Improved Sub-Basalt Seismic Imagery. Can Outcrops in East Greenland Suggest a Solution?

The Hold-with-Hope project has the primary aim to investigate the possibility of imaging sedimentary structure beneath plateau basalts. Fieldwork in the Hold-with-Hope region of north-east Greenland revealed uplifted sediments that provided field examples analogous to the volcanic margins of north-west Europe. Mapping of eleven distinct strata, ranging from Carboniferous basement to Paleocene basalts, characterised the region with N-S and NE-SW trending normal faults and beds dipping 20 degrees to the WSW. The entire succession is intruded by primary basaltic dykes, with potential targets for hydrocarbon exploration in the Jurassic and early Cretaceous sandstones. The mapped surfaces were then converted into a 35×15×14 km3 volume sampled on a 20 m grid with rock properties assigned from borehole data drilled in the Faroe Shetland trough. All units were considered homogeneous except the basalt succession, which was determined as a random velocity distribution with distinct correlation lengths in each orthogonal direction. This method, derived from the von- Kàrmàn power spectrum, provided a Gaussian velocity range which was weighted to match velocity distributions from previously drilled basalt sequences. Realistic plateau basalts were generated as a single volume with autocorrelation functions and power spectra that matched the results derived from drilled data. Finally the phase-screen forward modelling technique was used to generate a synthetic seismic reflection data on a scale comparable to real industrial acquisition. The data, acquired with a deep-tow low-frequency source was processed to image the intra- and sub-basalt reflectors. Final stacked sections are presented alongside exploding reflector data, vertical seismic profiles and gravity plots from the same region.