Nasser Ashrafi Articles List

List of Articles Nasser Ashrafi

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1 - Geochemistry of the Paleocene Sediments from SW Ahar: Implications for Provenance, Tectonics and Source Rock Weathering
Nasser Ashrafi Behzad Hajalilou

The mineralogy and geochemistry of Paleocene shales and interbedded siltstones in the southwestern of Ahar town (NW Iran) were studied by optical microscopy, XRD, SEM, XRF, and ICP-MS techniques. The mineralogical composition, mainly characterized by calcite, quartz, fe More

The mineralogy and geochemistry of Paleocene shales and interbedded siltstones in the southwestern of Ahar town (NW Iran) were studied by optical microscopy, XRD, SEM, XRF, and ICP-MS techniques. The mineralogical composition, mainly characterized by calcite, quartz, feldspar, dolomite, muscovite, magnesiohornblende, chlorite, illite, montmorionite, palygorskite, and koninckite, suggests relatively fast erosion of the parent rocks and incipient metamorphism for the studied sediments. The values of weathering indices and the Index of Compositional Variability, as well the mineralogy of the sediments imply moderate weathering in the parent rocks and deposition as first cycle sediments. The shales exhibit higher Al2O3/TiO2 (≈21), La/Sc, and Th/Cr values corresponding to felsic and/or intermediate source rocks. The geochemical character of sediments including ∑REE=116 ppm, (La/Yb)N=8.3, (Eu/Eu)=0.78, and the immobile elemental ratios values suggest an immature continental arc setting. The typical shale and chondrite normalized REE patterns of the shales are comparable with continental arc terrigenous sediments and Andean-type andesites. The inferred tectonic setting for the studied shale is in agreement with the tectonic evolutionary history of NW Iran during the Upper Cretaceous-Upper Paleocene. According to the present data, we conclude that the ultimate provenance of the studied shale and its interbedded siltstone and thin detritic limestone was probably the Upper Cretaceous sediments with the geoenvironment of acidic to intermediate volcanic rocks and marl. Manuscript profile
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2 - Cooling history and exhumation of the Nepheline Syenites, NW Iran: Constraints from Apatite fission track
Nasser Ashrafi Noriko Hasebe Ahmad Jahangiri

Thermal history and apatite fission-track ages were determined for the Kaleybar, Razgah and Bozqush alkaline intrusions which display Eocene-Oligocene stratigraphic age. These subduction-related intrusions are located in the Alborz-Azerbaijan magmatic belt which is char More

Thermal history and apatite fission-track ages were determined for the Kaleybar, Razgah and Bozqush alkaline intrusions which display Eocene-Oligocene stratigraphic age. These subduction-related intrusions are located in the Alborz-Azerbaijan magmatic belt which is characterized by a Paleogene magmatic flare-up associated with extensional/transtensional tectonism. The mean of Uranium content and apparent age for apatites of the Bozqush, Kaleybar, and Razgah were obtained 21.8 (±3.8), 9.5 (±5.7), and 24.5 (±11.3) ppm and 29 (±1.8), 36.6 (±3.0), and 40.7 (±1.3) Ma (σ), respectively, which represented the time that the rocks of intrusions were last at temperatures of 60 ˚C to 110 ˚C. The results indicate that the apatite apparent ages are in concord with the stratigraphic ages. The apatite fission track ages and track lengths distribution were combined to construct time-temperature history by inverse modeling, which represented the all samples resided in the partial annealing zone (PAZ) for a significant period of time. The apatite fission track analysis indicated relatively complex cooling history for the host rocks because of the magmatic activity, as it was occurred during Cenozoic in the Alborz-Azerbaijan magmatic belt. The time-temperature curves of the studied intrusions begun with a relatively rapid initial cooling and followed by long residence at the PAZ temperature (heating stage). The time-temperature paths indicate that the start of rapid recent cooling to the surface temperatures was occurred at 5 Myrs. Manuscript profile
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3 - Study of A-type granite from the South of Lake Urmia, Sanandaj-Sirjan Zone: implications for the Neotethys opening in Iran
Nasser Ashrafi Mehrdad Pourmohsen Morovvat Faridazad
10.30495/ijes.2022.1941506.1657

The magmatic evidence of the Neotethys opening in Iran, such as the Late Paleozoic A-type granitoids, was mainly discovered along the Sanandaj-Sirjan Zone and parallel to the Neotethys suture. Therefore, they may provide important clues about the geodynamic evolution of More

The magmatic evidence of the Neotethys opening in Iran, such as the Late Paleozoic A-type granitoids, was mainly discovered along the Sanandaj-Sirjan Zone and parallel to the Neotethys suture. Therefore, they may provide important clues about the geodynamic evolution of the Sanandaj-Sirjan Zone. The South of Lake Urmia (SLU) granite is situated near the Khalifan A-type pluton (315±2 Ma) with a cover of the Permian sediments. The rock-forming minerals of the SLU granite consist of quartz, alkali-feldspars (K-rich and microperthitic), sodic plagioclases, biotite (Fe-rich), zircon, apatite, and Fe-Ti oxides. The chemical composition of the SLU granite is characterized by high FeOt/MgO and (Na2O+K2O)/CaO ratios, which are typical features of A-type granites. Furthermore, the studied rocks exhibit the chemical characters of the A1 subgroup of A-type granites with peraluminous and K2O-rich affinities. On the multi-element spider plot, the SLU granite shows distinct negative Ba, Sr, P, and Ti anomalies and positive Pb anomalies. Moreover, the Chondrite-normalized rare earth elements (REE) patterns display slope downwards from LREE to HREE, with flattening at the HREE end and distinct negative Eu anomalies. The ratios of trace elements provide evidence for the contribution of the OIB-like mafic melts with crustal interactions to generate the granitic magmas of the SLU pluton. The compositional and stratigraphic features of the SLU granite are also consistent with an extensional setting during the Late Paleozoic in Iran. Therefore, the genesis of the SLU granite can be attributed to the syn-rift magmatism of the Cimmerian terranes. A comprehensive review of the Late Paleozoic rocks occurrence shows that they mainly are emerged in the northeast margin of the Sanandaj-Sirjan Zone and around the structural depressions such as Lake Urmia (so-called Tertiary fore-arc or Mesozoic back-arc). Manuscript profile

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List of Articles Nasser Ashrafi