Document Type : Original Research Paper

Authors

1 Geological Survey of Iran, Tehran, Iran.

2 Tectonic Laboratory, Paris 6 University, Paris, France.

3 Geological Survey of Iran, Tehran, Iran

Abstract

In northern Iran the Eo-Cimmerian orogeny resulting from this collision is associated with a regional unconformity and a major change in sedimentation. From Norian to middle Bajocian (Shemshak group), 030° trending extension is indicated by syndepositional normal faults. We assign this extensional tectonics to the rifting phase preceding the oceanic opening of the South Caspian Basin. Dalichai and Lar formations, late-Bajocian to Neocomian in age, conformably cover the Shemshak in central Alborz. They are contemporaneous with the opening of the South Caspian marginal basin. In Alborz, the lower part of the Cretaceous sequence is associated with E-W to WNW-ESE trending normal fault systems associated with magmatism related to an N-S to NNE-SSW trending extension during this period. The Cretaceous-Palaeogene boundary is marked by a major regional unconformity. This unconformity is related to a major inversion of the southern margin of the South Caspian basins. During the early-middle Eocene, southern Alborz is characterized by a rapid subsidence of the Karaj basin. Syndepositional E-W to WNW-ESE trending normal faults are common in the Karaj Formation. They are associated with a well-determined N-S to NNE-SSW extension. We assign the Karaj basin to a back-arc basin related to the NE subduction of the neo-tethyan oceanic lithosphere beneath the southern margin of Eurasia.

Keywords

References
Alavi Naini, M., 1992- Kimmerian event in Iran. Scientific Quarterly Journal (GSI), Vol. 2, N° 5: 38-47.
Alavi, M., 1991- Tectonic map of the Middle East (1/5 000 000). Geol. Surv. Iran, Tehran.
Alavi, M., 1994- Tectonics of the Zagros orogenic belt of Iran; new data and interpretations. Tectonophysics: 211-238.
Alavi, M., 1996- Tectonostratigraphic synthesis and structural style of the Alborz mountain system in Northern Iran. Journal of Geodynamics, 21(1): 1-33.
Allen, M. B., Vincent, S. J., Alsop, G. I., Ismail-zadeh, A. & Flecker, R., 2003- Late Cenozoic deformation in the South Caspian region: effects of a rigid basement block within a collision zone. Tectonophysics, 366(3-4): 223-239.
Angelier, J., 1975- Sur l’analyse de mesures recueillies dans les sites failles: l’utilité´ d’une confrontation entre les méthodes dynamiques et cinématiques. C. R. Acad. Sci. Paris D 281: 1805– 1808.
Angelier, J., 1979- Néotectonique de l'arc égéen. Soc. géol. Nord, pub., l-3: 418.
Annells, R. N., Arthurton, R. S., Bazley, R. A., Davies, R. C., M., Rahimzadeh, F. & Rashtian, K., 1985-Explanatory text of the Qazvin and Rasht quadrangle map. Geol. Surv. Iran, Tehran, Iran: 94 p.
Assereto, R., 1966- The Jurassic Shemshak Formation in central Elburz (Iran). Rivista Italinana di Paleontologia e stratigraphia, 72: 1133-1182.
Barrier, E. & Vrielynck, B., 2009- Paleotectonic maps of the Middle East. Middle East Basins Evolution Programme (MEBE).
Belov, A. A., 1981- Tectonic History of the Alpine Fold Belt in the Paleozoic Nauka, Moscow. In Russian.
Berberian, F., Muir, I. D., Pankhurst, R. J. & Berberian, M., 1982- Late Cretaceous and early Miocene Andean-type plutonic activity in northern Makran and Central Iran. J. Geol. Soc. London, 139: 605-614.
Berberian, M. & King, G., 1981- Towards a paleogeography and tectonic evolution of Iran. Canadian Journal of Earth Sciences, 18: 210–265.
Berberian, M., 1983- The southern Caspian: a compressional depression floored by a trapped, modified oceanic crust. Canadian Journal of Earth Sciences, Vol. 20: 163–183.
Besse, J., Torcq, F., Gallet, Y., Ricou, L. E., Krystyn, L. & Saidi, A., 1998- Late Permian to Late Triassic palaeomagnetic data from Iran: constraints on the migration of the Iranian block through the Tethyan Ocean and initial destruction of Pangaea. Geophysical Journal International, 135: 77-92.
Boulin, J., 1991- Structures in Southwest Asia and evolution of the eastern Tethys. 21l-268.
Brunet, M. F., Korotaev, M. V., Ershov, A. V. & Nikishin, A. M,. 2003- The South Caspian Basin: a review of its evolution from subsidence modelling. In: Brunet, M.-F and Cloetingh S. (Eds) Integrated Peri-Tethyan basins studies (Peri-Tethys Programme). Sedimentary Geology, 156, 119-148.
Clark, D. L., Davies, R. G., Hamzehpour, B. & Jones, C. R., 1975- Explanatory text of the Bandar-e-Pahlavi Quadrangle. Map. Geo. Surv. Iran, Tehran. 198 p.
Davoudzadeh, M. & Schmidt, K., 1984- A Review of the Mesozoic Paleogeography and Paleotectonic Evolution of Iran. N. Jb Geol. Paläont. Abh., 168: 182-207.
Dercourt, J., Zonenshain, L. P., Ricou, L. E., Kazmin, V. G., Le Pichon, X., Knipper, A. L., Grandjacquet, C., Sbortshikov, I. M., Geyssant, J., Lepvrier, C., Pechersky, D. H., Boulin, J., Sibuet, J. C., Savostin, L. A., Sorokhtin, O., Westphal, M., Bazhenov, M. L., Lauer, J. P. & Biju-Duval, B., 1986- Geological evolution of the tethys belt from the Atlantic to the Pamirs since the Lias. Tectonophysics, 123(1-4): 241-315.
Dercourt, J., Gaetani, M., Vrielynck, B., Barrier, E., Biju-Duval, B., Brunet, M., F., Cadet, J. P., Crasquin, S., Sandulescu, M. (Eds.), 2000- Atlas Peri-Tethys. Palaeogeographical Maps. CCGM/CGMW, Paris (24 maps and explanatory notes: I –XX; 269).
Fauvelet, E. & Eftekhar-Nezhad, J., 1992- Explanatory text of the Gonabad Quadrangle Map (1/ 250 000). Geol. Surv. Iran, Tehran.
Furon, R., 1941- Géologie du plateau iranien (Perse-Afghanistan-Beloutchistan). Paris, Mém. Mus. Nal. Hist. Natur., 7/7: 177-414.
Fürsich, F., Wilmsen, M., Seyed-Emami, K., Cecca, F. and Majidifard, M.R., 2005- The upper Shemshak Formation (Toarcian–Aalenian) of the Eastern Alborz (Iran): Biota and palaeoenvironments during a transgressive–regressive cycle. Facies, 51 (1–2): 365-384.
Fürsich, F. T., Wilmsen, M., Seyed-Emami, K. & Majidifard, M. R., 2008- Lithostratigraphy of the Upper Triassic-Middle Jurassic Shemshak Group of northern Iran. In: Brunet, M.-F., Wilmsen M. and Granath J. W. (Eds) South Caspian, North to Central Iran Basins, Geological Society London, Special Publication (accepté).
Horton, B. K., Hassanzadeh, J., Stockli, D. F., Axen, G. J., Gillis, R. J., Guest, B., Amini, A., Fakhari, M. D., Zamanzadeh, S. M. & Grove, M., 2008- Detrital zircon provenance of Neoproterozoic to Cenozoic deposits in Iran: Implications for chronostratigraphy and collisional tectonics. Tectonophysics.
Jenny, J., 1978- Précambrien et Paléozoïque inférieur de I’Elbourz oriental entre Aliabad et Shahrud, Iran du nord-est. Ecl. Geol. Helv., 70: 761-770.
Kazmin, V. G. & Tikhonova, N. F., 2005- Early Mesozoic Marginal Seas in the Black Sea and Caucasus Region: Paleotectonic Reconstruction. Geotectonics, Vol. 39, N° 5: 349-363.
Kazmin, V. G. & Tikhonova, N. F., 2006- Late Cretaceous-Eocene Marginal Seas in the Black Sea-Caspian Region: Paleotectonic Reconstructions. Geotectonics, Vol. 40, N° 3: 169–182.
Kazmin, V. G., 1991- Collision and rifting in the Tethys Ocean: geodynamic implications. Tectonophysics, 196: 371–384.
Kazmin, V. G., Ricou, L. E. & Sbortshikov, I. M., 1986- Structure and evolution of the passive margin of the Eastern Tethys. Tectonophysics, 123: 153-179.
Kazmin, V. G. & Sborschikov, I. M., 1989- Paleozoic and early Mesozoic deformations on the Caucasus, and their place in the Tethys history. In: Belov, A.A., Satian, M.A. (Eds.), Geodynamics of the Caucasus. Nauka, Moscow, 46– 54 (in Russian).
Kristan-Tollmann, E., Tollmann, A. & Halnedani, A., 1979- Beitraige zur Kenntnis der Trias yon Persien. I. Revision der Triasgliederung, Rhfit fazies im Raum yon Is fahan und Kossener Fazieseinschlag bet Waliabad SE Abadeh. Wien, Mitt. oster. geol. Ges., Vol. 70: 119-186.
Lemaire, M. M., Westphal, M., Gurevitch, E. L., Nazarov, K., Feinberg, H. & Pozzi, J. P., 1997- How far between Iran and Eurasia was the Turan plate during Triassic-Jurassic times? Geologie en Mijnbouw, 76: 73–82.
Nabavi, M. H. & Seyed-Emami, K., 1977- Sinemurian ammonites from the Shemshak Formation of north Iran (Semnan area. Alhorz). N. Jb. Geol. Paläont. Abhand., 153(70-85).
Nazari, H., 2006- Analyse de la tectonique récente et active dans l’Alborz Central et la région de Téhéran : « Approche morphotectonique et paléoseismologique ». Thèse, Université Montpellier II, Montpellier, 247 p.
Poursoltani, M. R., Moussavi-Harami, R. & Gibling, M. R., 2007- Jurassic deep-water fans in the Neo-Tethys Ocean: The Kashafrud Formation of the Kopet-Dagh Basin, Iran. Sedimentary Geology, Vol. 198(1-2): 53-74.
Rad, F. K., 1986- A Jurassic delta in the eastern Alborz, NE Iran. Journal of Petroleum Geology, 9(3): 281-294.
Repin, Y., 1987- Stratigraphy and paleogeography of coal-bearing sediments of Iran. Unpublished Report. Nat. Iran Steel Comp., Tehran: 1:1-326; 2:1-198; 3:37 [in Persian].
Ricou, L. E., 1994- Tethys reconstructed: plates, continental fragments and their boundaries since 260 Ma from Central America to South-eastern Asia. Geodinamica Acta (Paris), 74: 169-218.
Rieben, E. H., 1966- Geological observation on alluvial deposits in northern Iran. Geological Survey of Iran, Tehran; Iran.P. 39.
Ruttner, A. W., 1993- Southern borderland of Triassic Laurasia in NE Iran. Geologische Rundschau, 82: 110– 120.
Sabzehei, M., 1993- Geological Map of Zardu (1/ 100 000). Geol. Surv. Iran, Tehran.
Saidi, A., 1995- Calendrier de la migration permo-triasique et morcellement mésozoïque des éléments continentaux de l’Iran., Thèse, Univ. Pierre et Marie Curie, Paris, France, 298 p.
Saidi, A., Brunet M. F., & Ricou L. E., 1997- Continental accretion of the Iran Block to Eurasia as seen from Late Paleozoic to Early Cretaceous subsidence curves. Geodin. Acta, 10: 189-208.
Sengör, A. M. C. & Kidd, W. S. F., 1979- Post-collisional tectonics of the Turkish-Iranian plateau and a comparison with Tibet. Tectonophysics, 55(3-4): 361-376.
Sengör, A. M. C., 1984- The Cimmeride orogenic system and the tectonics of Eurasia. Geological Society of America Special Paper 195: 181–241.
Seyed-Emami, K. & Alavi-Naini, M., 1990- Bajocian stage in Iran. Mem. Descrit. Carta. Geol. Ital., 40: 215-221.
Seyed-Emami, K., 2003- Triassic in Iran. Facies, 48: 91–106.
Seyed-Emami, K., Fürsich, F., Wilmsen, M., Schairer, G. & Majidifard, M., 2005- Toarcian and Alenian (Jurassic) ammonites from the Shemshak Formation of the Jajarm area (eastern Alborz, Iran). Palaeo. Zeitschrift, 79/3: 349-369.
Shahidi, A., 2005- Evolution tectonique et géodynamique des chaînes de l’Alborz et du Kopet-Dagh (Iran) depuis le Mésozoïque, Journées des Doctorants, 16 et 17 juin 2005, Ecole des Mines de Paris.
Shahidi, A., 2008- Evolution tectonique du Nord de L'Iran (Alborz et Kopet-Dagh)     depuis le Mésozoïque. Thèse, Université Pierre et Marie Curie (Paris 6), 500 p.
Shahidi, A., Barrier; E. & Brunet, M. F., 2008a- Tectonic and late Triassic-Middle Eocene extension in central Alborz, Iran. Scientific Quarterly Journal (GSI), Vol. 17, N° 1 (Special Issue): 4-25  
Stampfli, G., Mosar, J., Favre, P., Pillevuit, A. & Vannay, J., 2001- Permo-Mesozoic evolution of the western Tethys realm: the Neo-Tethys East Mediterranean Basin connection. Peri-Tethys Memoire 6, peri-Tethyan Rift/Wrench Basins and Passive Margins, Tome 186: 51-108.
Stampfli, G. M., 1978- Etude géologique générale de I'Elburz oriental au S de Gonbad-e-Qabus (Iran. N-E). Thèse, Université de Genève, 328 p.
Steiger, R., 1966- Die Geologie der West-Firuzkuh area (Zentral Elburz, Iran). Mitt. Geol. Inst. Eth. Univ. Zürich: 145.
Stöcklin, J., 1974- Northern Iran: Alborz Mountains. Geol. Soc. Lon., Special Publication, N° 4: 213-234.
Taheri, J., Fürsich, F. T. & Wilmsen, M., 2008- Stratigraphy, depositional environments, and geodynamic significance of the Upper Bajocian-Bathonian Kashafrud Formation (NE Iran). In: Brunet, M.-F., Wilmsen M. and Granath J. W. (eds) South Caspian, North to Central Iran Basins, Geological Society London, Special Publication (accepté).
Taraz, H., 1974- Geology of the Surmaq-Dehbid area, Abadeh region, Central lran. Internal report, Geol. Surv. lran, Tehran, Vol. 37: 1-138.
Vaez-Javadi, F. & Ghavidel-Syooki, M., 2006- Systematic Study of Spore and Pollen in Shemshak Formation, Jajarm Area. Scientific Quarterly Journal (GSI), Vol. 12, N° 56: 94-123.
Vaziri Moghadam, H. & Taheri, A., 2004- Study of Ichnofossils and Ichnofacies of the Upper Part of the Shemshak Formation at Tazareh Area (North East Damghan). Scientific Quarterly Journal (GSI), Vol. 12, N° 51-52: 46-57.
Völlmer, T., 1987- Zur Geologie des nordlichen Zentral-Elburz zwischen Chalus- und Haraz-Tal, Iran. Mitteilungen aus dem Geologisch-Palaontologischen. Institut der Universitat Hamburg, 63: 1–125.
Zonenshain, L. P., Kuzmin, M. I., & Natapov, L. M., 1990- Geology of the USSR: a plate-tectonic synthesis. In: Page, B.M. (Ed.), American Geophysical Union, Geodyn. Ser., Washington, DC, vol. 21, 242.