Shear strain localisation from the upper mantle to the middle crust of the Kohistan arc (Pakistan)
| Autor: | Gerold Zeilinger, Shahid Hussain, Hamid Dawood, N. M. Chaudhry, Jean-Pierre Burg, Laurent Arbaret |
|---|---|
| Přispěvatelé: | Institut des Sciences de la Terre d'Orléans (ISTO), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Departement Erdwissenschaften [ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Institute of Geology, University of the Punjab, Museum of Natural History, Institute of Geological Sciences [Bern], University of Bern |
| Jazyk: | angličtina |
| Rok vydání: | 2005 |
| Předmět: |
010504 meteorology & atmospheric sciences
Continental collision Subduction Geology Ocean Engineering Crust 010502 geochemistry & geophysics 01 natural sciences Mantle (geology) Shear (geology) Transition zone Shear stress [SDU.STU.VO]Sciences of the Universe [physics]/Earth Sciences/Volcanology Shear zone Petrology Seismology ComputingMilieux_MISCELLANEOUS 0105 earth and related environmental sciences Water Science and Technology |
| Zdroj: | Geological Society Special Publication Geological Society Special Publication, 2005, 245, pp.187-202. ⟨10.1144/GSL.SP.2005.245.01.02⟩ Geological Society Special Publication, 2005, 245, pp.25-38. ⟨10.1144/GSL.SP.2005.245.01.02⟩ |
| DOI: | 10.1144/GSL.SP.2005.245.01.02⟩ |
| Popis: | International audience; Shear structures from mantle to middle crust levels of the Kohistan palaeo-island arc, in Pakistan, are described. Pre-Himalayan ductile shear zones show a wide variety in size and shape, and developed from gabbro subsolidus to amphibolite facies conditions. Their lithological context and geological history give insights into mechanisms that initiate shear strain localization, factors that control stabilization of deformation in shear zones and flow properties at the mantle–crust transition. Shear strain localization began within compositional gradients. Gabbros were more prone to localization into anastomosing patterns than diorites and granites, which show more homogeneous strain. Shear strain localization during cooling led to less numerous but longer and thicker shear zones. Viscous heating within shear zones resulted in melt production and segregation in deformation structures, and seems to have taken part in the plutonic history of the arc. Using Kohistan as an example, we suggest that the plutonic, lower crust of arcs is strongly affected by subhorizontal, synmagmatic shear zones, probably consistent with the bulk flow direction of the subduction zone. These features can obviously be preserved in collision orogens and may be mistaken for structures documenting the continental collision. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|