Lithospheric foundering and underthrusting imaged beneath Tibet.
Nat Commun 2017;
8:15659. [PMID:
28585571 PMCID:
PMC5467168 DOI:
10.1038/ncomms15659]
[Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 04/12/2017] [Indexed: 11/08/2022] Open
Abstract
Long-standing debates exist over the timing and mechanism of uplift of the Tibetan
Plateau and, more specifically, over the connection between lithospheric evolution
and surface expressions of plateau uplift and volcanism. Here we show a T-shaped
high wave speed structure in our new tomographic model beneath South-Central Tibet,
interpreted as an upper-mantle remnant from earlier lithospheric foundering. Its
spatial correlation with ultrapotassic and adakitic magmatism supports the
hypothesis of convective removal of thickened Tibetan lithosphere causing major
uplift of Southern Tibet during the Oligocene. Lithospheric foundering induces an
asthenospheric drag force, which drives continued underthrusting of the Indian
continental lithosphere and shortening and thickening of the Northern Tibetan
lithosphere. Surface uplift of Northern Tibet is subject to more recent
asthenospheric upwelling and thermal erosion of thickened lithosphere, which is
spatially consistent with recent potassic volcanism and an imaged narrow low wave
speed zone in the uppermost mantle.
The timing and mechanism of uplift of the Tibetan plateau continues to be a source
of debate. Here, the authors present a new tomographic model revealing a T-shaped high
wave speed structure beneath South-Central Tibet and interpret this an upper-mantle
remnant from lithospheric foundering.
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