Abstract

Like most other major continental rifts, the Baikal rift zone (BRZ) in Siberia is presumably underlain by a hot and partially molten mantle, which has a reduced seismic velocity relative to surrounding areas. Recent seismic tomography studies, however, gave conflicting results about the depth extent and even the existence of the low-velocity anomaly beneath the BRZ, suggesting that additional constraints are needed. Here we present results from stacking of about 1700 radial P-to-S receiver functions from a single long-running seismic station, TLY, located at the SW tip of Lake Baikal. A clear uplift of the 410 km discontinuity (d410) with a magnitude of about 47 km relative to the south margin of the Siberian platform is observed beneath the rift. Currently available seismic results suggest that the uplift is unlikely to be caused by addition of water to mantle transition zone (MTZ) silicates but is the result of a 550°C reduction in temperature in the vicinity of the d410. In addition, the 660 km discontinuity (d660) shows a downward trend toward the rift from the south, suggesting that the entire MTZ might have a low temperature beneath the rift. The thickening of the MTZ suggests a high-velocity anomaly of about 2% in the MTZ, and rules out the possibility that the rifting is caused by a mantle plume originated in or beneath the mantle transition zone.

Department(s)

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

mantle discontinuity; mantle plume; rift zone; rifting; seismic tomography; seismic velocity; transition zone; uplift; Baikal Rift Zone; Eurasia; Russian Federation; Siberia; Siberian Platform

International Standard Serial Number (ISSN)

2169-9356

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2006 American Geophysical Union (AGU), All rights reserved.

Publication Date

01 Nov 2006

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