Mantle Transition zone
Mantle Transition zone
Schematic model of the Mantle Transition zone below the Lesser Himalaya in Uttarakhand based on the results of our analysis and Common Conversion Point imaging of radial P-receiver functions.
Brief Description of our modelling results as shown in the figure:
The common conversion point (CCP) stacking method on radial P-wave receiver functions revealed differences in the depths of the 410-km (d410) and 660-km (d660) mantle discontinuities in the Uttarakhand Himalaya. Variations in discontinuities varied from 395 to 420 km (mean: 406±8 km) for d410 and 645 to 675 km (mean: 659±10 km) for d660. An average thickness of 255±7 km is predicted for the mantle transition zone (MTZ), which ranges from 240 to 265 km. We find a low-velocity layer above the d410 discontinuity in our models. This layer is 16±7 km thick and varies in depth from 350 to 385 km, with a mean depth of 369±13 km. The aforementioned observations suggest the probable presence of a hydrated mantle transition zone below the Uttarakhand Himalaya. Additionally, we model a 199 km thick low-velocity layer above the d660 discontinuity. The layer is located at depths of 590-640 km, with an average depth of 62016 km. As revealed in South Africa and China, this layer may be caused by old subducted oceanic material or increasing water content at the lower mantle transition zone ((Kohlstedt et al., 1996; Huang et al., 2005). A schematic of the Mantle transition zone beneath the Lesser Himalaya in Uttarakhand has been constructed using the aforementioned modelling outcomes as shown in the attached Figure. The model depicts a d410 with a shallower depth, a d660 with a deeper depth, an LVL positioned above the d410, and an LVL positioned above the d660.
