Multi-phase inversion tectonics related to the Hendijan–Nowrooz–Khafji Fault activity, Zagros Mountains, SW Iran

Highlights

  • Inverted structures are important criteria for the identification of certain structural styles.
  • Analysis of thickness variations of growth strata revealed the kinematics of the fault.
  • Fault has experienced a multi-phase evolutionary history over six different deformation events.
  • The structural development of the study area was ultimately controlled by the collision.

Abstract

Distinctive characteristics of inverted structures make them important criteria for the identification of certain structural styles of folded belts. The interpretation of 3D seismic reflection and well data sheds new light on the structural evolution and age of inverted structures associated to the Hendijan–Nowrooz–Khafji Fault within the Persian Gulf Basin and northeastern margin of Afro-Arabian plate. Analysis of thickness variations of growth strata using “T-Z plot” (thickness versus throw plot) method revealed the kinematics of the fault. Obtained results show that the fault has experienced a multi-phase evolutionary history over six different extension and compression deformation events (i.e. positive and negative inversion) between 252.2 and 11.62 Ma. This cyclic activity of the growth fault was resulted from alteration of sedimentary processes during continuous fault slip. The structural development of the study area both during positive and negative inversion geometry styles was ultimately controlled by the relative motion between the Afro-Arabian and Central-Iranian plates.

Introduction

Inversion tectonics was introduced by several authors (e.g. Glennie and Boegner, 1981, Cooper and Williams, 1989) to describe changes of tectonic regime from extension to compression, and vice versa. After introducing different type of inverted structures (i.e. positive and negative types) by Williams et al. (1989), several examples of these structures were recognized and described worldwide (e.g. Biji, 2006 and references cited therein). Positive and negative inverted structures are created in response to change of tectonic regime following the contractional reactivation of inherited normal faults or extensional reactivation of inherited reverse faults, respectively (Fig. 1). Distinctive characteristics of inversion-related structural geometries consist of anomalous variations of fault-throw with depth, thicker strata on the hanging wall of thrusts faults and footwall shortcut thrusts (Cooper and Williams, 1989). The recognition of inverted structures is important in the oil industry because inversion can: a) modify the burial history of a sedimentary basin, b) uplift sediments above sea level generating secondary porosity, c) modify the attitude of the sedimentary package, allowing different directions of fluid migration with time, d)reactivate older faults, changing their sealing properties and e) form complex structures at depth and care needs to be taken to differentiate these from single event compressive thin-skinned thrust structures (Coward, 1994).

Constraining reactivation processes has practical implications for improving the evaluation of seismic hazards (Lisle and Srivastava, 2004) and assessing the impact of reactivation on fault seal quality and fluid migration (Holdsworth et al., 1997). The main gaol of this study is to describe and quantify the style of inversion tectonics adjacent to the Hendijan–Nowrooz–Khafji Fault from the Persian Gulf Basin and northeastern margin of the Afro-Arabian plate (Fig. 2). Due to the occurrence of large oil and gas resources of Iran and Saudi Arabia (Fig. 3) in the vicinity of this fault, it has tremendous geological and industrial importance. The Hendijan high and the Burgan–Azadegan high with NE–SW and N–S trends are the most prominent structural features in the Persian Gulf Basin. The Hendijan and Burgan–Azadegan high are structural trends were named based on elongated topographical feature in north part of Persian Gulf (the geological map of National Iranian Oil Company in SW Iran at scale 1:10,00,000). The Hendijan high in SW Iran hosts several Iranian and Saudi Arabian oil fields (Abdollahie Fard et al., 2006). The Hendijan Fault is one of the Important Lineaments that have Arabian tectonic trend and refer of a syncline structure in Arabian plate (Bahroudi and Talbot, 2003). These structures extend to the N within the Zagros Mountains (Fig. 2). Hence, we discuss the kinematic evolution of the Hendijan Fault based on the quantitative interpretation of 3D seismic reflection and well data. In this paper, we present new tectono-sedimentary data based on the geological interpretation of seismic sections to support the occurrence of a multi-phase inversion tectonics related to the Hendijan–Nowrooz––Khafji Fault activity within the Zagros Mountains, SW Iran. Based on the interpretation of growth strata and seismic stratigraphy, this paper describes the geometry styles of inverted structures and reliably approximates the age of the beginning of the positive and negative inversions in the Persian Gulf Basin.

Section snippets

Geological and tectonic settings

The Zagros Mountains is one of the most active collisional orogens within the Alpine–Himalayan orogenic belt. Closure of the Neotethys Ocean which resulted from oblique convergence between the Afro-Arabian plate and Central Iranian plate during the Cenozoic led to formation of this belt (Mouthereau et al., 2012 and references cited therein). Both the Zagros Range and its foreland belong to the northeastern part of the Afro-Arabian Plate. The Persian Gulf Basin, a rich region of hydrocarbon

Methods

In active tectonic settings, growing structures often control the deposition process at different scales (Vergés et al., 2002). Growth fault activity led to change in the sediment thickness across the fault (i.e. synsedimentary fault). This event causes the differences in thickness of sediments both on the footwall and hanging wall during time of fault activity. Fault throws subsequent to the sedimentation of each horizon and the fault movement history can be determined using these thickness

Analysis of throw versus time

The long-term evolution of the fault displacement rate during time was analyzed in order to determine the major factor which controls short-term thickness variations in growth strata (i.e. fault movement or sedimentation dynamics). This research focuses on the study of variation of the vertical throw of each timeline during time (Fig. 9). These particular stratigraphic surfaces can be considered as representing a nearly instantaneous event at the scale of a sedimentary basin or such km-scale

Tectonic inversion adjacent to the Hendijan–Nowrooz–Khafji Fault

Reactivation of faults activity during different deformation phases has been reported for several tectonic regimes worldwide (Cooper and Williams, 1989). The stresses acting along the plate margins can be transmitted far into the foreland resulting in the reactivation of pre-existing normal faults (Ziegler et al., 1995). Moreover, changes from early extension to later contraction in the foreland domains which previously affected by normal faulting have promoted positive tectonic inversion (

Conclusion

Kinematic Analysis of the Hendijan–Nowrooz_Khafji Fault based on T-Z plot method provided a long-term evolution characterized by altered rate of the fault continuous slip during 240.55 millions of years. Based on the detailed interpretation of a high quality 3D seismic reflection sections, the throw versus times measurements reveal six phases of the fault activity with different rate of throw in each phase. Two distinct mode of reactivation (i.e. positive and negative inversion) are recognized

Acknowledgments

The authors would like to thank the editor Professor Eriksson for his editorial authority. We gratefully acknowledge constructive reviews by an anonymous reviewer, which helped to considerably improve the scientific content and presentation of the manuscript. Important comments by Professor Timothy Kusky improved the presentation of the paper. Important supports by the research council of Ferdowsi University of Mashhad and Shiraz University are gratefully acknowledged.

References (52)

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