scholarly journals Tectonic magnetic lineation and oroclinal bending of the Alborz range: Implications on the Iran-Southern Caspian geodynamics

Tectonics ◽  
2015 ◽  
Vol 34 (1) ◽  
pp. 116-132 ◽  
Author(s):  
Francesca Cifelli ◽  
Paolo Ballato ◽  
Habib Alimohammadian ◽  
Jafar Sabouri ◽  
Massimo Mattei
Keyword(s):  
Magnetic Lineation ◽  
Alborz Range

scholarly journals Thermal maturity of the Upper Triassic–Middle Jurassic Shemshak Group (Alborz Range, Northern Iran) based on organic petrography, geochemistry and basin modelling: implications for source rock evaluation and petroleum exploration

2011 ◽  
Vol 149 (1) ◽  
pp. 19-38 ◽  
Author(s):  
ALI SHEKARIFARD ◽  
FRANÇOIS BAUDIN ◽  
KAZEM SEYED-EMAMI ◽  
JOHANN SCHNYDER ◽  
FATIMA LAGGOUN-DEFARGE ◽  
...  
Keyword(s):  
Middle Jurassic ◽  
Vitrinite Reflectance ◽  
Upper Triassic ◽  
Petroleum Exploration ◽  
Thermal Maturity ◽  
Northern Iran ◽  
Carbonaceous Shales ◽  
Petroleum Generation ◽  
Central Eastern ◽  
Alborz Range

AbstractOrganic petrography and geochemical analyses have been carried out on shales, carbonaceous shales and coals of the Shemshak Group (Upper Triassic–Middle Jurassic) from 15 localities along the Alborz Range of Northern Iran. Thermal maturity of organic matter (OM) has been investigated using vitrinite reflectance, Rock-Eval pyrolysis and elemental analysis of kerogen. Reflectance of autochthonous vitrinite varies from 0.6 to 2.2% indicating thermally early-mature to over-mature OM in the Shemshak Group, in agreement with other maturity parameters used. The shales of the Shemshak Group are characterized by poor to high residual organic carbon contents (0.13 to 5.84%) and the presence of hydrogen-depleted OM, predominantly as a consequence of oxidation of OM at the time of deposition and the hydrogen loss during petroleum generation. According to light-reflected microscopy results, vitrinite/vitrinite-like macerals are dominant in the kerogen concentrates from the shaly facies. The coals and carbonaceous shales of the Shemshak Group show a wide range in organic carbon concentration (3.5 to 88.6%) and composition (inertinite- and vitrinite-rich types), and thereby different petroleum potentials. Thermal modelling results suggest that low to moderate palaeo-heat flow, ranging from 47 to 79 mW m−2 (57 mW m−2 on average), affected the Central-Eastern Alborz basin during Tertiary time, the time of maximum burial of the Shemshak Group. The maximum temperature that induced OM maturation of the Shemshak Group seems to be related to its deep burial rather than to a very strong heat flow related to an uppermost Triassic–Liassic rifting. The interval of petroleum generation in the most deeply buried part of the Shemshak Group (i.e. Tazareh section) corresponds to Middle Jurassic–Early Cretaceous times. Exhumation of the Alborz Range during Late Neogene time, especially along the axis of the Central-Eastern Alborz, where maximum vitrinite reflectance values are recorded, probably destroyed possible petroleum accumulations. However, on the northern flank of the Central-Eastern Alborz, preservation of petroleum accumulations may be expected. The northern part of the basin therefore seems the best target for petroleum exploration.

Magnetic fabric in carbonatic rocks from thrust shear zones

2021 ◽  
Author(s):  
Sara Satolli ◽  
Claudio Robustelli Test ◽  
Elena Zanella ◽  
Dorota Staneczek ◽  
Fernando Calamita ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Pure Shear ◽  
Shear Zones ◽  
Magnetic Fabric ◽  
Structural Deformation ◽  
Axis Orientation ◽  
Main Thrust ◽  
Magnetic Lineation ◽  
Magnetic Fabrics ◽  
And Cluster Analysis

<p><strong> </strong></p><p>The aim of this study is to investigate how structural deformation in shear zones is documented by the anisotropy of magnetic susceptibility (AMS). The study area is located in the Pliocene outer thrust of the Northern Apennines, which involved Cretaceous to Neogene calcareous and marly rocks. Here, brittle-ductile tectonites show different characteristics along two differently oriented thrust ramps: the NNE-SSW-trending oblique thrust ramp is characterized by the presence of S tectonites, while the NW-SE-trending frontal ramp is characterized by the presence of SC tectonites.</p><p>Samples for AMS fabric investigation were collected on shear zones from three sectors of the belt, at different distance from the main thrust to detect possible magnetic fabric variations. The three study area are characterized by different combinations of simple and pure shear, thus different degree of non-coaxiality, which has been quantified through the vorticity number W<sub>k</sub>.</p><p>Specimens were measured with an AGICO KLY-3 Kappabridge at the CIMaN-ALP Laboratory (Italy) on 15 different directions mode. Only measurements with all three F-statistics of the anisotropy tests higher than 5 were accepted as reliable. Moreover, outliers characterized by ± 2σ difference with respect to the mean value of AMS scalar parameters were excluded from further analysis. In order to distinguish groups of specimens affected by different sedimentary or tectonic processes, we identified clusters of AMS scalar parameters; when clusters were not defined by these parameters, we applied a combination of contouring and cluster analysis on each principal axis to identify different subfabrics.</p><p>The magnetic fabric revealed straightforward correlations with structural data and specific changes of AMS axis orientation depending upon the increasing of deformation (lower vorticity number) and proximity to the main thrust. Similar evolution was detected in different deformation regimes. Overall, the magnetic fabric is more sensitive to the simple shear deformation, as the magnetic lineation tends to parallelize mostly with the computed slip vector; however in pure-shear dominated regimes, the magnetic lineation becomes parallel to the transport direction when the deformation is really intense (sites at less than 15-30 cm from the thrust plane).</p><p>The applied combination of density diagrams and cluster analysis on AMS data successfully allowed discriminating subfabrics related to different events, and shows a great potential to unravel mixed sedimentary and/or tectonic features in magnetic fabrics.</p>

Magnetic fabric from Quaternary volcanic edifices in the extensional Bransfield Basin: internal structure of Penguin and Bridgeman islands (South Shetlands archipelago, Antarctica)

2021 ◽  
Author(s):  
B Oliva-Urcia ◽  
J López-Martínez ◽  
A Maestro ◽  
A Gil ◽  
T Schmid ◽  
...  
Keyword(s):  
Flow Direction ◽  
Orientation Distribution ◽  
Scoria Cone ◽  
Lava Flows ◽  
Magnetic Fabric ◽  
Scattered Electron ◽  
Magnetic Lineation ◽  
South Shetlands ◽  
Bransfield Basin ◽  
Electron Imaging

Summary Studying the magnetic fabric in volcanic edifices, particularly lava flows from recent eruptions, allows us to understand the orientation distribution of the minerals related to the flow direction and properly characterize older and/or eroded flows. In this work, the magnetic fabric from recent (Quaternary) lava flows (slightly inclined in seven sites and plateau lavas in two sites), pyroclastic deposits (two sites from a scoria cone) and volcanic cones, domes and plugs (three sites) from Penguin and Bridgeman islands, located in the Bransfield back-arc basin, are presented. The volcanism in the two islands is related to rifting occurring due to the opening of the Bransfield Strait, between the South Shetlands archipelago and the Antarctic Peninsula. The direction of flow of magmatic material is unknown. Rock magnetic analyses, low temperature measurements and electron microscope observations (back-scattered electron imaging and Energy Dispersive X-ray analyses) reveal a Ti-poor magnetite (and maghemite) as the main carrier of the magnetic fabric. Hematite may be present in some samples. Samples from the center of the lavas reveal a magnetic lineation either parallel or imbricated with respect to the flow plane, whereas in the plateau lavas the magnetic lineation is contained within the subhorizontal plane except in vesicle-rich samples, where imbrication occurs. The magnetic lineation indicates a varied flow direction in Bridgeman Island with respect to the spreading Bransfield Basin axis. The flow direction in the plateau lavas on Penguin Island is deduced from the imbrication of the magnetic fabric in the more vesicular parts, suggesting a SE-NW flow. The volcanic domes are also imbricated with respect to an upward flow, and the bombs show scattered distribution.

Ordovician echinoderms from the Tabas and Damghan regions, Iran: palaeobiogeographical implications

2005 ◽  
Vol 176 (3) ◽  
pp. 231-242 ◽  
Author(s):  
Bertrand Lefebvre ◽  
Mansooreh Ghobadipour ◽  
Elise Nardin
Keyword(s):  
South China ◽  
Central Iran ◽  
East Central ◽  
First Report ◽  
Middle Ordovician ◽  
Alborz Range ◽  
First Time

Abstract Two echinoderm assemblages are described in the Middle Ordovician of Iran (Darriwilian). The Simeh Kuh section (Damghan area, eastern Alborz range) has yielded a rich and diverse blastozoan fauna consisting of fistuliporite (Echinosphaerites, Heliocrinites) and dichoporite rhombiferans (cheirocrinids indet., hemicosmitids indet.), as well as aristocystitid (Sinocystis) and sphaeronitid diploporites (Glyptosphaerites, Tholocystis). Heliocrinites, cheirocrinids, hemicosmitids, Glyptosphaerites, and Tholocystis are reported for the first time in the Ordovician of Iran. A less diverse assemblage was collected in the Shirgesht section (Tabas area, Derenjal Mountains), and represents the first report of Ordovician echinoderms in east-central Iran. The Shirgesht fauna includes fistuliporite rhombiferans (Heliocrinites), aristocystitid and sphaeronitid diploporites. The new Iranian material documents some of the earliest known assemblages of diploporites and rhombiferans, and thus, brings important information on the radiation of these two major blastozoan classes. The two Iranian echinoderm faunas show relatively strong affinities with contemporary faunas from Baltica, the northern Gondwanan margin (e.g. Bohemia, Morocco), Sibumasu, and South China terranes. Aristocystitids suggest stronger links between Iran, and regions from the “Province à Amphorides” (northern Gondwanan margin, Sibumasu, South China). These observations support a palaeogeographical position of Iran at intermediate palaeolatitudes during the early Middle Ordovician, in the periphery of the northeastern Gondwanan margin.

The Extinct Dialect of Tajrish: Caspian or Persian?

2011 ◽  
Vol 4 (2) ◽  
pp. 246-271 ◽  
Author(s):  
Habib Borjian
Keyword(s):  
Transition Zone ◽  
Central Alborz ◽  
Alborz Range ◽  
Administrative Center

Abstract Once spoken in the Alborz foothills north of Tehran, the vernacular of Shemirān and its administrative center Tajrish was greatly influenced by the Caspian languages spoken northward across the Alborz range, in its valleys and in the Caspian littoral. This study of Tajrishi draws on the texts collected by Valentin Zhukovskii in the 1880s as well as two recent documentations of smaller size. It reveals that Tajrishi and the adjoining vernaculars constitute the southernmost part of the Caspian-Persian linguistic transition zone in Central Alborz.

Deploying depositional and stratigraphic evidence in kinematic investigations along multi-role faults: The case study from the eastern Mosha Fault, central Alborz Range, northern Iran

2020 ◽  
Vol 187 ◽  
pp. 104086
Author(s):  
Hamid Reza Javadi ◽  
Meyssam Kouhpeyma ◽  
Parisa Gholami Zadeh ◽  
Amir Naeimi ◽  
Mohammad Reza Sheikholeslami ◽  
...  
Keyword(s):  
Northern Iran ◽  
Central Alborz ◽  
Alborz Range ◽  
Mosha Fault

Investigation of a Vine-Matthews Magnetic Lineation from a submersible: The source and character of marine magnetic anomalies

1983 ◽  
Vol 88 (B4) ◽  
pp. 3403 ◽  
Author(s):  
Ken C. Macdonald ◽  
Stephen P. Miller ◽  
Bruce P. Luyendyk ◽  
Tanya M. Atwater ◽  
Loren Shure
Keyword(s):  
Magnetic Anomalies ◽  
Magnetic Lineation ◽  
Marine Magnetic Anomalies
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