Detrital zircon U–Pb geochronology of the Murree Formation, western Himalaya, Pakistan: provenance and tectonic implications for Himalayan exhumation

The Murree Formation is the oldest continental sequence in the Himalayan foreland basin and holds significant information about the Himalayan exhumation following the India-Asia collision. This study explains the provenance of the Murree Formation using detrital zircon U-Pb geochronology supplemented with sandstone petrography to unravel the Himalayan exhumation in Pakistan. The sandstone provenance indicates the sediment was sourced from recycled orogen and suture belts, supporting a post-collisional origin. The source rocks, shown by the ternary plot (QpQnuQu), comprise plutonic and medium to high-rank metamorphic rocks prevalent in the Higher Himalaya (HH), Tethyan Himalayan (TH), and Lesser Himalaya (LH). The zircon ages are mainly ~ 1200–400 Ma, with two minor clusters (~1900–1400 Ma and ~ 2600–2300 Ma). This pattern is compatible with a Himalayan source mainly from the TH, HH, and partly from LH. Notably, the age populations < 200 Ma are in minor percentages, which indicates the hindrance from the Kohistan – Ladakh Arc (KLA) (Asian source) to the foreland basin due to the uplift of the TH and HH blocks. Combining the petrography and zircon U – Pb geochronology, a tectonic model is proposed, which suggests fold – thrust belt propagation to the south after the India – Asia collision. During the deposition of the Murree Formation in the foreland basin, TH and HH blocks were already uplifted in the western Himalaya, which provided major detritus. Along with this significant contribution, a minor contribution from a part of the LH is also suggested. This suggestion is based on the presence of Cambro – Ordovician detrital zircon ages, mainly from the plutonic source indicative of erosion of the Cambro – Ordovician granites and metamorphic rocks due to the initial phase of uplift along the Panjal fault.