GEOSCIENCES
Year:2025 | Volume:35 | Issue:2|Papers Count:7

The metamorphosed Gohar Zamin iron deposit (643 Mt @ 54.3 % Fe, 2.04 % S, 0.12 % P) is hosted by mica schist, quartz schist, calc-schist and meta-basite. of greenschist facies that formed during Cimmerian orogeny. The presence of coarse-grained quartz dropstones and garnet-bearing schist clasts in the schistose rocks and CIA values (41.83 to 95.42) suggests a syn-glaciomarine pelitic with basaltic eruptions. ∑REE+Y patterns display slight LREE enrichment, low-moderate Y/Ho ratios, flat HREE patterns and negative Eu anomaly during pelitic rocks deposition. As a result of metamorphism, the magnetite-hematite ores display coarse grained texture (> 0.2 mm) that is an advantage for mineral separation, mineral processing and milling of the ore.

The Tavousieh manganese deposit occurs in the Soghan region southwest of Kerman province. This region is a part of the southern Sanandaj-Sirjan zone, formed during the Mesozoic to Cenozoic subduction of the Neo-Tethys oceanic crust beneath the central Iranian subcontinent. This deposit occurs in the ophiolite mélange radiolarite chert and is interbedded with pelagic limestones of Late Cretaceous. Petrographic and X-ray diffraction (XRD) studies show that the main Mn ores include pyrolusite, braunite, and todorokite with dispersed, colloform and cockade textures. The high contents of SiO2 concerning Al2O3 and Fe2O3, high Zn (96-410 ppm) content, and low Ni, Cu, and Co contents (95-646 ppm) of the studied samples reveal the influence of hydrothermal fluids in their formation. However, the REE distribution patterns indicate that hydrogenous processes also played a role in their occurrence, and accordingly, this deposit can be classified as hydrothermal-hydrogenous. By comparing the Fe2O3/TiO2 and LaN/CeN ratios of the Tavousieh and Nasirabad Mn deposits, it can be concluded that they formed as a result of manganese deposition in the Neo-Tethys Ocean from the oceanic ridge toward the continental margin.

The northwest Nain copper deposit is located in the Eocene volcanic-sedimentary sequence of the Urumieh-Dokhtar magmatic arc. The copper bodies are found in specific porous units, such as andesitic volcanic breccias, amygdale basalt, and andesite, and are mainly controlled by steep dipping fault zones. The alteration in the northwest of Nain involves epidote-chlorite, siliceous, and hematite alteration associated with mineralization. The major copper sulfides found are chalcopyrite, covellite, and chalcocite, which display disseminated, open-space filling, vein-veinlet, and replacement textures. Manto-type copper mineralization in this area is attributed to the mixing of primary hydrothermal fluid with basin and sea waters, with temperatures ranging from 149 to 321°C, and their average salinity is 7.7% wt.% NaCl equiv. The host units exhibit enrichment in light rare earth elements (LREE) and large ion lithophile elements (LILE), and depletion in high field strength elements (HFSE). These geochemical features, along with trace element modeling, suggest that all the host rocks were mainly formed by fractional crystallization of a common parental magma derived from partial melting of an enriched subcontinental lithospheric mantle source, and that the magma assimilated crustal materials during ascent and emplacement. Based on indicators such as tectonic setting, host rock, mineralization controlling factors, mineralogy, and texture, the copper deposit in the exploration area of Northwest Nain can be classified as a Manto-type deposit.

The Isfahan plain is located in the Sanandaj-Sirjan zone with geographical coordinates of 545000 to 581000 and 3606000 to 3627000. Subsurface sedimentary sequence in this plain is divided into 4 main zones and 6 subzones. Zone A is the rock outcrops and bedrock sequence in this plain. Zone B consists of alluvial fan deposits including a variety of talus cons (B1), coarse-grained to fine-grained (B2), and mud-flow (B3) sediments. Zone C consists of fine-grained playa deposits with pedogenic limestones, formed in depressed areas outside the Zayandeh-Rud alluvial plain. Zone D is the Zayandeh-Rud alluvial plain, divided into upper fine-grained (D1), middle coarse-grained (D2), and lower fine-grained (D3) units. Fine-grained sediments were deposited in calm and stagnant conditions, and coarse-grained sequences were deposited by river's flood currents. The flatness of plain, widening of bed, and uplift of bedrock in the eastern part of river's path led to the river's exit from main path in the Isfahan plain. Presence of coarse-grained fluvial deposits with high roundness and sphericity in an upward-diminishing sequence in the central, northern, and northeastern areas of the Isfahan plain indicates the existence of an abandoned channel of the Zayandeh-Rud river to the northeastern parts of this plain.

In recent years, the salinization in coastal aquifers, where agriculture is always developing, requires the investigation of aquifer vulnerability to water salinity. In the Ajab-Shir aquifer, to investigate the GALDIT vulnerability framework, which includes six layers such as type of aquifer (G), Aquifer hydraulic conductivity (A), Groundwater level above the sea level (L), distance from the coastline (D), quality Impact of saline water intrusion (I) and Aquifer thickness (T) used. Meanwhile, TDS values used to validate zoned vulnerability map. Also, to ensure the certainty of the available data, as well as to improve the weight and fix expert's errors in determining the weight of GALDIT layers, fuzzy logic (Sugeno), genetic algorithm (GA), random subspace algorithm (RS) and decision tree algorithm (M5P) were used. The results showed the correlation coefficient of about 0.5, 0.81, 0.6, 0.8, and 0.8 between GALDIT, GALDIT-F, GALDIT-GA, GALDIT-RS, and GALDIT-M5P with TDS, respectively. The south and south-east parts of the plain show the highest salinity potential and correlation values showed the good performance of GALDIT-F, GALDIT-RS and GALDIT-M5P methods in this study.

This study investigates the geometry and folding pattern of the East Band-e-Lengeh anticline, located in the Coastal Fars subzone, using 5 structural cross-sections and one longitudinal section derived from seismic line data, geological maps, and exploratory well data. The analysis reveals that the anticline is an almost symmetric fold with an overall elliptical to box-shaped geometry. Based on structural studies and interpretation of seismic lines, the southern limb of the East Band-e-Lengeh structure is affected by a reverse fault originating from the Dashtak formation. According to calculations using the excess area method, the folds detach at a depth of approximately 11 km, indicating that the deformation mechanism of the sedimentary cover in this anticline is a faulted detachment fold. Tectonic thickening of evaporites in the Dashtak formation (Middle Triassic) occasionally forms a detached horizon within the sedimentary cover, altering the geometry of Mesozoic and Cenozoic formations compared to the reservoir horizon of the Dehram group (Permo-Triassic) and causing axial shift. A UGC map of this horizon has been generated to explore the saddle-shaped relationship between the central segment of the anticline and its eastern segment and evaluate the exploration target horizon (Dehram group). Based on cross-section balancing using the bed-length conservation method, the shortening of the anticline is estimated at approximately 4%.

The Dorud fault is a key seismic segment of the young Zagros fault, stretching northwest-southeast from the Arjang area to Borujerd. This study examines the latest tectonic movements, young tectonic phenomena, and paleoseismology of the Dorud segment near Darb Astaneh village in eastern Dorud county. To achieve this, a 45-meter trench was dug in the NE-SW direction across the Dorud fault zone, revealing 9 paleo seismic events on the trench's eastern wall. These earthquakes had magnitudes ranging from 6.6 to 7.4 and a mean return period of approximately 104 ± 7 years. The findings suggest that large earthquakes triggered by the Dorud fault can produce magnitudes up to 7.4, surface ruptures of around 45 km, and slips of up to 3.83 ± 0.1 m per event, consistent with the EvI′, EvII′, and 1909 events attributed to repeated fault movement.