IPY-568 CRITICAL REVISION OF GONDWANA BREAKUP (GONDWANA GGPP)

PROYECTO ARGENTINO

There are many controversial ideas about how Gondwana broke up with different
rigid plate models that include a variety of proposed segmentations for the
South American continent to accommodate the various subplates. The timing is
constrained by seafloor magnetic anomalies and the rotation poles derived from
them. Palaeographical reconstructions need to also be constrained by
geological and paleontological data, but frequently the kinematic modelers do
not have the requisite expertise. On the other hand, researchers with a
geological background detect and recognize phenomena by studying rocks and the
fossil record but often infer geologically compelling scenarios that do not
accurately meet the physics involved.

Gondwana GGPP will bring together specialists in Geology, Geophysics,
Paleontology, and Paleomagnetism [GGPP] to study the diverse tectonic models.
Collectively they can fill the knowledge gaps that heretofore have precluded
the formulation of a single comprehensive model for the break-up of Gondwana.
The opening of the SW Weddell Sea and the southern South Atlantic will be the
main focus of the project. The timings of the two openings are very much linked
together. The age of the Paran�-Etendeka hotspot [~132 Ma] is known and the
same age as the earliest seafloor spreading magnetic anomalies in the southern
South Atlantic, suggesting that it is improbable that there was a triple
junction in the Weddell Sea prior to 132 Ma. On the other hand, if there is
clear evidence for a medium to deep sea north of the Falkland-Malvinas Plateau
earlier than 132 Ma then a triple junction could have been established earlier.

Presently, there is conflicting evidence and at least 4 competing tectonic
models. The paleontology from wells drilled on the Falkland/Malvinas Plateau
and off the coast of Argentina need to be incorporated in the tectonic
analysis. In addition, the ages of the Colorado, Salado and San Jorge Basins in
Argentina as well as those of the Bredefort Basins off South Africa will
provide important information regarding the break-up history of Gondwana and
the early formation of the Weddell Sea. Paleomagnetic studies of the tectonic
domains around the South Atlantic both prior to and during Gondwana break-up
are essential to understanding the early break-up.

The main project objectives include:
1) Organize the existing magnetic anomaly picks defining quality factors with
reference to a single Geomagnetic Time Scale.
2) Revise the models of major plate drift through mapping of flowlines,
synthetic isochrons and geographic reconstructions.
3) Investigate the extensive basalt outpourings (Bouvet, Karoo and
Paran�-Etendeka) and the relationship between them.
4) Improve the paleomagnetic record around the South Atlantic to test and
quantify the rigidity of the South American, African and Antarctic plates
during initial break-up.
5) Revise the fossil match of the Gondwanide plates. Create data bank.
6) Revise the stratigraphic records. Create data bank.
7) Organize existing data and metadata to comply with JCADM standards.
8) Identify targets for high resolution magnetics and gravity surveying as well
as future scientific drilling targets.

PROJECT MEMBERS

Dra. Marta E. Ghuidella - Instituto Ant�rtico Argentino
Dr.Sergio Marenssi - Instituto Ant�rtico Argentino, CONICET
V�ctor A. Ramos - Universidad de Buenos Aires - CONICET, ARG
Augusto Rapalini - Universidad de Buenos Aires - CONICET, ARG
Rub�n Somoza - Universidad de Buenos Aires - CONICET, ARG
Haroldo Viz�n - Universidad de Buenos Aires - CONICET, ARG
Lawrence Lawver - University of Texas at Austin, USA
Ian Dalziel - University of Texas at Austin, USA
David Macdonald - University of Aberdeen, UK

All published material will contain clear geo-referencing information (i.e.
projection and scale, etc.) as well as digital mapping tools to use the maps or
make additions to them. Data archiving and metadata will follow the Joint
Committee for Antarctic Data Management standards.

This project addresses an item listed in one of the SCAR GSSG Initiatives for
IPY: A benchmark map series and hence it will have a strong link with the
Tectonic Map of the Earth'’s Polar Regions project. It will also be a
component of and/or collaborate with POLARGATES, as it will provide a revision
of base material for the interpretation of new Geophysical data.