EUROPROBE News 9
GEORIFT: Geodynamics of Intracratonic
Rifting
by Randell Stephenson (Amsterdam)
and Georift colleagues
Precambrian cratons form the oldest and most stable
parts of the Earth's lithosphere. Their sedimentary cover preserves a long and detailed
record of intraplate deformations, ranging from rifting, hot-spot magmatism and the uplift
of broad arches, to thermal subsidence of intracratonic basins, compressional reactivation
with basin inversion, and crustal and lithospheric buckling. These deformations reflect
changes in the intraplate stress regime and must be related to plate boundary and mantle
processes. The East-European Craton (EEC), largely covered by Phanerozoic sedimentary
successions, forms the core of Europe and consists of a collage of continental and
arc-related terranes that were welded together during Proterozoic times. The overlying
East-European Platform (EEP) sedimentary succession represents one of the globe's best
natural laboratories for studying the response of craton lithosphere to changing tectonic
stress regimes. In particular, Devonian and Early Carboniferous rifting of EEC lithosphere
reflects a fundamentally different tectonic setting to that of the North American part of
what was then one contiguous continental plate; this has important implications for
understanding the driving mechanisms of intracratonic rifting.
GEORIFT addresses the mechanisms of rifting by
means of regional studies of the Late Proterozoic-Palaeozoic sedimentary basins of the EEP
as well as by detailed analysis of the exceptionally well documented Pripyat-Dniepr-Donets
(PDD) Basin, the largest and deepest Late Palaeozoic rift in Europe.
Highlights of GEORIFT include:
Availability of a vast geological and geophysical
data base, permitting development and quantitative testing of tectonic and
tectono-sedimentary models and their comparison with neotectonic analogues.
Analysis of the entire geodynamic record of the EEC
from the Riphean to the Present concentrating on the Late Palaeozoic, a period of
exceptionally intense rifting, causing the development of major sedimentary basins, some
of which host important hydrocarbon provinces.
Integrated geological-geophysical study of the PDD
basin with its exceptionally well documented structural and stratigraphic record, to
better understand the interplay of tectonic, magmatic, climatic, eustatic, and other
processes during the evolution of rifted intracratonic sedimentary basins.
Potential to resolve fundamental questions about
the dynamics of rifting and basin inversion and tectonic controls on post-rift subsidence
and sedimentation.
Comparison of the evolution of the EEC, in a plate
tectonic framework, with that of the North American and other cratons in order to
distinguish relative sea-level changes induced by intraplate deformations from those
related to eustatic fluctuations.
Development of proposals for acquisition of new
deep seismic near-vertical and wide-angle reflection surveys across the PDD basin and
other sedimentary basins of the EEC.
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