TORUD FAULT is located in 110 Km away from the south of Damghan and trends ENE-WSW that is approximately E-W at its west end. In this termination region, observed structures indicate a special aspect of strike-slip FAULT terminations. These structures are of two sets: the first set are structures trending approximately N-S and are mainly compressional ones such as thrust FAULTs and folds both verging to the east. These structures are in Paleozoic and Mesozoic rocks. Right lateral and normal shear structures, microfolds, foliations, and lineations are also associated with them. The second set is structures having NE-SW direction and include open gentle folds and younger thrusts which both verge to the south. They are mainly in Cenozoic and younger rocks but have made notable changes in older rocks too. Direction of TORUD Mountain and its surrounding FAULTs to direction of Arabia - Eurasia convergence, and effects of rotation and compression of Lut block and movements of its surrounding FAULTs, led to transpressional deformation in the area under study The direction of slip in this system was related to tactors that were mentioned above and has been changed in response to the local changes of stress field. Strain in some locations has been partitioned into two components: shearing; and compression. They operated contempo-rarily or in two separate times. Other minor structures such as Reidel and P shears and folds of wrench tectonic also exist as they are predictable in shear zones.

The only geologic evidence of the neotectonic activity of the TORUD region is its seismisity which assumed to be related to the TORUD seismogenic FAULT. This FAULT has been overlain by the Quaternary alluvium in the major part of its length. Therefore, the study of morphotectonical characteristics of the region gives more evidences about its activity. Calculation of three morphotectonic indices including stream length - gradient (SL) and ratio of valley - floor width to valley height (Vf) of stream channels and mountain ITont sinuosity (Smf) shows high SL values (425-1044) and low Vf (2.68-3.34) and Smf (1.05-1.44) values and indicate that the region has activity specially at two parts: central part (near the mountain front) and northwestern part (near the main divide of the TORUD mountains) and therefore the tectonic activity class of the region can be number I. The activity of the central part can be due to the movements of the TORUD FAULT. The activity of the northwestern part is the result of the uplift of the region which is related to the at least one FAULT parallel with the TORUD FAULT that has formed the relic mountain fronts at recent past. The distribution of strain of this activity shows the progressive deformation from north northwest to south southeast and from west to east.

The studied area is located in the S Shahrood, and NE of Central Iran structural zone. Many basaltic dikes in this area intruded into the Eocene volcanic rocks and some of them contain many gabbroic enclaves. Plagioclase (labradorite, bytownite-anorthite), calcic amphibole (pargasite-magnesiohastingsite), and calcic pyroxene (diopside-augite) are the essential minerals of these rocks. Magma forming of these rocks has mainly subalkaline nature and during their crystallization fugacity of oxygen has been high. Pyroxene and amphibole geothermometry suggest crystallization equilibrium temperatures of host basaltic rocks, dikes and enclaves, at 1100-1200° C and 825-1038° C, respectively. Al-in amphibole barometer in host basaltic rocks, dikes and enclaves show that pressures ranging between 8. 51-9. 21 kbar, 7. 41-9. 16 kbar and 6. 84-7. 46 kbar, respectively, and based on pyroxene at 2-8 kbar. . The geochemical characteristics of studied rocks show strong compositional similarities and indicate that the nature and origin of host basaltic rocks, dikes and enclaves are the same and most likely the magmatic reservoir of them were at depths of 33 to 25 km of the lower crust. Gabbroic enclaves were the result of the initial crystalline separation of host basaltic rocks, which was later brought to the surface by dikes from the depth of the magmatic chamber.

Granitoid bodies of  south of Damghan with northeast-  southwest trend have intruded into the  Eocene volcanic,volcanoclastic and Cretaceous carbonate deposits. Recent studies have revealed that the Al content of hornblende in calc-alkaline granitoids varies linearly with pressure of crystallization, thereby providing a mean of determining depth of pluton emplacement. Based on results of electron microprobe analyses, amphibole minerals present in these bodies, according to Leake are ploted in the field of calcic amphiboles and show Actinolite, Actinolite-Hornblende and Magnesio hornblende composition. Calculated pressures of emplacement , using the Al-content of Hornblende, for these bodies ranging from about 0.51 to 0.98 Kbar (about depth of 1.8 to 3.5 Km).The altimate equilibration temperatures of minerals were calculated using different thermometers ranging from 613 to 772 oC.

TORUD-Chah Shirin volcanic-plutonic complex, related to Eocene series, is located about 130 kilometers south of Shahrood, in the south and north of TORUD village. This zone is located in 54˚ 20’ to 55˚ 20’ east longitude and 35˚ 10’ to 35˚ 40’ north latitude. The presence of several mineral occurrences, especially base metal veins of epithermal origin and the intrusion of igneous acidic to intermediate bodies in volcanic rocks of the area caused different alternation and mineralization in some parts of the area and increased the economic importance of the magmatic complex for geological studies. False color composites (FCC), band ratios (BR) and spectral angle mapping (SAM) which were performed on ASTER dataset for discrimination of alteration of argillic, advanced argillic, phyllic and prophyllitic zones and evaluation of results by XRD analysis, are the fundamental information for this research. The field studies and XRD analyses of different zones resulted in adaptation with logical operator algorithms and revealed unremarkable volcanic alteration zone in the south of TORUD, in comparison with volcanic zone in the north of TORUD. In addition, altering in threshold of algorithm band ratio can be used to find better results in discrimination of argillic and phyllic alterations. Then based on the presence of indicator minerals of advanced argillic alteration in the north of TORUD, like alonite and prophillite, the optimal threshold for discrimination of this zone from argillic zone by logical band ratio algorithm was determined. The results were evaluated as acceptable, compared to field study. On the other hand, spectral character of remarkable minerals of this zone, like chlorite and epidotite, in band ratio of Aster 8(9+7) with threshold of 2. 3, is reported appropriate for land surveying of proplitic zone in the north and south of TORUD village.

Study area is located in 130 km Southeaster of Damghan city and North of the Jandagh desert between TORUD- Moalleman villages. This area situated in Central Iran zone and located between two major FAULTs, TORUD FAULT in South and Anjilu FAULT in North. This region belongs to TORUD-Chahshirin volcano-plutonic band with metamorphic substructure. Volcanic rocks of this area consist of dacite, andesit, trachyandesit, tuff, rhyodacite, rhyolite and andesibasalt also the plutonic rocks consist of Granite and Granodiorite to Diorite. The Paleozoic and Mesozoic sedimentary rocks separated in west of this area. These rocks consist of so many fractures in this FAULT shear zone that with penetration of hydrothermal solution in fractures and FAULT system, without mineral veins and mineralized (Au, Ag, Cu, Pb, Zn and Para genes) veins are formed. Near of them different dykes penetrated in some fractures that altered the host rocks. General and detailed geological research (in 12 regions of this area) showed that this area contains of so much fracture and FAULTs that formed relation of left lateral shear zone.Determinated of these small and huge fractures were classified them to D, P, X, T, R and R' fracture groups that each one have tectonic specifics. Another way research of dykes and fracture of them, showed tension regions that located in west and central of study area and agreement with T, R and D types of fracture. Notice to these fractures controlled mineralized veins, we studied all of fractures and the veins of them in 12 Mining areas that resulted mineralized veins located in R, R' and D types of fracture.

Detailed geological and structural analysis of north of TORUD-Moalleman area (Central Iran), between Anjilu FAULT in north and TORUD FAULT in the south, led to tectonic elements of this limit such as fractures and relative of their mechanism with left lateral sheared zone of two main FAULTs. This study provides a movement system of Chalu, Gandi and Hafez FAULTs in this shear zone. On the basis of kinematics findings and using general methods of FAULT slip analysis (orientation of slip plane, slip vector, shape of stress ellipsoid and angle of internal friction) region stress field were calculated after determining the angle of internal friction for each one of FAULT limits. Then, the main stress orientation determinates for combination data that values of s1, s2, s3 were 195/10, 339/78 and 104/07 respectively. The shape of stress ellipsoid was defined on the basis of shape factor, [R= (s2-s3) / (s1-s3)], (Angelier, 1975). The R-value for whole studied regions was about 0.5 and deformation type was mainly left lateral transpressional with reverse component. Such results are evident from N-NE (N195) trending s1 in the region and northward movement of the lithosphere. These finding are in line with field research results of fractures, FAULTs and mechanism in this general shear zone.

One of the major strengths of a Geographic Information System (GIS) in geosciences is the ability to integrate and combine multiple layers into mineral potential maps showing areas which are favorable for mineral exploration. These capabilities make GIS an extremely useful tool for mineral exploration. Several spatial modeling techniques can be employed to produce potential maps. However, these methods can be divided into knowledge -and data- driven techniques. The goal of this study is to use GIS in mapping gold deposit potentials in TORUD-Chah Shiran area. After collecting relevant exploration data and defining appropriate exploration model for the mineralization zone, several layers including proved mineralization map, geological map, remote sensing derived, alteration map, geochemical and aeromagnetic maps were imported in to GIS environment. For integrated exploration modeling, two methods were used: fuzzy logic and weight of evidence methods. Finally, the results of the two methods were compared. The result of each method had statistical problems but these problems were alleviated using the map of differences that was in a good agreement with reality.

The study area is located in the south of Damghan, 160 km south of Shahrood, and 17 to 30 km south of TORUD village. The area geologically, lies in the Cenozoic magmatic belt, a part of the Alpine-Himalayan belt, in the north of the structural zone of Central Iran (Aghanabati, 2004). The Cenozoic magmatic belt has been studied by many researchers (e.g., Ghorbani, 2005; Khajehzadeh, 2009; Mardani-Beldaji, 2011; Tayefi, 2014; Yousefi, 2017). The volcanic rocks in the southern part of the TORUD area have not been comprehensively studied. Therefore, it requires a detailed study. So, for the purpose of this study attempt has been made to investigate and to study the nature of magma, tectonic setting, and the petrogenesis of the volcanic rocks using the geochemical data of the whole rock. Also, the results of this study have been compared with some areas belonging to the Cenozoic Era located in the north of the structural zone of Central Iran.Regional GeologyThe area under study in the TORUD-Moalleman magmatic belt belongs to the Chah-Shirin-Sabzevar-Khaf magmatic complex, located in the western part of this magmatic complex. In this magmatic belt, the Eocene volcanic rocks, including the main volume of igneous rocks are basic to acidic in composition. The predominant rocks are basaltic to intermediate rocks. The TORUD-Moalleman magmatic belt is mainly composed of volcanic rocks with a lithological composition consisting of olivine-basalt, basalt, andesite, and dacite rocks and their pyroclastic equivalents, as well as plastic and limestone interlayers.Analytical methodsDuring field surveying, 50 samples of the volcanic rocks with the least alteration were collected. From these samples, 30 thin sections were prepared for microscopic studies and 11 samples were selected for ICP-MS geochemical analyses for minor elements and XRF for major elements and were sent to ACME Laboratory in Vancouver (Canada). GCDkit, Excel, and Corel Draw software were used to check the results obtained from the whole rock chemistry analyses and drawing diagrams.PetrographyThe study rocks include volcanic rocks ranging from andesite to basalt. The basalts are dark gray to black in color with glomeroporphyritic, microlithic, sieve, and trachytic textures containing plagioclase and clinopyroxene as the main minerals. These minerals along with olivine and magnetite can also be seen in the form of microcrystals in the background of the rock, and their accumulation have created the glomeroporphyritic texture in these rocks. Secondary minerals are chlorite, iron oxide, zeolite (natrolite and analcime), calcite, and gypsum, filling the holes.The andesites are light gray to slightly dark with porphyritic and glomeroporphyritic textures and are dominated by amphibole (green and brown hornblende), plagioclase, and clinopyroxene as the main, biotite, iron oxide, sphene, and zircon. as the minor, as well as sericite, chlorite, calcite, and epidote as the secondary minerals.Whole Rocks Chemistry The data obtained from the whole rock geochemical analyses display that the volcanic samples of the TORUD area are classified as the andesite and basalt, placed mostly in the range of calc-alkaline series (medium potassium). LREE and LILE enrichment, HREE and HFSE depletion and Nb, Ta, and Ti negative anomalies of these rocks point to their formation in subduction zones. Also, as the tectonic diagrams display the rocks belong to the active continental margin. The rocks under study have mostly mantle origin and are derived from an enriched lithospheric mantle. The flat HREE patterns also show that melting occurred in the mantle, above the stability field of garnet. Therefore, the parent magmas were formed by the melting of spinel lherzolite at a depth of 80 to 100 km and evolved due to fractional crystallization as well as contamination caused by subducted sediments and the continental crust.DiscussionThe rare elements pattern of the study rocks in spider diagrams show the cogenesis of these rocks and the role of differential crystallization as the main mechanism of their formation. Based on geochemical data, the study samples and compared volcanic rocks share similar characteristics. Therefore, the normalized REE patterns with chondrite (Nakamura, 1974) NMORB (Sun and McDonough, 1989) and MORB (Pearce, 1983), indicate the enrichment of LREEs (such as La, Ce) and LILEs (e.g., Ba, K, U, Pb, Cs) compared to HREEs and HFSEs (i.e. Nb, Ta, Ti, P) indicating that the rocks under study were formed in the active continental arc margin. The samples have no negative anomaly of Eu. Volcanic rocks with the age of late Eocene and Oligo-Miocene and basaltic to trachy-basaltic composition range from alkaline to sub-alkaline rocks and volcanic rocks with the age of middle Eocene with andesite to trachy-andesite composition have the nature of calc-alkaline.ConclusionsThe volcanic rocks in the south of TORUD, with calc-alkaline and medium potassium nature, are mainly composed of basalt and andesite characterized by LREE enrichment, negative Nb-Ta-Ti anomaly, and the high ratio of LILE/HFSE. These characteristics point to the formation of these rocks in the subduction zones.The rocks under investigation have low SiO2 content, high amounts of Sr, no significant Eu anomaly, and Mg# content greater than 40. These geochemical features indicate a mantle source for the studied volcanic rocks. The changes of Rb/Y versus Nb/Y show the enrichment by subduction components or crustal contamination in the magmatic evolution of these rocks. Based on the geochemical investigations, the productive magma originated from a spinel lherzolitic source at a depth of about 80 to 100 km; during the ascent of magma, as a result of fractional crystallization and contamination, the magma derived from the mantle has been enriched and gave rise to lithological diversity.