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The Oligocene Lar igneous complex is located in the Sistan suture zone of Iran, being emplaced in Paleocene to Eocene flysch-type rocks. This complex includes mainly intermediate K-rich volcanic (trachyte, latite and andesite) and plutonic (syenite and monzonite) rocks that belong to shoshonitic magma. The geochemical characteristics of the Lar igneous complex, such as an enrichment of LREE and LILE relative to HREE and HFSE, respectively, a negative anomaly of Ti, Ba and Nb and a positive anomaly of Rb and Th are similar to those of arc-type igneous rocks. Tectonic discrimination diagrams also show that rocks of the Lar igneous complex fall within the arc-related and post-collisional fields and K-enrichment of these rocks confirm the post-collisional setting. Based on geochemical features, the Lar igneous complex magma was derived from partial melting of a phlogopite-bearing, enriched and metasomatised lithospheric mantle source and the magma was affected by some evolutionary processes like fractional crystallisation and crustal contamination.

Sefidabe and Hyderabad antimony ore deposits are located in the southwest of Sefidabe and in the Sistan Suture Zone. In order to structural analysis of these areas, at first, using satellite images, tectonic lineaments were extracted and the areas with the highest density of length and direction were determined. Then, in the field surveys, veins, faults and mineralization occurred along them were taken. By using stress analysis software, the direction of the principal stresses in the area and the relationships between these structures, tectonic faults and mineralization were analyzed. Compressive shear zones with a northwest-southeast trend are caused by a constraining bend formed between the two of Neh and West-Asagi main faults, is the main factor of mineralization in the study area. This positive flower structure has strongly affected the Paleogene sedimentary and igneous rocks of the region. The Moore's circle indicate a compressional to wrench tectonic regime with the maximum stress direction (03/215) in the northwest-southeast. In this stress regime, in addition to thrust faults, a group of conjugate faults with an acute angle and tensile fractures aligned with the direction of maximum principal stress have formed, which have provided a suitable environment for fluid injection by creating weak zones. [ABSTRACT FROM AUTHOR]

The Lar Cu-Mo prospect is located 20 km north of Zahedan in Sistan and Baluchestan Province. This area is geologically situated in the Sistan Suture Zone. The Cu-Mo mineralization occurs as silicic veins in the Lar igneous rocks and includes hypogene chalcopyrite, bornite, and molybdenite mineralization. The syenite to monzonite host rocks occur as stock and dyke and display granular to porphyritic texture. In this study, mineral chemistry and petrographic examination of igneous rocks are used to constrain the crystallization conditions of the magma. The compositional range of plagioclase is relatively narrow (0.11%-26.05% An), whereas that of potassium feldspar is wide (11.80%-96.02% Or). Analyses of representative Lar biotite samples with electron microprobe analysis suggest that crystallization took place at average temperature of 731 °C. Amphiboles are calcic and compositionally range from pargasite to ferro-pargasite, edenite, actinolite, and magnesio-hornblende. Estimation of temperature and pressure using calcic amphibole geothermobarometry equations indicates that crystallization is estimated to have taken place at 831 °C and 7.65 kbar. Clinopyroxenes are mainly diopside and were crystallized in a magma chamber at an average temperature and pressure of 926 °C and 7.54 kbar, respectively. According to the mineral composition, the studied igneous rocks are calc-alkaline in magmatic series and were crystallized from a calc-alkaline oxidized magma. The whole-rock chemical data show that the study rocks are shoshonitic and high-K calc-alkaline. [ABSTRACT FROM AUTHOR]

The Lar Cu-Mo prospect is located 20 km north of Zahedan in Sistan and Baluchestan Province. This area is geologically situated in the Sistan Suture Zone. The Cu-Mo mineralization occurs as silicic veins in the Lar igneous rocks and includes hypogene chalcopyrite, bornite, and molybdenite mineralization. The syenite to monzonite host rocks occur as stock and dyke and display granular to porphyritic texture. In this study, mineral chemistry and petrographic examination of igneous rocks are used to constrain the crystallization conditions of the magma. The compositional range of plagioclase is relatively narrow (0.11%-26.05% An), whereas that of potassium feldspar is wide (11.80%-96.02% Or). Analyses of representative Lar biotite samples with electron microprobe analysis suggest that crystallization took place at average temperature of 731 °C. Amphiboles are calcic and compositionally range from pargasite to ferro-pargasite, edenite, actinolite, and magnesio-hornblende. Estimation of temperature and pressure using calcic amphibole geothermobarometry equations indicates that crystallization is estimated to have taken place at 831 °C and 7.65 kbar. Clinopyroxenes are mainly diopside and were crystallized in a magma chamber at an average temperature and pressure of 926 °C and 7.54 kbar, respectively. According to the mineral composition, the studied igneous rocks are calc-alkaline in magmatic series and were crystallized from a calc-alkaline oxidized magma. The whole-rock chemical data show that the study rocks are shoshonitic and high-K calc-alkaline. [ABSTRACT FROM AUTHOR]

The Shurchah antimony-bearing area is located in the Eastern Iranian flysch zone. The Cretaceous to Eocene schists and phyllites are the oldest geological units in the area. These rocks have been intruded by granitic bodies, felsic dikes, and quartz and stibnite veins. The granitic rocks in this area are composed of granite, granodiorite and aplite dikes. The granitoid rocks are generally massive, gray and coarse-grained with granular, porphyritic and cataclastic textures and contain mainly plagioclase, K-feldspar, quartz, biotite, muscovite and opaques. These rocks are commonly peraluminous to metaluminous, calcalkaline and related to a magmatic arc. The SiO2 content of the intrusions varies from 61 to 75 wt.%. Variation diagrams show linear trends, with increasing SiO2 content Al2O3, CaO, FeOt, MgO, and TiO2 amounts decrease whereas, K2O and Na2O contents increase. On the base of MORB and ORG-normalized diagrams, the negative anomalies of Nb, Ti and positive anomalies of K, Rb, Th, U and especially Pb revealed an igneous mantle origin, especially the role of Sistan subduction oceanic crust and overlaying mantle wedge in the genesis of these rocks and also, the role of continental crust in magmatic contamination. [ABSTRACT FROM AUTHOR]

Mahour polymetal ore deposit is located in the eastern margin of Lut block, 130 Km west of Nehbandan. The supergene mineralization mainly occurs as a north-south trend in the Tertiary altered volcanic rocks. The supergene minerals mainly occur as iron hydroxide, Cu-carbonates, Cu and Pb sulfates and Cu sulfides. Goethite, malachite, azurite, chalcosite, covellite, linarite and atacamite are common supergene minerals in the Mahour ore deposit that were formed by oxidation of the hypogene sulfides. Some of these minerals were analyzed by electron probe microanalyses (EPMA). Ag content is considerable in most of these minerals. Covellite from the Mahour has high Pb, Zn and Ag contents. The chemistry of the supergene minerals and the way of their formation will be discussed in this paper. [ABSTRACT FROM AUTHOR]