INVESTIGADORES
GHIGLIONE Matias
congresos y reuniones científicas
Título:
CONCAVE-TO FORELAND INDENTER AND THE FORMATION OF AN ARCUATE THRUST SYSTEM IN SANDBOX EXPERIMENTS: A COMPARISON WITH THE SOUTHERNMOST ANDES PROMONTORY
Autor/es:
GHIGLIONE, M.C.; CRISTALLINI, E.O.
Lugar:
Mendoza
Reunión:
Conferencia; Backbone of the Americas, GSA Mendoza; 2006
Resumen:
One of the most conspicuous large-scale features of the entire Andean
chain is the progressive change in strike from the N-S oriented
Patagonian Andes to the E-W trending Fuegian Andes. This bend was
originally named the Patagonian Orocline assuming complete oroclinal
bending. However, the kinematic evolution of the bend is still a matter
of discussion, and the possibility to disclose the overall tectonic
history of the region hinge in determine whether the southernmost Andes
are a truly Orocline, or if they evolved as a primary bend.
Although paleomagnetic studies could be a useful tool to unveil the
kinematic evolution of the curve through the analysis of declination
anomalies, paleomagnetic data from the region is still very scarce and
show an irregular pattern of rotations. However, the region was affected
by multiple phases of spatially superimposed deformation since the
Paleozoic, including many processes that may have produce vertical-axis
rotations. We use analogue experiments to test whether the
map-shape of the southernmost Andes and its structural features can be
related to Tertiary oroclinal bending or if to the contrary they are a
recess since at list the Late Cretaceous. The focus was made on the
interaction between the basement-internal domain and the thin skinned
fold-thrust belt. Since the Cordilleran basement-domain became
tectonically consolidated during Late Cretaceous times, we consider that
it behaved as a rigid indenter colliding against the soft tertiary
sedimentary cover. The experiments described in this work investigate
three possible tectonic configurations, including the oroclinal
hypothesis with rotational indentation, and the primary bend theory:
two-phase indentation and diagonal indentation. A geometry of
concave-to-foreland-indenter is in agreement with the structural pattern
and the along-strike variations of orogenic shortening. Further work is
necessary to test the influence of the Late Cretaceous Rocas
Verdes-marginal basin closure in the formation of the promontory.