Document Type : Original Paper

Authors

Department of Geology, Faculty of Basic Sciences, Tarbiat Modares University, Tehran, Islamic Republic of Iran

Abstract

Suture zones within continental collision zones generally considered as deep-seated thick-skinned thrusts/shear zones rotted in lower crust. Main Zagros Revers Fault (MZRF) is the suture zone for continental collision between the Afro-Arabia and Eurassia plates. The fault comprises of a main thrust in its NW part (Baneh area) while is partitioned to four fault splays in its SE part (Sharekord area). Evaluation of deformation conditions of the MZRF fault rocks carried out using quartz, feldspar and calcite twins’ microstructures as well as mineral composition indicates that the fault has propagated from various conditions correspond to different brittle to brittle-ductile transition zones. This implies localization and partitioning of deformation along strike of the Zagros suture zone. In the Baneh area, the suture zone is an emerged deep-rotted ductile zone, while in the Shahrekord area, this zone is detached at a basal detachment zone between basement and cover and then partitioned into four fault splays through its propagation to the upper structural level. This show that suture zones in orogenic belts might have changes along strike from thick-skinned to thin-skinned thrusts.

Keywords

Main Subjects

  1. Van der Pluijm BA, Marshak S. Earth structure: an introduction to structural geology and tectonics; 1997.
  2. Şengör, ACl. Plate tectonics and orogenic research after 25 years: A Tethyan perspective. Earth-Science Reviews. 1990;27(1-2):1-201.
  3. Braudy N, Gaschnig R, Wilford D, Vervoort J, Nelson C, Davidson C, et al. Timing and deformation conditions of the western Idaho shear zone, West Mountain, west-central Idaho. Lithosphere. 2017; 9 (2):157-83.
  4. Barr TD, Dahlen F. Brittle frictional mountain building: 2. Thermal structure and heat budget. Journal of Geophysical Research: Solid Earth. 1989; 94 (B4):3923-47.
  5. Karabinos P, Ketcham R. Thermal structure of active thrust belts. Journal of Metamorphic Geology. 1988; 6 (5):559-70.
  6. Vityk MO, Bodnar RJ, Dudok IV. Fluid inclusions in “Marmarosh Diamonds”: evidence for tectonic history of the Folded Carpathian Mountains, Ukraine. Tectonophysics. 1996; 255 (1-2):163-74.
  7. Burkhard M. Calcite twins, their geometry, appearance and significance as stress-strain markers and indicators of tectonic regime: a review. Journal of structural geology. 1993; 15 (3-5):351-68.
  8. Tullis J, Yund RA. Diffusion creep in feldspar aggregates: experimental evidence. Journal of Structural Geology. 1991; 13 (9):987-1000.
  9. Agard P, Omrani J, Jolivet L, Whitechurch H, Vrielynck B, Spakman W, et al. Zagros orogeny: a subduction-dominated process. Geological Magazine. 2011; 148 (5-6):692-725.
  1. Berberian M, King G. Towards a paleogeography and tectonic evolution of Iran. Canadian journal of earth sciences. 1981; 18 (2):210-65.
  2. Sadeghi S, Yassaghi A. Spatial evolution of Zagros collision zone in Kurdistan, NW Iran: Constraints on Arabia–Eurasia oblique convergence. Solid Earth. 2016; 7 (2):659-72.
  3. Yassaghi A, Marone C. The relationship between fault zone structure and frictional heterogeneity, insight from faults in the High Zagros. Tectonophysics. 2019; 762:109-20.
  4. Gidon M, Berthier F, Billiautt J, Halbronn B, Maurizot P. Sur quelques caractères de la tectonique néocrétacée dans la région de Borudjerd (Zagros oriental, Iran). Comptes Rendus de l'Académie des Sciences. 1974; 278(Série D):577.
  5. Karim KH, Koyi H, Baziany MM, Hessami K. Significance of angular unconformities between Cretaceous and Tertiary strata in the northwestern segment of the Zagros fold–thrust belt, Kurdistan Region, NE Iraq. Geological Magazine. 2011; 148(5-6):925-39.
  6. Kazmin V, Ricou L-E, Sbortshikov I. Structure and evolution of the passive margin of the eastern Tethys. Tectonophysics. 1986; 123(1-4):153-79.
  7. Allen MB, Armstrong HA. Arabia–Eurasia collision and the forcing of mid-Cenozoic global cooling. Palaeogeography, Palaeoclimatology, Palaeoecology. 2008; 265 (1-2):52-8.
  8. McQuarrie N, van Hinsbergen DJ. Retrodeforming the Arabia-Eurasia collision zone: Age of collision versus magnitude of continental subduction. Geology. 2013; 41 (3):315-8.
  9. Mouthereau F, Lacombe O, Vergés J. Building the Zagros collisional orogen: timing, strain distribution and the dynamics of Arabia/Eurasia plate convergence. Tectonophysics. 2012; 532: 27-60.
  10. Mouthereau F, Tensi J, Bellahsen N, Lacombe O, De Boisgrollier T, Kargar S. Tertiary sequence of deformation in a thin‐skinned/thick‐skinned collision belt: The Zagros Folded Belt (Fars, Iran). Tectonics. 2007; 26 (5).
  11. Allen MB, Kheirkhah M, Emami MH, Jones SJ. Right-lateral shear across Iran and kinematic change in the Arabia—Eurasia collision zone. Geophysical Journal International. 2011; 184 (2): 555-74.
  12. Jackson J. Partitioning of strike‐slip and convergent motion between Eurasia and Arabia in eastern Turkey and the Caucasus. Journal of Geophysical Research: Solid Earth. 1992;97(B9):12471-9.
  13. Jackson J, McKenzie D. Active tectonics of the Alpine—Himalayan Belt between western Turkey and Pakistan. Geophysical Journal International. 1984; 77 (1):185-264.
  14. Talebian M, Jackson J. A reappraisal of earthquake focal mechanisms and active shortening in the Zagros mountains of Iran. Geophysical Journal International. 2004; 156 (3):506-26.
  15. Copley A, Jackson J. Active tectonics of the Turkish‐Iranian plateau. Tectonics. 2006; 25 (6).
  16. McQuarrie N, Stock J, Verdel C, Wernicke B. Cenozoic evolution of Neotethys and implications for the causes of plate motions. Geophysical research letters. 2003; 30 (20).
  17. Mohajjel M, Fergusson C, Sahandi M. Cretaceous–Tertiary convergence and continental collision, Sanandaj–Sirjan zone, western Iran. Journal of Asian Earth Sciences. 2003; 21 (4):397-412
  18. Takin M. Iranian geology and continental drift in the Middle East. Nature. 1972; 235:147-50.
  19. Nemati M, Yassaghi A. Structural characteristics of the transitional zone from internal to external parts of the Zagros orogen, Iran. Journal of Asian Earth Sciences. 2010; 39 (3):161-72.
  20. Mitra G, Marshak S. Basic Methods of structural Geology, Prentic–Hall. Inc, New Jersey. 1988:232-3.
  21. Rietveld HM. A profile refinement method for nuclear and magnetic structures. Journal of applied Crystallography. 1969; 2 (2):65-71.
  22. Ferrill DA, Morris AP, Evans MA, Burkhard M, Groshong Jr RH, Onasch CM. Calcite twin morphology: a low-temperature deformation geothermometer. Journal of structural Geology. 2004; 26 (8):1521-9.
  23. Aswad KJ, Aziz NR, Koyi HA. Cr-spinel compositions in serpentinites and their implications for the petrotectonic history of the Zagros Suture Zone, Kurdistan Region, Iraq. Geological magazine. 2011; 148 (5-6):802-18.
  24. Trouw RA, Passchier CW, Wiersma DJ. Atlas of Mylonites-and related microstructures: Springer Science & Business Media; 2009.
  25. Hirth G, Tullis J. Dislocation creep regimes in quartz aggregates. Journal of structural geology. 1992; 14 (2):145-59.
  26. Stipp M, StuÈnitz H, Heilbronner R, Schmid SM. The eastern Tonale fault zone: a ‘natural laboratory’for crystal plastic deformation of quartz over a temperature range from 250 to 700 C. Journal of structural geology. 2002; 24 (12):1861-84.
  27. Passchier CW, Trouw RA. Microtectonics: Springer Science & Business Media; 2005.
  28. Fossen H. Structural geology: Cambridge university press; 2010.
  29. O’Hanley D. Oxford monographs on geology and geophysics. Serpentinites Records of Tectonic and Petrological History. 1996; 34.
  30. Iyer K. Mechanisms of serpentinization and some geochemical effects (Ph. D. Thesis). Oslo: University of Oslo, 2007. 2007.
  31. Blasband B, White S, Brooijmans P, De Boorder H, Visser W. Late Proterozoic extensional collapse in the Arabian–Nubian shield. Journal of the Geological Society. 2000; 157 (3):615-28.
  32. Al-Husseini MI. Origin of the Arabian Plate structures: Amar collision and Najd rift. GeoArabia. 2000; 5 (4):527-42.
  33. Sepehr M, Cosgrove J. Structural framework of the Zagros fold–thrust belt, Iran. Marine and Petroleum geology. 2004; 21 (7):829-43.
  34. McClay K, Buchanan P. Thrust faults in inverted extensional basins. Thrust tectonics. 1992:93-104.
  35. Sadeghi S, Yassaghi A, Fathollahi M. Structural Analysis of the Main Recent Fault and its Relation with the Main Zagros Reverse Fault in Kurdistan. Scientific Quarterly Journal of Geosciences. 2013; 22 (88):41-50.
  36. Kruse R, Stünitz H, Kunze K. Dynamic recrystallization processes in plagioclase porphyroclasts. Journal of Structural Geology. 2001; 23 (11):1781-802.