Paleostress analysis on Paleozoic syn-depositional faults in the eastern Alborz, northern Iran

برش چلچلی در حدود 70کیلومتری شمال غرب شاهرود در مسیر جادة شاهرود- گرگان (توسکستان) و حدود 5کیلومتری شرق روستای چهارباغ برای بررسی گذر دونین- کربنیفر و تغییرات فونای کنودونتی ارزیابی شد. ضخامت رخنمون بررسی‌شده، 397 متر و شامل 182 متر از بخش بالایی سازند خوش ییلاق و 215 متر از سازند مبارک است که درمجموع 11 واحد سنگی تفکیک و تعداد 40 نمونه به وزن حدود 4- 5 کیلوگرم عمدتا از واحدهای سنگ آهک برداشت شد. با آماده‌سازی و بررسی نمونه‌های مطالعه‌شده، 340 عنصر کنودونتی به دست آمد که به شناسایی 47 گونه و زیرگونه متعلق به 16 جنس و تفکیک 15 زیست‌زون کنودونتی از فامنین پیشین تا تورنزین پسین منجر شد. شناسایی گونه‌های کنودونتیAlternognathus, Bispathodus, Branmehla, Clydagnathus, Gnathodus, Icriodus, Mehlina, Palmatolepis, Polygnathus, Neoplygnathus, Protognthodus, Pseudopolygnathus, Scaliognathus, Doliognathus, Siphonodella and Scaphignathus که از گونه‌های جهان‌گستر و شاخص در مطالعة فامنین- تورنزین هستند، به تعیین محدودة سنی 12 زیست‌زون از فامنین پیشین تا فامنین پسین (Upper Palmatolepis triangularis Zone to Bispathodus ultimus Zone) برای بخش بالایی سازند خوش ییلاق و تعیین محدودة 3 زیست‌زون از تورنزین پیشین تا تورنزین پسین (?Protognathodus kockeli Zone to Scaliognathus anchoralis-Doliognathus latus zone ) برای بخش مطالعه‌شده از سازند مبارک انجامید. حضور افق‌های نازک شیل تیره در زیر گذر DC و همراهی آنها با کنودونت‌های دور از ساحل نظیر بیسپاتودیدها و پالماتولپیدها، حاکی از افزایش سطح آب به بالاترین تراز تا نزدیک به انتهای فامنین پسین است؛ در ادامه حضور 8- 10 متر ماسه‌سنگ‌های کوارتز آرنایتی دارای چینه‌بندی متقاطع و فاقد فونای کنودونتی ناشی از پس‌روی سطح آب دریا و ورود مواد آواری به حوضه، شاهدی بر تغییرات زیستی و سنگی در حادثة هنگنبرگ در برش چلچلی است. در شروع تورنزین، افزایش تدریجی و دوبارة پلی‌گناتیدها، پروتوگناتوئیدها و سایفونودلیدها نیز که در ادامه با گناتوئیدهای دور از ساحل جایگزین می‌شوند، حاکی از پیشروی دوبارة سطح آب پس از حادثة هنگنبرگ است.

The transition from the Ediacaran-Cambrian Gondwana active margin to the rifting and opening of the Rheic and Paleotethys Oceans forms a turning point in the history of the Peri-Gondwanan Terranes. There are few better places to study the Pre-Cambrian and Paleozoic evolution of the northern Gondwana margin better than in the Central Iranian Microplate (CIM). The Alborz Mountains of northern Iran, formed by inversion of the Paleozoic Paleotethys passive margin of the Central Iranian Plate during successive collision phases since the Late Triassic, is one of the places where Paleozoic rocks are well exposed. The aim of this study is to elucidate the Paleozoic structural-tectonic framework and the transition of geodynamic regimes. We present the first paleostress analysis of the Paleozoic evolution of Alborz, were carried out for 49 sites, ranging from Cambrian to Permian outcrops in the Central and Eastern Alborz.We focus on the orientation of the pre-orogenic Paleotethys margin and the evolution of the Paleozoic stress field by inversion of fault slip data, starting with the Central and Eastern Alborz. Syn-sedimentary faults, i.e. those not reactivated by later tectonic events, were the main target of measurements for the paleostress analysis. Calculated paleostress tensors show a constant north-south extension stress regime throughout the Paleozoic during successive geodynamic regimes, from the Gondwana active margin to the Paleotethys post-rift passive margin. The extension was accommodated by east-west oriented (current reference frame), margin-parallel normal faults. These intra-formational faults are parallel to the main basin-bounding faults, which were repeatedly reactivated during later inversion and extension phases.

This study is a part of an ongoing floristic study in Eastern Alborz mountain range (Iran). The flora and vegetation of this area are less known compared to those of Central Alborz. The study area indicates the regionally significant connection between the Kopet Dagh-Khorassan and Central Alborz. A total of 41 rare-threatened taxa belonging to 26 genera and 15 families are presented. According to the IUCN criteria, our checklist identifies 3 taxa classified as Critically Endangered (CR), 19 taxa as Endangered (EN), 4 taxa as Vulnerable (VU), 4 taxa as Near Threatened (NT), 3 taxa as Least Concern (LC), and 8 taxa as Data Deficient (DD). Among them, 28 are hemicryptophytes, followed by chamaephytes (7 species), geophytes (4 species), and therophytes (2 species). During 10 years of field investigations on the semi-arid areas of Eastern Alborz, some rare-threatened endemic species have been rediscovered in the region. Geographic distribution maps of all rare species together with the accompanying species and their conservation status were drawn up. It is noteworthy that some rare species are known only from their locus classicus and no new specimens have been collected during the last 30 to 80 years. A total of 10 taxa were reported for the first time from Eastern Alborz, primarily exhibiting a disjunct distribution pattern occurring in the high elevations of Zagros, Alborz and/or other mountain ranges in SW Asia.

New fieldwork was carried out in the central and eastern Alborz, addressing the sedimentary succession from the Pennsylvanian to the Early Triassic. A regional synthesis is proposed, based on sedimentary analysis and a wide collection of new palaeontological data. The Moscovian Qezelqaleh Formation, deposited in a mixed coastal marine and alluvial setting, is present in a restricted area of the eastern Alborz, transgressing on the Lower Carboniferous Mobarak and Dozdehband formations. The late Gzhelian–early Sakmarian Dorud Group is instead distributed over most of the studied area, being absent only in a narrow belt to the SE. The Dorud Group is typically tripartite, with a terrigenous unit in the lower part (Toyeh Formation), a carbonate intermediate part (Emarat and Ghosnavi formations, the former particularly rich in fusulinids), and a terrigenous upper unit (Shah Zeid Formation), which however seems to be confined to the central Alborz. A major gap in sedimentation occurred before the deposition of the overlying Ruteh Limestone, a thick package of packstone–wackestone interpreted as a carbonate ramp of Middle Permian age (Wordian–Capitanian). The Ruteh Limestone is absent in the eastern part of the range, and everywhere ends with an emersion surface, that may be karstified or covered by a lateritic soil. The Late Permian transgression was directed southwards in the central Alborz, where marine facies (Nesen Formation) are more common. Time-equivalent alluvial fans with marsh intercalations and lateritic soils (Qeshlaq Formation) are present in the east. Towards the end of the Permian most of the Alborz emerged, the marine facies being restricted to a small area on the Caspian side of the central Alborz. There, the Permo-Triassic boundary interval is somewhat similar to the Abadeh–Shahreza belt in central Iran, and contains oolites, flat microbialites and domal stromatolites, forming the base of the Elikah Formation. The P – T boundary is established on the basis of conodonts, small foraminifera and stable isotope data. The development of the lower and middle part of the Elikah Formation, still Early Triassic in age, contains vermicular bioturbated mudstone/wackestone, and anachronostic-facies-like gastropod oolites and flat pebble conglomerates. Three major factors control the sedimentary evolution. The succession is in phase with global sea-level curve in the Moscovian and from the Middle Permian upwards. It is out of phase around the Carboniferous–Permian boundary, when the Dorud Group was deposited during a global lowstand of sealevel. When the global deglaciation started in the Sakmarian, sedimentation stopped in the Alborz and the area emerged. Therefore, there is a consistent geodynamic control. From the Middle Permian upwards, passive margin conditions control the sedimentary evolution of the basin, which had its depocentre(s) to the north. Climate also had a significant role, as the Alborz drifted quickly northwards with other central Iran blocks towards the Turan active margin. It passed from a southern latitude through the aridity belt in the Middle Permian, across the equatorial humid belt in the Late Permian and reached the northern arid tropical belt in the Triassic.

The active changeover from the transpression to the transtensional tectonic regime in eastern Alborz, Northern Iran

In highly populated urban areas such as Tehran, with over 17 million inhabitants, identifying active faults is essential to hazard and risk management. Tehran is located in central Alborz within the Arabia-Eurasia collision zone. The region is the manifestation of interplay between structural systems of the western and eastern Alborz. The study area focuses on the Lavizan and Babaei fault-related fold structures as the main Quaternary features of the Tehran piedmont. Tehran's rapid urbanization in the past few decades has made it impossible to access fault traces and the associated geomorphic features in the field. This research is the first study which uses photogrammetric methods to extract detailed 3D data and digital terrain model (DTM) from archival imaging. Historical aerial photographs were acquired from 1955-1965, before the city's development. A DTM with a spatial resolution of about 86 centimeters, an orthophoto-mosaic, and a three-dimensional model were created employing photogrammetric methods. The geomorphic analysis of the model reveals lateral unidirectional eastwards growth of the Lavizan and Babaei structures during Pleistocene and Holocene. The presence of wind gaps developed from water gaps, and sharp fault scarps in the upper Pleistocene and Holocene geomorphic surfaces testify this lateral propagation. This study presents a typical example for a long-lasting tectonic activity and its Holocene continuation on the E-W fault-related fold structures, which directly affect urban areas in the Iranian metropolitan.

Crop wild relatives (CWR) are the most important genetic resources to improve and ensure global food security. Following Vavilov studies on CWRs, Iran is categorized in the higher ranks of conservation priorities. However, the species in this area are severely exposed to threats which make it necessary to protect them. Accordingly, the initial step to their conservation is to crate an ecological database. Despite the extensive efforts and valuable publications in the Iranian flora, little attention has been paid to the patterns and diversity centers of CWRs in Iran. The current study analyzed 804 grid cells (20820Km) in the Iranian geographic boundaries. Besides, nothing was recorded from 229 grid cells, though, 14 taxa (15.73%) were recorded from one grid cell. In this study, 3911 georeferenced locations of monocots CWRs were reported in Iran that belonged to 331 species, i.e. 80 genera of 16 plant families. Besides, Central Alborz, Eastern Alborz as well as northern and central sections of Zagros showed the highest diversity, respectively. Also, Poaceae (117), Amaryllidaceae (73), and Asparagaceae (36) showed the highest richness of species. Moreover, the Iranian monocots CWRs were categorized in 9 classes of elevation ranging from 0 m to more than 4000 m, and elevation ranging between 1500 to 2000m and 1000 to 1500m above the sea level with

Crop Wild Relatives (CWR) has the potential to contribute to food security. These ‎taxa ‎can donate advantageous traits to counter biotic as well as abiotic stresses and improve ‎the ‏quality of crops. This study aims to provide as many details as possible on distribution ‎‎patterns and centers of diversity to identify and establish modern protected areas in Iran. ‎In ‎total, 539 species of CWR, belonging to 258 genera of 75 ‎plant families have been studied. ‎Using prioritization criteria (gene pool level, range of distribution, and ‎economic value) 17 ‎families, 35 genera and 94 species of CWR have been identified ‎in Iran, the highest diversity ‎was found in central Alborz, eastern Alborz, and the northern sections of Zagros. Several ‎geographic zones can be classified as national genetic reserves. ‎Iranian CWR were distributed ‎in 9 classes, ranging in elevation from 0 m to more than 4,000 ‎m. Species with a high ‎conservation value include: Rosa pimpinellifolia, Rosa ‎webbiana, Pyrus turcomanica, ‎Crataegus sanguinea, Vicia pannonica, Vicia grandiflora, ‎Lathyrus pseudo-cicera, Lactuca ‎wilhelmsiana, Cornus mas and Cornus sanguinea. The main ‎achievement of this study has ‎been to identify the distribution patterns and the ‎priorities for conservation of these valuable ‎taxa for the first time. Our results show ‎that these prominent taxa of CWR have the potential ‎not only to improve food and ‎economic security at a national level, but can also contribute to ‎global food security. Thus, an urgent and cohesive plan for their management is critical.‎

The increasing rate of irreversible damages to natural habitats has reinforced the need for gathering biodiversity fundamental data to conservation. Priority setting is the most important step in protection programs. Solanaceae as the the one of important economic families of eudicots distributed throughout North and South America, Europe, Africa, Asia, Australia, and the South Pacific. Up to now, little attention has been paid to the patterns and diversity centers of Solanaceae in Iran. The present study describes in as much detail as possible the spatial distribution, areas with greater species richness, and centers of diversity for taxa. An ecogeographical database was developed using the records that corresponds to 3123 herbarium specimens belong to 2560 localities. The localities were marked using ArcView version 3.2 (ESRI 2000) on geo-referenced maps (1/106) of Iran. The distribution patterns of the taxa were mapped per 1° × 1° universal transverse Mercator grid cells (100 km2 with the exception of boundary area). Threatened categories of Iranian Solanaceae, including CR (43.4%) and VU (34%), mainly (58.9%) distributed in Irano-Turanian phytochorion. Solanaceae represents the highest richness in the central Alborz, Zagros, Kopet Dagh and Makran Mountains based on recent criteria. The conservation value of habitats of Solanaceae in Iran ranges from 0.15 (in coastline of Persian Gulf) to 11.19 (in eastern Alborz).

Hadi Jahangir, Mansoureh Ghobadi Pour, Alireza Ashuri & Arash Amini, December 2015. Terminal Cambrian and Early Ordovician (Tremadocian) conodonts from Eastern Alborz, north-central Iran. Alcheringa ##, ###-###. ISSN 0311-5518.Uppermost Cambrian (Furongian) and Lower Ordovician (Tremadocian) deposits of eastern Alborz in northern Iran contain several successive low- to moderate-diversity conodont associations including 13 genera and 19 species of euconodonts, paraconodonts and protoconodonts, which define six biozones: 1, the Proconodontus muelleri; 2, Eoconodontus notchpeakensis; 3, Cordylodus andresi; 4, Cordylodus proavus; 5, Paltodus deltifer; and 6, Paroistodus proteus zones. With the exception of Cordylodus andresi, which is otherwise known from Baltoscandia and from the Oaxaquia terrane (Mexico), all index-taxa are geographically widespread, allowing long-range correlation within the Cold Domain or the North Atlantic Province, and in particular with Baltica. Invasion of euconodonts in the Alborz region, defined by the first occurrence of Proconodontus muelleri, coincides closely with a steady rise in sea level and termination of carbonate sedimentation, whereas the transition from the Proconodontus muelleri to Eoconodontus notchpeakensis zones occurs during a highstand interval unlike in Laurentian sequences. The interval corresponding to the Cordylodus andresi and Cordylodus proavus zones, and the transition from the Paltodus deltifer to Paroistodus proteus zones coincided with unstable sea levels and the formation of shoal complexes. The lower boundary of the Floian Stage can be provisionally placed slightly below the first documented occurrence of Acodus sp. cf. A. kechikaensis, somewhat below the second unit of andesitic lava flows in the Simeh-Kuh section.Hadi Jahangir [jahangir.hadi@gmail.com] and Alireza Ashuri [ashouri2001@yahoo.com] Department of Geology, Faculty of Sciences, Ferdowsi University, Azadi Square, Mashhad 91775-1436, Iran; Mansoureh Ghobadi Pour* [mghobadipour@yahoo.co.uk; m.ghobadipour@gu.ac.ir] and Arash Amini [a.amini@gu.ac.ir], Department of Geology, Faculty of Sciences, Golestan University, Gorgan 49138-15739, Iran. *Also affiliated with Department of Geology, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK.

Ghobadi Pour, M., 21 June 2019. Ordovician trilobites from Deh-Molla, eastern Alborz, Iran. Alcheringa 43, 381–405. ISSN 0311-5518Seventeen species from 14 genera of Tremadocian and Darriwilian trilobites, plus two taxa recognizable only down to family level, have been documented from the Lower to Middle Ordovician succession of the Deh-Molla area, southeast of Shahrud in northern Iran. Two species, Asaphellus intermedius and Conophrys multituberculatus, are new to science. Unlike previously documented Iranian faunas, the early Tremadocian trilobite assemblage is characterized by proliferation of the olenid Chungkingaspis sinensis, which is also known as the eponymous taxon of the basal Ordovician trilobite biozone in South China. This is the first record of the occurrence of the olenid biofacies in the Ordovician of Iran. Overall, both the Tremadocian and Darriwilian trilobite assemblages show distinct similarity to the contemporaneous faunas of South China down to species level. Trilobite-based correlation with the Ordovician succession of South China confirms the existence of a hiatus at the base of the Ordovician succession in the eastern Alborz and a significant gap, with the upper Tremadocian, Floian and Dapingian parts of the succession completely missing in Deh-Molla.Mansoureh Ghobadi Pour [mghobadipour@yahoo.co.uk and m.ghobadipour@gu.ac.ir], Department of Geology, Faculty of Sciences, Golestan University, Gorgan 49138-15739, Iran. *Also affiliated with Department of Natural Sciences, Natural Museum of Wales, Cardiff, Cathays Park, Cardiff CF10 3NP, UK.

Abstract:The Mobarak Formation is near the town of Kiyasar in the south‐east of Sari city, northern Iran. This formation conformably overlies the Geirud Formation (Upper Devonian). The lower part of the Mobarak Formation consisting of shales and thin‐ to medium‐bedded limestone toward the top of these sequences changes into alternations of dark limestone and interbedded gray to black shales. Weathered yellow thick‐bedded shales are observed at the top of the section. This formation is covered unconformably by sandstones attributed to the Dorud Formation (Lower Permian). The thickness of the formation in this region is 250 m. Four rock units have been recognized in this section. Foraminiferal biostratigraphy shows that the age of the Mobarak Formation in the Kiaysar region ranges from Lower Tournaisian to Early Middle Visean. The foraminifer Zones FAZ1 and FAZ2 are correlated with the Lower Tournaisian and Upper Tournaisian, whereas Zones FAZ3 and FAZ4 correlate with the Visean. Affinities exist between specimens recorded in the Kiyasar section with species known from other regions in eastern and Central Alborz, but there are important differences in their appearance.

<p>Iran is a mosaic of continental blocks that are surrounded by Palaeo-Tethyan and Neo-Tethyan oceanic relics. Remnants of the ophiolitic rock assemblages are exposed around the Central Iranian Microcontinent (CIM), discretely along the Sanandaj-Sirjan Zone and in Jaz-Murian. The Present-day “ring” distribution of the Iranian ophiolites is not straightforwardly explained by a simple subduction zone architecture. One of the key features to solve the Iranian puzzle is the CIM which is surrounded by Sabzevar ophiolites in the north (99-77 Ma), Birjand-Nehbandan ophiolites in the east (~110 Ma) and Inner Zagros ophiolites in south-southwest (~103-94 Ma). The CIM consists of three major fault bounded sub-blocks, from east to west, Lut, Tabas, and Yazd. They represent an Atlantic-type continental margin that began rifting in Permo-Triassic as a result of opening of Neotethys Ocean. Subsequent convergence in Cretaceous to Paleogene time close the ocean basins around the CIM and emplaced the ophiolites onto the passive margins. Neogene Arabia-Eurasia collision induced replacement structures e.g., strike‐slip reactivation of normal faults that were associated with major block rotations.</p><p>We aim to kinematically restore the opening and closure history of the ocean basins found as ophiolitic relics around the CIM. Key in our analysis is the Doruneh and Great Kavir faults of Central Iran that continues into northern Afghanistan as the Herat Fault. Present-day GPS velocity vector measurements and deformation pattern show a NE-SW orientated shortening in Iran. Structural analysis of the Doruneh Fault indicates slip sense inversion before ~5 Ma. This observation is consistent with the deactivation of the dextral Herat Fault. Pre-Pliocene dextral movement in excess of 500 km along the Doruneh and Great Kavir faults may kinematically accommodate a major counter-clockwise rotation (~65<span>o</span>) of the CIM since the late Jurassic that has been inferred based on previous palaeomagnetic studies. This enables the transport of the Jandaq ophiolite from Aghdarband in the north to Anarak region of Central Iran and, duplication of curved Birjand-Nehbandan ophiolites in Sistan suture. If correct, this may imply that the closure history of the Central Iranian basins is directly connected to the large-scale Cretaceous to Paleogene extrusion tectonics in western Tibet and Hindu Kush regions. This preliminary study shows restoration of the post-Mesozoic deformation is essential to reconstruct the suture zones and pre-collisional setting in Iran, Afghanistan, and Pakistan.</p>

Fault kinematics and active tectonics at the southeastern boundary of the eastern Alborz (Abr and Khij fault zones): Geodynamic implications for NNE Iran

Discovery of new open-air Paleolithic localities in Central Alborz, Northern Iran