فهرست مطالب علی اصغر مریدی فریمانی

Understanding regional tectonics and characterizing local processes greatly benefit from local measurements of paleo-stress direction. Mathematical techniques based on the inversion of fault slip data are one of the frequently used techniques for detecting the direction of the paleo-stress (Balansa et al., 2022; Zhang et al., 2020; Angelier 1994; Jentzer et al., 2017). The deformed area of Koleh-Sangi is situated structurally in the centert of the Sistan Suture Zone, north of Zahedan. Sistan Suture Zone is a most intricate structural regions that several research have been conducted to comprehend the past deformation of this area. Given that the studied region has several faults and fractures, the orientation of paleo-tectonic stresses has mostly been dependent on the orientation of faults and the relative movement along them, and the results of structural analysis and paleo-stress investigations were ignored. Therefore, it is essential to conduct this research, and its findings may contribute to a better knowledge of the Sistan Suture Zone.

A kinematic process results in slickenside and movement along the fault. For many years, structural investigations have employed the kinematic study index to identify several types of paleo-stress, including fault lines, shear zones, veins, and stylolites. The slickenside fault planes can be employed as movement or kinematic markers (Hancock 1985; Roberts 1996; Roberts and Michetti 2004). The range of structural components, such as slickenside, have been considered in the reconstruction techniques for paleo-stress. The four stress tensor parameters are based on the amount and direction of slide on the fault plane (Angelier, 1989; 1991). These parameters, which include the principal stress axes σ1≥σ2≥σ3, are introduced in the form of the following equation with the title R, which is the same as the ratio of the magnitude of the stress ellipse. These parameters depend on the ratio of the magnitude of the intermediate stress σ2, the maximum σ1, and the minimum σ3 principal stresses.

It was attempted to take the spatial features of faults and their related structures from four sites with varied ages of deformed rocks to calculate the paleo-stress parameters in the different area (areas A, B, C and D). According to the main goal of the article, it has been tried to take into account the early and late geological events. The properties of the fault planes, the slickenside, as well as the fault's Cross-cutting relationships and movement, were collected during the field surveys. The stress ratio (φ) has been fluctuating between 0.3 and 0.9 based on observations made and the interpretation of the data acquired in the MIM software from four areas with varying rock ages. The maximum and minimum trend and plunge of the computed axes were drawn on the contour diagram for each range to produce a specific pattern to estimate the orientation of the stress axes, and the most compatible planes for the axes were identified on the diagram.

The earliest rock formations in the area, were impacted by a compressional phase that occurred at an N84°E.The second phase of progressive deformation indicates the N59°E.Its compressional direction has been determined to be N10°. This compressional direction is consistent with both the compressional trend determined by GPS (Vernant et al, 2004) and the trend obtained for the major faults in this region,) such as the Zahedan dextral strike-slip fault, the Nosratabad dextral strike-slip fault and reverse faults with a north-northwest strike (Berberian et al., 2000; Walker and Khatib, 2006). According to the available data and earlier investigations, this deformation phase occurred during or after the Eocene and has persisted up to the current day.A transtension regime is visible in the youngest phase in Paleocene and Oligocene-Miocene outcrops. This phase may be brought on by normal faults along fold axes, on the hanging wall of thrust faults and associated with north-south strike-slip faults. The latest stage of deformation in the area may be explained by the presence of the Zahedan strike-slip fault, which has a significant amount of displacement throughout its length.

Two mechanisms such as horizontal and vertical principal stress can create different fractures and faults in the rocks. The first one is tectonic forces as a result of the motion of plate tectonics and the second one is buoyancy forces as a result of magmatic activity (Ruch et al., 2016). The Kuh-Sefid granite emplaced in the flysch rocks of eastern Iran, southeast of Taftan, and the central part of the Zahedan-Saravan granite belt has provided a good opportunity to study the influence of tectonics and magmatic activity in creating fractures in this region. This granite, metamorphic halo, and surrounding rocks have been affected by different fractures system. The main purpose of this article is to investigate the role of tectonics and the main faults in the emplacement of Kuh-Sefid granite and the creation of obvious lineaments in this mass and the surrounding rocks, which can be a suitable basis for further studies on this little-known area.

In order to analysis of fractures and faults in the study area at the first, the system of fractures and faults in the intrusive mass and host rocks are extracted using remote sensing and satellite image processing. In this study, Landsat 8 satellite images with pass number LC08_L1TP_156041 were used to identify the lineaments. Then, using GIS, these structures were differentiated and categorized based on the orientation, regional maximum stress, and their cross-cutting relationship.

The granite unite has several main north-south lineaments parallel to each other. In metamorphic units, based on the position of this unit in relation to the granite unit, these structures were divided into five equal parts that have different orientations. Lineaments analysis of sedimentary rocks (Flysch): Based on the position of this unit in relation to the granite unit, extracted lineaments were divided into nine equal parts and then the rose diagram of each part was drawn. According to the genetic relationship between fracture structures and the direction of maximum stress in the region (Angelier, 1989; 1991), long lineaments that have displacement along their length were considered faults and used to estimate the direction of the maximum principal stress in the region. Kuh-Sefid granite as the youngest geological unit in the region, the granite mass intruded into the sedimentary rocks and creates a metamorphic halo in them. The existence of systematic fractures of the main mass shows that it was affected by tectonic stresses after cooling, but it should also be noted that the rise of granite masses can cause vertical stress and related fractures in the host rocks. These features have provided a suitable situation to investigate the tectonic history of the region and the effect of the main faults and the rise of the granite mass on creating brittle structures such as fractures and faults. The data obtained from remote sensing studies and statistical analyses of lineaments and faults at a glance show relatively active tectonics affected by different phases in the region According to the obtained, data two-phase of deformation from old to new are suggested. D1: progressive phase, which with the direction of maximum northeast-southeast stress causes the development of northeast-southwest conjugate fractures, and then the activity of faults parallel to Saravan fault provided a suitable environment for the intrusion of granitic mass. Simultaneously with the intrusion of the mass, radial fractures have developed in the surrounding rocks. After cooling and creating a metamorphic halo, the continuation of stress along the same direction has caused conjugate fractures in the main granite mass. Subsequently, the newer phase D2 due to the active tectonics of the region, by creating north-south faults, cuts and displaces all the old structures and Saravan fault.

The extraction of lineaments of the Koh-Sefid granite, the metamorphic halo, and the surrounding flysch rocks show the role of tectonics and magmatic activity in creating of these structures. The study of cross-cutting relationships and the classification of faults and lineaments show two deformation phases in the region. The initial phase, which is proportional to the general stress along the northeast-southwest direction, is a progressive phase, and the final phase, in accommodates the active tectonic regime of the region, acting as north-south dextral strike-slip faults.

The Zagros orogeny as a central part of the Alpine-Himalayan orogenic belt is one of the most seismically active intracontinental fold-and-thrust belts on the Earth, and has an important role in active tectonics of the Middle East. The Hormuz Salt and several intermediate decollement levels, appears to be responsible for the most aseismic deformation of the Zagros sedimentary cover, and also to control the development of a large panel of fold structures, from detachment to fault-propagation folds with varying wavelength and rooting depth. The Dalan anticline located in the Fars province and mantled by soft Oligo-Miocene sediments in SW of the Central Zagros. For the kinematic and geometric analysis of the anticline based on satellite images, geological maps and field observations, three structural cross section perpendicular to fold axis have been studied. Comparing the position of the Dalan fold axis and axial plane in the aa', bb' and cc' cross sections indicates that in the axis of the anticline was rotated about 15 degrees toward the southeast. Regard to interlimb angle estimations and Ramsay classifications from all three cross sections, Dalan anticline is the open fold and 1B-1C classes, respectively. Based on geometrical and kinematic analysis and comparison from studied models such as Sattarzadeh et al, (2000) and Mitra (2003), the Dalan anticline is detachment fold type and compatible with the Lift –off Model With syncline evacuation model. In this model, limb rotation, migration of ductile sediment in outer hinges and syncline to core of anticline occurred.

The study of factors that control volcanoes can help analysesize the risk of triggering an the next eruption. Taftan is a Quaternary volcano of southeast Iran, formed as the result of subduction of Oman oceanic lithosphere underneath the continental Iranian plate that emplaced onto compressional tectonic setting such as strongly folded and faulted Eocene flysch and Cretaceous ophiolites. This volcano has several centers that are directed along a northeast to southwest from old to new. In order to investigate the role of the tectonic regime to evolution of Taftan volcano, structural elements such as Dikes, Fractures, crater opening of Anjerk amphitheater, the direction of centers and direction of springs have been studied. The resulting data of these elements represent a northeast-southwest directed extensional stress in the Taftan body which has created an extension area in the northwest-southeast direction. But earthquakes and structural trends of pre volcanic rocks underlying Taftan show a maximum regional compressional northeast-southwest striking. Recent relevant data such as structural analysis, analog modeling, field data demonstrating that volcanism can occur in compressional tectonic settings associated with thrust faulting. In other words magma can transport beneath the volcano to the surface along the thrust faults. Based on these data we proposed a model that demonstrates the substrate thrust fault (as magma path) splits into two faults within the volcano: A shallow-dipping one, with reverse movement, propagates towards the volcano flank, and a steeper-dipping one, with normal movement, propagates upwards and causes northeast-southwest extensional area along the centers parallel to thrust fault of substrata. The suggested model in this study proposes a next eruption point in the southeast of the currently active point.

Among the sedimentary units of the east flysch basin in the Nosrat-Abad area, where in the 105km northwest of Zahedan, there is a sandstone-conglomerate unit with an Oligo-Miocene age. The depositional environment of this deposit was fluvial which has been morphologically dissected in several portions; this unit covers the Eocene sandstone-shale deposits by an angular unconformity about 30 degrees. The measured thickness is about 2650 meters. The composed particles and pebbles are in various grain size. On the other hand, sandstone, siltstone, and mudstone accompany the conglomerate unit. Field observations document the unit was formed in a fluvial depositional environment. Imbrication and cross, smooth, and lens-shaped bedding are the main recognizable sedimentary structures. Moreover, the caved and filled structure are seen. Note that there is difference between the lithology of the pebbles in the conglomerate and the rocks composing the flysch zone, the pebbles could be originated from the west side, where in the Lut block. The recognized fossils from limestone pebbles are belong to the families such as Orbitolina, Alveolina, Nummulite, and Miliolid, consequently, the age of conglomerate-sandstone unit must be younger than Eocene and cover by Conglomarate Quaternary probably could be Oilgo-Miocene.

Monogenic basaltic cinder cones and lava flows from west of Khash are part of volcanic arc of northern Makran, formed as a result of subduction of Oman oceanic lithosphere beneath the Eurasian plate. The basalts belong to medium-K calc-alkaline series as they contain high Al2O3 (16.5- 19.04 wt. %) and CaO (8.4- 12.0 wt. %) and moderate amounts of K2O (0.5- 1.1 wt. %). They share arc geochemical features such as high LILE/HFSE ([Rb/Zr]N-MORB up to 19) LILE/LREE ([Ba/La]N-MORB up to 4.86) and LREE/HREE ([La/Yb]N-MORB up to 10), and depletion of Ta, Nb, Zr, and Ti relative to N-MORB. Partial melting models indicate that near-primary basalts were derived from an enriched source type mantle wedge peridotite after low to medium degrees (2-10%) of partial melting. This source peridotite was enriched in LREE and LILE, by subduction derived fluids in the supra-subduction zone. Negative correlation of Th/La vs. Sm/La, and relationships between Pb/Ce and Th/Nb values of the studied basalts which are between two end compositions of global subducting sediment (GLOSS) and N-MORB are indicative of significant contribution of subducting sediments to the genesis of the basaltic rocks. Estimates made using binary mixing model are indicative of about 16% of sediment participation in the magma genesis. Low Pb/Ce ratio (1.6 - 11.1), compared to OIB (>20) may be a signature of participation of fluids resulted from dehydration of the subducting slab.

Textural and Geochemical characteristics of plagioclase phenocrysts in Andesitic and basaltic rocks of Bazman volcano (from Makran volcanic arc) show evidence of interaction between basaltic and andesitic magmas. Plagioclase phenocrysts in andesites and basalts are composed of three major parts of core, mantle and rim, with similarity of the anorthite contents in cores and mantles. The cores of the phenocrysts, which seem to be in equilibrium with the andesitic magma rather than the basaltic one (­An39-60), exhibit different styles of oscillatory zoning. The trace element (Fe, Mg, Sr, Ba) concentrations in different zones of the cores also remain constant or change proportional to the anorthite content and may exhibit dynamic processes in the magma reservoir during the core formation in andesitic magma. The engulfed cores and sieve texture in the mantles of plagioclases may have formed in response to changes in temperature and composition of the surrounding melt. Elevated anorthite content of plagioclases (An40-65), accompanied by jump of the Fe, and Mg content, in addition to change in the patterns of Sr, and Ba in the sieve-textured mantle may show the replenishment of magma reservoir by new basaltic magma. Increase of An in the rim of basaltic plagioclases (from An53 to An74) and decrease of An in the rims of andesitic plagioclases (from An69 to An53), indicate that the two magmas gained their contrasting compositional identity most probably as a result of sudden upward movement. These constraints, along with other evidence like weakly-zoned pyroxene microphenocrysts with rounded rims, suggest that the rocks originated in the course of replenishment of mafic melts either with chemical or/and thermal interaction of the melts.

Taftan volcano young to age Pliocene-Quaternary and semi-active volcanic system is located 50 kilometers north of the city of Khash. It seems in this area the phenomenon of young volcanoes and tectonically active area morphology have played a major role. According to population centers around the volcano and the earthquake of high magnitude in this area (earthquakes related to Saravan fault), study tectonic activity in this area is important. The Taftan active structures around the importance of this issue twice. The purpose of this study Taftan active tectonic drainage basins, environment and level of tectonic activity in the region is relative. In the field of geomorphic indicators have been used for the study of tectonic activity. These indicators include: the drainage basin asymmetry (Af), mountain front sinuosity (Smf), the slope of the valley (Sl), floor width to valley height (Vf), hypsometric integral (Hi). The index for evaluating relative active tectonic (Iat) basin and sub-basin of the study area were used. A recent survey shows that Neotectonic an important role in the evolution of geomorphic region. Based on the proposed model, recognized three tectonic zones in the study area: (zone with relatively high tectonic activity), this zone is observed only in two sub-basin, 4-B and 9-C, (zone of tectonic activity relative to average) the wide area of the region in this area, it is important that the structures can be noted in the northwest of Dargiaban, Iranshahr fault and fault Saadat-abad, (zone with relatively low tectonic activity) this zone has observations in two sub-basin only 5-C, 1-D, 9A and 8. The results of the analysis of indicators and field observations indicate tectonic activity are also within the scope of Taftan volcano (quantitatively) and its surroundings.

The under study area is located at the north east of Iran at the vicinity of Torbat e jam city. The main faults like Golbano، Gourband، Jahan-Abad، Rasoul-Abad and Kajab are located at a short distances from Torbat e jam city. Gourband fault is the largest fault in alluvial sediments of Torbat e jam plain that has north west – south east trend. Studying the geotectonical activity of the mentioned fault regarding its proximity to the city and locating various villages in its neighboring has a great importance. In this research، the effect of recent movements of this fault on the structural geomorphology of the region has been studied. To evaluate geotectonic actions of the studied fault، morphotectonic (Smf، V، SL) has been used as the main tool. Studying neotectonic morphology indices indicate high activity of this fault. The existence of fault rises، changing route of streams and channels، ‘V’ shape valleys، folds of quaternary sediments and change of color in sediments at the fault zone are of the important geomorphologic indices that is observed in field surveying and in connection with the movement of Gourband fault. The movement in channels indicates the youngest movement along this fault، the direction of these channels also indicates the right direction of slip movement in the mentioned fault. The existences of rise in neogen sediments at the location of superficial effect of fault also indicate rising and reserved component in this fault.

Development of drainage basins has close relation with geomorphologic and geologic parameters. Therefore, study the relation between structural parameters like faults and development of drainage basins has greatly considered in hydrology and hydrogeology studies. Saravan drainage basin is a perfectly long basin that is extended along Saravan fault. In this survey, the method for studying morphometric and geology indices has been implemented for development of drainage basin. Clearly, present morphology is reflecting the erosion and geological processes particularly in Quaternary age. Saravan drainage basin is in the south-east part of Iran and has developed on flysch of this area. Drainage of Saravan basin joins to Mashkid river and finally leads to Pakistan. Different factors and parameters are important in formation and development of drainage basins including topographic, litho logy and structural factors. One of the important factors in development of this drainage basin is the evolution and activity of Saravan thrust fault. Saravan fault with N135-145 trend has located on the north edge of Quaternary alluvial of the basin. The fault slope is approximately at same direction with flysch layering and slope direction’s is 45-60 degree toward north-east. Saravan catchment basin is a long basin with 5.07 length to width ratio. Prepared maps and profile sections show a clear tilting and asymmetric basin. Morph metric index of tilting of basin (T) is maximum 0.72 and is maximum 0.83 in alluvial basin part. Asymmetric AF index is equal to 62/28 and it is equal 78/74 in the alluvial part. Clear asymmetric of basin and fault position on the north edge basin with average Smf equal to 1.42 showes that Saravan fault has been relatively an active fault. This fault has affected on formation and morphogenesis of Saravan drainage basin during its evolution.Younger northern-southern faults with dextral strike-slip (as Gosht fault) has caused small bent on general trend of alluvial along the drainage basin.

Makran East-West trend expanded in two countries of Iran and Pakistan. The geological characteristics of this zone attract the geologist’s attention from long time ago. The length of this plain is about 900 km and its width is around 300 km that situated in land. Major studies has been started since 70s and continued by different geologists around the world to the present time. Key studies related to the systematic researches that contain the total area of Makran caused providing the Makran’s geological reports or the Seismic profiles of the seabed Oman. In these studies the situation and tectonic position of Makran and also the direction and rate of relative motion of Arabian plate and Oman sea to the north becomes clear and has effects on diverse kinds of analysis such as neotechtonics, raised beaches, sediment deformation style, folding and magmatism in Makran. Extent and variety of geological issues on Makran’s studies caused to consider the related researches in six major categories such as “General studies on geology”, “Tectonic and structural studies”, “Geophysical studies”, “Seismicity studies”, “Mineral and Hydrocarbon studies” and “Neotectonics and Raised beaches studies”.

Sungun Porphyry Copper Deposit is located about 130 km to the northeast of Tabriz, northeast Iran. This deposit contains 796 million tons of ore with 0.61% Cu, 0.01% Mo, 0.016 ppm Au, 9.75 ppm Bi and Re (0.09 wt% of molybdenite). This research studies the physico-chemical environment using the chemical properties of minerals of this deposit. This deposit is related to granodiorite-diorite dikes and granodiorite stock that intruded into sedimentary and volcanic rocks of Cretaceous and Eocene. Dominant alterations are potassic, phyllic, argillic and propylitic from center outward which are characteristics of continental margin porphyry copper deposits. Simultaneously with the supergene mineralization, an iron cap of iron oxides, iron hydroxides, copper oxides, sulfates, carbonates and copper phosphates were developed on top of the deposit and along the fractures. In conclusion, based on mineral chemistry, in 450 ºC and 0.5 kb pressure (PT condition of potassic zone), sulfur fugacity and pH is determined to be as: log¦S2=-18 to -24 an pH=2.5 to 7.5. In 350 ºC and 0.5 kb pressure (PT condition of phyllic zone), oxygen and sulfur fugacities are: logƒO2= -20 to -33 and log¦S2=-6 to -15.

Posah cave is located near Skel-Abad village, beside the Zahedan-Khash road, about 114 km south of Zahedan city and about 22 km in the west of Taftan Mountain in the north of Baluchistan. This cave has been developed in a flysch unit consisting mainly of thin-bedded sandstone and shale layers. The roof of the cave is composed of Taftan lahar, a mudflow poorly sorted and consists mostly of volcanic ash with pyroclastic materials produced by Taftan volcano. The Posah cave is a unique pseudokarst cave in both the region and the whole country. The results of XRD and XRF analyses on two specimens of rocks from the cave have shown that rock units in the area are insoluble. Moreover, there is no significant difference between Ca2+ concentration values in the surface and ground waters. Therefore, it can be concluded that the cave has been developed in insoluble rocks. This paper deals with the development of the cave from a geological point of view.