Document Type : Original Research Paper

Authors

1 Department of Geology, Lahijan Branch, Islamic Azad University, Lahijan, Iran

2 Department of Geology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran

3 Department of Geology, Faculty of Sciences, Islamic Azad University, North Branch, Tehran, Iran

Abstract

Many examples of tear faults are observed in Tabas block. These faults are usually seen in belts with active folds. In this research, an example of the mentioned faults has been studied. The axis of the Kamarmahdi anticline has a north-south trend. In the north of Kamarmehdi anticline, there is a fault with an approximate trend of N75E which does not have a clear shear sense on the ground, and the geological structures on both sides of this fault are also different. This research has been done to determine the shear direction of the said fault. For determining the shear sense of this fault, a geological map with a scale of 1:1000, was prepared and the boundary of the rock units and the folding axis are taken as a guide to calculate the fault shear direction. The amount of heave (143m) and throw (331m) of fault was determined after preparing the geological cross sections on both sides of the tear fault, using AutoCAD software. By determining the movement direction of the fault, the existence of the tear fault and its displacement has been proven, and the movement pattern of the formation of the tear fault has been presented.

Keywords

Main Subjects

Aghanabati, A., 2010. Geology of Iran. 3rd Edition, Geological Survey of Iran, 586 p. (In Persian)
Aghanabati, A., 1992. An introduction to the Mid-Cimmerian (Middle Jurassic) tectonic event. Scientific Quarterly Journal of Geosciences, 2(6), 2-5. (In Persian with English Abstract).
Alavi, M., 1991. Sedimentary and structural characteristics of the Paleo–Tethys remnants in North Eastern Iran. Bull. Geol. Soc. of Amer., 103, 983-992.
Allmendinger, R.W., 1999. Introduction to structural geology. Cornell University, New York, 275 p.
Ameri, H., Dastanpour, M., Khalilizade, H., and Zamani, F., 2013. Plant fossil remains from the Bajocian–Bathonian of Hojedk Formation, Babhutk area, Kerman, Iran. Arabian Journal of Geosciences, 7 (6), 2293–2302. DOI:10.1007/s12517-013-0878-5
Babaei, S., Dehbozorgi, M., and Hakimi-Asiabar, S., 2017. Assessment of active tectonics by using morphometric indices in Central Alborz. Iranian Association of Geomorphology, Quarterly Quantitative Geomorphological researches, 1,40-56.
Badihagh, M. T., Sajjadi, F., Farmani, T. and Uhl, D., 2019. Middle Jurassic palaeoenvironment and palaeobiogeography of the Tabas Block, Central Iran: palynological and palaeobotanical Investigations. Palaeobiodiversity and Palaeoenvironments, V. 99, 379–399. DOI:10.1007/s12549-018-0361-0.
Cooper, M., 1992, The analysis of fracture systems insubsurface thrust structures from the Foothills ofthe Canadian Rockies, in McClay, K. R., ed., Thrust tectonics: London, Chapman and Hall. p. 391–405.
Ford, M., Williams, E.A., Artoni, A., Verges, J. and Hardy, S., 1997. Progressive evolution of a fault-related fold pair from growth strata geometries, Sant Llorens De Morunys, Se Pyrenees. J. Struct. Geol., 19, 413–441.
Ghassemi, M. R., Aghanabti, A., Saeidi, A., 2023. Orogenic and epeirogenic events in Iran. Geological Survey of Iran, Scientific Quarterly Journal of Geosciences, 33(1), 87-106. (In Persian).
Hakimi-Asiabar, S., Bagheriyan, S., 2018. Exhumation of the Deylaman fault trend and its effects on the deformation style of the western Alborz belt in Iran. International Journal of Earth Sciences, 107, 539-551.
Hakimi-Asiabar, S., 2019. Structural deformations of Dona mine. Scientific Quarterly Journal of Geosciences, 110, 235-246. (In Persian).
Hakimi-Asiabar, S., Pourkermani, M., Shahriari, S., Ghorbani, M., Ghasemi M.R. 2011. Geological zones of western Alborz Mountains. Journal of Sciences Islamic Azad University, 21, 113-124.
Linzer, H.G., Ratschbacher, L., Frisch, W., 1995. Transpressional collision structures in the upper crust: The fold-thrust belt of the Northern Calcareous Alps. Tectonophysics, 242, 41–61.
 Lisle, R. J., 2004. Folding". Geological Structures and Maps: 3rd Edition. Elsevier. pp. 33. ISBN 0-7506-5780-4.
Malek-Mahmoudi, M., Nazari, H., Ghorbani, M. andChizari, Sh., 2014. Relationship between tectonic structures and vein mineralization of Kammermehdi fluorite mine. International Specialized Congress of Earth Sciences.(In persion)
Mitra, S., 1988. Three-dimensional geometry and kinematic evolution of the Pine Mountain thrust system, southern Appalachians. Geological Society of America Bulletin, 100, 72–95.
Mousavi, M. J., 1381. Palynostratigraphy, paleoecology, paleobiogeography and sedimentary environment of the Shamshak Group (Nayband Formation) in the southern and northern slopes of Nayband Mountain, PhD Thesis, Science and Research Unit, Islamic Azad University.(In persion)
Ortner, H., Kositz A., Ernst,W., and Dimitrios, S., 2015. Geometry of growth strata in a transpressive fold belt in field and analogue model: Gosau Group at Muttekopf, Northern Calcareous Alps. Austria, Basin Research, 28(6), 1-21.
Twiss, R.J. and Moores, E.M., 1992. Structural geology. W.H. Freeman & Company, 532 p.
Samarbakhsh, S., Emami, M. H., Mortazavi, S.M., and Vosoughi-Abedini, M., 2023. Geochemistry and petrology of Upper Triassic basic volcanic rocks in the Central Alborz region, south of Pole Sefid. Scientific Quarterly Journal of Geosciences, 33(1), 123-142. (In Persian).
Stöcklin, J., 1968. Structural history and tectonics of Iran. American Association of Petroleum Geologists Bulletin,Vol. 52 (7), 1229-1258.
Vaez-Javadi F. and Abbaszadeh, M., 2022. Biostratigraphy of plant macrofossils of the Mazino, southwest of Tabas, Central East of Iran and its palaeoecological analysis. Geological Survey of Iran, Scientific Quarterly Journal of Geosciences, 32(4), 209-220.
Vaez-Javadi, F., 2018. Middle Jurassic flora from the Hojedk Formation of Tabas, central east Iran: Biostratigraphy and Palaeoclimate implications. RivistaItaliana di Paleontologia e Stratigrafia, 124 (2), 299-316. doi.org/10.13130/2039-4942/10083.
VaezJavadi, F., 2014. Triassic and Jurassic Floras and Climate of Central-East Iran. Geological Survey of Iran- Rahi publication, Tehran, 290 pp.
Zapata, T. and Allemendinger, R.W.,1996. Growth stratal records of instantaneous and progressive limb rotation in the Precordillera thrust belt and Bermejo Basin, Argentina: Tectonics, 15, 1065–1083.
Zanchi, A., Malaspina, N., Zanchetta, S., Berra, F., Benciolini, L., Bergomi, M., Cavallo, A., Javadi, H. R. and Kouhpeyma, M., 2015. The Cimmerian accretionary wedge of Anarak, Central Iran. Journal of Asian Earth Sciences, V. 102, pp. 45-72.