Paleomagnetism From Central Iran Reveals Arabia‐Eurasia Collision Onset at the Eocene/Oligocene Boundary

Geophysical Research Letters, Journal Year: 2023, Volume and Issue: 50(12)

Published: June 22, 2023

Abstract We present two robust and well‐dated paleomagnetic poles from upper Eocene Oligocene volcanics in the Urumieh‐Dokhtar magmatic arc, Central Iran. These place Iran ∼3.7°–3° of latitude south its position between ca. 40 23 Ma. Our new declination data indicate that block may have experienced a ∼11.6° clockwise rotation since Late Eocene. integrated our with retrodeformed margins Zagros collision zone contemporaneous Arabia positions to better constrain age configuration Eurasia assembly process. In model, Arabia‐Eurasia occurred first western Main suture 35 30 Ma then diachronously spread eastwards. paleogeographic reconstruction initial continental timing supports as first‐order driver global cooling, Red Sea rifting, Mediterranean extension.

Language: Английский

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The onset of Neo-Tethys subduction in the Early Jurassic: evidence from the eclogites of the North Shahrekord Metamorphic Complex (Sanandaj-Sirjan Zone, W Iran)

Geological Magazine, Journal Year: 2023, Volume and Issue: 160(12), P. 2067 - 2090

Published: Dec. 1, 2023

Abstract Geodynamic models implying subduction of continental crust either consider this process happening during collision, when the margin lower plate attempts subduction, or in pre-collisional stages, tectonic erosion upper extensional allochthons drag channel. In Zagros orogen (W Iran), high-pressure rocks are known only from Sanandaj-Sirjan Zone, NE Main Thrust. Here, eclogites North Shahrekord Metamorphic Complex suggest slices derived (Central Iran) onset Neo-Tethys along southern Iran. Eclogites record a clockwise pressure-temperature-time path, with pre-eclogitic epidote-amphibolites-facies phase assemblages preserved garnet cores, stage, and subsequent retrogression at amphibolite-facies conditions. By means forward thermodynamic modelling 40 Ar/ 39 Ar geochronology, peak metamorphism has been constrained 1.9-2.1 GPa 550-600 °C, 191-194 Ma time span. The following exhumation lasted least until 144 Ma. Our data that traces back prior to 190 Ma, involving together oceanic lithosphere also scraped off by processes.

Language: Английский

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Cenozoic Dextral Shearing Along the Arusan Sector of the Great Kavir–Doruneh Fault System (Central Iran)

Tectonics, Journal Year: 2021, Volume and Issue: 40(11)

Published: Oct. 17, 2021

Abstract The structural analysis of large intracontinental wrench faults is fundamental for deciphering the long‐term evolution continental crust in complex areas terms their geodynamic and large‐scale crustal block displacements. In this contribution, we demonstrate a pre‐Miocene dextral activity present‐day left‐lateral Great Kavir ‐ Doruneh Fault System (GKDFS, Central Iran), one major active strike‐slip extending from Afghan border to Nain region between Iran Sanandaj‐Sirjan Zone. We document important shearing recorded along segment GKDFS, Arusan (AFS), located east Jandaq, close trace GKDFS. AFS include several ENE‐WSW striking strands exposed length more than 50 km, which couple pre‐Cretaceous ophiolites metamorphic basement units with Cretaceous succession Khur basin. fault shows transpressional structures consistent shear including thrusts en échelon folds affecting carbonate units. Paleostress reconstruction based on mesoscopic related geometry allowed establish vorticity parameters indicating that deformation occurred total simple regime calculated Wk 0.9 1. enormous Meso‐Cenozoic displacements entire GKDFS are attested by up hundreds kilometers offset Paleotethys suture zone, NE western Iran.

Language: Английский

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The Meran-Mauls Fault: Tectonic switching from compression to transpression along a restraining bend of the Periadriatic Fault

Journal of Structural Geology, Journal Year: 2023, Volume and Issue: 172, P. 104878 - 104878

Published: May 18, 2023

The WSW-ENE Meran-Mauls Fault (MMF) represents a break in the broadly E-W trending Periadriatic (PAF), separating Southern Alps from N-verging wedge of European Alps. Understanding MMF evolution is mandatory to reconstruct role entire PAF during belt since late Cenozoic. Structural and microstructural analyses paleostress calculations based on fault-slip data suggest occurrence four evolutionary stages for MMF: 1) top-to-the-SE mylonites; 2) brittle faulting; 3) dextral faulting with re-activation previous structures; 4) N–S compression associated conjugate sets mainly strike-slip fault systems. Paleostress reconstructions point σ2-σ3 permutation stage 2 3, resulting switch pure thrusting strike-slip, followed by an anticlockwise rotation principal stress axes 4, regime related compression. Geochronological thermochronological 39-22 Ma age 1, 22-17 2, less than 17 3. Our reconstruction strongly supports interpretation as restraining bend PAF, which was weakly reactivated along its eastern portion later displaced NNE-SSW left-lateral faults.

Language: Английский

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Mode and timing of the Early Cretaceous transgression in Iran: Insights from the stratigraphic evidence of sea-level changes and geodynamic events

Journal of Asian Earth Sciences, Journal Year: 2023, Volume and Issue: 254, P. 105736 - 105736

Published: May 27, 2023

The study of selected logs from the Central-Eastern Iran Microplate (CEIM; area Arusan) and Sanandaj–Sirjan Zone (SSZ; areas Esfahan east Tiran) constrains timing evolution Cretaceous successions, resting unconformably on older sediments or non-conformably metamorphic basement. marine transgression occurred almost synchronously a levelled topography, documenting previous deep erosion. Above basal siliciclastic unit, rudist- orbitolinid-rich lower Aptian limestone ("Orbitolina Limestone", Shak Kuh Formation, Taft Formation) were deposited. Later, stratigraphic three studied differentiates, changes in depositional environments, reflecting different subsidence rates. In Tiran area, marls cherty limestones covering shallow-water record deepening trend. A differentiation environment is observed at Arusan, where conglomerates to west pass basinal sandstone east. Here, Coniacian-Campanian reprise carbonate production (with skeletal rich rudists, ostreids, abundant orbitoidids) covered by marls. north glauconitic hardground chert important during early Cenomanian, followed (middle Cenomanian). synchronous deposition successions large parts CEIM, SSZ North-Iranian domains suggests rapid regional controlled sea-level rise. Stratigraphic occurring late Aptian–Cenomanian times, recording onset tectonic events differently affecting aforementioned domains, likely related opening oceanic seaways CEIM SSZ.

Language: Английский

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The composite Triassic–Eocene Poshteh pluton, eastern Iran, an Eo-Cimmerian element south of the main Paleotethys suture

International Journal of Earth Sciences, Journal Year: 2022, Volume and Issue: 111(3), P. 969 - 985

Published: Feb. 5, 2022

Abstract The composite Poshteh Pluton, at the northeastern margin of Central Iranian Microplate near Taybad in eastern Iran, is positioned a critical tectonic junction, south inferred main Paleotethys suture and along major regional Doruneh Fault system. It consists two distinct intrusions. Quartz monzonite dated this study by zircon U–Pb ID-TIMS to 215.8 ± 0.5 Ma, an age that coincides with time closure during late collisional stages Eo-Cimmerian Orogeny. geochemically very similar coeval plutons present north suture, where they intruded Carboniferous-Permian arc sequences, ophiolites flysch. quartz located position Anarak related complexes further west, which previously have been interpreted as reflecting Mesozoic Cenozoic disruption Orogen extensional transtensional processes. Triassic was subsequently invaded granite 41.23 0.31 Ma. emplacement part structurally controlled system associated hydrothermal alteration Fe mineralization. thus member widespread Eocene Oligocene plutonic suite region, likely result delamination melting subcontinental lithosphere.

Language: Английский

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Chemical composition of detrital chrome spinel and clinopyroxene from the Middle Eocene to lowermost Oligocene sandstones of central Iran (Nain area): Constraints on ophiolite provenance

Geochemistry, Journal Year: 2023, Volume and Issue: 83(3), P. 125983 - 125983

Published: April 18, 2023

Language: Английский

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