A Receiver Function Investigation of the Indian Shield Crust and Upper Mantle Transition Zone

P-wave receiver functions have been obtained at 57 broad-band stations located in the Indian shield. This receiver function data set is the result of a collaborative effort between the National Geophysical Institutes of India and the University of South Carolina to collect broadband data in India, with the purpose of investigating structural variations of its underlying crust and upper mantle. The Indian shield can be regarded as an amalgamation of several Precambrian terranes, ranging in age from early Archean to late Proterozoic. The SONATA lineament, a linear feature extending eastwards for ~1300 km from the west coast of India, is a major crustal feature of the shield which is characterized as a narrow gravity "low" within a broad region of gravity "high" in the SONATA belt. Knowledge of the crust and uppermost mantle structure of this region is important to improve our understanding of the Precambrian evolution of the Indian subcontinent and the origin and nature of the SONATA lineament. The new receiver function data set provides a unique opportunity to investigate the seismic structure of the Indian crust and upper mantle with unprecedented detail. To achieve this goal we will present (i) estimates of the crustal thickness and bulk Vp/Vs and (ii) detailed S-wave velocity structure of the Indian shield crust, and (iii) a ~1500 km long transect from the Southern Granulite Terrane to the Indogangetic plains mapping seismic discontinuities down to the upper mantle transition zone.