Unroofing history of the Jambil and Jawar carbonatite complexes from NW Pakistan: constraints from fission-track dating of apatite

Abstract

The Peshawar Plain Alkaline Igneous Province (PAIP) is exposed north of the Peshawar Plain in NW Pakistan. It stretches from Tarbela in the east up to Loe-Shilman near the Pakistan–Afghanistan border in the west. Within the PAIP, carbonatites are found at Loe-Shilman, Sillai-Patti, Jambil, Koga and Tarbela. Small isolated sill-like bodies and plugs of carbonatites are exposed in the Jambil area, about 10 km SE of Mingora in Lower Swat. Small isolated bodies of carbonatites have also recently been discovered at the locality of Jawar, about 4 km north west of the Sillai Patti carbonatite. Fission-track dating studies on the apatite yielded ages of 15.7±0.4 and 25.2±1.0 Ma for the Jambil and Jawar carbonatites, respectively. Uplift-induced denudation and cooling rates of (0.19±0.04) mm y −1 and (5.73±1.15) °C Ma −1 for Jambil carbonatite, (0.12±0.03) mm y −1 and (3.57±0.73) °C Ma −1 for Jawar carbonatite, and (0.13±0.03) mm y −1 and (3.97±0.82) °C Ma −1 for Sillai Patti carbonatite, respectively, were estimated. Comparison of the data indicates that all three-carbonatite complexes have experienced similar uplift-induced denudation and cooling rates during the past 25–15 Ma.