NSF PR 98-86 - December 11, 1998
This material is available primarily for archival
purposes. Telephone numbers or other contact information
may be out of date; please see current contact information
at media
contacts.
Scientists Study 100-Million-Year-Old Volcanism in
the Indian Ocean
Clues to Earth's internal dynamics may lie in the
remote southern Indian Ocean, in a submarine plateau
one-third the size of the United States. For the next
two months, geologists with the Ocean Drilling Program
(ODP), funded in large part by the National Science
Foundation (NSF), will unearth the secrets of the
Kerguelen Plateau, an example of a unique type of
Earth feature, a large igneous province (LIP).
LIPs are areas where magma wells up from deep beneath
Earth's surface and forms molten rock; they may be
expressions of the largest volcanic events in the
planet's history. One of the least understood features
in the ocean basins, LIPs preserve a record of volcanism
and may have affected Earth's past environment by
altering ocean circulation, climate conditions and
sea level.
A team of 28 scientists will study an LIP that originally
formed from the Kerguelen Plateau and a now separate
but related nearby feature, Broken Ridge. To investigate
the history of Kerguelen Plateau and Broken Ridge,
the scientific team will retrieve core samples from
as deep as one kilometer below the seafloor using
advanced drilling technology aboard the JOIDES Resolution,
the world's largest scientific drill ship.
The JOIDES Resolution is scheduled to depart Fremantle,
Australia, on December12, and conclude the expedition
on February 11, 1999. Mike Coffin of the University
of Texas Institute for Geophysics and Fred Frey of
the Massachusetts Institute of Technology will lead
the scientific team. The scientists hope to resolve
questions about the Kerguelen Plateau's eruption history
by analyzing samples of sediment and lava collected
in cores taken from deep beneath the seafloor. Since
its formation, the plateau has subsided to water depths
of more than a kilometer.
Earth has experienced massive volcanic episodes with
magma emanating from the deep mantle many times. Such
episodes were relatively common between 150 and 50
million years ago, but have been infrequent during
the past 50 million years. Due to their inaccessibility
beneath the oceans, few large igneous provinces have
been sampled and dated for comparison with similar
provinces on land, explains Bruce Malfait, ocean drilling
program director at NSF. Adds Frey, "When results
of the expedition are combined with previous seafloor
drilling studies, the Kerguelen 'hot spot' will provide
the best understood long-term record of hot spot volcanism."
Subsequent analysis of the core materials, both aboard
the ship and in land-based laboratories, will enable
scientists to reconstruct the volcanic history of
this region, including both the timing of eruptions
and changes in the chemical composition of the lavas.
States Coffin, "Large igneous provinces provide the
only known record of ancient deep Earth dynamics.
Kerguelen Plateau and Broken Ridge hold the history
of one of the largest and longest-lived volcanic events
on Earth. The results of this expedition will contribute
greatly to our understanding of how mantle hot spots
behave through time, and their possible effects on
the global environment." The Kerguelen hot spot continues
to erupt today at Heard and McDonald Islands in the
Indian Ocean.
|