Seismic Reflectivity
Analysis of Regional Unconformities
on Ross Sea Continental Shelf: A
Geophysical Fingerprint for Antarctic Ice Sheet Grounding Surfaces
Adeniyi Saanumi,
Louisiana State University, Baton Rouge, Department of Geology &
Geophysics, Baton Rouge, Louisiana USA. [email protected]
Past seismic stratigraphic studies along the continental shelf of Antarctic
passive margins interpreted regional glacial unconformities
as Cenozoic ice-sheet
grounding surfaces. These
unconformities
are manifested on seismic profiles as reflectors
exhibiting regional extent and cross-cutting relationships between underlying
and overlying units. In the Ross Sea, Antarctica, we model the offset-dependent
seismic reflectivity patterns of these
unconformities
as an alternative to
using stratal patterns . Six
multichannel seismic lines were run in the
North-Basin sector of Ross Sea outer continental shelf in 2003. In an attempt to characterize interpreted
glacial
unconformities
using offset-dependent reflectivity, moveout-corrected
common midpoint data are stacked to highlight differences in the reflector
continuity and amplitudes between various offset-dependent attribute sections. Amplitude variation with offset analysis
indicates a contrast in rock properties between proglacial
deposits and glacio-marine deposits. Regional
unconformities
were found to partly coincide
with reflectors exhibiting high gradient and intercept on attribute stack. Quality
and resolution of seismic data may have limited the understanding and
description of regional
unconformities
. Non-uniqueness of offset dependent
anomalies is also a concern.