The Offshore New Harbour Project: deciphering the Middle Miocene through Late Eocene seismic stratigraphy of Offshore New Harbour, western Ross Sea, Antarctica

Abstract

AbstractIn the Austral spring of 2008, over 48 km of multi-channel seismic data were collected offshore of New Harbour, which is located in the western most Ross Sea, Antarctica. This project is part of the ANDRILL (Antarctic Geological Drilling) Programme's Offshore New Harbour Project, with its aim to investigate the stratigraphic and tectonic history of the inner shelf of southern McMurdo Sound. Correlating the seismic data to CIROS-1 and ANDRILL AND-2A drillholes provided age dates ranging from Late Miocene to at least Late Eocene for the reflectors and lithological descriptions for the seismic units. This permitted development of a glacial history of this area, resulting in dividing the seismic data into three units: an Upper Eocene–Lower Oligocene unit; an Upper Oligocene–Lower Miocene unit; and a Middle Miocene and younger unit. The seismic section below 700 mbsf has two possible interpretations: (1) substantial Eocene strata are present downdip of CIROS-1, which would represent a potential future-drilling objective for the ANDRILL Programme; or (2) these reflectors may be equivalent to Devonian strata recovered at the Cape Roberts 3 as the two-way traveltime of Eocene and Devonian strata are nearly identical, making it difficult to discriminate between them in seismic data.