Search

The Palaeozoic magmatic history of Central Iran is related to the subduction of the Proto‐Tethys Ocean and the amalgamation of Gondwana continental fragments. This study presents whole‐rock geochemistry, Sr–Nd isotope and zircon U–Pb–Hf ages of shoshonitic plutonic rocks (e.g., monzonite–syenite) from the north Posht‐e‐Badam (NPB) district with a view to constrain their petrogenetic and tectono‐magmatic evolution during the Palaeozoic. The geochemical data show moderate enrichment in large‐ion lithophile elements and Ti, large positive Pb anomalies, and depletion or moderate enrichment in high‐field‐strength elements (e.g., Nb and Ta), typical of continental arcs. Zircon LA–ICP–MS U–Pb ages are in the range of 444–428 Ma. The Sr–Nd–Hf isotope data, for example, (87Sr/86Sr)i = 0.7073 to 0.7089, εNd(t) = −1.4 to −0.2, and εHf(t) = −3.6 to +7.7, indicate derivation of the magma from a mantle source. The numerical modelling shows a contribution of less than 10% crustal assimilation and ~3% sediment into the melt‐derived mantle. We propose that metasomatic enrichment occurred during the subduction of Proto‐Tethyan Ocean between the Iranian microcontinents, leading to the formation of a shoshonitic melt. We infer that the recorded ages coincide with a continental rift episode followed by a rear arc tectonic region that spread along the northern active margin of Gondwana. Further, the change in magma affinity from calc‐alkaline (~474–512 Ma) to shoshonitic (444–428 Ma) in Central Iran is probably related to the gradual steepening of the slab dip angle and trench‐ward migration of the front arc into the region above metasomatically enriched rear arc mantle. [ABSTRACT FROM AUTHOR]

The Lut Block is a potential porphyry-style mineralized region in Iran including the well-explored Shadan porphyry gold-copper deposit, which has an extensive zone of gold- and copper-bearing stockwork-like sheeted veins. The structural setting of this deposit is a key to understanding the genesis of the mineralization. Our field studies show that the mineralization occurs as steeply dipping ore bodies along NW–SE transpressional faults. The zones with a high frequency of veins and volume of veins have a NW–SE trend, which is closely related to transpressional faults. We propose that such a compressional regime inhibits focused ore-forming fluid flow to higher levels in the crust. After a local change in stress field, fluid depressurization and channeling along transpressional faults generated the sheeted veins. This indicates an important role of these transpressional faults in focusing and controlling mineralization within this porphyry deposit, which has important implications for the exploration of porphyry deposits on a regional scale. The spatial distribution of sheeted veins is used to examine gold anomalies from lithogeochemical data extracted by fractal models. The results show that a combination of high vein density and high vein volume areas with gold anomalies could result in identifying areas with greater potential at the deposit to regional scale. [ABSTRACT FROM AUTHOR]

Introduction Shadan gold deposit, known as the first hitherto discovered Au-rich porphyry deposit in Iran, locates at ca. 120 km SW of Birjand, the north segment of the Lut block. The Lut block, as one of the main tectonic blocks in the eastern Iran, surrounds by dominantly flysch and ophiolite sequences, which are the remnants of Neotethyan ocean called the Sistan Ocean during Late Cretaceous (Zarrinkoub et al., 2012). The closure of the Sistan Ocean was followed by the collision of the Lut and Afghan blocks occurred during the Middle Oligocene-Middle Miocene. This activity brought forth extensive calc-alkaline magmatism together with forming various mineral crystallization and deposits throughout the Lut block (e.g., Karimpour et al., 2011; Camp and Griffis, 1982; Tirrul et al., 1983). The Eocene time is diagnosed as the peak of the mineralization in the Lut block, e.g., Hired Au epithermal deposit and Maherabad Au porphyry deposit (Karimpour et al., 2012; Richards et al., 2012). Intermediate plutonic and sub-volcanic rocks in composition with a NW-SE trending intermittently intruded into Eocene volcanic tuffs. The main trigger of Au mineralization is hosted by diorite-monzodiorites Shadan region, appear as the porphyry textures, and dominantly consist of mafic mineral phenocrysts, e.g., biotite and hornblende. Building on the work of Richards et al. (2012), the biotites Middle Eocene (37-40 Ma), and can be defined as one of the oldest hitherto known porphyry deposits in Iran (Aghazadeh et al., 2015). This study shed light on investigating the geochemical characteristics of Shadan gold deposit in the course of formation. Our results would be beneficial to further explore of similar Au deposits in the Lut block and beyond. Material and methods In the current study, we provide analytical procedures to prospects the geochemical characteristics of Shadan gold deposit as; (1) petrographical studies on 15 thin sections of the host rocks, e.g., outcropped bodies and drilling cores, in order to draw a relationship between the main lithologies; (2) petrographical studies on 85 thin and thin-polished sections of outcropped and drilling cores to further examination of the main alterations types in association with mineralization; (3) petrograpical studies on 53 thin-polished sections to classify the types of vein-veinlet systems; (4) petrograpical studies 6 doubly-polished sections of quartz-sulfide veins-veinlets applied for microthermometric analyses of fluid inclusions. Petrographical and microthermometric studies were performed at the microthermometry laboratory of the Technical University of Klausthal, Germany using a standard petrographic microscope (Zeiss model), a heatingcooling stage model THMSG600 made by Linkham equipped with a nitrogen injection pump model LNP, temperature control device model TMS94 and water injection pump (for high temperatures); (5) SEM analysis to recognize the occurrences of gold and its host minerals using a FEI Quanta 250 device with an analysis point of 1 to 3 micrometers, an acceleration voltage of 15 keV, a beam intensity of 80 A and a distance of 10 mm. Results and discussionsIntensive hydrothermal alteration in the prospecting region is concentrically zoned and encompassed wide spectrum of alteration types, in terms of mineral assemblage, e.g., potassic, phyllic, propylitic and argillic. The inner segment of the porphyry system is composed of potassic alteration (i.e., biotite-rich), appears as complex association with phyllic alteration, and surrounds by propylitic alteration. The complex association between potassic and phyllic alterations can be defined as the overprinting of potassic by phyllic products, which show high-grade gold mineralization. In the Shadan Au deposit, the potassic section exposes near the surface, indicating intense erosion. Mineralization in Shadan Au deposit classifies as supergene and hypogene. The former is characterized by malachite, azurite, chrysocolla, neotocite and iron oxide-hydroxides. The latter are specified by the occurrence of pyrite, chalcopyrite, covellite and magnetite. Our findings of the field observation appear that the supergene zone show no remarkable thickness in Shadan region, In the current study, vein-veinlet, hydrothermal breccias and disseminated mineralization are distinguished as the most common forms of mineralization. Volumetrically, the vein-veinlet mineralization constitutes the largest segment of the ore bodies. The average grade of gold is 0.5 ppm, however, in some cases, the grade of gold yielded from the phyllic zone as well as the associated veins shows higher grade and reaches up to 7 ppm, a typical feature in Au-rich porphyry deposits (Kesler et al., 2002). Au mineralization occurs as native gold, electrum and calaverite (AuTe2). The Au in sulfide ore sections dominantly forms as native, and hosts by pyrite. The average grade of copper reaches 0.15%. Malachite and chalcopyrite are the common Cu-bearing minerals in the prospecting region. Magnetite, as the most important Fe-bearing mineral, forms from magnetite veinlets to disseminated grains in the plutonic and volcanic rocks. The Shadan Au porphyry are characterized by diverse vein-veinlet systems including (1) M-type; (2) Atype; (3) B-type; (4) anhydrite-gypsum veins; (5) D-Type, as the frequent and important group with significant impact in mineralization; and (6) late veins include quartz, carbonate, and pyrite veins. Three major types of fluid inclusion are recognized in B-and D-type quartz veins/veinlets, including vapor-rich fluids or I-type (VL), aqueous fluids or II-type (LV), and hypersaline fluids or ІII-type (LVH). The temperature of homogenization and salinity in LV fluid inclusions varies from 298-420°C and 6.4-24.3 wt.% NaCl. The Th and salinity of LVH inclusions are ranging from from 238-582°C and 36.2-69 wt.% NaCl, respectively. Microthermometric investigations appear that the homogenization of halitebearing inclusions (LVH type) occurred in two different manners; 63 vol.% of inclusions, homogenized by halite disappearance, and 37 vol.% are halite-bearing fluid inclusions which were homogenized by L-V homogenization. This finding is in line with with the behaviour of halite-saturated inclusions in hydrothermal-magmatic mineralization systems, and results from fluid supersaturation with NaCl before homogenization or entrapment of primary fluids at high pressure as proposed by (Rusk et al. (2008) or heterogeneous entrapment of a halite-saturated hydrothermal brine (Sun et al., 2017). In addition, the cogenetic presence of high-salinity and vapor-rich inclusions, a common feature in porphyry deposits, imply the boiling or separation processes (Lecumberri Sanchez, 2013). Therefore, based upon petrographical and microthermometric studies of fluid inclusions, were boiling and mixing processes are the plausible explanations for the ore deposition in Shadan Au deposit. Conclusion Collisional magmatism in the Lut block is the result of the convective removal of lithosphere mantle and upwelling asthenosphere within an extensional tectonic regime. Many Au-rich porphyries are formed in magmatic arcs that have been affected by extensional processes over a period of time, such as the Cerro Corona and Minas Conga deposits in northern Peru, the Marte, Lobo, Refugio, and Cerro Casale deposits in the Maricunga Belt, northern Chile. Many Au-rich porphyries are coeval with volcanic units, the composition of which is often andesitic to dacitic or trachyandesitic to latitic. In the Shadan gold deposit, andesitic units with Eocene age also are widespread in the area. Banded veinlets are one of the hallmarks of gold-rich porphyry deposits, which may be due to the reopening of the vein or the re-entry of silica into certain bands, first identified in Maricunga gold-rich porphyry deposits in Chile. Another distinctive feature in the vein-veinlet systems of Shadan gold deposit is the presence of type Aand M veins, which are abundant in gold-rich porphyry deposits as compare with molybdenum-rich porphyry copper deposits. In the Shadan Au-rich deposit, the mineralization-related pluton contains hornblende phenocrysts or biotite, implying hydrous melt of the parent magma. The presence of hydrothermal magnetite in various alterations invokes a highly oxidized melt. Therefore, a hydrous melt with high fO2 and volatiles context is envisaged for the mineralization-related magma in Shadan region. Finally, Cu / Au ratio (> 40,000 for gold-poor and <40,000 for gold-rich deposits) is applied as a geochemical index to classify Shadan as a gold-rich porphyry deposit. Accordingly, the gold and copper are 0.5 g/t and1500 g/t, respectively, and thus, Cu / Au ratio ~3000 of the Shadan deposit can be classified as "gold-only" or "gold-rich" porphyry deposits. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to evaluate the effect of four weeks of high intensity interval training (HIIT) with beetroot juice supplementation (BJ) on serotonin and dopamine receptors in hippocampal tissue, as well as anxiety and depression in middleaged diabetic rats. Materials and Methods: In this experimental study, 28 diabetic female rats (55 mg/kg, induced by streptozotocin) aged 12-14 months, weighing 280-320 g, were divided into (1) diabetic control (DC), (2) BJ, (3) HIIT, and (4) HIIT+BJ groups. Also, 7 healthy rats were included in the healthy control (HC) group to evaluate the effect of diabetes induction on the research variables. HIIT was performed for four weeks, 4 sessions per week (70-95% of maximum speed at high intensities; 50-60% of maximum speed at low intensities). Also, BJ was fed daily to rats at a dose of 10 ml/kg. Results: Hippocampal expression of dopamine receptor-1 (Dop.R), 5-hydroxytryptamine receptor (5-HT. R), open arm entry percentage (OAE%) and movement rate in the HIIT, BJ and HIIT+BJ groups were significantly higher than the DC group. In the HIIT+BJ group, open arm time percentage (OAT%) was higher than the DC group. Levels of Dop.R gene expression were more affected by HIIT, and levels of 5-HT. R were more affected by BJ supplementation; also, HIIT+BJ had a synergistic effect on reducing anxiety and depression. Conclusion: Although HIIT was more effective than BJ and HIIT+BJ on Dop.R and BJ supplementation on 5-HT.R and improved anxiety and depression, both of HIIT and BJ were complementary in improving dopamine and serotonin receptordependent anxiety and depression and enhanced each other's effects. [ABSTRACT FROM AUTHOR]

The Tafresh plutons that include Ahmadabab diorite, Vasfonjerd monzonite, Mehrezamin diorite and Chahak diorite, located to the east of Tafresh city, north-central Iran, are part of Urumieh-Dokhtar magmatic arc. U-Pb dating of zircon grains provides emplacement ages of 22.3 ± 1 Ma for the Ahmadabad diorite, and tightly clustered ages of 22.2 ± 0.2 Ma, 21.3 ± 0.2 Ma, and 21.7 ± 0.4 Ma for Vasfonjerd monzodiorite, Mehrezamin diorite-monzonite, and Chahak diorite-monzonite plutons, respectively. These rocks are metaluminous to weakly peraluminous, calc-alkaline, and characterized by enrichment in light rare earth elements, Nb-Ta negative anomalies, and high LILE/HFSE ratios. Tafresh plutonic rocks originated from a parental magma source and experienced different degrees of partial melting. Geochemical signatures of Tafresh plutonic rocks, such as a wide range of Y/Nb (2.7–8.4) and low Zr/Nb (19.5–35.) ratios, Nb/Ta (11.46–18.15), argue for mantle–crust interaction during generation of Tafresh magmas. Relatively low Nb/La ratios further indicate that the lithospheric mantle played a significant role in melt generation. HREE signatures (i.e. decrease Dy/Yb with increasing SiO2) preclude substantial involvement of garnet either in the residue, both during partial melting and fractionation of the magma. The plutons are a product of final stages of subduction-related magmatism prior to the collision between the Arabian and Eurasian tectonic plates. [ABSTRACT FROM AUTHOR]

This paper presents UPb zircon dating and element compositions for Miocene intrusive rocks in NE Tafresh situated in the central Urumieh‐Dokhtar Magmatic Arc. These intrusive rocks, consisting of granodiorite and diorite, were emplaced during the Early Miocene (19.07–20.37 Ma), following extensive submarine volcanic activity in the Eocene. In normalized multi‐element diagrams, all the analysed rocks are characterized by enrichments in large ion lithophile elements (e.g., Ba, Rb, and Sr) and depletions in high field strength elements (e.g., Nb, Ta, and Hf) and display geochemical features typical of subduction‐related calc‐alkaline arc magmas. The enrichment of light rare earth elements and flat heavy rare earth elements patterns reflect amphibole fractionation from relatively hydrous, calc‐alkalic magmas. The geochemical features and ages of the Tafresh intrusive rocks suggest that the Neo‐Tethys Ocean did not close completely in the region until the Miocene and is consistent with a diachronous collision starting in the NW and closing later in the SE. [ABSTRACT FROM AUTHOR]