The Offshore New Harbor Project: Investigating the Greenhouse World to Icehouse World Transition
The Offshore New Harbor (ONH) Project is to study sediments deposited in Antarctica during the transition from the Greenhouse World (34-100 Ma) to Icehouse World (<34 Ma). The ONH Project is part of the Antarctic Geological Drilling Program called ANDRILL. ANDRILL aims to recover stratigraphic intervals for interpreting Antarctica’s climate and glacial history over the past 50 million years.
The goal of the Offshore New Harbor Project is to address two widely recognized but unresolved issues regarding Antarctica’s history: 1) the Paleogene cryospheric (>34 million years ago) development in Antarctica; and 2) the abrupt climate shift across the Eocene/Oligocene transition (circa 34 million years ago).
Offshore New Harbor is located off the eastern coast of East Antarctica in the western Ross Sea. It is situated on the eastern edge of the Victoria Land Basin, which is one of several sedimentary basins in the Ross Sea. These basins permitted thick sedimentary successions to be deposited and preserved. It is along the margin of the Victoria Land Basin that we expect to first image and then core sedimentary archives deposited during the Greenhouse World.
Why drill at offshore New Harbor?
Previous seismic and borehole projects in the New Harbor and Southern McMurdo Sound provide a regional setting.
Previous seismic and borehole projects in the New Harbor and Southern McMurdo Sound provide a regional setting. This includes seismic studies (e.g.. Polar Duke, 1990, Italian seismic survey, 1991, Nathaniel B. Palmer, 2004) and continuous long coreholes (e.g., CIROS-1 upper Eocene, L. & U. Oligocene, lower Miocene, MSSTS-1 U. Oligocene, L. Miocene, DVDP-15 lower Miocene, Southern McMurdo Sound Drilling Project (2007)
Why offshore New Harbor?
While there have been a number of successful drilling expeditions in Antarctica, currently there are no cored sediments older than ~37 Ma from Antarctica.
ONH is an ideal locale to tackle these questions because existing data suggest substantial strata deposited during Eocene time and across the Eocene/Oligocene boundary; and “mid” Oligocene are preserved updip of current borehole locations (CIROS-1). This interpretation is based on previous low-resolution seismic data that suggests late Eocene strata at CIROS-1 dips 10-20˚. This implies that strata at the base of CIROS-1 truncates against younger strata at a depth of ~200 meters below sea floor, 2-4 kilometers updip of CIROS-1. The ONH seismic survey will use and improve upon new over-sea-ice seismic reflection surveying techniques that employ a Generator-Injector (GI) air gun seismic source and a snow streamer.
The Offshore New Harbor Seismic and Gravity Expedition (October-December, 2008)
In late 2008, The Offshore New Harbor Project will conduct a multichannel seismic reflection and gravity survey to investigate the stratigraphic and tectonic history of westernmost Southern McMurdo Sound from the Greenhouse World (Eocene) to the start of the Icehouse World (Oligocene). This year’s survey represents an important step for identifying future drilling targets for the Antarctic Geological Drilling (ANDRILL) Program. ANDRILL aims to recover stratigraphic intervals for interpreting Antarctica’s climate and glacial history over the past 50 million years.