Two-sided asymmetric subduction; implications for tectonomagmatic and metallogenic evolution of the Lut Block, Eastern Iran

West directed subduction zones show common characteristics, such as low structural elevation, deep trench, steep slab and a conjugate back-arc basin that are opposite to those of the east directed subduction zones. The tectonomagmatic and metallogenic setting of the Lut Block is still a matter of debate and several hypotheses have been put forward. Despite some authors denying the influence of the operation of Benioff planes, the majority propose that it occurred beneath the Afghan Block, while others consider that oceanic lithosphere was dragged under the Lut Block. Cu-Au porphyry deposits seem to occur in an island arc geotectonic setting during the middle Eocene while Mo-bearing deposits are coincident with the crustal thickening during Oligocene. We introduce new trace element and isotope geochemical data for granitoids and structural evidences testifying the two-sided asymmetric subduction beneath both Afghan and Lut Blocks, with different rates of consumption of oceanic lithosphere

Petrography, geochemistry and tectonic significance of the Mahoor granitoids (Lut Block, Eastern Iran)

The Mahoor granitoids are Cu–Zn-bearing porphyries that outcrop in the central part of the Lut Block, about 135 km south-west of Nehbandan (eastern Iran). These granitoids occur mainly as dykes and stocks that intrude Eocene volcanics. Petrographically, all the studied intrusives display porphyritic textures with mm-sized phenocrysts, most commonly of plagioclase and hornblende, embedded in a fine-grained groundmass with variable amounts of plagioclase, hornblende, clinopyroxene, quartz and opaques. Hydrothermal alteration affected these granitoids, as revealed by the common occurrence of sericite, chlorite, sphene/leucoxene, epidote and calcite. Chemical classification criteria show that the intrusives may be named as gabbrodiorites, diorites, monzodiorites and tonalites. Major element geochemistry reveals that all the studied lithologies are typically metaluminous (A/CNK ≤ 0.94) and, in addition, suggest, that they constitute a suite belonging to the high-K calc-alkaline series. Magnetic susceptibility (1485 × 10-5 SI) together with mineralogical and geochemical features show that they belong to magnetite granitoid series (I-type). In primitive mantle-normalized trace element spiderdiagrams, the analysed samples display strong enrichment in LILE compared to HFSE (15.5 ≤ RbN/YN ≤ 45.9), accompanied by negative anomalies of Nb, Ta and Ti. REE chondrite-normalized plots show slight to moderate LREE enrichment (4.9 ≤ LaN/LuN ≤ 8.4) and negative Eu anomalies (Eu/Eu* ratios vary from 0.65 to 0.88). Tectonic characteristics also indicate that the study area is emplaced in a volcanic arc setting. The whole set of geochemical data suggest that the Mahoor granitoids are co-genetic, belong to the calc-alkaline series and have been originated in an active continental margin setting. Sulfide mineralizations (pyrite, chalcopyrite and sphalerite) related to these granitoids are common and occur both disseminated and as hydrothermal veins, indicating a high mineralization potential for this area

Zircon U-Pb geochronology, geochemistry, Sr-Nd isotopic compositions, and tectonomagmatic implications of Nay (NE Iran) postcollisional intrusives in the Sabzevar zone

The mafic to felsic intrusive rocks of Nay (IRN) are located in the northeast of the central Iranian block. In this study, we present new major and trace element geochemistry, U-Pb zircon ages, and Sr-Nd isotopic data to discuss the origin of the IRN postcollisional units. The oldest units in the Nay area belong to Paleocene–early Eocene volcanic and pyroclastic series including basalt-andesite, latite, dacite, and tuff. These series are crosscut by subvolcanic and granitoid rocks with lithological composition varying from quartz gabbro to K-feldspar granite. The youngest igneous activity is represented by quartz monzodiorite dikes. Hornblende-biotite quartz monzonite from Nay granitoids was dated at 40 Ma (zircon U-Pb). The IRN rocks are metaluminous to peraluminous with high-K calc-alkaline and shoshonitic affinities. They display enrichment in light REEs [(La/Yb)N = 3.79–8.71] and LILEs (such as Ba, Th, Rb, U, and K), with depletion in HFSEs (such as Nb, Zr, Y, and Ti). All rocks have negative Eu anomalies [(Eu/Eu*)N = 0.17–0.88] and relatively flat heavy REE patterns [(Gd/Yb)N = 1.12–1.69]. Granitoids have initial 87Sr/86Sr values from 0.7053 to 0.7061 and εNd values from –1.65 to –0.02 calculated at 40 Ma. The geochemical composition of IRN rocks along with the low ISr and positive εNd values and mantle model ages of 0.6–0.8 Ga indicate that two end-members, enriched mantle and a continental crust, were involved in the magma generation. We argue that the Eocene IRN magmatism occurred as a postcollisional product by asthenospheric upwelling owing to the convective removal of the lithosphere during an extensional collapse of the central Iranian block.publishe

Fluid inclusion geothermometry of various alteration – mineralization zones of Chah-shaljami prospect, Eastern Iran

منطقه اکتشافي چاهشلغمي در خراسان جنوبي و در کمربند آتشفشاني – نفوذي بلوک لوت قرار گرفته است. تودههاي نيمه عميق گرانيتوئيدي مربوط به اليگوسن، درون تواليهاي آتشفشاني - پيروکلاستيک ائوسن نفوذ کردهاند. انواع کانيهاي دگرساني شامل آلونيت، ژاروسيت، کلريت، ديکيت، سريسيت، مونتموريلونيت، کوارتز و اکسيدهاي آهن شناسايي شدهاند. کانيسازي شامل پيريت، آرسنوپيريت، موليبدنيت، کالکوپيريت، اسفالريت، گالن و انارژيت است. ميزان دما و شوري بالاي سيالات درگير در زون دگرساني سيليس - کلريت ميتواند در تعيين مرکز سيستم کانيسازي در اکتشافات بعدي مورد استفاده قرار گيرد. دما و شوري سيالات به سمت زون دگرساني کوارتز حفرهاي در حال کاهش است که احتمالا نشان دهنده افزايش دخالت آبهاي جوي ميباشد. شواهد زمينشناسي، دگرساني، کانيسازي و تحول سيالات هيدروترمال نشان دهنده کانيسازي اپيترمال سولفيداسيون بالا مرتبط با سيستم پورفيري عمقي در منطقه ميباشد. کليد واژهها: بلوک لوت، آلونيت، سيالات درگير، اپيترمال.Chah-shaljami exploration area is located in the Southern Khorasan and belongs to the Lut Block volcanic-plutonic belt. Oligocene subvolcanic granitoids intruded into Eocene volcanic - volcaniclastic sequences. Alteration minerals include alunite, jarusite, chlorite, dickite, sericite, montmorillonite, quartz and iron oxide. Mineralization includes pyrite, arsenopyrite, molybdenite, chalcopyrite, sphalerite, galena and enargite. High temperature – salinity of fluid inclusions from sericite alteration is an indicator that can direct the next exploration toward the mineralization center. Temperature – salinity of fluid inclusions decrease toward the vuggy quartz alteration which indicate the increase of the role of meteoric fluids. The gathered data on alteration, mineralization and hydrothermal fluids together with field evidence evidence indicate that the high-sulfidation epithermal mineralization is related to the deep porphyry system in the area

Hydrothermal fluids evolution from various alteration – mineralization zones of Dehsalm porphyry type system, Lut block, Eastern Iran

منطقه اکتشافي دهسلم در خراسان جنوبي و در کمربند آتشفشاني – نفوذي بلوک لوت قرار گرفته است. تودههاي نيمه عميق حدواسط تا اسيدي مربوط به اليگوسن، درون تواليهاي آتشفشاني، ماسهسنگ و سيلتستون ائوسن نفوذ کردهاند. زونهاي دگرساني شامل انواع پتاسيک، پروپليتيک، سريسيت- رسي، اپيدوتي، سريسيت - کلسيت - سيليس و سيليسي ميباشند. کانيسازي بصورت رگه – رگچهاي و پراکنده شامل مگنتيت، پيريت، موليبدنيت، کالکوپيريت، بورنيت، طلا، آرسنوپيريت، اسفالريت، گالن، کوليت، ديژنيت و کانيهاي سولفوسالت ميباشد. مطالعه سيالات درگير تاثير فرايندهاي جوشش، ناآميختگي، سرد شدن و رقيق شدگي توسط آيهاي جوي را طي تحول سيالات کانهساز نشان داده است. ميزان دما و شوري سيالات درگير از زون دگرساني پتاسيک به سمت زون دگرساني سريسيتي - رسي در حال کاهش است که احتمالا نشان دهنده افزايش دخالت آبهاي جوي ميباشد. شواهد زمينشناسي، دگرساني، کاني- سازي و تحول سيالات هيدروترمال نشان دهنده کانيسازي سيستم پورفيري در منطقه ميباشد. کليد واژهها: بلوک لوت، سيالات درگير، جوشش، سيستم پورفيريDehsalm exploration area is located in the Southern Khorasan and belongs to the Lut Block volcanic-plutonic belt of the Lut block. Oligocene intermediate to acidic subvolcanic rocks intruded into Eocene volcanic, sandstone and siltstone sequences. Alteration zones include potassic, propylitic, sericite – calcite – silica, sericite – argillic, epidote and silicification. Vein – veinlet and disseminated mineralization comprise magnetite, pyrite, molybdenite, chalcopyrite, bornite, arsenopyrite, sphalerite, galena, covellite, digenite and sulfosalts. Fluid inclusion studies have shown the affect of boiling, fluid immiscibility, cooling and dilution processes by meteoric fluids during the evolution of mineralizing fluids. Temperature – salinity of fluid inclusions decrease from potassic through sericite – argillic alteration which indicate the increase of the role of meteoric fluids. The gathered data on alteration, mineralization and hydrothermal fluids together with field evidence indicate that a porphyry type mineralization system occurs in the area

Geochemistry, Sr-Nd Isotopes and Zircon U–Pb Geochronology of Intrusive Rocks: Constraint on the genesis of the Cheshmeh Khuri Cu mineralization and its link with granitoids in the Lut Block, Eastern Iran

The Cheshmeh Khuri prospecting area, part of the Tertiary volcanic-plutonic rocks in the Lut Block (central eastern Iran), comprises Middle Eocene granitoid and volcanic (with basaltic andesite to rhyolite composition) sequences that intruded pyroclastic rocks. Copper mineralization is related to the granitoid rocks. The mafic rocks occur mainly as dykes and are related to a younger magmatic activity (post-mineralization) in the area. The main hydrothermal alteration zones include quartz-sericite-pyrite ± carbonate (QSP ± C), argillic, and propylitic. Mineralization (pyrite, chalcocite, chalcopyrite, sphalerite, galena and magnetite) occurs as disseminated, stockwork and vein-type. The granitoids have features typical of high-K calk-alkaline, metaluminous, and belong to magnetite granitoid series. Primitive mantle normalized trace element spider diagrams display enrichment in LILE, such as Rb, Ba, and Cs, compared to those of HFSE. Chondrite-normalized REE plots show moderately to slightly strong LREE enriched patterns, and a negligible negative Eu anomaly. Rb-Sr whole rock–feldspar–biotite-hornblende and zircon U-Pb ages between ~44.6 and ~43.4 Ma (Middle Eocene) were obtained in granitoid samples. Initial 87Sr/86Sr ratios of granitoids range from 0.7047 to 0.7054, and their εNdi values vary from −1.1 to +0.8. Initial 87Sr/86Sr ratios of mafic rocks range from 0.7043 to 0.7047, and the εNdi values vary from +0.7 to +3.5. The whole set of geochemical data of rocks in the study area indicate an origin of the parental melts in a subduction-modified upper mantle in post-collisional extension-related zone. The primitive magmas of granitoids underwent contamination and assimilation through being exposed to the continental crust, while primitive magmas of the mafic rocks do not have relevant crustal contribution. The geochemical and radiogenic isotope data for the granitoids associated with mineralization in the Cheshmeh Khuri area in comparison with those of other prospects in the Lut Block indicate that mantle has played a crucial role in their petrogeneses and metallogeneses. Due to the crustal contamination and assimilation, the proportion of mantle component that was involved in the granitic magma shows a decrease in the Cheshmeh Khuri area. It seems that the Cheshmeh Khuri area has the lowest potential for a significant amount of Cu-Au agglomeration.publishe

U-Pb zircon geochronology, geochemistry, and petrogenesis of the Hamech intrusions in the Kuh-e-Shah volcano-plutonic complex, Eastern Iran

The Hamech area is located in the west of Kuh-e-Shah volcano-plutonic complex, close to the boundary between the Lut Block and Sistan Suture Zone (SSZ), and is composed of monzonite to diorite porphyries and rare gabbro that intruded into older volcanic rocks. U-Pb zircon dating indicates an age of 36.9 ± 1 Ma for gabbro (Late Eocene, Priabonian) and 38.6 ± 0.5 Ma for dacite (Late Eocene, Bartonian). Geochemically, the studied intrusions are dominantly I-type, high-K calc-alkaline, and metaluminous features. Primitive mantle-normalized trace-element spider diagrams of these rocks present enrichment in ion lithophile elements such as Cs, Rb, Ba, K, and Sr and depletion in high field strength elements such as Nb, Ti, Zr, and heavy rare earth elements. Besides, chondrite-normalized rare earth elements plots of the rocks show enrichment in light rare earth elements (6.85 < LaN/YbN < 9.72) and a lack or weak negative Eu anomaly (Eu/Eu* = 0.81–1.02). The initial 87Sr/86Sr and 143Nd/144Nd ratios for the rocks from 0.704541 to 0.704880 and from 0.512633 to 0.512691, respectively, when recalculated to an age of 39 Ma. The εNd(i) values vary from +0.87 to +1.99, which fits into a suprasubduction mantle wedge source for the parental melts. All data suggest that the Hamech intrusions developed in a low maturity continental margin arc setting related to the convergence of the Afghan and Lut Blocks and subduction of Sistan oceanic crust during the Eocene.publishe

An android application for estimating muscle onset latency using surface EMG signal

Background: Electromyography (EMG) signal processing and Muscle Onset Latency (MOL) are widely used in rehabilitation sciences and nerve conduction studies. The majority of existing software packages provided for estimating MOL via analyzing EMG signal are computerized, desktop based and not portable; therefore, experiments and signal analyzes using them should be completed locally. Moreover, a desktop or laptop is required to complete experiments using these packages, which costs. Objective: Develop a non-expensive and portable Android application (app) for estimating MOL via analyzing surface EMG. Material and Methods: A multi-layer architecture model was designed for implementing the MOL estimation app. Several Android-based algorithms for analyzing a recorded EMG signal and estimating MOL was implemented. A graphical user interface (GUI) that simplifies analyzing a given EMG signal using the presented app was developed too. Results: Evaluation results of the developed app using 10 EMG signals showed promising performance; the MOL values estimated using the presented app are statistically equal to those estimated using a commercial Windows-based surface EMG analysis software (MegaWin 3.0). For the majority of cases relative error <10. MOL values estimated by these two systems are linearly related, the correlation coefficient value ~ 0.93. These evaluations revealed that the presented app performed as well as MegaWin 3.0 software in estimating MOL. Conclusion: Recent advances in smart portable devices such as mobile phones have shown the great capability of facilitating and decreasing the cost of analyzing biomedical signals, particularly in academic environments. Here, we developed an Android app for estimating MOL via analyzing the surface EMG signal. Performance is promising to use the app for teaching or research purposes. © 2019, Shiraz University of Medical Sciences. All right reserved

U–Pb zircon geochronology, petrochemical and Sr–Nd isotopic characteristic of Late Neoproterozoic granitoids of the Bornaward complex (Bardaskan-NE Iran)

The Bornaward granitoids in the Taknar zone are located in the northeast of the central Iranian block in northeast Iran (Khorasan Razavi province), about 280 km southwest of Mashhad city and 28 km northwest of Bardaskan city. Taknar zone is an exotic block, bordered by two major faults, the Great Kavir fault in the south and Rivash fault in the north. Intrusive rocks of the study area, called the Bornaward granitoid complex (BGC), include of granite, alkali granite, syenogranite, leucogranite, granophyre, monzogranite, granodiorite, tonalite, diorite and gabbro intruded into the center of Taknar zone. These intrusive rocks affected low grade metamorphism. The results of U-Pb zircon dating on two granite samples, one belonging to the Taknar mine west of the study area and the other the Bornaward granitoids in the eastern part of study area, and also one granodiorite the Taknar mine area and one diorite the Bornaward area, yield ages of the granites as 540.5±2.9 Ma (Taknar mine area) and 550.41 3.21,-4.54 Ma (Bornaward area), the granodiorite as 550±6.9 Ma and diorite as 551.96±4.32 Ma, all Late Neoproterozoic. The Bornaward intrusive bodies are classified as belonging to the ilmenite-series of reduced granitoids. Some small high magnetite-granite and tonalite outcrops in the study area are classified as belonging to the magnetite-series of oxidized granitoids. Chemically, most granitoids of the study area are S-type middle-high metaluminous to slightlymiddle peraluminous and belong to tholeiite, calc-alkaline to high-K calc-alkaline rock series with enrichments in LIL (Cs, Rb and Ba, U, K, Zr, Y, Th) elements and depletion in HIL (Sr and Nb, Ta, Ti) elements. Chondrite-normalized Rare Earth Elements (REEs) plots indicate minor enrichments of LREEs in comparison with HREEs, with (La/Yb)N between 1.04 -7.90 and total of REEs of the samples between 44.8 ppm (minimum) and 293.5 ppm (maximum) with strong negative anomaly of Eu compared to other Rare Earth elements. The Bornaward granitoid have an initial 87Sr/86Sr and 143Nd/144Nd ranging 0.703514 to 0.716888 and 0.511585 to 0.512061, respectively, when recalculated to an age of 550 to 538 Ma, consistent with the new radiometric age results. Initial εNd isotope values for granite, granodiorite and diorite range -6.73 to 2.52. TDM age of the BGC is 1.08-1.70 Ga. This indicates that the Bornaward granitoid complex (BGC) derived partial melting of distinct basement source regions with very high initial 87Sr/86Sr and underwent extensive crustal contamination

Petrography, geochemistry, tectonic setting and petrogenesis of volcanic rocks in Robaie area (South of Damghan)

سنگهای منطقة رباعی، در کمربند ترود چاهشیرین در جنوب دامغان، شامل واحددهای آتشفشدانی ائوسدن بدا ترکید آنددزیت و - تراکیآندزیت هستند. سنگهای آذرین نیمهژرف بهصورت استوک و دایک با ترکی دیوریت، مونزونیت و مونزودیوریت پورفیری در این واحدها نفوذ کردهاند. بافت اصلی سنگهای آتشفشانی پورفیریتیک است و درشتبلورهایی از کانیهای پلاژیدوکلاز، هورنبلندد و بیوتیت دارند. آپاتیت و زیرکن کانی فرعیِ این واحدها هستند. این سنگها بیشتر سرشدت شوشدونیتی و یدک نموندة نیدز سرشدت کالکآلکالن پتاسیم بالا دارند. غنیشدگی از LILE و LREE ، بههمراه تهیشدگی از HREE و HFSE و ناهنجاری منفی عنصدرهای Nb و Ti همراه با شواهد دیگر، مانند نسبت بالای Th/Yb در این سنگهای آتشفشانی، نشاندهندد پیددای آنهدا در یدک محدی مرتب با فروران در مرز فعال قارهای هستند. مقدار Sr86Sr/87 ، Nd144Nd/143 اولیه و iNd)ε ( آنددزیت بدهترتی برابربدا 704445 / 0 ، 512691 / 0 و 29 / 2 است. همة این ویژگیها پیدای سنگهای آتشفشانی منطقة رباعی را از ذوببخشی گو گوشدتهای در بدالای پهنة فروران تأیید میکنند. یافتههای سنگشناسی همراه با دادههای زمینشیمیایی عنصرهای کمیاب و خاکی کمیاب نشاندهند گرای کالکآلکالن، آلای و هضم مواد پوستهای، جدای بلورین و پیدای ماگما سازند آنها در پهنههای فرورانشی است.The rocks of the Robaie area located in the Torud-Chahshirin belt and south of Damghan, includes the Eocene andesite and trachyandesite rocks in which subvolcanic igneous rocks as stoke and dyke with diorite, monzonite and monzodiorite porphyry composition are intruded. The main textures of volcanic rocks are porphyritic characterized by plagioclase, hornblende and biotite phenocrysts as well as apatite and zircon as minor minerals. The rocks studied are mainly of shoshonitic nature and only one sample is considered as high-K calc-alkaline. Several line of evidence including LILE and LREE enrichment, HREE and HFSE depletion, high Th/Yb with negative anomalies of Ti, Nb and the position of the samples on the tectonic discrimination diagrams indicate that the volcanic rocks in discussion were emplaced into the subduction zone related to an active continental margin setting. The initial 87Sr/86Sr, 143Nd/144Nd ratios and (εNd)i value of andesite are 0.704445, 0.512691 and 2.29, respectively. The whole set of evidence confirms that the studied volcanic rocks were generated from partial melting of the mantle wedge above the subduction zone. Petrographic observations along with geochemistry of rare earth and trace elements suggest that the calc-alkaline affinity of the rocks studied and their parent magma from a subducted-related environment as well as crustal assimilation and fractional crystallization.publishe