Study of Petrography and petrogenesis of Monavvar area Spessartite dykes (East Azerbaijan Province)

Many lamprophyric dykes' outcrops are found in Azerbaijan (in the northwest of Iran). These dykes which were the subject of many studies are including camptonite dykes in Misho Mountain, kersantite dykes of Goye-Poshti Mountain of Maragheh, camptonite and sannaite dykes in Horand, minette dykes of Varzeghan, minette dykes of Marand, minette dykes of Khoy, and minette dykes of Saray volcano.For the first time, Amel (1994) reported the occurrence of lamprophyre in the Monavvar region. According to him, this lamprophyre is spessartite and has Calc-alkaline affinities. In this study, we performed a detailed petrographic study of this lamprophyre. Besides, by using clinopyroxene mineral chemistry and whole rock chemistry, we try to investigate the petrogenesis of these lamprophyres from different aspects.General geologyMonavvar region is located in the east Azerbaijan province of Iran. Monavvar region is a part of the Alborz-Azarbaijan zone. Field observations show two spessartite dykes intruded in the andesitic lavas of the studied region. The age of andesitic lava and spessartite dykes is Plio-Quaternary because the andesitic lava intruded in Pliocene pyroclastic lava. Spessartite has a blackish-brown color in the hand specimens.PetrographyThe main petrographic texture of these lamprophyres is the Porphyry texture. The major minerals are plagioclase microliths (10-15 volume %), orthoclase (5-10 volume %), hornblende phenocrysts with burnt rim (40-50 volume %), clinopyroxene (>20 volume %), and biotite (10-15 volume %). The accessory minerals include zircon, sphene, and apatite.The plagioclase has higher content than orthoclase and both of these minerals could be seen only as microlith. Regarding the nomenclature scheme of Le Maître (2002), these features indicate that these lamprophyres are spessartite.Mineral ChemistryThe mineral chemistry of amphibole shows a magnesio-hastingsite composition. However, biotite is phlogopite-eastonite and feldspars are orthoclase and oligoclase in composition.DiscussionMineral chemistry of clinopyroxene studiesThe clinopyroxenes are in the field of Quad in the Q-J diagram and diopside in the En-Fs-Wo diagram.According to the AlVI+2Ti+Cr-AlIV+Na diagram for clinopyroxenes, Monavvar spessartite has occurred in almost the stable and low oxygen fugacity status.  Based on Soesoo (1997), the clinopyroxenes were crystalized under 1100-1200 ℃ and 2-6 kbar. The chemical composition of clinopyroxenes indicates subduction-related volcanic arcs and within-plate tholeiitic environments.Whole rock geochemistry of Monavvar spessartiteMost lamprophyre samples are plotted in the trachybasalt field on the total alkali (K2O+Na2O) versus silica (Si2O) classification diagram. They show alkali basalt composition on the Zr/Ti2O-Nb/Y plot.  K2O-Si2O diagram classified them as calc-alkaline lamprophyres.REE GeochemistryIn the spider diagram of studied samples, Nb and Ti show a distinctive negative anomaly, and U, La, K, Th, and Ba show a positive anomaly. HFSEs depletion and LILEs enrichment of samples are characteristics of shoshonitic and calc-alkaline magma. Negative Nb and Ti anomalies could be a result of Ti-bearing mineral segregation or high oxygen fugacity. LILEs enrichment could indicate that aqueous fluid is present during magma-forming processes or crustal contamination during magma evolution. Y depletion could happen as a result of amphibole segregation.  All samples show highly fractionated steep REE patterns which means a distinctive enrichment of LREEs relative to HREEs. LREEs enrichment occurs as a result of small degrees of magma partial melting. However, this feature is a character of shoshonitic and calc-alkaline magma. The REE pattern of Monavvar spessartite does not show an Eu anomaly. In the basic rocks, concurrent crystallization of amphibole and plagioclase caused a lack of Eu anomaly.Tectonic setting of Monavvar SpessartitesBased on the Zr-Y diagram and Nb-Zr-Ce/P2O5 diagram, Monavvar spessartites are ascribed to an arc-related tectonic setting.Petrogenesis of Monavvar SpessartitesBased on the whole rock composition of Monavvar spessartite, Ni=68-92 ppm, Co=1-23 ppm, Cr=59-125 ppm, and Mg#=25-32%. These values mean the lamprophyres could not be considered as the primary magma, but probably they are very close to the primary magma composition. On the other hand, on Dy/Yb-La/Yb diagram, the samples are scattered in the field of garnet-bearing mantle zone. Similarly, the La/Yb-La diagram indicates the garnet presence in the source peridotite, in addition to the 5-15 % of mantle peridotite partial melting for producing Monavvar spessartite melt.Geodynamics of Monavvar regionAccording to Rock (1991), petrographical, mineralogical, and geochemical investigations revealed M6 and M7 magmas for the Monavvar spessartites. M6 was produced by contamination of primary magma by mantle elements and M7 was produced by crustal contamination of primary magma. By considering this, the function of strike-slip dextral faults in Azerbaijan (northwest of Iran) could be responsible for Monavvar spessartites formation. Due to the mentioned faults function, transcurrent basins are made across the faults. Transcurrent basins caused low partial melting degrees of the metasomatized lithospheric mantle and produced alkaline basic magma. Contamination of this magma in different depths could form spessartite magma

Subduction-related mafic to felsic magmatism in the Malayer-Boroujerd plutonic complex, western Iran

The Malayer–Boroujerd plutonic complex (MBPC) in western Iran, consists of a portion of a magmatic arc built by the northeast verging subduction of the Neo-Tethys plate beneath the Central Iranian Microcontinent (CIMC). Middle Jurassic-aged felsic magmatic activity in MBPC is manifested by I-type and S-type granites. The mafic rocks include gabbroic intrusions and dykes and intermediate rocks are dioritic dykes and minor intrusions, as well as mafic microgranular enclaves (MMEs). MBPC Jurassic-aged rocks exhibit arc-like geochemical signatures, as they are LILE- and LREE-enriched and HFSE- and HREE-depleted and display negative Nb–Ta anomalies. The gabbro dykes and intrusions originated from metasomatically enriched garnet-spinel lherzolite [Degree of melting (fmel) ~ 15%] and exhibit negative Nd and positive to slightly negative εHf(T) (+ 3.0 to − 1.6). The data reveal that evolution of Middle Jurassic magmatism occurred in two stages: (1) deep mantle-crust interplay zone and (2) the shallow level upper crustal magma chamber. The geochemical and isotopic data, as well as trace element modeling, indicate the parent magma for the MBPC S-type granites are products of upper crustal greywacke (fmel: 0.2), while I-type granites formed by partial melting of amphibolitic lower crust (fmel: 0.25) and mixing with upper crustal greywacke melt in a shallow level magma chamber [Degree of mixing (fmix): 0.3]. Mixing between andesitic melt leaving behind a refractory dense cumulates during partial crystallization of mantle-derived magma and lower crustal partial melt most likely produced MMEs (fmix: 0.2). However, enriched and moderately variable εNd(T) (− 3.21 to − 4.33) and high (87Sr/86Sr)i (0.7085–0.7092) in dioritic intrusions indicate that these magmas are likely experienced assimilation of upper crustal materials. The interpretations of magmatic activity in the MBPC is consistent with the role considered for mantle-derived magma as heat and mass supplier for initiation and evolution of magmatism in continental arc setting, elsewhere

Active tectonics of Iran deduced from earthquakes, active faulting and GPS evidences

Iran is an ideal natural laboratory for studying the kinematics and dynamics of plate interactions because of the various tectonic processes encountered, including continental collision, subduction of oceanic lithosphere (Makran) and a sharp transition between a young orogen (Zagros) and a subduction zone (Makran). In this research, tectonic evolution of Iranian Plateau during Cenozoic convergence between Arabian and Eurasian plates is reviewed and youngest tectonic activities in the plateau such as active faults, earthquakes, magmatism, and young volcanism and GPS velocities are described. Iran is one of the most seismically active countries in the world, being crossed by several major fault lines that cover at least 90% of the country. These earthquakes occurred along the active faults of Iran and show various mechanisms of fault movements

Recent tectonic activity of Iran deduced from young magmatism evidences

Closure of the Neo-Tethys Ocean during Mesozoic and Cenozoic is one of the most important stages of tectonic evolution of Iranian Plateau. Subduction of the oceanic lithosphere under the southwestern border of Central Iran, caused plutonic and volcanic activity between the Jurassic and Quaternary within and adjacent to the southern margin of Central Iran. During closure of the ocean, two major subduction-related arcs trending parallel to the Main Zagros Thrust, the Mesozoic Sanandaj-Sirjan (SSMA) and the Tertiary to Plio- Quaternary Urumieh-Dokhtar magmatic arcs (UDMA) have been formed. Quaternary volcanic activity, generated by a complex combination of geodynamic and petrogenetic processes associated with the evolution of the Alpine-Himalayan collision belt. This volcanic activity has produced both andesitic stratovolcanoes and fields of basaltic cones and plateau lavas. Upper Miocene to Pliocene-Quaternary volcanic activity is observable in Makran, UDMA, Qom-Baft, Anar and northern Lut

Solubility of Anthracene in C1-C3 Alcohols from (298.2 to 333.2) K and Their Mixtures with 2-Propanone at 298.2 K

Article discussing the solubility of anthracene in C1-C3 alcohols from (298.2 to 333.2) K and their mixtures with 2-propanone at 298.2 K

Environmental impacts and mineralogical characteristics of dust storm in Middle-East

Middle Earth, including Iran, Iraq, China and Syria has been recognized as one of the most important primary sources of dust. Intensive investigations have been conducted to study the chemical composition, sources and deposition of Middle Earth particles. However, analysis of individual Middle Earth particles show that about one fifth of all the particles are mineral aggregates, and at least one fourth of the particles contain sulfur. X-ray diffraction (XRD) is used to quantify the phase and the clay mineral compositions of Middle Earth samples. Phases in the Middle Earth sample collected during the 20 March 2002 dust storm episode included clay minerals, noncrystalline materials, quartz, calcite, plagioclase, potassium feldspar, pyrite, hornblende, and gypsum in descending order. Clay minerals are mainly illite/smectite mixed layers (78%), followed by illite (9%), kaolinite (6%), and chlorite (7%). Particulate matter (PM) less than 10 mm are enriched with clay minerals and deficient with quartz by mass compared with the total suspended particulates collected during an Middle Earth episode. The PM less than 10 mm collected during the two severe dust storm episodes is characterized by the absence of dolomite, high quartz/clay ratio, and dominance of illite/smectite mixed layers in clay minerals

Mineralogy and geochemical properties of dust storm in Sistan region and Khuzestan Province, Iran

In recent years, dust storms coming from western neighboring countries are drastically increased dust storms and affecting western and eastern part of Iran. This phenomenon is caused a lot of environmental and socio-economic problems. Sistan is a region located in southeast Iran with extensive wind erosion. X-Ray Diffraction (XRD) analysis of airborne and soil dust samples from Sistan shows that the dust mineralogy is dominated mainly by quartz (30-40%), calcite (18-23%), muscovite (10-17%), plagioclase (9-12%), chlorite (~6%) and enstatite (~3%), with minor components of dolomite, microcline, halite and gypsum. X-Ray Fluorescence (XRF) analyses of all the samples indicate that the most important oxide compositions of the airborne and soil dust are SiO2, CaO, Al2O3, Na2O, MgO and Fe2O3, exhibiting similar percentages for both stations and soil samples. However Khuzestan Province is located in southwest Iran with sandy deserts. XRD result from Khuzestan show that mineralogical composition of these dust particles can be divided into three groups: (1) Carbonate group (calcite mineral), (2) Silicate group (quartz mineral) and (3) Clay group (Kaoline mineral). The most important minor phase is Gypsum. SEM studies indicate that these particles were found in rounded, irregular, prismatic and rhombic shapes. XRF and ICP analyses of the samples show that the most important oxide compositions of airborne dusts are SiO2, Al2O3, Fe2O3, CaO and MgO. This research can be help to find the impact of geological units on the wind erosion lands for finding dust storm sources in the states of western and eastern parts of Iran

Determining magmatic series and oxygen fugacity of volcanic rocks in the east of Kamu, north of Isfahan, based on biotite chemistry

Volcanic rocks of interest are situated in the middle part of the Urumieh-Dokhtar Magmatic Arc (UDMA). They are parts of a vast magmatic province located in the north of Bitlis-Zagros suture zone. Having a prevailing porphyritic texture, these rocks include phenocrysts of plagioclase, amphibole and biotite in a matrix composed of feldspar, quartz, opaque, glass and microlite and mineralogically show composition of dacite to andesite. Minerals are mostly fresh. Effects of alteration are limited to weak chloritization and saussuritization in some amphiboles and rim of plagioclases, respectively. All of the analyzed biotites in the Miocene-Pliocene volcanic rocks in the east of Kamu are of Mg-biotite. According to a widespread classification of micas to 6 general end-members, biotites of interest are averagely composed of 55.45% phlogopite, 15.90% talc, 12.72% Ti-phlogopite, 11.44% eastonite, 3.71% ferri-eastonite and 0.78% muscovite. Chemical composition of biotites indicates a calk-alkaline magmatic series for the magma from which biotites are crystallized. Estimation of the oxygen fugacity of magma, based on chemical composition and Fe3+ content of biotite, shows that the oxygen fugacity was limited to FMQ buffer in quality and was about 10-15 bar in quantity. This value accords the oxygen fugacity for intermediate-acidic volcanic rocks

Geochemistry and petrogenesis of the Feshark intrusion (NE Isfahan city)

Introduction Granitic rocks are the most abundant rock types in various tectonic settings and they have originated from mantle-derived magmas and/or partial melting of crustal rocks. The Oligo-Miocene Feshark intrusion is situated in the northeast of the city of Isfahan, and a small part of Urumieh–Dokhtar Magmatic Arc is between 52º21' E to 52º26'E and 32º50' N to - 32º53' N. The pluton has intruded into lower Eocene volcanic rocks such as rhyolite, andesite, and dacite and limestone. Analytical methods Fifteen representative samples from the Feshark intrusion were selected on the basis of their freshness. The major elements and some trace elements were analyzed by X-ray fluorescence (XRF) at Naruto University in Japan and the trace-element compositions were determined at the ALS Chemex lab. Results The Feshark intrusion can be divided into two phases, namely granodiorite with slightly granite and tonalite composition and quartz diorite with various quartz diorite and quartz monzodiorite abundant enclaves according to Middlemost (1994) classification. The quartz diorite show dark grey and are abundant at the western part of the intrusive rocks. Granodiorite are typically of white-light grey in color and change gradually into granite and tonalite. The granodiorite and granite rocks consist of quartz, K-feldspar, plagioclase, biotite, and amphibole, whereas in the quartz diorites the mineral assemblages between different minerals are very similar to those observed in the granodiorite. However, amphibole and plagioclase are more abundant and quartz and K-feldspar modal contents are lower than in the granodiorite whereas pyroxene occurs as rare grains. They are characterized as metaluminous to mildly peraluminous based on alumina saturation index (e.g. Shand, 1943) and are mostly medium-K calc-alkaline in nature (Rickwood, 1989). Discussion In the Yb vs. La/Yb and Tb/Yb variation diagrams (He et al., 2009), the studied samples show small variations in La/Yb and Tb/Yb ratios, suggesting fractional crystallization. Chondrite-normalized REE patterns (Sun and McDonough, 1989) of all the samples essentially have the same shape with light REE (LREE) enrichment, flat high REE (HREE) and significant negative Eu anomalies. All of the samples exhibit similar trace element abundance patterns, with enrichment in large ion lithophile elements (LILE) and negative anomalies in high field strength elements (HFSE; e.g. Ba, Nb, Ta, P, and Ti) compared to primitive mantle (Sun and McDonough, 1989). The enrichment of LILE and LREE relative to the HFSE and HREE along with Nb, Ta, and Ti anomalies display close similarities to those of magmatic arc granites (Pearce et al., 1984) and also negative Nb–Ti anomalies are thought to be related to the fractionation of Ti-bearing phases (titanite, etc.). Moreover, these are the typical features of arc and / or crustal contamination (Kuster and Harms, 1998), while the negative P anomalies should result from apatite fractionation. The increasing of Ba and slightly decreasing Sr with increasing Rb, indicate that plagioclase fractionation plays an important role in the evolution of the studied intrusion. Tectonic environment discrimination diagrams such as Nb vs. Y, Nb vs. Yb+Ta (Pearce et al., 1984) and Th/Yb vs. Ta/Yb (Pearce, 1983) with enrichment in the LILE and LREE relative to HFSE and HREE and negative anomaly in the Nb, Ti and Eu indicate that their initial magma is generated in the subduction zone related to an active continental margin setting. ‏The rocks genesis determining diagrams such as Nb vs. Nb/U (Taylor and McLennan, 1985), Ti vs. Ti/Zr (Rudnick et al. 2000), (La/Sm)cn vs. Nb/U (Hofmann et al., 1986), and Sr/Y vs. Y (Sun and McDonough, 1989) show that the magma was probably generated by partial melting of amphibolitic continental crust. References He, Y., Zhao, G., Sun, M. and Han, Y., 2009. Petrogenesis and tectonic setting of volcanic rocks in the Xiaoshan and Waifangshan areas along the southern margin of the North China Craton: Constraints from bulk-rock geochemistry and Sr-Nd isotopic composition. Lithos, 114(1-2): 186-199. Hofmann, A.W., Jochum, K.P., Seufert, M. and White, W.M., 1986. Nb and Pb in oceanic basalts: new constraints on mantle evolution. Earth and Planetary Science Letters ,79(1-2): 33-45. Kuster, D. and Harms, U., 1998. post – collisional potassic granitoids from the southern and northwestern parts of the late neoporterozoic East African Orogen: a review. Lithos. 45(1-4):177-195. Pearce, J.A., 1983. The role of sub-continental lithosphere in magma genesis at destructive plate margins. In: C.J. Hawkesworth and M.j. Norry (Editors), continental basalts and mantle xenoliths. Shiva Publications, Nantwhich, pp. 230-249. Middlemost, E.A.A. 1994. Naming materials in the magma/igneous rock system. Earth- Science Review. 37(3-4): 215–224. Pearce, J.A., Harris, N.B.W. and Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology, 25(4): 956 – 983. Rickwood, P.C., 1989. Boundary lines within petrologic diagrams which use of major and minor element. Lithos, 22(4): 247-263. Rudnick, R.L., Barth, M., Horn, I. and McDonough, W. F., 2000. Rutile-Bearing Refractory Eclogites: Missing Link Between Continents and Depleted Mantle. Science, 287(5451): 278-281. Shand, S.J., 1943. The Eruptive Rocks. 2nd edition. John Wiley, New York, 444 pp. Sun, S.S. and McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes. Geological Society, London, Special Publications, 42, pp. 313-345. Taylor, S.R. and McLennan, S.M., 1985. The continental crust: its compositions and evolution. Blackwell, Oxford, 312 pp