|
1 CEESR, School of Geological Sciences, Kingston University, Kingston-upon-Thames KT1 2EE, UK p.treloar{at}kingston.ac.uk
2 Department of Earth Sciences, Leeds University, Leeds LS2 9JT, UK
3 Department of Earth Sciences, Liverpool University, Brownlow Street, Liverpool L69 3BX, UK
4 Research School of Geological Sciences, Birkbeck College and University College London, Gower Street, London WC1E 6BT, UK
New amphibole, muscovite and biotite Ar-Ar and K-Ar data and zircon and apatite fission track data are presented from the western margin of the Nanga Parbat syntaxis as well as from the Indus and Astor valley sections which cross the syntaxis. Amphibole data date a regional cooling through 500°C at 25±5 Ma and are inconsistent with earlier suggestions that the peak of regional metamorphism was Neogene in age, although there is no doubt that some rocks were still at upper amphibolite facies temperatures as recently as 5 Ma. The data can be used to constrain structural models for syntaxial uplift. After an initial phase of crustal-scale buckling, bodily uplift of the syntaxis was along subvertical shear zones developed along its margins, although with a significantly higher time-averaged strain rate for shears developed along the western margin than along the eastern margin. The latter may be antithetic to the former. These shears were operative from 10 to < 1 Ma. In the southwestern part of the syntaxis, this subvertical uplift was superseded, since 6 Ma, by uplift along moderately SE-dipping NW-vergent shears on the hanging wall of which are located Neogene-aged migmatites.
This article has been cited by other articles:
 |
|
 |
|
  R. R. Jones, R. E. Holdsworth, M. Hand, and B. Goscombe Ductile extrusion in continental collision zones: ambiguities in the definition of channel flow and its identification in ancient orogens Geological Society, London, Special Publications, 2006; 268: 201 - 219. [Abstract] [PDF]
|
|
