Document Type : Original Research Paper

Author

Geological Survey of Iran, Tehran, Iran

Abstract

Some structural evidences of continental transpression are studied and compared with experimental modeling results in the Birk area. These evidences are: fold axes have a double plunging en-echelon pattern. Fold axes mean orientations and fracture cleavages strike form angles less than 45 degrees with the boundary faults. Strike-slip faults have an en-echelon and domainal pattern. Synthetic P Shears are more abundant than synthetic R shears. Flat tension vein (and normal faults) planes lie at a high-angle with respect to folds axes and this condition proposes some amounts of hinge-parallel extensions. Inclined dextral layer-parallel detachment faults and related structures such as asymmetric dextrally verging minor folds, traspressional and trastensional faults and large-scale half flower structures are other structural features of dextral transpression. It is believed that partitioning of dextral component of wrench-dominated continental transpression is due to reactivation of N-S striking basement faults in late Neogene.

Keywords

References
Berberian, M., Jackson, J. A., Qorashi, M., Talebian, M., Khatib, M. & Peristly, K., 2000-The 1994 Sefidabeh earthquakes in eastern Iran: blind thrusting and bedding- plane slip on a growing anticline, and active tectonics the Sistan suture zone,Geophys. J. Int, 142: 283-299. 
Berberian, M. & King, G. C., 1981- Towards a paleogeography and tectonic evolution  of Iran, Canadaian Journal of Earth Sciences, 18: 210-265.
Camp, V. E. & Griffis. R. J., 1982- Character, genesis and tectonic setting of igneous rocks in the Sistan sucture zone, Eastern Iran, Lithos, 15, 3: 221-239.
Eftekharnezhad, J., Lioyd. B., Squire, A ., Odinga, M., McCormic, C. & Griffiths, P., 1987- Geological map of Nareh-Now quadrangle-Scale 1:250000, No. M-12, GSI.
Fossen, H., Tikoff, B. & Teyssier, C., 1994- Strain modeling of transpressional and transtensional deformation, Norsk Geologisk Tidsskrift, 74: 134-145.     
Goscombe, B., Hand, M., Gray, D. & Mawby, J., 2003- The metamorphic architecture  of a transpressional orogen; the Kaoko Belt. Namibia, Jornal of Petrology, 44, 4: 125-138.
Harland, W. B., 1971- Tectonic transpression in Caledonian Spitzbergen, Geological Magazine, 108: 27-42.
James, A. I. & Watkinson, J., 1994- Initiation of folding and boudinage in wrench shear and transpression, Journal of Structural Geology, 16, 6, 883-893.
Jamison, W. R., 1991- Kinematics of compressional fold development in convergent wrench terranes, Tectonophysics, 190: 209-232.
Jones, R. R., Holdworth, R. E., Clegg, P., McCaffrey, K. & Tavernelli, E., 2004- Inclined Transpression, Journal of Structural Geology, 26: 1531-1548.
Jones, R. R. & Tanner, P. G., 1995- Strain partitioning in transpression zones, Journal of Structural Geology, 17: 793-802.
Keller, J. V. A., Hall, S. H. & McClay, K. R., 1997- Shear fracture pattern and microstructural evolution in transpressional fault zones from field and laboratory studies, Journal of Structural Geology, 19, 9: 1531-1548.
McCall, G. J. H., 1997- The geotectonic history of the Makran and adjacent areas of southern Iran, Journal of Asian Earth Sciences, 15, 6: 517-531
McCall, G. J. H., Eftekharnezhad, J., Kidd, R. G. W., Haligan, R., Kousha, N., Lloyd, B., McCormic, C., Malett, C. W., Morgan, K. H., Nuun, G. A. G., Deighton, I., Rosario, P. C., Doepel, M. G., Forte, W. S., Jones, D. R., Spencer, L. k., Odinga, M., Squire, A., Porter, D. J., Stanistreet, I. G. &  Redfern, P., 1994-  Explanatory text of the  Saravan quadrangle map scale 1:250000,No: M-13, GSI, 246p.
Richard, P., Mocquet, B. & Cobbold, P., 1991- Experiment on simultaneous faulting and folding above a basement wrench fault, Tectonophysics, 188:133-141.       
Schreurs, W. P. &  Colletta, B., 2002- Analogue modelling of Continental Transpression, Journal of the virtual Explorer, 6: 67-78.
Sadeghian, M., Bouchez, L. J., Nedelec, A., Siqueira, R. & Valizadeh, M. V., 2005- The granite pluton of Zahedan(SE Iran): a petrological and magnetic fabric study of a syntectonic sill emplaced in transtensional setting, Jounal of Asian Earth Science, 25: 301-327.
Tavernelli, E., Holdworth, R. E., Clegg, P., Jones, R. R. & McCaffrey, K. J. W., 2004- The anatomy and evolution of a transpressional imbricate zone: sothern Upland, Scotland, Journal of Structural Geology, 26: 134-136.
Tikoff, B. & Peterson, K., 1998- Physical experiments of transpressional folding, Journal of Structural Geology, 20, 6: 661-672.
Tirrul, R., Griffis, R. J., Bell, I. R. & Camp, V. E., 1983- The sistan suture zone of eastern Iran, Geological society of American bulletin, 94: 134-150.
Walker, R. & Jackson, J., 2004- Active tectonics and late Cenozoic strain distribution in central and eastern Iran, Tectonics, 23: TC5010,doi:                               10.1029/2003TC001529.