Seismic imaging of crust beneath the Dharwar Craton, India, from ambient noise and teleseismic receiver function modelling

We use cross-correlation of continuous 18 months (2009 February to 2010 August) ambient noise data recorded over 35 broad-band seismographs in the Archean Dharwar Craton and the adjoining granulite terrain to generate Rayleigh-wave group velocity maps in the period 5-28 s. This is supplemented with longer period data (40-70 s) from earthquake source. Combined group velocity measurement was inverted jointly with the teleseismic receiver functions obtained at 50 stations (includes 15 stations operated during 1998-2002) to produce shear velocity image of the crust. The velocity image reveals thinner crust (34-38 km) in the late Archean (∼2.7 Ga) Eastern Dharwar Craton (EDC), while all other terrains (mid-Archean and Proterozoic) have crustal thickness from 40 to over 50 km. The mid-Archean (3.36 Ga) greenstone belt of the Western Dharwar Craton (WDC) has the thickest crust (∼50 km). The average crustal V s beneath the EDC is ∼3.70-3.78 km s−1 as compared to 3.80-3.95 km s−1 beneath the WDC. We observe significant lateral variation in the thickness of lower crust (V s ∼ 3.8-4.2 km s−1): ∼10-15 km in the EDC compared to ∼20-30 km in the WDC. The lowermost part of the crust (V s ≥ 4.0 km s−1) is thin (