Palaeozoic and Pliocene tectonic evolution of the Salt Range constrained by low‐temperature thermochronology

Abstract

The Salt Range in Pakistan exposes Precambrian to Pleistocene strata outcropping along the Salt Range Thrust (SRT). To better understand the in‐situ Cambrian and Pliocene tectonic evolution of the Pakistan Subhimalaya, we have conducted low‐temperature thermochronological analysis using apatite (U‐Th‐Sm)/He and fission track dating. We combine cooling ages from different samples located along the thrust front of the SRT into a thermal model that shows two major cooling events associated with rifting and regional erosion in the Late Palaeozoic and SRT activity since the Pliocene. Our results suggest that the SRT maintained a long‐term average shortening rate of ~5–6 mm/yr and a high exhumation rate above the SRT ramp since ~4 Ma.

Multi-Proxy Provenance Analyses of the Kingriali and Datta Formations (Triassic–Jurassic Transition): Evidence for Westward Extension of the Neo-Tethys Passive Margin from the Salt Range (Pakistan)

“…The glacigenic diamictites of the Tobra Formation e.g., [45] and the overlying deglaciation shale/mudrocks of the Dandot Formation with cold water Eurydesma fauna [40] of Gondwanan characters may be an indication of the westward extension of the synrift sequence in the SRS. A gentle angular unconformity (1-2 • ) exists between the Tobra Formation and the underlying Cambrian strata (Figure 2) in the Salt Range [131]. This correlates with the angular unconformity between Upper Devonian to Tournaisian limestones and the overlying rift sequence in the THS [132].…”

“…A possible destruction of the unstable minerals during diagenesis may have further facilitated the formation of quartz arenites [147][148][149][150]. However, lack of evidence does not allow reliable understanding of the diagenetic history of the present sediments, while the recently published burial history of the area [131] does not indicate deep burial of the strata during Mesozoic.…”

Tectonic geomorphology of the Jhelum fault zone & its contiguous regions in western Himalaya

“…The active geomorphic landforms and their influence on the drainage pattern suggest that the ongoing plate scale deformation is heterogeneously distributed on various fault system in the west of the HKS, which has not to be quantified yet (e.g. Cortés-Aranda et al, 2017;Shah et al, 2020;Ghani et al, 2020). This is remarkably different from the deformation observed in the eastern portion of the HKS where the Himalayan frontal thrust faults accommodate about half of the plate convergence and the deformation is not distributed over a large region as is observed in the Pakistan and Afghanistan regions (Vassallo et al, 2015;Bilham, 2019).…”

“…The Himalaya orogenic system is a textbook example of the continent-continent collision that involves lithospheric plates of India and Eurasia since Eocene (Ni & Barazangi, 1984;Avouac, 2007;Shah et al, 2020;Ghani et al, 2020).…”

“…The other active faults are the Kalabagh Fault, the Salt Range Thrust, the Mahesian Anticline, and the Chaman fault (Cortés-Aranda et al, 2017;Ghani et al, 2020). The pattern of Holocene faulting has been related to in-sequence deformation, which is in contrast to the observation of active out-of-sequence thrusts mapped in the eastern portions where Medlicott-Wadia Thrust and Kashmir basin faults accommodate the ongoing convergence (Vassallo et al, 2015;Shah, 2015;Shah & Malik, 2017).…”