Recent tectonic activity in Central Alborz Mountain, Iran: morphometric analysis and knickpoint identification
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http://jms.imde.ac.cn https://doi.org/10.1007/s11629-019-5945-2
Recent tectonic activity in Central Alborz Mountain, Iran: morphometric analysis and knickpoint identification Parisa SHOKRI1
https://orcid.org/0000-0002-0763-3789; e-mail: [email protected]
Maryam DEHBOZORGI1*
https://orcid.org/0000-0002-2072-5821;
Saeid HAKIMI ASIABAR2
https://orcid.org/0000-0003-3120-4498; e-mail: [email protected]
e-mail: [email protected]
*Corresponding author 1 Department of Earth Science, Kharazmi University, Tehran, 15719-14911, Iran 2 Department of Geology, Lahijan Branch, Azad University, Gilan, 1616, Iran Citation: Dehbozorgi M, Shokri P, Hakimi Asiabar S (2020) Recent tectonic activity in Central Alborz Mountain, Iran: morphometric analysis and knickpoint identification. Journal of Mountain Science 17(12). https://doi.org/10.1007/s11629-0195945-2
© Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract: Alborz, as part of the Alpine-Himalayan
orogeny belt, has been the result of the convergence of the Central Iranian and Eurasian plate since the late Triassic. The study area located in Central Alborz encompasses different Quaternary faults. Thus, the present study aimed to evaluate the effect of faults on river landforms through morphotectonic indices and the causes of knickpoints and knickzones in the Bedrock Rivers in part of Central Alborz. To this end, six morphometric indices such as longitudinal gradient (SL), hierarchical anomaly (Δa), the bifurcation index (R), hypsometric integral and hypsometric curve (Hi-Hc), relative relief (Bh), and basin shape (Bs) were calculated and analyzed in 38 sub-basins of the area. Finally, the area was divided into extremely high, high, medium, and low tectonic activity areas using the relative tectonic activity (IAT). Normalized steepness and concavity indices along with the longitudinal profiles of the streams were obtained using Matlab and Arc GIS software. Based on the findings, the existence of slope-break knickpoints at the mountain piedmont at the outlet of large rivers Received: 23-Jun-2020 1st Revised: 30-Jul-2020 2nd Revised: 31-Aug-2020 Accepted: 14-Sep-2020
through active faults demonstrated that most of these landforms were created by movements along the main faults such as Khazar, Nusha, Soheil, Deylaman, Kashachal, representing high tectonic activity in the central and southern parts of the study area. However, the values of these indices were extremely low and indicated low tectonic activity in the northern parts located in the embayment part of the Caspian Sea. Finally, the findings revealed that these classes correspond well to the areas with landforms such as V-shaped and narrow valleys, gorges, deflected and offset streams, deformed Neogene, and Quaternary units that indicate the post-Neogene activity. Keywords: Morphotectonic; Bedrock rivers; Knickpoint; Quaternary Fault; Uplift; Central Alborz
Introduction Bedrock Rivers play
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