The significance of switch in convergence direction in the Alborz Mountains, northern Iran: Insights from scaled analogue modeling

2017 ◽  
Vol 5 (1) ◽  
pp. SD81-SD98 ◽  
Author(s):  
Majid Shahpasandzadeh ◽  
Hemin Koyi ◽  
Faramarz Nilfouroushan
Keyword(s):  
Active Tectonics ◽  
Deformation Pattern ◽  
Eurasian Plate ◽  
The South ◽  
South Caspian Basin ◽  
Northern Iran ◽  
The North ◽  
Structural Style ◽  
Analogue Models ◽  
North Of Iran

The switch in direction of convergence between Central Iran and the Eurasian Plate is believed to have a significant impact on the structural style in the Alborz Mountains, in the north of Iran. To understand the deformation pattern and investigate the influence of the South Caspian Basin kinematics since the middle Miocene on the structural styles and active tectonics of the Alborz Mountains, a series of scaled analogue models were prepared, in which passively layered loose sand simulating the sedimentary units were subjected to orthogonal and subsequently oblique shortening by a rigid indenter. Model results indicate that during the shortening, an arcuate-shaped foreland-vergent imbricate stack forms in front of the indenter. The orthogonal shortening is characterized by a prevailing right-lateral and left-lateral oblique-slip motion in the east and west of the model, respectively. This shift in kinematics contradicts the proposed preneotectonic (orthogonal) model of the Alborz. However, during oblique shortening, model results show that deformation is mainly accommodated by left-lateral transpression within the sand wedge and internal deformation. Oblique shortening is consistently accommodated by continued left-lateral motion on the west-northwest-trending oblique thrusts, whereas the east–west-trending thrusts and the preexisting east-northeast-trending right-lateral oblique thrusts reactivate as left-lateral oblique faults. Precise monitoring of the model surface also illustrates partitioning of shortening into the foreland-vergent left-lateral thrusting in the south and hinterland-vergent back thrusting in the north. These model results are generally consistent with field observations and GPS data of structure and kinematics of the Alborz Mountains.

Geotectonic evolution of the Bransfield Basin, Antarctic Peninsula: insights from analogue models

2008 ◽  
Vol 20 (2) ◽  
pp. 185-196 ◽  
Author(s):  
M.A. Solari ◽  
F. Hervé ◽  
J. Martinod ◽  
J.P. Le Roux ◽  
L.E. Ramírez ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
South Shetland Islands ◽  
The South ◽  
The West ◽  
Shetland Islands ◽  
Scotia Ridge ◽  
The North ◽  
Analogue Models ◽  
Bransfield Basin ◽  
The Phoenix

AbstractThe Bransfield Strait, located between the South Shetland Islands and the north-western end of the Antarctic Peninsula, is a back-arc basin transitional between rifting and spreading. We compiled a geomorphological structural map of the Bransfield Basin combining published data and the interpretation of bathymetric images. Several analogue experiments reproducing the interaction between the Scotia, Antarctic, and Phoenix plates were carried out. The fault configuration observed in the geomorphological structural map was well reproduced by one of these analogue models. The results suggest the establishment of a transpressional regime to the west of the southern segment of the Shackleton Fracture Zone and a transtensional regime to the south-west of the South Scotia Ridge by at least c. 7 Ma. A probable mechanism for the opening of the Bransfield Basin requires two processes: 1) Significant transtensional effects in the Bransfield Basin caused by the configuration and drift vector of the Scotia Plate after the activity of the West Scotia Ridge ceased at c. 7 Ma. 2) Roll-back of the Phoenix Plate under the South Shetland Islands after cessation of spreading activity of the Phoenix Ridge at 3.3 ± 0.2 Ma, causing the north-westward migration of the South Shetland Trench.

scholarly journals The western termination of the South Pyrenean Triangle Zone; a structural and geophysical characterization.

2021 ◽  
Author(s):  
Pablo Santolaria ◽  
Concepción Ayala ◽  
Emilio L. Pueyo ◽  
Félix M. Rubio ◽  
Ruth Soto ◽  
...  
Keyword(s):  
Upper Eocene ◽  
The South ◽  
The North ◽  
Triangle Zone ◽  
Structural Style ◽  
Lower Oligocene ◽  
Thrust Belts ◽  
Stratigraphic Model ◽  
Structural Architecture ◽  
Surface Geology

<p>The presence of multiple evaporite levels strongly influence the structural style and kinematics of fold-and-thrust belts. Particularly (but not exclusively) in their fronts, it is common for these décollements to favor the formation of triangle zones. In the central portion of the Pyrenees, the South Pyrenean Triangle Zone represents the frontal part of this chain, that involves the Oligocene-Miocene Ebro Basin foreland deposits. We have focused on its western termination, characterized by a salt-cored anticline that laterally passes to a backthrust which dies out to the west. These structures are detached on the Upper Eocene-Lower Oligocene syntectonic evaporite Barbastro Formation (and lateral equivalents) that acted as a multidetachment unit. To the north, the south-directed Pyrenean thrust unit detached on Middle-Upper Triassic evaporites to finally glide along the Upper Eocene-Lower Oligocene décollement horizons.</p><p>In this contribution, we present a detailed structural and stratigraphic model of this triangle zone termination, constructed accordingly to two major approaches (1) constraining the geometry and structural architecture based on surface geology, interpretation of seismic lines (>900 km) and wells and, (2) obtaining the 3D density distribution of the detachment level (Barbastro Fm. and lateral equivalents as well as deeper, Triassic evaporites) using gravity stochastic inversion by means of more than 7000 gravity stations and 1500 actual density data from surface rocks. All in all, this multidisciplinary approach allows us to characterize the western termination of the South Pyrenean Triangle zone as the transition from a ramp-dominated and multiple triangle zone to a detachment-dominated one whose geometry, kinematics, and location were controlled by the distribution and heterogeneity of the Upper Eocene-Lower Oligocene syntectonic décollements and the southern pinch-out of the basal detachment of this unit.</p>

scholarly journals Refinements in biostratigraphy, chronostratigraphy, and paleogeography of the Mississippian (Lower Carboniferous) Mobarak Formation, Alborz Mountains, Iran

GeoArabia ◽  
2009 ◽  
Vol 14 (3) ◽  
pp. 43-78
Author(s):  
Paul L. Brenckle ◽  
Maurizio Gaetani ◽  
Lucia Angiolini ◽  
Maryamnaz Bahrammanesh
Keyword(s):  
Western Europe ◽  
The South ◽  
Northern Iran ◽  
Lower Carboniferous ◽  
Upper Carboniferous ◽  
Incertae Sedis ◽  
The North ◽  
Northern Side ◽  
Calcareous Microfossils ◽  
Alborz Region

ABSTRACT Detailed sampling of limestones from the Mobarak Formation at the Abrendan and Abnak measured sections in the eastern and central Alborz Mountains, northern Iran, yielded a diverse assemblage of Tournaisian – Lower Visean (Mississippian/Lower Carboniferous) calcareous microfossils (foraminifers, algae, incertae sedis). The Abrendan locality contains Tournaisian foraminifers in the upper part of the formation that correlate to the Ivorian and upper Courceyan – lower Chadian substages of western Europe and the Kosvinsky Horizon of the Russian Platform. Brachiopods confirm a Tournaisian age for the lower part of the Mobarak, which lacks age-diagnostic calcareous microfossils. Lower Visean foraminifers at Abnak provide good correlation to the western European Moliniacian and Arundian substages and the Russian Bobrikovsky Horizon. Synthesis of foraminiferal data from this and other published reports indicates that the top of the Mobarak Formation becomes increasingly older across the Alborz to the southeast, caused most likely by Pennsylvanian (Upper Carboniferous) exposure and erosion in the south followed by a latest Pennsylvanian – Early Permian transgression from the north. The microbiota at both sections and the macrofossils at Abrendan show close affinity to the warm-water Paleo-Tethyan Ocean, seemingly contradicting Early Mississippian paleomagnetic reconstructions placing the Alborz region at 45–50° South latitude. The discrepancy is not resolvable at this time, but the answer may lie in the circulation of Paleo-Tethyan currents to the south along the Gondwanan shelf, rather than to repositioning the Alborz region to the northern side of the Paleo-Tethyan Ocean.

The Mid-Cimmerian tectonic event (Bajocian) in the Alborz Mountains, Northern Iran: evidence of the break-up unconformity of the South Caspian Basin

2009 ◽  
Vol 312 (1) ◽  
pp. 189-203 ◽  
Author(s):  
Franz Theodor Fürsich ◽  
Markus Wilmsen ◽  
Kazem Seyed-Emami ◽  
Mahmoud Reza Majidifard
Keyword(s):  
Caspian Basin ◽  
The South ◽  
South Caspian Basin ◽  
Northern Iran ◽  
Tectonic Event ◽  
Break Up

scholarly journals PEMETAAN BAHAYA GEMPA BUMI DAN POTENSI TSU-NAMI DI BALI BERDASARKAN NILAI SEISMISITAS

2017 ◽  
Vol 18 (1) ◽  
pp. 20
Author(s):  
Bayu Baskara ◽  
I Ketut Sukarasa ◽  
Ardhianto Septiadhi
Keyword(s):  
Northern Region ◽  
Maximum Magnitude ◽  
Eurasian Plate ◽  
The South ◽  
The North ◽  
Australian Plate ◽  
Back Arc ◽  
Sea Area ◽  
Earthquake Data

Bali is one of the areas prone to earthquake and tsunami as being at the junction of two plates, namely the Eurasian plate and the Indo-Australian plate is located in the south of Bali and back arc trust zones are located in the North of Bali. We need research on the potential dangers of earthquakes and tsunami in Bali are based on the value of seismicity which is interpreted by the value of b and a. This study uses earthquake data on the coordinates 6?-11? SLand 114?-116? EL with 339 data that was processed using Zmap in order to obtain the value of b at 1.57 ± 0.008 and the value of a is 10.6 and maximum magnitude of 7.1 Mw. From mapping the values ??of b and a known area that has the highest value of b and a lies in the sea area to the south of Bali, Karangasem and Buleleng to the northern region of Bali. Furthermore, for mapping the tsunami in Bali using the TOAST application obtained tsunami prone areas of Bali, Kuta Beach, East Buleleng and Karangasem.

scholarly journals Spatio-temporal variation of throughfall in a hyrcanian plain forest stand in Northern Iran

2018 ◽  
Vol 66 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Saleh Yousefi ◽  
Seyed Hamidreza Sadeghi ◽  
Somayeh Mirzaee ◽  
Martine van der Ploeg ◽  
Saskia Keesstra ◽  
...  
Keyword(s):  
Canopy Cover ◽  
Forest Stand ◽  
Systematic Sampling ◽  
Northern Iran ◽  
The North ◽  
Lack Of Information ◽  
North Of Iran ◽  
Forest Watersheds ◽  
Spatio Temporal ◽  
Systematic Sampling Method

Abstract Elucidating segregation of precipitation in different components in forest stands is important for proper forest ecosystems management. However, there is a lack of information on important rainfall components viz. throughfall, interception and stemflow in forest watersheds particularly in developing countries. We therefore investigated the spatiotemporal variation of important component of throughfall for a forest stand in a Hyrcanian plain forest in Noor City, northern Iran. The study area contained five species of Quercus castaneifolia, Carpinus betulus, Populus caspica and Parrotia persica. The research was conducted from July 2013 to July 2014 using a systematic sampling method. Ninetysix throughfall collectors were installed in a 3.5 m × 3.5 m grid cells. The canopy covers during the growing/leaf-on (i.e., from May to November) and non-growing/leaf-off (i.e., from December to March) seasons were approximately 41% and 81%, respectively. The mean cumulative throughfall during the study period was 623±31 mm. The average throughfall (TF) as % of rainfall (TFPR) during leaf-on and leaf-off periods were calculated 56±14% and 77±10%, respectively. TF was significantly (R2 = 0.97, p = 0.00006) correlated with gross precipitation. Percent of canopy cover was not correlated with TF except when gross precipitation was <30 mm. A comparison between leaf-off and leaf-on conditions indicated a significantly higher TFPR and corresponding hotspots during leaf-on period. TFPR also differed between seasons with a maximum amount in winter (82%). The results of the study can be effectively used by forest watershed managers for better perception of hydrological behavior of the Hyrcanian forest in the north of Iran under different silvicultural circumstances leading to getting better ecosystem services.

scholarly journals Active tectonics of the South Caspian Basin

2002 ◽  
Vol 148 (2) ◽  
pp. 214-245 ◽  
Author(s):  
J. Jackson ◽  
K. Priestley ◽  
M. Allen ◽  
M. Berberian
Keyword(s):  
Active Tectonics ◽  
Caspian Basin ◽  
The South ◽  
South Caspian Basin

scholarly journals Molecular Study of Benzimidazole Resistance in Teladorsagia circumcincta Isolated from Sheep in North of Iran

2019 ◽  
Author(s):  
Rahim NEMATI ◽  
Aliasghar BAHARI ◽  
Pezhman MAHMOODI ◽  
Alireza SAZMAND
Keyword(s):  
Anthelmintic Resistance ◽  
Molecular Study ◽  
Nucleotide Polymorphisms ◽  
Northern Iran ◽  
The North ◽  
Specific Pcr ◽  
Teladorsagia Circumcincta ◽  
Pcr Rflp ◽  
North Of Iran ◽  
Allele Specific

Background: Resistance to benzimidazole (BZ) compounds is common in Teladorsagia circumcincta populations in sheep and goats worldwide. Given the importance of anthelmintic resistance and shortage of information on single nucleotide polymorphisms (SNPs) in this prevalent nematode in Iran, this study was conducted. Methods: From June to September 2016, abomasa of 139 sheep of different sexes and ages in Amol City slaughterhouse, northern Iran were examined for isolation of nematodes. Totally 45 male T. circumcincta confirmed by both microscopical and nested-PCR-RFLP methods were included in this study. Susceptibility or resistance of each single T. circumcincta worm to benzimidazoles was assessed using allele-specific PCR. Results: Frequency of genotypes in the present study were 33.33% heterozygote BZ and 66.67% BZ homozygote sensitive. No homozygote resistant worm was found. Conclusion: Resistance against BZs in T. circumcincta of sheep has occurred at a low prevalence in the north of Iran. However, mutated genes might get dominant under drug selection in future. Hence, periodic investigations for early detection of mutated alleles in nematode populations using accurate and sensitive molecular methods such as PCR-RFLP is recommended.

Active tectonics of the South Caspian Basin

2002 ◽  
Vol 148 (2) ◽  
pp. 214-245 ◽  
Author(s):  
James Jackson ◽  
Keith Priestley ◽  
Mark Allen ◽  
Manuel Berberian
Keyword(s):  
Active Tectonics ◽  
Caspian Basin ◽  
The South ◽  
South Caspian Basin
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