WSW-Trending Deformation Between Babusar Pass and Toshe Gali Area, Northern Pakistan
Abstract
The Himalaya and Karakoram Mountain ranges of northern Pakistan are the product of multiple deformational phases from continental collision events that trapped the Kohistan island arc between the Asian and Indo-Pakistan plates to the development and emergence of the Nanga Parbat syntaxis. Field work along the Main Mantle Thrust (MMT) and within the Indo-Pakistan plate rocks in the area between Babusar Pass and Toshe Gali was aimed at an understanding of the kinematic relationship between these deformational phases. The MMT is the suture between rocks of the Indo-Pakistan plate and rocks of the Kohistan sequence. Workers in adjacent areas have found evidence that the MMT has southeast-directed transport of the Kohistan rocks over the Indo-Pakistan plate. In the study area that deformation has been overprinted by a ductile fabric that has top-to-the-WSW sense of shear on a shallowly WSW- plunging stretching lineation. This ductile fabric is pervasive at the MMT contact, within the Indo-Pakistan plate cover sequence below the MMT. but decreases in intensity in the Indo-Pakistan plate basement rocks and the Nanga Parbat gneiss. If this ductile fabric represents normal fault movement then this deformation may have been responsible, in part, for the exhumation of the Nanga Parbat massif.
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