Frontiers and Opportunities in Antarctic Geosciences * Certosa di Pontignano * 29-31 July 2004
ANDRILL Stratigraphic Drilling Project in Southern McMurdo Sound (SMS):
An Overview of Sites and Scientific Objectives
D. HARWOOD1, F. FLORINDO2, C. FIELDING1, R. LEVY1, S. PEKAR3
& ANDRILL SCIENCE COMMITTEE4
1
Department of Geosciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0340 USA *Corresponding author (dharwood1@unl.edu)
2
Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna murata 605, 00143, Roma, Italy
3
Queens College School of Earth and Environmental Sciences, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367 USA
4
c/o ANDRILL Science Management Office, University of Nebraska-Lincoln, Lincoln, NE 68588-0851 USA
The ANDRILL Program will drill in Southern McMurdo Sound (SMS) to obtain new information on Neogene climate
and cryospheric history. Target strata are middle Miocene to Recent in age, and span several key steps in the evolution
of Antarctic climate. The McMurdo Sound region lies at the juncture between components of the West Antarctic Rift
system (Victoria Land Basin - VLB), the Transantarctic Mountains (TAM) and the Erebus Volcanic Province. Faultand flexure-related subsidence associated with rifting and volcanic loading has provided accommodation space adjacent
to the rising TAM. McMurdo Sound is also one of a limited number of locations that have been influenced by three
significant components of the Antarctic cryospheric system: East Antarctic Ice Sheet (EAIS), Ross Ice Shelf/West
Antarctic Ice Sheet, and Ross Embayment sea-ice. These cores will record a tectonic history of these elements and also
document the variable influence of the above cryospheric elements on sedimentation and on the Antarctic paleobiota.
Two drillholes (500-700 m) will sample a multiple sequence of clinoform reflectors that expand basinward. Packages of
clinoform refectors are bounded by two widespread erosional surfaces. The two drillholes will recover a composite
thickness of ~1000m of strata that lie stratigraphically above the lower Miocene section recovered at the top of the
nearby CIROS-1 drillcore, and above the interval recovered by the Cape Roberts Project (through regional seismic
correlation). We anticipate the recovery of expanded middle and upper Miocene sections, which are interrupted by
regional erosion in McMurdo Sound by glacier ice.
Antarctic records from middle Miocene are significant because they can test interpretations derived from global proxy
records that invoke a change from a warm climatic optimum (~17 Ma) to the onset of major cooling (~14 Ma) and the
formation of a quasi-permanent ice sheet on East Antarctica. The SMS project will also provide an opportunity to
investigate the age of a sequence of incised surfaces and channels that may be linked to global lowstand of sea-level
(~10 Ma). Secondary target strata of Pliocene and Pleistocene age in a distal marine setting will complement and build
on coastal and fjord sediment records from DVDP and CIROS-2 drillcores. The SMS site is well-connected to the grid
of seismic lines in the VLB, hence the recovered sections will provide excellent chronostratigraphic control for regional
seismic surfaces and units important for interpreting regional stratal architecture for dating Neogene and younger
subsidence and rift fault history. The Dry Valleys region has been central to debate regarding the history and character
of the Neogene EAIS and southern high latitude climate evolution. Divergent views persist in part due to the lack of
high-quality stratigraphic sections of middle and upper Miocene and Pliocene marine sediments. Specific scientific
objectives are to: document the initial onset and subsequent history of sea-ice presence/absence; document the evolution
of Neogene terrestrial vegetation; establish a Late Neogene sea-level record; test whether stable polar climate conditions
persisted for the last 15 m.y.; document meltwater discharge events; construct a composite event history of glacial and
interglacial events across a coastal to deep basin transect. Interested scientists are urged to contact the co-chief scientists
D. Harwood and F. Florindo for more information.