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A Paleostress Inversion and AMS Research of the Neogene Kinematics of the Potwar Plateau and the Salt Range, NW Himalaya

The main tectonic processes in the Himalayas are produced by the continuing convergence of the Indian Plate and the Eurasian Plate. The India-Eurasian collision is considered to have begun at 50–60 Ma, preceding the closure and total obliteration of the Neotethys oceanic lithosphere (DeCelles et al., 2002; Kapp and Decelles, 2019; Molnar and Tapponnier 1978; Meade 2007; Najman et al. 2010). The Indian Plate has been deformed into multiple fold-thrust belts at this period. The Sulaiman Range in the west and the Potwar Plateau in the northwest are examples (Figure 1). The Chaman Fault, a suture zone that divides the Indian Plate from the Eurasian Plate and demarcates the former position of the Neotethys, defines the western boundary of the Sulaiman Range, an east-verging fold-thrust belt.

The Himalayas are separated between the Indus Suture Zone (Main Mantle Thrust in Figure 1) – defined in the south by the Main Mantle Thrust – and the Himalayan Frontal Thrust (MFT) by foreland propagating sequences of thin-skinned thrust sheets and fold belts bounded by major faults (Figure 1). The Greater Himalayas are bounded in the north by the Indus suture (MMT) and in the south by the Main Central Thrust (MCT). The Greater Himalayas are composed of rocks metamorphosed to about 30 Ma, volcanic and sedimentary rocks, and are bounded by the Indus suture in the north (MMT) and the Main Central Thrust (MCT) in the south (Chaudhry and Ghazanfar 1990; DiPietro and Pogue 2004). The Lesser Himalayas are composed of Proterozoic metamorphosed rocks that really are overlain by sedimentary rocks, the youngest of which are Eocene-Oligocene marine deposits (DiPietro and Pogue 2004).

Between the Main Boundary Thrust (MBT) in the north and the Main Frontal Thrust (MFT) in the south, a continental foreland fold-thrust belt known as the Potwar Plateau and the Salt Range developed (Lillie 1987; McDougall et al. 1993). (Figure 1c). The Siwaliks Group of Neogene sedimentary rocks occupies the Foreland Basin (Potwar Plateau). These strata are connected to the propagation of the Himalayan deformation front southwards into the Potwar Plateau and Salt Range, which captured all of the major deformation phases associated with the development of the Himalayan frontal foreland basin during the Neogene (Baker et al. 1988; Yeats and Thakur 2008). However, no comprehensive studies have been conducted to determine the region's kinematics, which is needed to resolve the various stages of deformation at the Himalayan front.

Using newly obtained kinematic data based on fault slip data sets and AMS data collected from Siwaliks Group rocks exposed in the Potwar Plateau and the Salt Range, this article attempts to explain the Neogene deformation history of the NW Himalayan deformation front. We used the results of paleostress inversion with AMS vectors, which typically correspond to major strain axes in slightly to mildly deformed sedimentary rocks, to achieve this goal (Hirt et al. 1993; Sagnotti and Speranza 1993; Henry 1997; Borradaile 2001; Pares and Van Der 2002). The Potwar Plateau is also mildly deformed, as evidenced by the broad and gentle folding, and it lacks serious internal strike-slip displacement. As a consequence, the stress and strain axes' orientations are reported to demonstrate correlation in the region.

article source : https://www.tandfonline.com/doi/full/10.1080/00206814.2021.1929514

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