Provenance of a Blocky Debris Flow Deposit in Mid-continental Slopes (Espírito Santo Basin, SE Brazil)

The provenance of an Oligocene-Miocene Mass Transport Deposit (MTD) in mid continental slope Espírito Santo Basin, SE Brazil was analysed using seismic facies and measurement of preserved blocks. Our method, applied to a high-quality 3D seismic volume from the Espírito Santo Basin (SE Brazil), provides information on the location of source areas of MTDs, their bulk composition and styles of disaggregation in relation to their transporting distances. Whenever blocks of strata are found, their orthogonal axes are measured to estimate parameters such as Maximum Projection Sphericity Index (MPSI), Oblate Prolate Index (OPI), and ratio of short and intermediate axes (ds/di). Eighty two (82) blocks mapped in the MTD have no preferred orientation: they have compact-bladed, bladed, elongate, very-bladed, very-platy and very-elongate shapes. Average block thickness, area coverage and volume are ~128.82m, 0.802 sq. km and ~0.196 cubic km with mean MPSI, OPI, flatness and elongation ratios of 0.398, 0.991, 0.19989 and 0.59861. In addition, the presence of equant blocks with c/a>0.4 and c/b>0.65 ratios are typical of proximal areas in MTDs, reflecting small transporting distances. Thus, the new method used in this research provides an alternative technique to kinematic indicators for determining the provenance of blocky debris flow deposits.