Iman Monsef | Institute for Advanced Studies in Basic Sciences (original) (raw)

Papers by Iman Monsef

Precambrian research, Jun 1, 2024

HAL (Le Centre pour la Communication Scientifique Directe), Jul 9, 2023

HAL (Le Centre pour la Communication Scientifique Directe), Aug 20, 2017

Siliceous banded and nodular iron ores intercalated in mica schists and marbles of Precambrian ag... more Siliceous banded and nodular iron ores intercalated in mica schists and marbles of Precambrian age, were studied from the NW part of Iran (Takab region). The iron ore is composed of magnetite, which was partly transformed into maghemite and hematite along fractures and cleavages during a major oxidizing deformation event. Quartz shows undulose extinction. Both quartz and iron oxides partly form 120° triple junctions, but essentially grain boundary migrations. In the nodular ore, grain boundary migration is more pronounced leading also to grain isolation quartz is partially annealed. Iron oxides are agglomerated, elongated and disrupted. These finding indicate a longer recrystallization episode in the nodular ore. The iron oxide grains contain inclusions of euhedral, zoned and corroded zircons and euhedral monazite. Magnetite contains traces of Al. Hematite and goethite show higher Al, Si and Ca contents. Later hydrothermal solutions precipitated goethite surrounding the magnetite-hematite-maghemite grains and replacing hematite. Barite and uraninite occur in fractures of iron oxides, Mn-Ba-Pb oxi-hydroxides and scheelite occur interstitial to iron oxides.

فصلنامه علمی علوم زمین, Feb 20, 2012

In Khoy ophiolitic massif (NW of Iran) three types of quartzite and also quartz bearing veins can... more In Khoy ophiolitic massif (NW of Iran) three types of quartzite and also quartz bearing veins can be distinguished: massive quartzite, quartz bearing veins in the amphibolites and siliceous veins in the radiolarian cherts. Massive quartzites contain quartz porphyroclasts associated with very small-deformed quartz neoblasts. These quartzites are deformed in regime I and recrystallized as grains bulging. Siliceous veins in the cherts have Cu-carbonate impregnations in the field. Very large grains of quartz with well-developed triple point junctions can be distinguished in thin section. Their pattern of c-axes distributions doesn't show any special orientation. The pattern of c-axes distributions in the quartz bearing veins in the amphibolites is consistent with prism and rhomb slip system along direction. Water in these veins is at the origin of soluble structures and precipitation of clay minerals. SEM analysis on the soluble fovea as the result of water operation has revealed high amount of water.

Petrology, Mar 15, 2011

The Jurassic magmatic sequences in the southern part of Sanandaj-Sirjan Zone show significant geo... more The Jurassic magmatic sequences in the southern part of Sanandaj-Sirjan Zone show significant geochemical variations during their compositional evolution. These magmatic sequences have exposed in the Hoseinabad region with Early to Middle Jurassic age and in Hajiabad region with Late Jurassic to Early Cretaceous age. The parent magma of the first sequence in Hoseinabad region, with island arc tholeiite (IAT) affinity have been originated from the spinel lherzolite mantle source with primitive mantle (PM) composition. This mantle source is affected by liquids and sediments resulted from the subducting slab. The parent magma of the second sequence in Hajiabad region with island arc tholeiite to transitional affinity have been resulted from the garnet-spinel lherzolite mantle source with E-MORB composition. These compositional changes may be related to high sediment and hydrothermal fluxes which resulted from the deep subducted slab into the mantle wedge. These magmatic sequences are originated during the subduction of the Neo-Tethyan oceanic lithosphere under the Sanandaj-Sirjan Zone, during the Early Jurassic to Early Cretaceous time, in the island arc tectonic environment.

Ofioliti, Nov 27, 2014

The Janatabad peridotites are exposed in the Hajiabad-Esfandagheh Melange Zone in the southern pa... more The Janatabad peridotites are exposed in the Hajiabad-Esfandagheh Melange Zone in the southern part of Iran. These peridotites are dominantly composed of harzburgites with small lenses and veins of chromitite ores surrounded by dunite sheaths. Harzburgites have accessory chromites characterized by moderate X Cr of 0.59-0.61, and X Mg of 0.52-0.58, resembling depleted mid-ocean ridge peridotites, supposed to have originated as the residue from a high degree of partial melting and MORB-like magma extraction at the inception of subduction. Dunites can be divided into two types: Type 1 dunite with moderate X Cr of 0.53-0.62 and X Mg of 0.48-0.53, and Type 2 dunite with high X Cr of 0.63-0.67 and low X Mg of 0.40-0.48. Two distinctive melts are required for the formation of these dunites: a MORB-like melt for the Type 1 dunite, and a transitional-like melt for the Type 2 dunite. These compositional variations from MORB to melts transitional between MORB and boninite are due to the hydrous fluids derived from the subducted oceanic slab into the overlying mantle wedge at the beginning of the down dip motion of the slab. Al-rich podiform chromitites, characterized by relatively low X Cr of 0.53-0.54 and relatively high X Mg of 0.60- 0.71, may have formed from MORB-like melts. In particular, the interaction between primitive MORB-like melts and depleted harzburgites produced Type 1 dunites and secondary silica-rich melts from which Al-rich chromitites crystallized. Type 2 dunites can be generated by the interaction between transitional-like melts and depleted harzburgites above a lithosphere in subsidence. Accordingly, it is inferred that the Janatabad peridotites formed by rifting of a Late Triassic to Early Jurassic embryonic ocean during subduction initiation of Neo-Tethyan lithosphere in an intra-oceanic environment.

EGUGA, Apr 1, 2009

Sabzpushan fault zone is chosen as a case study for deformation analysis of the simply folded Zag... more Sabzpushan fault zone is chosen as a case study for deformation analysis of the simply folded Zagros tear faults. Sabzpushan fault zone is one of the most fault zones that crosses simply folded Zagros belt at approximate trend of N150-170. These fault zones are stretched from NW to SE of Shiraz province. These zones have strike slip-dextral movement with normal dip slip component. Deformation analysis along the Sabzpushan fault zone are done by field work, processing of satellite images, detecting and enhancing of lineaments, Digital Elevation Model (DEM), Slope map, Aspect map, Hill Shade images, lineament map and lineament density map. These data indicate the area is active from the view point of tectonics and morphotectonics. It seems from the deformation evidences such as: change of trend in Babakouhi anticline (N of Shiraz), rotation of the axis in Derak anticline (NW of Shiraz), uplifting in northeast part of Derak anticline and uplanded synclines as Ghalat syncline (NW of Shiraz) and Soltanabad syncline (S of Shiraz). The existences of numerous fractures in the studied area are caused by the activity of the Sabzpushan fault zone. Conclusion of this research can be extended to other simply Zagros tear faults such as Izeh, Kazeroon, Karebas and Sarvestan fault zones.

Geochimica et Cosmochimica Acta Supplement, May 1, 2005

Journal of Asian Earth Sciences, Apr 1, 2010

... These peridotites can be divided into two types: (1) type 1 peridotites with Al-rich spinels ... more ... These peridotites can be divided into two types: (1) type 1 peridotites with Al-rich spinels (Cr number of 0.16–0.26, and Mg number of 0.64–0.76), resembling the fertile abyssal peridotites, supposed to have originated as the residue from <15% partial melting and mid-ocean ...

Minerals, Jun 6, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

فصلنامه علمی علوم زمین, Aug 23, 2009

The Nain ophiolitic massif, in the north of Nain town, consisted in lhezolitic-gabbroic (pegmatit... more The Nain ophiolitic massif, in the north of Nain town, consisted in lhezolitic-gabbroic (pegmatitic) bodies. Harzburgites, amphibolites, isotropic gabbros, pillow lavas, gabbroic sills and dikes, pyroxenitic dikes, wherlitic dikes and gabbroic impregnations are also found. ...

EGU General Assembly Conference Abstracts, Apr 1, 2009

ABSTRACT The Dehshir ophiolite as a tectonic slice of the Nain-Baft ophiolitic melange is distrib... more ABSTRACT The Dehshir ophiolite as a tectonic slice of the Nain-Baft ophiolitic melange is distributed around the Nain-Dehshir ophiolite at the northwestern part of the Lut block. This ophiolitic massif is composed of several tectonic slices, consisting of mantle tectonites, pegmatite gabbros, isotropic gabbros, basaltic flows, pillow lavas, metamorphic rocks and upper Cretaceous sediments. Petrographically the mafic rocks are characterized by crystallization of plagioclase and then clinopyroxene typical of MORB materials. Amphibole in these rocks is pale-green fibers of actinolites as a secondary, last-stage crystallized phase. Geochemically the some of mafic rocks are represented by enrichment in heavily mobile large ion lithophile elements and depletion in least mobile high field strength elements. On the other hand some rocks are geochemically similar to MORB materials. These geochemical properties are consistent with derivation of these rocks from an arc-related environment. We can suggest an intra-oceanic arc environment between the Sanandaj-Sirjan zone and the Lut block for the genesis and evolution of the Dehshir ophiolite during lower to upper Cretaceous. This arc-related setting can explain the occurrence of mafic rocks with depletion in HFSE and/or MORB-like basaltic rocks. The presence of Upper Cretaceous limy sediments is evidence suggesting the initiation of intra-oceanic subduction in the Dehshir basin at least during middle Cretaceous. Keywords: Dehshir ophiolite; Nain-Baft ophiolitic melange; Lut block; intra-oceanic arc; Iran

Sensors, Apr 2, 2021

Afghanistan Research Journal - Natural Science

Earth-Science Reviews, May 1, 2022