Geoscience Reference
In-Depth Information
Figure 10.13.
(a) A south-north section from India across the Himalayas and Tibet
at 92-93
◦
E summarizing the results of teleseismic and controlled-source studies and
showing the geometry of the converging plates. PR, Poisson's ratio. There are two
possible interpretations of these data: (1) that India underthrusts as far as the
Banggong-Nujiang suture and (2) that India underthrusts only as far as the Zangbo
suture before the plate dips steeply into the mantle. In case (2) the Lhasa terrane
must have a very thick crust with a rigid lower crust and mantle. Colour version Plate
27. (Zandt, personal communication 2001). (b) The deviation of seismic P-wave
velocity from a standard model of the mantle along a line across India and the
Himalayas to Tibet. Note the thick high-velocity regions associated with the India-
Eurasia collision through the upper mantle. Deep high-velocity anomalies may be
subducted oceanic plate now in the lower mantle. Colour version Plate 25(d).
(Spakman, personal communication 2003.)
