Shear velocity model for the Kyrgyz Tien Shan from joint inversion of receiver function and surface wave data
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Authors
Gilligan, Amy
Roecker, Steven W
Priestley, Keith
Nunn, Ceri
Publication Date
2014-07-09Journal Title
Geophysical Journal International
ISSN
0956-540X
Volume
199
Pages
480-498
Language
English
Type
Article
Metadata
Show full item recordCitation
Gilligan, A., Roecker, S. W., Priestley, K., & Nunn, C. (2014). Shear velocity model for the Kyrgyz Tien Shan from joint inversion of receiver function and surface wave data. Geophysical Journal International, 199 480-498. https://doi.org/10.1093/gji/ggu225
Abstract
The Tien Shan is the largest active intracontinental orogenic belt on Earth. To better
understand the processes causing mountains to form at great distances from a plate
boundary, we analyse passive source seismic data collected on 40 broad band stations
of the MANAS project (2005-2007) and 12 stations of the permanent KRNET seismic
network to determine variations in crustal thickness and shear wavespeed across the
range. We jointly invert P- and S-wave receiver functions with surface wave observations
from both earthquakes and ambient noise to reduce the ambiguity inherent in the images
obtained from the techniques applied individually. Inclusion of ambient noise data improves constraints on the upper crust by allowing dispersion measurements to be made
at shorter periods. Joint inversion can also reduce the ambiguity in interpretation by
revealing the extent to which various features in the receiver functions are amplified
or eliminated by interference from multiples. The resulting wavespeed model shows a
variation in crustal thickness across the range. We find that crustal velocities extend
to ∼ 75 km beneath the Kokshaal Range, which we attribute to underthrusting of the
Tarim Basin beneath the southern Tien Shan. This result supports the plate model of
intracontinental convergence. Crustal thickness elsewhere beneath the range is about 50 km, including beneath the Naryn Valley in the central Tien Shan where previous studies
reported a shallow Moho. This difference apparently is the result of wavespeed variations
in the upper crust that were not previously taken into account. Finally, a high velocity
lid appears in the upper mantle of the Central and Northern part of the Tien Shan,
which we interpret as a remnant of material that may have delaminated elsewhere under
the range.
Keywords
Crustal Structure, Tomography, Intra-plate processes, Intra-plate processes, Surface Waves and Free Oscillations, Asia
Sponsorship
km, including beneath the Naryn Valley in the central Tien Shan where previous studies
reported a shallow Moho. This difference apparently is the result of wavespeed variations
in the upper crust that were not previously taken into account. Finally, a high velocity
lid appears in the upper mantle of the Central and Northern part of the Tien Shan,
which we interpret as a remnant of material that may have delaminated elsewhere under
the range.
Identifiers
External DOI: https://doi.org/10.1093/gji/ggu225
This record's URL: https://www.repository.cam.ac.uk/handle/1810/245417
Rights
Attribution 2.0 UK: England & Wales, Creative Commons Attribution License 2.0 UK
Licence URL: http://creativecommons.org/licenses/by/2.0/uk/