Evidence for development of transpressional duplex in the west of Shahroud- eastern Alborz
Subject Areas :Keywords: Contractional duplex Transpressional zone Shahroud fault system Astaneh fault Eastern Alborz.,
Abstract :
The study area is located in the southern boundary of the Eastern Alborz range between North Shahroud Fault and Astaneh Fault. The exposed formations are from Paleozoic to Cenozoic in age. Several structural surveys such as geometrical analysis of folds and geometrical and kinematical analysis of faults were studied. Field observations and software analysis revealed that most folded structures show a northeast-southwest trend in the eastern area and an east-west axis in the western area. Due to location of E-W trending mesoscopic folds on the hanging-wall of Tazareh thrust fault, these mesoscopic folds are fault-related folds. Axes and axial plane of folds revealed that macroscopic folds with a tendency toward south-east, are consistent with flower structure of the Alborz range. Available faults in the area have two trends: northeast-southwest in the eastern part and east-west trend in the western area, and their arrangements give a scaly situation to the area. Therefore, due to existence of east-west compressional structures, it could be suggested that Dehmolla contractional duplex is developed as a result of strike-slip faulting between Shahroud and Astaneh faults.
آقانباتي، س. ع.، 1383. زمین‌شناسی ايران. انتشارات سازمان زمین‌شناسی و اكتشافات معدني ايران، 606.
- باقري، م. قرشي، م. و مهديزاده، س.، 1385. تحليل ساختاري دوپلكس امتدادلغز چاشم در خاور منطقه فيروزكوه. فصلنامه علمي‌پژوهشي علوم زمين، شماره 60. 92-115.
- رحیمی، ب.، 1381. مطالعات ساختاری رشته¬کوه البرز در شمال دامغان. پایان¬نامه دکتری، دانشگاه شهید بهشتی. 195.
- نعمتی، م. هتسفلد، د. قیطانچی، م ر. طالبیان، م. میرزایی، ن. و سدیدخوی، ا.، 1391. لرزه¬زمین¬ساخت البرز میانی- خاوری و دامنه جنوبی آن با نگرشی بر زمین¬لرزه 7/5=Mw جنوب دامغان. فصلنامه علمی و پژوهشی علوم زمین، 86، 87-98.
- Alavi, M., 1996. Tectonostratigraphic synthesis and structural style of the Alborz Mountain system in northern Iran. Journal of Geodynamics, 21, 1–33.
- Allen, M.B., Ghassemi, M.R., Shahrabi, M. and Qorashi, M., 2003a. Accommodation of late Cenozoic oblique shortening in the Alborz range, northern Iran. Journal of Structural Geology, 25,5, 659–672.
- Allen, M. B., Vincent, S. J., Alsop, G. I., Ismail-zadeh, A. and Flecker, R., 2003b. Late Cenozoic deformation in the South Caspian region: effects of a rigid basement block within a collision zone. Tectonophysics, 366, 223-239.
- Axen, G.J., Lam, P.S., Grove, M., Stockli, D.F. and Hassanzadeh, J., 2001. Exhumation of the west-central Alborz Mountains, Iran, Caspian subsidence, and collision-related tectonics. Geological Society of America, 29, 559–562.
- Curren, I.S. and Bird, P., 2014. Formation and suppression of strike–slip fault systems. Pure and Applied Geophysics, 171,11, 2899-2918.
- Fleuty, M. J., 1964. The description of Folds. Geological Association Proceeding, 75, 461-492.
- Ghavidel-Syooki, M., 2006. Palinostratigraphy and Palaeogeography of the cambro-ordovician strata in the southwest of Shahrood city (kuh-e- Kharbash, near Deh-molla), central Alborz range, northern Iran. Rev. of Palaeobotany and Paleontology, 136, 81-95.
- Golonka, J., 2007. Geodynamic Evolution of the south Caspian Basin., in P. O. Yilmaz and G. H. Isaksen editors, Oil and Gas of the Greater Caspian area. AAPG Studies in Geology, 55, 17-41.
- González, D., Pinto, L., Peña, M. and Arriagada, C., 2012. 3D deformation in strike-slip systems: Analogue modelling and numerical restoration. Andean Geology, 39,2, 295-316.
- Guest, B., Axen, G.J., Lam, P.S. and Hassanzadeh, J., 2006. Late Cenozoic shortening in the west-central Alborz Mountains, northern Iran, by combined conjugate strike-slip and thin-skinned deformation. Geosphere, 2, 35-52.
- Guest, B., Stockli, D. f., Grove, M., Axen, G.J., Lam, P.S. and Hassanzadeh, J., 2006. Thermal histories from the central Alborz Mountains, northern Iran: Implications for the spatial and temporal distribution of deformation in northern Iran. Geological Society of America, 118, 1507-1521.
- Hollingsworth, J., Jackson, J., Walker, R. and Nazari, H., 2008. Extrusion tectonics and subduction in the eastern South Caspian region since 10 Ma. Geology, 36, 763-766.
- Hollingsworth, J., Nazari, H., Ritz, J.F., Salamati, R., Talebian, M., Bahroudi, A., Walker, R. T., Rizza, M. and Jackson, J., 2010. Active tectonics of the east Alborz Mountains, NE Iran: Rupture of the left‐lateral Astaneh fault system during the great 856 A.D. Qumis earthquake. Journal of Geophysical Research, 115, B12313
- Hudleston, P.J. and Treagus, S.H., 2010. Information from folds: A review. Journal of Structural Geology, 32, 2042-2071.
- Iturrieta, P.C., Hurtado, D.E., Cembrano, J. and Stanton-Yonge, A., 2017. States of stress and slip partitioning in a continental scale strike-slip duplex: Tectonic and magmatic implications by means of finite element modeling. Earth and Planetary Science Letters, 473, 71-82.
- Jackson, J., Priestley, K., Allen, M. and Berberian, M., 2002. Active tectonics of the South Caspian Basin. Geophysical Journal International, 148, 214–245.
- Krantz, R.W., 1995. The Transpressional strain model applied to strike-slip, oblique-convergent and oblique-divergent deformation. Journal of Structural Geology, 18, 1125-1137.
- Marrett, R. and Allmendinger, R.W., 1990. Kinematic analysis of fault-slip data. Journal of Structural Geology, 12. 973-986.
- McClay, K. and Bonora, M., 2001. Analog models of restraining stepovers in strike-slip fault systems. The American Association of Petroleum Geologists Bulletin, 85, 233-260.
- Ramsay, J.G. and Huber, M.I., 1987. The Techniques of Modern Structural Geology. Volume 2: Folds and Fractures. London, Academic Press.
- Şengör, A.M.C., 1990. A new model for the late Paleozoic–Mesozoic tectonic evolution of Iran and implications for Oman, in The Geology and tectonics of the Oman region. Geological Society of London. Special Publication, 49, 797–831.
- Shahpasandzadeh, M., Koyi, H. and Nilfouroushan, F., 2017. The significance of switch in convergence direction in the Alborz Mountains, northern Iran: Insights from scaled analogue modeling. Interpretation, 5,1, SD81-SD98.
- Stöcklin, J., 1968. Structural history and tectonics of Iran: A review. American Association of Petroleum Geologists Bulletin, 52, 1229–1258.
- Stöcklin, J., 1974 .Possible ancient continental margins in Iran. In: The geology of continental margins. Springer, 873-887.
- Twiss, R. J. and Moores, E. M., 2003. Structural Geology. Second Edition. New York, W. H. Freeman and Company. 532 .
- Vernant, P., Nilforoushan, F., Chery, J., Bayer, R., Djamour, Y., Masson, F., Nankali, H., Ritz, J.-F., Sedighi, M. and Tavakoli, F., 2004. Deciphering oblique shortening of Central Alborz in Iran using geodetic data. Earth and Planetary Science Letters, 223, 177–185.
- Vernant, P., Nilforoushan, F., Hatzfeld, D., Abassi, M., Vigny, C., Masson, F., Nankali, H., Martinod, J., Ashtiani, A., Bayer, R., Tavakoli, F. and Chéry, J., 2004. Contemporary crustal deformation and plate kinematics in Middle East constrained by GPS measurements in Iran and northern Oman. Geophysics Journal International, 157, 381– 398.
- Woodcock, N.H. and Fischer, M., 1986. Strike-slip duplexes. Journal of Structural Geology, 8, 725-735.
- Zanchi, A., Berra, F., Mattei, M., Ghasemi, M. R. and Sabouri, J., 2006. Inversion tectonics in central Alborz, Iran. Journal of Structural Geology, 28, 2023-2037.