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Andrill Program

ANDRILL Program

Frank Rack University of Nebraska-Lincoln

 

andrANDRILL (Antarctic geological DRILLing) is a multinational collaboration comprised of more than 250 scientists, students, and educators from five nations (Germany, Italy, New Zealand, the UK and the US) whose objective is to recover stratigraphic records from the Antarctic margin using drilling technology deployed from ice shelf and sea-ice platforms. ANDRILL’s primary objective is to drill back in time to recover a history of paleoenvironmental changes that will guide our understanding of how fast, how large, and how frequent glacial and interglacial changes were in Antarctica. Future scenarios of global warming and climate change require guidance and constraint from past history that will reveal potential timing frequency and site of future changes.

Andrill Program

Figure 1 – Map of the Victoria Land Basin, showing the location of the MIS and SMS drillsites. Also shown are the locations of earlier drilling in the region as part of the Cape Roberts Project (CRP), and earlier drilling expeditions. The dark blue area represents the area covered by the McMurdo Ice Shelf, which is buttressed by Ross Island, while the lighter blue is the area covered by seasonal or perennial sea ice.

Operations and logistics for ANDRILL are managed by Antarctica New Zealand. The scientific research is administered and coordinated through the ANDRILL Science Management Office (SMO), located at the University of Nebraska-Lincoln. The overall international budget for ANDRILL is approximately $30 million US, with approximately $13 million US funding the activities managed by the ANDRILL SMO, which includes annual subcontracts with US academic institutions to provide services for each project, and funding for the participation of US scientists in ANDRILL and post-expedition research support through the ANDRILL US Scientist Support Program. The use of DOSECC tools by the ANDRILL drilling system was facilitated through the efforts of Alex Pyne, Victoria University of Wellington.

The McMurdo Sound region was the first area for Antarctic drilling under the ANDRILL banner; however, future target areas for scientific drilling are located all around the Antarctic margin. Because of the wide range of proposed drilling targets, individual drilling objectives are grouped into portfolios based on logistical requirements. The first drilling portfolio was the McMurdo Sound Portfolio, with two specific projects being funded in this portfolio, namely, the McMurdo Ice Shelf (MIS) Project (drilled in 2006) and the Southern McMurdo Sound (SMS) Project (drilled in 2007).

The ANDRILL Program successfully recovered a 1285m-long succession of cyclic glacimarine sediment with interbedded volcanic deposits, in its first season of drilling from the McMurdo Ice Shelf (MIS). The MIS drillcore represents the longest and most complete (98% recovery) geological record from the Antarctic continental margin to date, and will provide a key reference record of climate and ice sheet variability through the Late Neogene (~13Ma to present). The DOSECC sediment coring tools (Figure 3) were used to recover shallow subsurface sediments near the seafloor-water interface prior to the installation of the ANDRILL riser system using push-, gravity- and piston-coring approaches. The outcomes of these operational and scientific activities are included in the contributions to the ANDRILL MIS Project’s Initial Results volume in Terra Antarctica (Naish, Powell, et al., 2007). The initial results of the ANDRILL SMS Project were assembled for publication in Terra Antarctica in early 2009.

Andrill Program1

Figure 2 – The ANDRILL MIS Project drillsite, showing the drill rig and the integrated systems that contribute to its operation, including equipment storage and laboratory vans.

Specific science objectives of the McMurdo Sound Portfolio include:

  • Obtain high-resolution sediment cores that record major glacial events and transitional periods over the past 40 million years;
  • Determine orbital and sub-orbital glacio-climatic fluctuations that vary on 100,000, 40,000, and 20,000 year cycles (e.g., Milankovitch cycles);
  • Obtain a refined record of the onset and development of the East Antarctic ice sheet (EAIS) from 40 million years ago;
  • Identify how the Antarctic region responded to past episodes of global warmth;
  • Derive a detailed history of Antarctic Holocene environmental change at the end of the last glaciation (since the last glacial maximum at 20,000 years ago); and,
  • Test global linkages between climate changes in the Northern and Southern hemispheres.

In 2006-2007, the ANDRILL Program drilled to a record depth of 1284.87 meters below seafloor, through an access hole in the 85 meter-thick McMurdo Ice Shelf. This is the deepest sub-bottom penetration a drilling rig has ever reached in the Antarctic region, and it is the first time a geological drilling system operated through a floating ice shelf over nearly 900 meters of water. These successes are amplified by the recovery of more than 98% of the drilled interval as sediment cores that represent a nearly unbroken geological history of substantial glacial and climatic variation. Alternations of clastic-rich glacial sediment and diatomaceous marine sediment indicate a dynamic history of West Antarctica’s ice shelf /sheet advancing and retreating more than 50 times during the last 5 million years.

Andrill Program2

Figure 3 – DOSECC coring tools used at ANDRILL

A team of fifty-eight scientists, technicians, educators and support staff from United States, New Zealand, Italy and Germany spent three months in the Crary Laboratory of McMurdo Station providing the initial description and characterization of the recovered core. Their initial results document how Antarctic ice sheets behaved during periods of global warmth greater than the present day. Volcanic ashes, microfossils and paleomagnetic stratigraphy provide ages of the sediments and a means to compare this high latitude climatic history with that of other regions. Climate and ice sheet models will extend these results and provide guidance regarding potential response by the West Antarctic Ice Sheet and Ross Ice Shelf to future scenarios of global warming. Frequency and apparent speed of the retreating ice shelf, leading to interglacial and open marine conditions in the Ross Embayment, will be one focus of future studies on these cores.

The ANDRILL drilling season began in early October 2007 with the deployment of the drilling system and remote camp at the start of the SMS Project, which is co-led by Drs. David Harwood (UNL) and Fabio Florindo (Italy). Several UNL Department of Geosciences faculty members are part of the SMS team, including Drs. Chris Fielding, Tracy Frank, and Richard Levy, as well as UNL graduate student Eva Tuzzi. UNL undergraduate student Jake Carnes is participating in the Mackay Sea Valley seismic survey, which is related to future ANDRILL proposal development activities.

 

Selected References:

Armand L.K., Crosta X., Romero O. & Pichon J.-J., 2005. The Biogeography of Major Diatom Taxa in Southern Ocean Sediments: 1. Sea Ice Related Species. Palaeogeogr., Palaeoclim., Palaeoecol., 223, 93–126.

Bannister S. & Naish T.R., 2002. ANDRILL Site Investigations, New Harbour and McMurdo Ice Shelf, Southern McMurdo Sound, Antarctica. Institute of Geological & Nuclear Sciences, Science Report 2002/01, 24 p.