Abstract-Imaging below the basalt for hydrocarbon exploration is a global problem because of poor penetration and significant loss of seismic energy due to scattering, attenuation, absorption and mode-conversion when the seismic waves encounter a highly heterogeneous and rugose basalt layer. The conventional (short offset) seismic data acquisition, processing and modeling techniques adopted by the oil industry generally fails to image hydrocarbon-bearing sub-trappean Mesozoic sediments hidden below the basalt and is considered as a serious problem for hydrocarbon exploration in the world. To overcome this difficulty of sub-basalt imaging, we have generated dense synthetic seismic data with the help of elastic finite-difference full-wave modeling using staggered-grid scheme for the model derived from ray-trace inversion using sparse wide-angle seismic data acquired along Sinor-Valod profile in the Deccan Volcanic Province of India. The full-wave synthetic seismic data generated have been processed and imaged using conventional seismic data processing technique with Kirchhoff pre-stack time and depth migrations. The seismic image obtained correlates with all the structural features of the model obtained through ray-trace inversion of wide-angle seismic data, validating the effectiveness of robust elastic finite-difference full-wave modeling approach for imaging below thick basalts. Using the full-wave modeling also allows us to decipher smallscale heterogeneities imposed in the model as a measure of the rugose basalt interfaces, which could not be dealt with ray-trace inversion. Furthermore, we were able to accurately image thin lowvelocity hydrocarbon-bearing Mesozoic sediments sandwiched between and hidden below two thick sequences of high-velocity basalt layers lying above the basement.

The lithospheric structure of Antarctica has been investigated from P- (PRF) and S- receiver functions (SRF) using the seismological data from Trans-Antarctic Mountain Seismic Experiment (TAMSEIS). For the stations deployed on the thick ice sheet, estimation of crustal parameters from PRF may be erroneous as the Moho conversions may interfere with the reverberations within the thick ice sheet. However, the free surface multiples are well observed in PRF. On the other hand, in SRFs, the primary conversions of interest and multiples are separated by the mother S-phase. Therefore, it is advantageous to interpret PRF and SRF jointly for the regions where we have thick low velocity layer at the top such as ice or sediments. The crustal structure and corresponding parameters have already been estimated by various workers, but here we interpret the PRF and SRF jointly to minimize the ambiguity and map the lithospheric architecture below TAM. Our analysis reveals that the average crustal thickness beneath the east Antarctica craton is ∼44 km with Vp/Vs ranging between ∼1.7 and 1.9. Below Trans-Antarctic Mountain (TAM), the average crustal thickness is ∼36 km with higher Vp/Vs of ∼1.8-2.0. The rift and the volcanic affected coastal region show erratic depths and Vp/ Vs, primarily due to the absence of either primary conversion or multiples in the receiver functions. A small number of stations far from the volcano show that the crust is thinnest (∼26 to 34 km thick) in the coastal part. The contribution of this study is the mapping of the lithospheric configuration, not done so far using SRF. The SRF section along a profile spanning E-, W-Antarctica and TAM reveals that the lithospheric thickness in the coast is ∼80 km and below TAM it is ∼120 km. In the central thick ice cover region, the lithosphere thickens upto ∼150 km towards Vostok highlands. The most intriguing feature in our SRF section is that the crust and lithosphere are shallow below TAM compared to the E-Antarctica. Further, we observe a mid-lithospheric low velocity layer confined mostly below TAM, suggesting that the thermal buoyancy could be the prime cause for the upliftment of TAM.