Petrology
Mohsen Zadsaleh; Fariborz Masoudi; Hamed Pourkhorsandi; Karen Fontijn
Abstract
Damavand is a young volcanic edifice with an elevation of 5610 meters formed in the middle of the central Alborz Mountain range (N Iran) during the Quaternary. Its edifice is composed of trachyte and trachyandesite rocks, pyroclastic fall and flow deposits and lahars, formed during several eruptions ...
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Damavand is a young volcanic edifice with an elevation of 5610 meters formed in the middle of the central Alborz Mountain range (N Iran) during the Quaternary. Its edifice is composed of trachyte and trachyandesite rocks, pyroclastic fall and flow deposits and lahars, formed during several eruptions and under different magmatic conditions. To investigate the crystallization trends in the Damavand magma chamber and its evolution over time, plagioclase internal textures in lava flows, pyroclastic flow and ash deposits were studied. Samples from six different lava flows and pyroclastic fall and density current deposits with different ages were collected. Plagioclase crystals with similar dimensions and sizes but with completely different textures, and plagioclases with different dimensions but similar textural characteristics were observed. Twenty-eight different texture types were observed in plagioclase crystals from lava flows, whereas only three texture types were distinguished in the pyroclastic deposits. A large population of plagioclase in pyroclastic deposits reveal the non-equilibrium crstallization in the Damavand magma chamber(s), while in lava flows, a series of plagioclase cumulates present both equilibrium and non-equilibrium crystallization conditions in the magmat chamber. Plagioclase crystals in the source magmas of lava flows have repeatedly remained in a non-equilibrium state without eruption, letting the crystals to overgrow. Changes in the rate of magma ascent, small- and large-scale convection cells in magma chambers, varying temperature and/or pressure, and different volumes of (non-)eruptible mush/melt, are some of the parameters that are revealed by our textural studies. In the period between about 7-450 ky ago, the magma chamber that led to the buildup of the young Damavand volcano, was in non-equilibrium conditions as demonstrated by individual crystals textures and chemistry. However, these conditions have not always led to volcanic eruptions.
Remote Sensing
A. Eskandari; S. Amini; F. Masoudi
Abstract
Monitoring quiescent volcano such as Damavan is vital. In this research, we investigate the changes of land surface temperature (LST) around the Damavand volcano during 23 years period. The evaluations were done on the thermal anomaly areas related to geothermal activity and results compared with non-anomalously ...
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Monitoring quiescent volcano such as Damavan is vital. In this research, we investigate the changes of land surface temperature (LST) around the Damavand volcano during 23 years period. The evaluations were done on the thermal anomaly areas related to geothermal activity and results compared with non-anomalously thermal areas. The surface thermal anomalies were detected on the basis of processing of Landsat day and night-time images and combination with geological information layers. The average of calculated values for geothermal heat flux (GHF) in the geothermal areas was 42 W/m2 (in the day-time image) and 20 W/m2 (in night-time image). The total radiant GHF in thermal anomaly areas estimated 50 MW (in night-time image) and 119 MW (in the day-time image). The thermal anomaly areas have a close spatial relationship with faults, hot springs, lithology, hydrothermal alterations, active deformation regions and subsurface high heat flow data. After determining thermal anomaly areas related to the geothermal activity, the changes of LST patterns were compared in the six TM and ETM+ images (captured from the same month and overpass time) during 1988- 2011. The highest temperatures were recorded in 2002 and 2007 images, that in line with seismic events and changes in hot springs chemistry. The thermal infrared remote sensing can be used as a cost effective and concise method for monitoring of quiescent and even dormant volcanoes of Iran.
K Shiaian; J Ghalamghash; M Vosoughi Abediny; F Masoudi
Abstract
The Bazman volcano is located in the Makran Magmatic Arc. The pyroclastic rocks and lava with rhyodacitic to basaltic composition and calc-alkaline affinities erupted from the central and lateral craters of this volcano during the Quaternary period. The primitive mantle normalized Multi-elements diagrams ...
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The Bazman volcano is located in the Makran Magmatic Arc. The pyroclastic rocks and lava with rhyodacitic to basaltic composition and calc-alkaline affinities erupted from the central and lateral craters of this volcano during the Quaternary period. The primitive mantle normalized Multi-elements diagrams show a relatively high abundance of LIL relative to HFS incompatible elements with negative anomalies of Nb and Ti. Their chondrite–normalized REE patterns are slightly enriched in LREE relative to HREE with negative Eu anomalies. These geochemical features suggest that the volcanic rocks of bazman formed in a subduction setting by partial melting of metasomatized mantle. On the base of La/Yb vs Dy/Yb and La/Sm vs Sm/Yb diagrams the sources of the magmas is phlogopite-spinel-lherzolite or/and phlogopite-garnet- lherzolite.
M Farhadian Babadi; F Masoudi; A.R Zarasvandi
Abstract
Considerable quantities of wastes are generated in drilling operation contain various components such as heavy metals and hydrocarbons. These wastes are discharged in pits or the sea, which their geochemical composition should be investigated for waste management. In this study, sampling of heavy water ...
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Considerable quantities of wastes are generated in drilling operation contain various components such as heavy metals and hydrocarbons. These wastes are discharged in pits or the sea, which their geochemical composition should be investigated for waste management. In this study, sampling of heavy water based mud additives; different lithology of the Gachsaran formation and soils around location was performed. After preparation, metal concentrations in samples were determined by ICP-MS method. The results showed that the concentration of metals such as lead, copper, arsenic, zinc, molybdenum, antimony, mercury, and strontium in the Gachsaran wastes are more than standards and soils of the region. In addition, the calculated correlation coefficients between elements in wastes showed that possible mineral phases as impurities associated with barite. The environmental assessments also suggested that these wastes are extremely polluted for Ag, Sb, As, Cu, Pb. Using pure barite could reduce the amounts of the heavy metals.
B Rahimzadeh; F Masoudi; Sh Ranjbar
Abstract
Scoria is one of the main pyroclastic units in Damavand volcano, which its main crystals are plagioclase, olivine and pyroxene. In this study, characterization of bubbles and their formation during the eruption considered using Bubble Size Distribution (BSD) method including study of volume, 3D modeling, ...
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Scoria is one of the main pyroclastic units in Damavand volcano, which its main crystals are plagioclase, olivine and pyroxene. In this study, characterization of bubbles and their formation during the eruption considered using Bubble Size Distribution (BSD) method including study of volume, 3D modeling, nucleation and bubble growth. For selected sample, thebubbles investigated in 3 perpendicular dimensions (X-Y-Z) and in total 16830 bubbles (X=7357, Y=5385, Z=4088) were measured and drawn. The Bubbles volumes calculated in 3 dimensions are X=47.21, Y=40.27, Z=40.01 percent. The Bubbles axes were calculated: X=1:1:4, Y=Z=1:1:3.4 and the 3D schematic shape is ellipsoid which the longest axis (L) is about 4 times longer than the other two axes (I, S). The L axis is parallel to the lowest pressure dictated on magma and the bubbles could be grown 4 times more in that direction. The bubbles shape of Damavand scoria is an ellipsoid with an average of 1:1:3.7 for its axes. The presence of 3 peaks in frequency distribution versus bubble size diagram, suggesting polymodal events of bubbles generation and in the Damavand volcano the bubbles nucleation occurred in 3 events(F1, F2, and F3). The nucleation density increased from F1 to F3 but the bubbles growth reduced in the same direction. The first group of bubbles formed in the magma chamber and the second group formed during the magma ascent. The third group of bubbles could form either in the space between earlier groups or in the last stage of magma eruption.
Rahimzadeh Bahman; F. Masoudi; S. M. Fatemi Aghda; T. Parhizkar; A. Pour Khorshidi
Abstract
In the north of Abyek - Qazvinmain road, various volcanic units contain olivine basalt, basalt, andesitic basalt, dacite, andesite and their associated tuffs with Eocene to Quaternary age are exposed. In order to examine geochemical and petrographic features effect on pozzolan activity, five samples ...
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In the north of Abyek - Qazvinmain road, various volcanic units contain olivine basalt, basalt, andesitic basalt, dacite, andesite and their associated tuffs with Eocene to Quaternary age are exposed. In order to examine geochemical and petrographic features effect on pozzolan activity, five samples of different rocks in the area crushed and analysed by thermogravimetric method in Housing and BuildingResearchCenter. Unweathered glassy tuff s with 26.83% pozzolanic activity ranked as good quality pozzolan. Relatively weathered tuffs and dacite present pozzolanic activities in the range of 21 to 24 % and are medium quality pozzolan. Lithic tuffs with 19.70% pozzolanic activity are in the weak quality pozzolan category. Generally, tuffs and dacits with no alteration and glass in their matrix are suitable alternatives to use as pozzolane in mix cement and lithic bearing tuffs with weathering are poor in pozzolanic features and are not recommended to be used in cement composition.
N. A. Rashidnejad Omran; A. A. Fattahi; F. Masoudi
Abstract
The late Eocene post-collisional Khoshoumi- Dar-Anjir intrusive complex consist of two adjacent Khoshoumi granite and Dar Anjir diorite plutons in Saghand area, located in 120 km northeast of Yazd in Central Iran structural zone. This complex intruded within high-grade metamorphic rocks of Chapedony ...
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The late Eocene post-collisional Khoshoumi- Dar-Anjir intrusive complex consist of two adjacent Khoshoumi granite and Dar Anjir diorite plutons in Saghand area, located in 120 km northeast of Yazd in Central Iran structural zone. This complex intruded within high-grade metamorphic rocks of Chapedony Complex. Syenogranite, monzogranite, granodiorite, tonalite and quartzdiorite constitiue its lithologies. Aplitic and micromonzonitic to microdioritic dikes crosscutting the entire body. Hybrid rocks and mafic microgranular enclaves with various shapes and sizes are widely seen in this complex. Geochemical investigations show that these rocks are metaluminous to moderately peraluminous, magnesian and high- K calc- alkaline I- and A-type granitoids. Chonderite- normalized REE patterns of both plutons and related dikes display intra-elemental fractionation (2.72 >(La/Yb)N >41.64) and concentration of LREE and Eu negative anomalies (ave Eu/Eu*= 0.63). Trace elements behavior represent depletion in Nb, Ti, P and enrichment in K, Rb, Ba and Th that could be assigned to mafic magma contamination by crustal materials. Their tectonic setting match with Volcanic Arc Granites (VAG) and Within Plate Granites (WPG). Petrographical, geological and tectonomagmatic characteristics of this intrusive complex are very similar to high- K calc- alkaline granites (KGC) and like most of them, fractional crystallization and mafic – felsic magma mixing play significant role in its evolution and petrogenesis.
F. Masoudi; M. Mohajjel; F. Shaker Ardekani
Abstract
The Zarrin area in the north of Ardekan is the part of Central Iran Zone. Some homogenous parts of Zarrin granite located in the shear zone changed to mylonites and ultramylonites. Microstructural evidence and deformation investigation show that chemical and structural changes occurred during the progressive ...
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The Zarrin area in the north of Ardekan is the part of Central Iran Zone. Some homogenous parts of Zarrin granite located in the shear zone changed to mylonites and ultramylonites. Microstructural evidence and deformation investigation show that chemical and structural changes occurred during the progressive deformation in mylonites. The most obvious chemical change is the noticeable decrease on Ti, Mg, Fe and P from mylonites to ultramylonites. Silica shows a slight increase in the mylonitic zone with progressive increase in modal quartz, but Al2O3 is nearly constant during the mylonitization. Because of decrease on feldspar porphyroclasts and feldspar grains in the matrix, compare to protomylonites, K2O decreases in mylonites. However, with relative increase on plagioclase, K-feldspar and epidote in the matrix, Ca, Na and K increase in ultramylonites. As a result of structural changes, quartz grains in weakly deformed protolith and protomylonite show recrystallization and sub grain. In a progressive deformation process, quartz in mylonites and ultramylonites reveals grain boundary migration in recrystallization. During the progressive deformation, K-feldspars become perthitic with fractures and plagioclases show kinking in their twins. With progress in deformation, recrystallization on K-felspar's margins and twins in plagioclase grains are formed. Based on structural evidence, temperature of 400ºC has been estimated for deformation in Zarrin area in protogranites and protomylonites. The temperature continuously increases up to 500ºC or more in green schist facies in the mylonites and ultramylonites.
