out to study the possibility of irrigation with Dalaki sulfur springs saline water and to determine the most efficient plant varieties tolerant to salinity. For this assessment, important parameters that influence the quality of irrigation water were calculated including major and heavy elements concentration, electrical conductivity, sodium and magnesium adsorption ratio, permeability index and residual sodium carbonate and they have been compared with standard values. The results showed that the spring waters are not suitable for irrigation, but due to shortage of water resources in the region and because of the fact that main occupation of inhabitants is farming, resistant plant varieties are recommended. In order to determine the appropriate variety, stan-dards were used and it was concluded that saltresistant plant varieties, including dates, barley, cotton, sugar beets, bobby wheat can been planted, with 50% yield. The appropriate management strategies are also presented such saline and fresh waters mixture to reduce land degradation and more reduction of product.

Ultramafic-mafic rocks and interbedded sedimentary rock association in the East of Fariman-Torbat-e-Jam lineament, Northeast of Iran, are interpreted as Paleozoic ophiolite and the cited lineament is regarded as the suture of Paleo-Tethys ocean. However, our studies on petrography and geochemical characteristics of igneous rocks of foregoing sequence have revealed some evidence in contrast to previous ideas. For example field relations and microscopy observations demonstrate volcanic to subvolcanic origin of both mafic and ultramafic rocks, and their distinctive geochemical properties compared to rocks the which formed at the subduction zone or constructive margins, including MORB or marginal basins. Various disequilibrium textures may be formed by undercooling of superheated melts. We have subdivided these rocks into komatiitic, picritic and tholeiitic varieties regarding to their different major, minor and trace elements composition which has reflected as various patterns in REE and spider diagrams. On the basis of ratios of incompatible immobile trace elements such as (Nb/Th) N versus (Nb/La) N, Nb/Th versus Zr/Y and La/Yb versus Th/Ta these rocks are similar to oceanic plate basalts (OPB). It is thus possible that regarding to their close spatial and temporal relations, and their position in Zr/Y versus Nb/Y diagram which have plotted upper than  DNb line they had been originated from a heterogeneous mantle plum source. Such a conclusion may be derived as well on the basis of high Fo content of fresh olivines up to 0.93, in komatiitic and picritic rocks which make necessary presence of a hot melt with high MgO content.

Today, it is common to use Rock-Eval Pyrolysis and its results for the determination and interp-retation of the characteristics of units of sedimentary basin. The aim of this study was to examine and compare hydrocarbon generation potential of Kazhdumi Formation by using Rock Eval analysis in Binak-4 well located in Dezful Embayment. For this purpose, geochemical investigation of Kazh-dumi Formation as the potential source rocks was carried out with 5 core samples in the studied areas. Investigation of the variation S1 + S2 and TOC parameters indicated that this formation is assessed a good source rocks in producing hydrocarbon in Binak-4 well. Based on HI versus Tmax plot the Kerogen content of this formation is mainly of type II and the deposit environment of this Formation is marine. Tmax examination also showed that this formation is not mature enough to generate hydrocarbon, and has not yet entered oil generation window.

The Khunik area is located in northeast Qaen city. The rock sequence in this area is composed of andesite, trachy andesite, andesitic basalt, aglomerate and tuff. Volcanic rocks of this area belong to Eocene volcanic activity. The alteration in area includes sericitization, argillization, chloritization, carbonatization and chertification, especially along the faults. The copper mineralization mostly located in andesitic sequences as malachite and azurite. To perform a primary exploration in the area, the stream sediment geochemical exploration method was used. In this regard, 42 stream sediment samples and to investigate the anomaly accuracy, 11 mineralized samples were taken. The analysis results for Au, Ag, As, Cu, Pb and Zn shows the copper anomalous in the area. The strongest correlation is found between Cu and Pb, Zn.