Publications

We use the term LAB for a global discontinuity marking the upper boundary of a seismic low velocity zone in the uppermost mantle, although lithosphere and asthenosphere are not seismic definitions. We apply the S receiver function technique which uses S-to-P converted waves beneath temporary or permanent seismic stations and which is perfectly suited for LAB observations. Around Tibet we observed the LAB in the Tarim and Sichuan Basins and in India near 100km depth. The Indian LAB is subducting down to about 250km depth below southern-central Tibet and the Asian LAB shows a flat subduction at 200km depth underneath the Tibetan LAB in north-east Tibet. That means we see in northern Tibet the Tibetan LAB overriding the Asian LAB. The Tibetan LAB is thickening at the contact with the Tarim Basin, but thinning at the contact with the Sichuan Basin. This thinning might be due to delamination of the lowest part of the lithosphere below eastern Tibet. In eastern China the transition from the shallow (~80km) oceanic LAB to the deeper cratonic LAB (~110-140km) is observed. In the western US the LAB is located near 60-80km using USArray data. It deepens to ~150km along a stripe from Texas, over the Colorado Plateau further north, interrupted by the Yellowstone plume chain. The cratonic LAB in the US is similarly to the LAB in cratonic parts of China located surprisingly shallow near 100km depth. Such a shallow cratonic LAB is not in agreement with results from surface wave tomography.

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Kind, R.; Kumar, P.; Yuan, X.; Sodoudi, F.; Heit, B.; Mechie, J. (2011): The Lithosphere-Asthenosphere Boundary (LAB) in China observed with Receiver Functions and Comparison with Western US. AGU 2011 Fall Meeting (San Francisco 2011).