HR: 17:30h
AN: T24C-07    [Abstracts]
TI: The Yulong Mountains Structural Culmination: Tectonic and Geomorphic Controls on Localized Uplift Rates and Exhumation
AU: * Studnicki-Gizbert, C
EM: chrissg@mit.edu
AF: Dept. of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 United States
AU: Wang, Y
T24C-07 AF: Institute of Geological Sciences, 131 Baita Road, Kunming, YN 00000 China
AU: Burchfiel, B C
EM: bcburch@mit.edu
AF: Dept. of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 United States
AU: Chen, L
T24C-07 AF: Institute of Geological Sciences, 131 Baita Road, Kunming, YN 00000 China
AB: The active tectonics of the Eastern margin of the Tibetan plateau are characterised by left-lateral faults accommodating clockwise rotation of crustal fragments and normal faults accommodating generally east-west directed extension in the wake of the northward propagating eastern Himalayan syntaxis. Within the corridor of transtensional deformation that extends from Dali to Zhongdian, the Jinsha (Yangzi) river interacts with a closed circuit of normal and transtensional faults and results in localised high mean and maximum elevations, anomalously high rock uplift rates and the exposure of deep structural levels and metamorphic rocks in the core of fault-bounded antiformal dome. Flexural uplift of the footwalls of the bounding normal faults due to tectonic and erosional unroofing can plausibly explain the high elevations in the core of the range. However, geomorphic indicators of high uplift rates do not unequivocally coincide with the distribution of uplift and subsidence predicted by such a model. Nor does such a model yield any insight into the role of extreme fluvial incision in either accommodating or driving anomalously high uplift rates (and thus total exhumation). Moreover, unlike the association of antiformal culminations with transverse rivers reported in many compressional belts (Simpson 2004 and references therein), localised erosional unloading ought to relieve vertical stresses driving extensional faulting. Alternatively, we envisage a model somewhat analogous to the reactive diapirs well known from salt tectonics: both tectonic extension and geomorphic unloading weaken and thin the brittle upper crust and accommodate localized, anomalously high rock uplift rates.
UR: http://darla.mit.edu/~chrissg/research/agu/yulong
DE: 1825 Geomorphology: fluvial (1625)
DE: 8107 Continental neotectonics (8002)
DE: 8109 Continental tectonics: extensional (0905)
DE: 8175 Tectonics and landscape evolution
SC: Tectonophysics [T]
MN: Fall Meeting 2005