Introduction 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. Materials and methods 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. Results and Discussion 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. Conclusion 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.

Padagi area is located in southern part of Sistan suture zone. In this area, the Eocene flysch-like rocks were intruded by Oligocene-Miocene igneous rocks as batholith, dacitic stock and dacitic to andesitic dike. The flysch is predominantly composed of altered phyllite, shale, sandstone and siltstone. The batholith is mainly an I-type granular granodiorite. The stock is associated with granodiorite porphyry, quartz-diorite porphyry, quartz-monzonite porphyry and andesite. The dikes, trending NE, are last magmatic phase, and porphyry texture. The igneous rocks in Padagi are mainly high K calc-alkaline and metaluminous belonging to continental margin post-collision magmatic arcs. The minor and rare earth elements, normalized to the primitive and the chondrite mantle, respectively, show that LREE and LILE are enriched relative to HREE and HFSE, respectively, a remarkable feature of igneous rocks related to volcanic arc. According to geochemical studies, for the Padagi samples could assume a garnet-bearing enriched asthenospheric and lithospheric sources with a partial melting of less than 5 % as parent magma generated in 80 to 100 km depth.

Introduction The Mahirud volcano-plutonic complex (Cheshme-Ostad Group) in east of Iran is tectonically situated in the north-eastern part of the Sistan suture zone near to the boundary with the Afghan block. This tectonic zone includes the Retuk complex in the west and the Neh complex in the east. These two accretionary-prism-ophiolitic assemblages underlie the Sefidabeh forearc sedimentary basin. The Mahirud complex consists of the Upper Cretaceous volcano-sedimentary sequence which is structurally overlain by the Paleogene sediments. The Upper Cretaceous-Lower Tertiary stratigraphical formations in this area are subdivided into two distinct groups: 1-The upper group includes the Paleocene-Early Eocene volcano-sedimentary succession; 2-The lower group Includes the Cretaceous flysch-type sediments. These units construct the Lahno anticline. The most important igneous constituents of the Mahirud volcano-plutonic complex comprises in a younger part including the acidic intrusions and an earlier part including intermediate to basic extrusions. Acidic rocks injected as intrusive bodies contain tonalite, granodiorites, quartz diorite and rare leuco-plagioclase tonalite and tronhjemite. The basic to intermediate rocks appeared as pillow to flow volcanic and sub-volcanic rocks including of basalts, basaltic andesite, andesite, tuff, and dacitic dikes. Field observation clearly suggests that the tonalitic stocks injected after the extrusion of the lavas, and enclosed, assimilated, and altered the basaltic pillow lavas. Method and Material The prepared thin-polished sections were studied by polarized microscope for petrographic descriptions in University of Sistan and Baluchistan. Electron probe micro analysis (EPMA) of minerals was conducted in wavelength-dispersion mode on a JEOL JXA-8600 super probe at Yamagata University of Japan with accelerating voltage of 15 kV, a beam current of 20 nA, a beam diameter of about 5 μ m, detection limits of 0. 05 wt. %, and maximum 40 s counting interval. Result and discussion According to the results of the previous research, volcanic rocks have the characteristics of the calc-alkaline to tholeiitic magmatic series and have been attributed to a rift tectonic setting. However, the results of recent work based on the spider diagram patterns normalized to N-MORB and Chondrite show the magmatic rocks are similar to the ones belong to the supra-subduction zone (SSZ) and especially recent Island arcs ( IAT) setting. The studying of the EPMA on the key minerals provides the same results. Plagioclase, hornblende, quartz, and biotite are the main minerals of the tonalitic stocks. Conclusion According to EPMA, the chemical composition of plagioclase illustrates ranging from bytownitein the core to albite in the rim documenting a normal zoning resulted by a normal differential crystallization. Amphibole is a calcic magnesio-hornblende and could crystalize by a magma originated in a subduction zone. According to Aluminum content in amphibole, the crystallization characters such as pressure, temperature, and oxygen fugacity are respectively between 1 and 2 kb, 700 and750° C, and a high fO2. These results confirm the consequence of our other studies which assumed the Mahirud volcano-plutonic complex was formed in an intra oceanic subduction zone.

Lakhshk deposit is located 28 km northwest of Zahedan and southwestern of Sistan suture zone. The main outcrops in the study area are Eocene schists consisting of calc-schist and quartz schist. These rocks metamorphosed under greenschist facies grade and were intruded by Oligocene rhyolitic and dacitic dikes and granitoid. The gold-antimony mineralization is structurally controlled by a NE–, SW fault zone and shear zone, and hydrothermal alterations were mainly occurred in the contact zones of granitoid and calc-schist units. The high-grade gold mineralization (3. 5 g/t) is spatially related to the intense sulfidation and silicification hydrothermal alteration zones in the inner parts of the zone as well as ductile-brittle (microfractures, fine veins/veinlets) deformation. The ore mineralogy is simple and includes pyrite, arsenical pyrite, stibnite, chalcopyrite, arsenopyrite, pyrrhotite, sphalerite, gold, electrum, goethite, and stibiconite. The study of fluid inclusions on gold ores quartz shows the homogenization temperature in quartz-sulfide veins/veinlets with mineralization between 200 to 330 °, C with a salinity of 8 to 13 wt. % NaCl equiv., which is compatible with the mixing and dilution process. Based on the results of geology, mineralogy, and fluid inclusion studies, gold mineralization in Lakhshak gold deposit is of orogenic type.

2The Sefidabeh and Heydar Abad antimony mines are located in the northwest of Zahedan in the Sistan suture zone.  The rock units in the area are Cretaceous ophiolitic complex, Eocene flysch sequence, Oligocene conglomerate and Oligocene intermediate igneous rocks. The antimony mineralization occurs as quartz-stibnite veins in the Oligocene conglomerate along the faulted zone. The hypogene sulfide minerals are stibnite with minor amounts of pyrite. The supergene minerals are hematite, goethite, limonite, stibiconite and senarmontite. The main alteration types are silicic, argillic and carbonate that occurred around the veins and are mainly characterized with quartz, chalcedony, clay and calcite. The common ore textures are open space filling and brecciated. Coliform and comb structure and bladed and acicular stibnite crystals are observed in microscopic and mesoscopic scales as well. The vein type hypogene sulfides are formed by hydrothermal fluids in fractures and faults The result of micro-thermometry of fluid inclusion in quartz show that the homogenization temperatures the ranges from 130 to 420 ºC and salinities ranges from 4 to 5.68 wt. % NaCl eq. that are mainly in range of those of epithermal ore deposits. The mineral assemblage, alteration types and ore texture show that antimony mineralization in Sefidabeh and Heydar Abad mines is of low-sulfidation epithermal type, which are controlled by strike-slip faults.

Olivine basalts from east of Nehbandan and Chahchocho regions belong to sodic alkaline and transitional magma series. Compared to alkaline olivine basalts (AOB), the transitional olivine basalts (TOB) have higher MgO, SiO2, Ni, Cr, Ba, Th, Pb, and U, and lower TiO2, FeOt, REE, and HFSE. High MgO, Mg#, Ni, and Cr (13. 8 wt%, 77, 531 and 860 ppm, respectively) of the TOBs indicate that their chemical composition is close to a primary magma in equilibrium with mantle peridotites, whereas, the same values of the AOBs (8. 3 wt%, 59, 155 and 176 ppm, respectively) are not quite close to a presumed primary magma. Based on petrographic and geochemical criteria, the TOBs have undergone both crystal fractionation and crustal assimilation, but the AOBs just show evidence of fractional crystallization. The enrichment of all rocks in the LREEs compared to the HREEs, LILEs relative to the HFSEs, together with the REE and multi-element patterns close to those of OIB may be indicative of an enriched asthenospheric-lithospheric mantle source. Non-modal batch melting models show that the AOBs are generated by ~7% partial melting of an asthenospheric mantle source at garnet lherzolite stability field. Furthermore, the TOBs are formed either by 7-15% partial melting of a metasomatized lithospheric mantle, or they are products of partial melting of an asthenospheric-lithospheric mantle source at 50% garnet-50% spinel lherzolite stability field.

1-Introduction During the evolution of orogenic belts in collisional zones, rock units undergoing deformation. Deformation is the transformation from an initial to a final geometry using rigid body translation, rigid body rotation, strain (distortion), and/or volume change (Dilation) (Ramsay and Huber, 1983). Folding, faulting, and layer-parallel homogeneous shortening are three mechanisms for the deformation (shortening) of layered rocks in orogenic belts (Dixon and Liu, 1992). The amount of shortening involved can be calculated in various scales, from microscopic to regional ones. On the regional scale, shortening can be calculated by restoration deformed structures to its original pre-deformational state. When two convergent plates colliding symmetrically each other (with the pure shear state), expects during active folding, symmetrical folds forming, but in conditions which the convergence rates (CR) of two plates are unequal: Have asymmetrical folds (and structures) been forming? Do faults transfer mass rocks from hinterland to foreland? Are the number of vergence movements in the plate with lower CR, is more than the other plate?...

Lakhshak deposit is located 28 km northwest of Zahedan in the Sistan suture zone. The rocks in the Lakhshak area predominantly consist of Eocene volcanosedimentary and metamorphosed (greenshist facies) rocks. The mineralogy of the ore is simple and consists of stibnite, pyrite, arsenopyrite, chalcopyrite, sphalerite, and electrum. The Lakhshak deposit is hosted in the shear and altered calc-shist unit which is associated with quartz, sericite-muscovite and sulfide alteration minerals. Based on geophysical studies, using induction polarity and special reSistance (IP/RS) in the Lakhshak sheared area, combined with the results of geological, metamorphic and mineralization information, calligraphic calcification units, fault zones and metamorphosed areas have a high potential for Au-Sb mineralization. Therefore, using the amount of changes in specific reSistance and chargeability, as well as the intensity of chargeability in the profiles, can appropriately identify the promising area for gold and stibnite mineralizations. This study indicates that the main characteristics of the geology and mineralization of the Lakhshak, such as the nature of the host rock, the form of mineralization, metamorphism and associated alterations, is similar to orogenic gold deposits.

Lakhshak deposit is located in the southwestern part of the Sistan suture zone and 28 km northwest of Zahedan. The exposed rock units include granitoid intrusion and dacite-rhyolite dykes with Oligocene age and calc schist and quartz schist with Eocene age, which have metamorphosed to the green schist facies. This complex has transformed under the influence of a shear zone with a northeast-southwest trend. The composition of intrusive masses placed in the range of granodiorite based on lithological charts. Based on petrographic studies, the minerals that make up the intrusive masses include quartz, alkali feldspar, plagioclase, biotite, sericite, muscovite, iron oxides and calcite. Among the most important types of alteration, we can mention sericite, sulfide, siliceous and carbonate alterations. Analysis of the distribution patterns of rare earth elements in the shear zone samples shows the enrichment of REE in the central parts of the shear zone (severe degrees of alteration and deformation) compared to the foot wall and hanging wall units (weak degrees of alteration and deformation) of the shear zone. The distribution pattern of these elements includes the enrichment of LREE compared to HREE, which can attributed to regional metamorphism at the green schist facies and the circulation of CO2 and SO42- fluids in the Lakhshak shear zone. In addition, the presence of positive and negative Eu anomalies in the shear zone indicates two different stages of alteration. Weak to moderate alteration has led to the creation of positive Eu anomaly and advanced alteration has caused severe decomposition of plagioclase as the main source of Eu and negative Eu anomaly.

The Bibi Maryam granitoid with NW– SE general trend has intruded into Nehbandan ophiolite complex in the northern Sistan suture zone. The massif was influenced by syntectonic emplacement and cooling and thus has recorded short-lived geological events related to crustal deformation. Development of microfabrics in this granitoid from magmatic to low temperature solid-state reflect the microstructural evolution with decreasing melt content during crystallization. There are clear evidences of synmagmatic deformation fabrics as well as evidences of high-T solid-state deformation that suggest these fabrics have been developed during or just after complete crystallization of magma. With continuous deformation, the low-temperature fabrics characterized by subgrains rotation recrystallization in quartz, orientation of quartz fine-grains and microfaults in feldspar. The foliation trajectories through out the massif show a dominant NW– SE orientation. The presence of synmagmatic deformation microstructures and the concordance of solid-state mesoscopic-scale planar fabrics with general regional structures imply that the time relationship between fabric development in the granitoid and regional tectonics within this part of Sistan zone.