TY - JOUR
T1 - Crustal strength in central Tibet determined from Holocene shoreline deflection around Siling Co
AU - Shi, Xuhua
AU - Kirby, Eric
AU - Furlong, Kevin P.
AU - Meng, Kai
AU - Robinson, Ruth
AU - Wang, Erchie
N1 - Funding Information:
This work was supported by a National Science Foundation grant ( EAR-0911587 ) to E.K. and K.P.F. Additional support to E.W. was provided by grants from the Chinese Academy of Sciences ( XDB03010500 ). We are grateful to Haijian Lu, Zhe Su, Tashi Wangdi and Feng Qu for assistance of the field work. We thank Phillip England and Roland Bürgmann for providing critical comments that significantly improved the manuscript.
Publisher Copyright:
© 2015 Published by Elsevier B.V.
PY - 2015/8/1
Y1 - 2015/8/1
N2 - Controversial end member models for the growth and evolution of the Tibetan Plateau demand quantitative constraints of the lithospheric rheology. Direct determinations of bulk crustal rheology, however, remain relatively sparse. Here we use the flexural rebound of lacustrine shorelines developed during the Lingtong highstand around Siling Co, in central Tibet, to place bounds on the effective elastic thickness (Te) and viscosity of Tibetan crust. Shoreline features associated with the Lingtong highstand complex ~60 m above present lake level are deflected from horizontal by 2-4 m over wavelengths of ~200 km. Optically stimulated luminescence dating of aggradational shoreline deposits indicates that these lake levels were reached at 6-4 ka. Assuming that surface loads were entirely supported by an elastic layer overlying an inviscid fluid, the range and spatial distribution of variations in shoreline elevation are consistent with deflections predicted by a uniform elastic plate with thickness, Te of 20-30 km. If viscoelastic relaxation in response to lake withdrawal is complete, our data suggest an average viscosity ≤1019Pas. These results imply that the apparent viscosity of the lower crust inferred over millennial timescales is comparable with that estimated from post-seismic relaxation over decadal timescale.
AB - Controversial end member models for the growth and evolution of the Tibetan Plateau demand quantitative constraints of the lithospheric rheology. Direct determinations of bulk crustal rheology, however, remain relatively sparse. Here we use the flexural rebound of lacustrine shorelines developed during the Lingtong highstand around Siling Co, in central Tibet, to place bounds on the effective elastic thickness (Te) and viscosity of Tibetan crust. Shoreline features associated with the Lingtong highstand complex ~60 m above present lake level are deflected from horizontal by 2-4 m over wavelengths of ~200 km. Optically stimulated luminescence dating of aggradational shoreline deposits indicates that these lake levels were reached at 6-4 ka. Assuming that surface loads were entirely supported by an elastic layer overlying an inviscid fluid, the range and spatial distribution of variations in shoreline elevation are consistent with deflections predicted by a uniform elastic plate with thickness, Te of 20-30 km. If viscoelastic relaxation in response to lake withdrawal is complete, our data suggest an average viscosity ≤1019Pas. These results imply that the apparent viscosity of the lower crust inferred over millennial timescales is comparable with that estimated from post-seismic relaxation over decadal timescale.
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U2 - 10.1016/j.epsl.2015.05.002
DO - 10.1016/j.epsl.2015.05.002
M3 - Article
AN - SCOPUS:84929319643
SN - 0012-821X
VL - 423
SP - 145
EP - 154
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
ER -