BASIN EVOLUTION OF THE LURESTAN REGION IN THE ZAGROS FOLD-AND-THRUST BELT, IRAN

A. Farzipour-Saein1, A. Yassaghi1*, S. Sherkati2 and H. Koyi3

1 Geology Department, Faculty of Sciences, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran.

2 National Iranian Oil Company, Exploration Directorate, Sheykh Bahaie Sq., Seoul Avenue, Tehran, Iran.

3 Hans Ramberg Tectonic Laboratory, Department of Earth Sciences, Uppsala University, Villavägen 1, SE-752 36 Uppsala, Swede

* Corresponding author: Department of Geology, Tarbiat Modares University, PO Box 14115-175, Tehran, Iran. email: yassaghi@modares.ac.ir

The evolution of the central part of the Lurestan region in the Zagros fold-and-thrust belt has been studied using newly generated isopach maps for different time intervals between the Late Cretaceous and the Miocene. The study was based on existing geological maps, gravity data, measured stratigraphic surface sections, original field work and well data. Understanding the processes which have influenced facies and thickness variations in the study area will have a significant impact on future hydrocarbon exploration.

Cenomanian carbonates assigned to the Sarvak Formation, the main reservoir unit in the study area, are composed of both pelagic and neritic facies. These facies occur along the roughly north-south trending “Anaran lineament”, interpreted to represent a palaeohigh, which influenced patterns of sedimentation in the Cretaceous-Tertiary. The palaeohigh formed as a result of the reactivation of a basement lineament in the Late Cretaceous. The continuing influence of this lineament on patterns of sedimentation during Oligocene – early Miocene time is indicated by a range of evidence including the presence of clinoform geometries.

Analysis of sedimentary thicknesses in the Zagros foreland basin between the Late Cretaceous and the early Miocene indicates progressive SWward migration of the depocentre. Late Cretaceous ophiolite obduction and plate margin convergence exerted a major influence on stratigraphic architecture, and controlled depocentre migration and foreland basin evolution.

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