Current and recent deformation of a crustal diapir, the example of Nanga Parbat : measurement and modelling

Project description

The Nanga Parbat massif, in the western syntaxis of the Himalayas, is a rare example of an active crustal diapir. In fact, numerous data points towards intense plio-quaternary deformation with fission-track ages on apatite of a few Ma, incision rates in excess of 10 mm/year, granite crystallisation ages as young as 700,000 years and an overlap, to the west of the massif, on the recent terraces of the Indus. Geodetic measurements show that there is no shortening on either side of the Massif and that it is tilted towards the west, as microseismicity also shows (Jouanne et al., 2014, 2020). However, the focus mechanisms available show the existence of an east-west extension at the heart of the Massif, in an extrados position. The ongoing deformation of Nanga Parbat is therefore not simply conditioned by a thrust bordering the massif. To study the deformation of this object, it is therefore necessary not only to quantify the current deformation of the entire network (re-measurement of the points installed in 2006 and 2018) but also to model the deformation in order to understand the parameters (erosion, position in the north-west Himalayan syntax) that control it.