Evolution and Controls of Facies Architecture in a Marginal Foreland Basin (Southeastern Pyrenees, Spain): Quantification By Magnetostratigraphy and Subsidence Analysis
DOCHERTY, CRAIG, DAVE WALTHAM, and CONXITA TABERNER
High resolution
, cross-basin magnetostratigraphy provides the ideal framework
for the quantification of foreland basin development. Combined with
lithostratigraphic correlation and well-constrained subsidence analysis, the
timing and duration of tectonic events, depocenter migration and lapse times for
basin infill can all be ascertained. This methodology is applied to the
evolution over a c.10 Myr. period of the mixed clastic/carbonate reservoir-scale
sedimentary bodies infilling the southeastern sector of the Eocene southpyrenean
foreland basin, Spain. The study area is flanked to the north and south by
thrust belts active during the basin's development. Quantitative analysis
reveals the individual movements of thrust sheets both from foreland and
hinterland, which resulted in a depocenter migratory pattern that was partly
oscillatory, partly Superposed as the deformation fronts closed together. Facies
architecture attests to these tectonic adjustments, where the formation of
deltas and carbonates in particular are very sensitive to
vertical
movements at
the basin's margins. One prominent erosion surface, that is not synchronous with
thrust movements, can only be explained by reactivation of pre-existing basement
faults. Hence this approach enables various tectonic factors that affect
reservoirs in complex tectonic settings to be distinguished in time and space,
with the obvious implications for basin closure and hydrocarbon migration.