Comment on "Displacement along the Karakoram fault, NW Himalaya, estimated from LA-ICP-MS U–Pb dating of offset geologic markers" published by Shifeng Wang et al. in EPSL, 2012


P.H. Leloup a,  R.F. Weinberg b, B.K. Mukherjee c, P. Tapponnier d, R. Lacassin e, E. Boutonnet a, f, M.-L. Chevalier g, F. Valli h, H. Li g, N. Arnaud i, J.-L. Paquette j.

a Laboratoire de Géologie de Lyon, Université de Lyon, Université Lyon 1, ENS de Lyon, CNRS, 2 rue Raphael Dubois, 69622 Villeurbanne, France
b School of Geosciences, Monash University, Clayton, Vic 3800, Australia
c Wadia Institute of Himalayan Geology, 33, GMS Road, Dehra Dun-248001, India
d Tectonics Group, Earth Observatory of Singapore, Nanyang Technological University, Singapore
e Equipe de Tectonique, Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ Paris Diderot, UMR 7154 CNRS, F-75005 Paris, France
f Institute of Geosciences, Johannes Gutenberg University Mainz, J.-J.-Becher-Weg 21, D-55128 Mainz, Germany
g State Key Laboratory of Tectonics and Continental Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
h Newmont Mining Corporation, Perth Area, Australia
i Géosciences Montpellier, UMR CNRS 5243, Université de Montpellier 2, France
j Laboratoire Magma et Volcans, UMR CNRS 6524, Université Blaise Pascal, Université de Clermont-Ferrand, France

Abstract:
Field evidence for syn-deformation migmatization and crystallization along the Karakorum fault contradicts the study of Wang et al. (2012). The ages of such magmatic rocks provide minimum ages for the onset of deformation at ~23 Ma in North Ayilari and ~19 Ma in Tangtse. The onset of deformation at 12 Ma in the Ayilari range inferred by Wang et al. (2012) from a muscovite Ar/Ar age is a cooling age, thus only a minimum age. The ~60Ma granodiorite bodies, the ophiolitic rocks and the south Kailash thrust that are correlated across the fault to provide a 52±72 km finite offset do not define reliable piercing points. Such observations as well as our previous work concur to show that the Karakorum fault initiated in the Oligo-Miocene, and has a long-term dextral slip-rate between 7.5 and 13mm/yr, approximately twice that proposed by Wang et al. (2012).

Earth and Planetary Science Letters 363 (2013) 242–245 

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The Karakorum fault zone