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SCAR GSSG - ADMAP Overview
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ADMAP Overview
The Antarctic continent plays a very important role in the plate tectonics
context and its most recent revisions. The study of the lithosphere and
the identification of relevant lateral discontinuities in Antarctica and
surrounding areas are essential to the understanding of the geodynamic
evolution of the continent.
Studies of the Antarctic continent rely extensively on magnetic anomaly
data, because of the extensive ice cover. Numerous magnetic surveys
have been carried out by the international community.
The objective for compiling the Antarctic digital magnetic database is
to enhance the geological and tectonic utility of these magnetic data.
This compilation will provide an improvement in understanding the regional
geology of the Antarctic, provide a regional framework for the interpretation
of smaller scale areas and enable a more effective selection of areas for
further investigation.
The multinational Antarctic Digital Magnetic Anomaly Project (ADMAP)
has been launched to compile near-surface and satellite magnetic anomaly
data into a digital map and database for the Antarctic continent and surrounding
oceans. The unified data set will be a powerful tool for determining the
structure, processes and tectonic evolution of the continent, together
with providing information valuable in the reconstruction of the Gondwanaland
and Rodinia supercontinents. The resulting merged potential field anomaly
maps connect geological mapping studies of the various programmes in terms
of parameters such as:
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major structure and composition of the continent. The magnetic (and gravity)
data provide 2-dimensional regional maps of structural grain in basement;
suture zones between basement terranes; the basement terranes themselves;
the nature of intra continental rifts and the extent of major faults;
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geological timing and kinematics associated with the evolution of the continent.
Relative ages and displacements can be derived from the detailed geophysical
mapping of rock units. The distinctive magnetic signatures of some plutons,
serpentinites, amphibolites, migmatites, young sedimentary basins and volcanic
rocks provide important markers for extracting both the orientation of
regional faulting and relative timing;
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information on the isostatic state of the lithosphere contained in long
wavelength magnetic anomalies, because the lower crust is a zone of strongly
enhanced magnetisation with respect to the upper crust and mantle. Magnetic
data, especially in combination with correlative gravity observations,
can provide significant insight into the thermal structure of the Antarctic
lithosphere;
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paleoenvironment and global change; from the reconstruction of Gondwana,
it might be possible to identify the locations of old oceans and therefore
infer circulation paths that would have affected past climates;
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essential information on the crustal contribution to the Earth's magnetic
field from a remote and poorly understood region. This effort will permit
improved global geomagnetic field modelling and assist with verification
and calibration of magnetometer observations obtained from polar orbiting
satellite missions (e.g. POGO, Magsat, Orsted). The integration of satellite
and near-surface magnetic anomalies will result in a compilation that accurately
portrays the fullest possible spectrum of magnetic anomalies for the Antarctic
lithosphere.
An international Working Group of Antarctic scientists
is currently committed to this project.