Accommodation of late Cenozoic oblique shortening in the Alborz range, northern Iran
- 21 August 2002
- journal article
- Published by Elsevier BV in Journal of Structural Geology
- Vol. 25 (5), 659-672
- https://doi.org/10.1016/s0191-8141(02)00064-0
Abstract
The Alborz range, northern Iran, deforms by strain partitioning of oblique shortening onto range-parallel left-lateral strike-slip and thrust faults. Deformation is due to the north–south Arabia–Eurasia convergence, and westward motion of the adjacent South Caspian relative to Iran. Roughly north–south shortening occurs on thrusts that dip inwards from the range margins. Precambrian basement is not exposed because of detachment along upper Proterozoic evaporites and the thickness of overlying strata (∼10 km). Other detachments occur within Phanerozoic sediments. Active left-lateral strike-slip faults trend ENE in the east of the range, WNW in the west. The eastern Mosha Fault has a left-lateral offset of ∼30–35 km. Shortening across the range is ∼30 km (25–30%) at the longitude of Tehran. This is hard to reconcile with the crustal thickness of ∼35 km, which is similar to adjacent basins. Percentage shortening across the Alborz is similar to the adjacent Kopet Dagh, but because the latter is twice as wide, finite shortening is roughly half. The difference may be accommodated by subduction of the adjacent South Caspian Basin northwards under the middle Caspian. South Caspian sediments began folding in the Pliocene; the present kinematics of the Alborz may have begun at this time, including a reversal from range-parallel right-lateral to left-lateral strike-slip faulting, but the regional stratigraphy indicates uplift as early as the mid Tertiary.Keywords
This publication has 23 references indexed in Scilit:
- Characteristics and consequences of flow in the lower crustJournal of Geophysical Research, 2000
- Transpression and transtension zonesGeological Society, London, Special Publications, 1998
- Late Cenozoic transpression in southwestern Mongolia and the Gobi Altai-Tien Shan connectionEarth and Planetary Science Letters, 1996
- The 1990 Rudbar‐Tarom Iranian earthquake sequence: Evidence for slip partitioningJournal of Geophysical Research, 1995
- Mountain building: strike-parallel motion and mantle anisotropyTectonophysics, 1991
- The Caucasus: an actual example of the initial stages of continental collisionTectonophysics, 1989
- Constraints on Arabian Plate motion and extensional history of the Red SeaTectonics, 1987
- Strike-slip duplexesJournal of Structural Geology, 1986
- Northern Iran: Alborz MountainsGeological Society, London, Special Publications, 1974
- Tectonic transpression in Caledonian SpitsbergenGeological Magazine, 1971