فصلنامه زمین شناسی ایران
پیاپی 61 (بهار 1401)

In this paper, concentration-number fractal method was used to study regional exploration and geochemical anomaly separation; also anomalies of index elements including gold, arsenic, silver, copper, antimony, lead, zinc and molybdenum in the Qalehdar exploration area (Isfahan province) was investigated. For this purpose, 336 samples of rock units were collected and analyzed by ICP-MS. Then the chemical analysis data were categorized and prepared after replacing the sensor data for processing..Using concentration-number fractal method, elemental anomalies in that area was identified and the anomalies were mapped. The results of geochemical studies in the area showed that different geochemical anomalies of Au, Mo, Cu, As, Sb, Pb, Zn are closely related to alteration zones and shallow plutons. These studies also led to the identification of a geochemical system.. After drawing the geochemical maps and identifying the anomalous regions, the anomalies of the various elements were correlated and a zoning was recognized. In this zoning from the center to the outside of the system,the anomalies respectively, include molybdenum (Mo), copper-molybdenum (Cu Mo), lead-zinc (Pb Zn) anomalies and finally the gold-arsenic anomaly (As Au) which is located at the periphery of the system.

The Sebandoon copper deposit is located in the northern part of the Sabzevar subzone. The rock units exposed in the area consist of upper Cretaceous volcano-sedimentary sequences of trachyte, trachyandesite, basalt, split, shale, dacite and sandstone. The Sebandoon native copper deposit comprises stratabound mineralization which is hosted in split basalt. The main ore structures and textures in the deposit include disseminate, veinlets, open space filling and replacement forms. The ore mineral assemblages are simple and consist of native copper, coprite and malachite and main gang minerals are zeolite, calcite, quartz, chlorite and epidote. Fluid inclusion studies on ore-bearing zeolite reveal that majority of primary inclusions are liquid-rich two-phase (LV) ones. The studies indicate homogenization temperatures were between 228 and 340°C and salinity varied between 0.6 to 5.7 wt% NaCl eq. Based on the evidence from geology, mineralogy, alteration, fluid inclusion, and geodynamic environment, the Sebandoon copper deposit is similar to Michigan copper type deposits, in which copper was leached from the basaltic rocks during burial metamorphism and the ore-forming fluids moved upwards and subsequently deposited as native copper due to low pressure and mixing with meteoric fluids.

In this research, the biostratigraphy of the Cretaceous deposits was investigated in the eastern margin of Lut Block in Khunik startigraphic section, west of Qaen, based on calcareous nannofossils. The stratigraphic interval mainly consists of marls with sandstone interlayers (196 m thick). According to the systematic studies, 30 nannofossil species belonging to 20 genera were identified. Based on the presence of index calcareous nannofossils such as Calcicalathina oblongata, Speetonia colligata, Eiffellithus striatus and the fossil assemblages Calcicalathina oblongata Zone (CC3), Cretarhabdus loriei Zone (CC4) and Lithraphidites bollii Zone (CC5) these deposits are equivalent to NK3A subzone – middle part of NC5B subzone. According to the determined biozones, early Valanginian to late Hauterivian age was suggested for the studied interval.

Saray volcano is an extinct volcano and is located in the east of Urmia Lake. This volcano mainly consists of Leucititic lava flows and their related pyroclastic materials forming a Sequence which repeated more than five times. Leucite phonolitic dykes, Lamprophyric (Minette, Monchiquite and Spessartite) lavas and dykes, Trachytic domes and dykes, Syenitic dykes and a small syenitic stock are other rock types of Saray volcano. Since clinopyroxene is present in all rock types of this volcano, mineral chemistry study of clinopyroxenes in all rock types of Saray volcano, could help us to explain the relationship between different rock types. Clinopyroxenes of Saray volcano have diopside, salite and fassaite compositions. The majority of studied clinopyroxenes crystallize under 3-4 kb pressure and 1150 centigrade temperature. Tectono-magmatically speaking, these clinopyroxenes were mostly formed within plate basalts. Although the composition of rock types of Saray volcano is very different, almost constant composition of clinopyroxene in all rock types, show the same origin for all clinopyroxenes. However, it can be concluded that all rock types have the same origin.

Groundwater control is an important issue during underground excavation in fractured rocks. More than any other factor, the lack of groundwater control can cause costs to rise.
In this study, the characteristics of the Surmeh Formation in Zimkan aquifer were analyzed using the recession curve of discharge water from the tunnel. The results show that behavior of the recession curve of discharge water from the tunnel is similar to discharge of the conduit flow system of karst springs. In the first seven days, the slope of the recession curve was high and equal to 0.041, but over time in considering to progress of tunnel excavation and 41 meters groundwater table drawdown in karstic aquifer of Surmeh Formation; the slope of the recession curve decreased and it became similar to diffuse flow system of the karstic aquifer. In the recession curve of discharge water from the  Nowsud Tunnel, all three porous systems, including conduit, semi conduit and diffuse are properly identifiable in time intervals of seven, 48, and 87 days respectively. with respect to similarities in the behavior of discharge water from the tunnel with karst springs, the hydrograph of recharge water into the tunnel can be used as a discharge below the base level of the karst hydrologic system in order to assess the dynamic reserve of the upper karst aquifer (above the tunnel level).

The studied area is a part of Eastern central Alborz, bestween southeastern piedmont of Alborz (NW of Damghan) and North Alborz Fault (South of Sari). The Alborz Mountain range which forms the heights of northern territory, separated the Caspian Depression from Iran central plateau. The Alborz is one of the Iranian mountain ranges that were deformed during two Cimmerian and Alpine organic events. This deformation is continued until the present day. This research is based on the satellite images, field investigations, drawing structural sections, stratigraphic sequences from the folded and thrusted parts of Alborz Mountains. The studied area is composed of numerous anticlines and synclines from South to North as Tuyeh- Darvar anticline, Sabour anticline, Talma- Darreh anticline, Alikhani syncline, Tarkan anticline, Babr cheshmeh syncline and anticline. Some of these folds are related to faulting which occured due to the typical continuous shortening and faulting of Alborz crust and destroyed their original patterns. The function of main faults and specially thrust faults played an essential role on the present models of mentioned folds. Regarding the axes of the folds, the effective compression over the area has a North, North Waste-South, South-East direction. This direction is perpendicular to axial trend of folds.
The physico-mechanical properties of Alborz geological units caused development of detachment surfaces on main faults. The shortening intensity and large displacements have led to disappearance of a limb or whole  fold. In this study the three surfaces of detachment were introduced inside the stratigraphic sequences from Precambrian to middle Eocene based on the well-known and documented data.