Synkinematic magmatism, heterogeneous deformation, and progressive strain localization in a strike-slip shear zone: The case of the right-lateral Karakorum fault - Université Clermont Auvergne Accéder directement au contenu
Article Dans Une Revue Tectonics Année : 2012

Synkinematic magmatism, heterogeneous deformation, and progressive strain localization in a strike-slip shear zone: The case of the right-lateral Karakorum fault

Résumé

New structural observations coupled with 15 U/Pb and 24 Ar/Ar new ages from the Karakorum shear zone (KSZ) constrain the timing and slip rate of the right-lateral Karakorum fault zone (KFZ), one of the great continental Asian strike-slip faults. In the Tangtse-Darbuk area, the Tangtse (SW) and Muglib (NE) mylonitic strands of the KSZ frame the less deformed Pangong Range. Inherited U/Pb ages show that granitic protoliths are mostly from the Karakorum and Ladakh batoliths, with a major Miocene melting event lasting from ≥21.5 to 13.5 Ma. Some of the Miocene granitic bodies show structural evidence for intrusion synkinematic to the KSZ. The oldest of these granitoids is 18.8 ± 0.4 Ma old, implying that deformation started prior to ∼19 Ma. Microstructural data show that right-lateral deformation pursued during cooling. Ar/Ar data show that ductile deformation stopped earlier in the Tangtse (∼11 Ma) than in the Muglib strand (∼7 Ma). Deformation ended at ∼11 Ma in the Tangtse strand while it is still active in the Muglib strand, suggesting a progressive localization of deformation. When merged with published observations along the KFZ, these data suggest that the KFZ nucleated in the North Ayilari range at least ∼22 Ma ago. The long-term fault rate is 0.84 to 1.3 cm/yr, considering a total offset of 200 to 240 km. The KSZ collected magma produced within the shear zone and/or deeper in crust for which the producing mechanism stays unclear but was not the lower crustal channel flow.

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Tectonique
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hal-00745066 , version 1 (10-05-2021)

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Emmanuelle Boutonnet, P.H. Leloup, Nicolas Arnaud, Jean-Louis Paquette, W. J. Davis, et al.. Synkinematic magmatism, heterogeneous deformation, and progressive strain localization in a strike-slip shear zone: The case of the right-lateral Karakorum fault. Tectonics, 2012, 31 (4), pp.TC4012. ⟨10.1029/2011TC003049⟩. ⟨hal-00745066⟩
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