جستجوی مقالات مرتبط با کلیدواژه "کاشان" در نشریات گروه "زمین شناسی"

Soil and sediments are considered to be the main places for absorption of heavy metals in contaminated environments (Priju and Narayana, 2007; Øygard and Gjengedal, 2009; Ahmed and Al-Hajri, 2009). Therefore, they are used in Heavy Metals Pollution Index in geochemical studies.Saadabad area that is a part of the Urumieh-Dokhtar magmatic belt is located at 30 km south of Kashan. The natural processes along with hydrothermal processes, altered areas and mineral activities on mineralization areas have potential for releasing toxic elements in the environment. Therefore, the presence of toxic elements in sediments of the Saadabad is expected.The purpose of this study is to evaluate the concentration of toxic elements and determine their source in the sediments of the Saadabad region.

To investigate the status of environmental pollution of sediments, 174 samples were collected from the surface of sediments in the Saadabad area. The samples were analyzed by ICP-MS spectroscopy for determination of elements such as As, Cd, Pb, Zn, Cu, Co in the Zarazma Laboratory, Tehran, Iran.

Geochemical studies are carried out using various statistical techniques to map the various elemental abnormalities. These maps play an important role in determining high- risk areas. The results of preliminary investigations showed that according to the correlations between the various elements studied the patterns of dispersion of various elements in the sediments of the Saadabad region are similar to each other. The anomalies observed of As and Cd in the southwest of the region can be attributed to the presence of travertine in this part of the region (Smedley and Kinniburgh, 2005).Maximum concentrations of Co and Fe in the central part of the Saadabad region are consistent with the location of igneous and sedimentary rocks, skarnification and hydrothermal alterations. The enrichment of elements Cu, Pb, and Zn in sediments of the Saadabad region, emphasizes the effective role of sulfide mineralization and hydrothermal alteration processes in the region.Several methods that are applied for the assessment of trace elements contamination as follows:1- Contamination Factor (CF) is defined as follows (Reboredo, 1993): 1) CF=Cm Sample/Cm.

The Qohrud granitoid is a part of the Urmia-Dokhtar magmatic assemblage. The main rock types are Miocene granite and tonalite. The hydrothermal activities were effective due to intrusion. Hydrothermal activities were more intense in the southern part of the pluton. This has produced relatively large automorph quartz crystals. The alteration of the granitoid wall rocks was accompanied with alteration of K-feldspar, plagioclase and biotite, which has released Sr, K, Rb and to the lesser amounts Al from the mineral structures into the hydrothermal fluid. ICP-MS analysis of quartz samples reveals increase in concentration of some elements including Li (10.33 ppm), Al (6900 ppm), K 9600 ppm) and considerably two elements Rb (1.2 ppm) and Sr (3.35 ppm), along with positive anomaly of HREE in comparison to LREE that all indicate an hydrothermal origin for the studied quartz crystals. Using Ti content of quartz or TitaniQ thermometer gives temperatures of 307 to 547°C with an average of 371°C for crystallization of the quartz crystals. This temperature is in good agreement with temperatures calculated by fluid inclusions (306 to 550° C).