نشریه زمین شناسی کاربردی پیشرفته
سال دوازدهم شماره 46 (زمستان 1401)

The geological units exposed in the Qaradash area are Paleozoic metamorphic rocks. Microscopic studies reveal that the skarnoid aureole in Qaradash is composed of garnet hornfels, garnet-pyroxene hornfels, pyroxene hornfels, epidote-garnet-pyroxene hornfels, epidote hornfels and marble subzones. Pb–Zn mineralization at Qaradash occurred as quartz-sulfide vein-veinlets within skarnoid aureole.The ore zone can be traced 200 m along strike and up to 15 m in width. The hydrothermal alteration includes of decarbonatization, actinolization-epidotization, carbonatization, and silicification. The ore minerals at Qaradash are pyrite, chalcopyrite, galena, sphalerite, and hematite. The gangue minerals include garnet, clinopyroxene, calcite, quartz, epidote, chlorite, and actinolite. Ore minerals display disseminated, vein-veinlet, brecciated, replacement, and relict textures. Similar Chondrite–normalized rare elements and REE patterns (McDonough and Sun, 1995) of ore and skarnoid aureole sub-zones samples indicate that they are genetically related. Based on mineralogical and textural studies, skarnification processes in the Qaradash occurrence can be divided into 2 stages including: (1) prograde metasomatic stage and (2) retrograde metasomatic stage. Pb–Zn mineralization occurred during retrograde metasomatic stage. Based on mineralogical and textural evidence, prograde metasomatic stage was formed simultaneously in 430–550 °C and ƒO2 was equal to 10-23 to 10-26 (e.g., Einaudi, 1982). According to mineralogical complex of the early retrograde stage, it seems that metasomatic fluids had ƒS2 ≈ 10-6.5 (e.g., Einaudi, 1982). Based on field evidences as well as ore geology, skarnoid aureole sub-zones, marble host rock, structure and texture and paragenetic sequences, we conclude that the Qaradash occurrence is a calcic Pb–Zn skarn mineralization.

The Golmandeh Metamorphic Complex is located in the Central East Iranian Microcontinent. In this research, structural and microstructural studies have been performed to determine the nature of the deformation in the Golmandeh metamorphic complex. The presence of microstructures such as mica fish, rotating porphyroclasts, and the S/C structure all indicate the top-to-northeast sense of shear. Based on the dynamic recrystallization studies, the deformation temperature in the Golmandeh Metamorphic Complex is estimated between 500 and 650° C. This condition correspond to amphibolite metamorphic facies. Using the Rigid Grain Net (RGN) method, the mean kinematic vorticity number was estimated to be 0.75. Based on the results of kinematic studies, the deformation regime in the Golmandeh Metamorphic Complex was determined as a general shear with contribution of 55% simple shear and 45% pure shear component.

Facies analysis of Garau Formation exposed in Lurestan Basin, High Zagros, folded belt Zagros led to indentification of three facies associations, representing basin plain, turbidite floor fan to outer ramp of a distally steepened ramp system. Basin plain deposits in central Lorestan Basin include plagic and hemi-plagic and turbidity deposits were developed in southern part of the Lorestan area. Analysis of depositional environment and facies of the Garau Formation reflect a three stage evolution model: 1) Early stage is represented by ramp drowning and basin plain expansion in an anoxic to dysoxic, low energy conditions with high productivity; 2) The activation of turbidity currents in the basin floor. These intervals are coincided with Leupoldina bloom and Oceanic Anoxic Event 1a (OAE1a). The middle part of the Garau Fm. is interpreted as fine-grained pelagic turbidites on base of their flat shape, sharp base, transitional top, Buma sequence and composition, which are composed mainly of intercalation of gravity flows and pelagic/hemipelagic deposits. The relative influence of sea level falls may result in an increase in sharp activation of turbidity currents and deposition of floor fans. 3) Stage 3 is represented by the recovery in the effectiveness of carbonate factory, favoured by the progressive shallowing of the depositional system and an increase in the abundance of pelagic foraminifers. These deposits reflect the shutdown of the turbidity and subordinate mass flows of the feeder system in the mainland and drowning of calciturbidites stage 2, likely as the result of a relative sea-level rise.

With the fast development of metropolitans, the huge production of construction and demolish waste has become a challenge for sustainable development of the cities. Although some efforts have been made to promote re-use and recycling of construction wastes. However, landfilling of waste, remained the most common method for the mentioned disposal. Therefore, site selection and finding a suitable place, is one of the most important steps in the management of the wastes. Due to the destructive environmental effects of the landfill, the selection of the suitable site should be done with accuracy and through a scientific process. In this study, considering geological criteria (fault, lithology, morphology and slope), environmental criteria (hydrology, geohydrology, groundwater depth and protected areas) and socio-economic criteria (residential areas, airports, industrial areas, communication lines, mines, transmission lines and land use) through the capabilities of GIS software and using a combination of Buckley fuzzy hierarchical analysis process methods and the ideal option, suitable locations has been selected for disposal of healthy and unhealthy construction waste in Tabriz city. Based on the obtained results, three places in the north, south and east of the Tabriz city have been selected separately for the disposal of healthy and unhealthy construction waste and demolish.

Changes in the quality of underground resources for various reasons, especially the unconventional use of these resources can have devastating effects on the environment.In this research, groundwater quality parameters including electrical conductivity, total soluble solids, acidity, sodium adsorption ratio, hardness, bicarbonate, chloride, sulfate, calcium, magnesium, sodium, potassium, and the sum of anions and cations were used. in this research, groundwater quality data related to piezometric water wells affiliated to the Hamadan Regional Water Company for four-year periods in 2009, 2013, 2017, and 2020 in the plains of Hamadan province have been used. The results of Moran and coefficient of gery show that the spatial distribution pattern of all water quality parameters in 2009 and 2020 is random and for the parameters of electrical conductivity and sodium adsorption ratio in 1992 and 1996, respectively, with a high level of confidence of 95% and 90%, respectively, it had a spatial distribution with a cluster pattern with high values. To investigate the spatial variations of electrical conductivity using the Kriging method, water quality maps in terms of electrical conductivity parameters for the years 2009, 2013, 2017, and 2020 have been prepared. The map of electrical conductivity changes prepared from 2009 to 2020 years shows that the amount of electrical conductivity in the city of Hamedan (Qahvand) and Razan and Kaboudar Ahang plains has more increasing changes, which indicates a decrease in groundwater quality in the case study area. Therefore, planning is necessary to correct the decline in groundwater quality.

In the present study, for biostratigraphic studies based on calcareous nanoplankton, marine deposits attributed to the Oligocene of Boujan section in the Sirjan region (Central Iran) have been sampled. The studied deposits consist of marl, limestone and shaly limestone with 392 meters in thickness. In this study, 27 well- preserved species belonging to 10 nannofossil genera were identified. According to the identified index species and nannofossil assemblages, nannofossil biozones Helicosphaera reticulata Zone (NP22/ CNO2/ CP16c), Sphenolithus predistentus Zone (NP23/ CNO3-CNO4/ CP17-CP18), Sphenolithus distentus Zone (NP24/ upper part of CNO4- lower part of CNO5/ CP19a), and Sphenolithus ciperoensis Zone (NP25/ upper part of CNO5-CNO6/ CP19b- CN1b) were determined for the studied deposits. Based on the stratigraphic position of investigated taxa and determined biozones, early Oligocene to late Oligocene (Rupelian to Chattian) was suggested for the investigated deposits. Based on the stratigraphic position of investigated taxa and determined biozones, early Oligocene to late Oligocene (Rupelian to Chattian) was suggested for the investigated deposits.

Fractal modeling is a useful tool for classifying various natural phenomena. Fractal methods evaluate relationships between all parameters, such as geochemical data and spatial distribution, without any data normalization. For this reason, fractal models are more exact and closer to reality. In this study, 1292 samples of Stream sediments on the 1:100000 geological sheet of Varcheh in the south of Arak were surveyed for geochemical exploration and analyzed by the ICP-MS method to detect 15 elements. The statistical parameters of Zn, Pb, Cu, and Ba, and histograms for these 15 elements showed a right-skewed distribution. In this case, the fractal method is among the best techniques for separating anomalies from the background. The element data were analyzed by the concentration-number (C-N) fractal method and then matched to alteration zones and faults plotted by ASTER multispectral imagery to detect minerals. The C-N fractal diagram was plotted for Zn, Pb, Cu, and Ba, and the most intensive anomalies for these elements have a grade greater than 524.8, 794.3, 223.9, and 944.1, respectively. Integrating the anomaly maps for Zn, Pb, Cu, and Ba with iron oxide, proplytic, argillic, and silicic alterations, fault maps, and the maps of mines and Varcheh mineral indices showed that the metal mines have mainly occurred in regions with a high fault density. The separated Pb and Zn anomalies are consistent and related to high fault and fracture density regions. They are also highly correlated with the silicic alteration plotted in the region.