Page 308 - Carbonate Platforms Facies, Sequences, and Evolution

U
ture
from
north
The
control
shallow
was
sea-level.
and from
ity in the
prevented
Climatic
or calcretes.
on
enlargement
and
Tectonism
respectively).
the
Sedimentary
emergent
of
Garcfa-Mondejar,
was
CONTROL S
The
of the basin
flysch
the
southwest
well-lit
carbonates
conditions
La
predominantly passive.
areas,
ON
processes
(Fig.
the widespread
1979).
(Ebro?
from
probably
trough,
sedimentation,
former
marine
during
22;
caused
the
fluvial
Demanda,
the
by
being
which
controlled
Pascal
waters.
most
the
and Northern
The
Subsequently,
determining
sediments
Asturias,
et al.,
resulted
Urgonian
deposited
sedimentary processes, tectonism and eustacy.
type
of sedimentation ('Utrillas' fluvial sandstones).
SEDIMENTATION
trough (Fig. 38) and suggests extension in a NE­
Albian tectonic pulse created an angular unconform­
character of the climate is deduced from the abun­
last areas of Urgonian carbonate sedimen­
have been warm and wet. Urgonian limestones con­
Four factors were probably most influential in deter­
and troughs, while platform-margin buildups restric­
subsidence. Nevertheless, the main syntectonic fea­
gravity deposits associated with foreslope environ­
rgonian was coincident with the maximum develop­
demonstrated by the abundance and size of mass­
SW direction. The source areas during this interval
wide areas. Tides redistributed sands over platforms
tain reef-building organisms, which indicate warm,
from
great
mining the nature of the Urgonian deposits: climate,
Massifs,
tectonic pulses and probably eustatic sea-level falls,
Cinco
must have been situated to the southeast and to the
configuration, thickness and geometry of the units,
basin
amounts of terrigenous materials inundated the area
angular unconformities and palaeobathymetry. The
humid
must
dant plant remains present in the coastal plain facies,
and
ted the circulation of water during periods of lowered
Villas and Quinto Real Massifs (Fig. 38) could have
Synclinorium-Huici
important
over
distribution of facies. Intermittent terrigenous influx
synsedimentary
had some influence, but they were more probably
1976;
ments and by the outstanding differences in thickness
lack evidence of arid conditions, such as evaporites
which
ment of differential subsidence in the basin. This is
tation were definitely abandoned when a new late
the
the
the
highs
fected
major
place,
1979).
source
tation.
Biscay.
intense
Halo
forrnity,
probably
NW -SE
extension
continued
and
transition;
entire
the
Mondejar,
Urgonian,
in
fr.om local
region
movements
The early
Mondejar &
of
Differential
in
(e.g. Fig. 22).
feature
the
and
basin
angular
the
basin
emplacement
1979).
correspond
can be
the
Aptian-Albian carbonate episode, Spain
resulted
in the
erosion
troughs
(6)
structural
of
basin
According to
was
were also important,
Pujalte,
northwards
late
in
main
late
from
(Fig.
All of
during
subsidence
Mondejar et al., 1987, fig.
since
to slight
trend
the
1975);
the
in the
considered
34),
rifting
them
was
the flysch
the
unconformity,
Albian.
Albian,
(2)
subdivided
late
and
over short distances (e.g. Fig. 24).
late
surfaces which,
at
axis
Urgonian
As
have
a
into
at
the basement that probably exploited
of
series.
Upper
the
the final
in the
already
this
of basin evolution in the
progressive
Albian
displaying
been
the
least
a
top
zone in the southwest of the region (Fig. 22).
new troughs,
pulse
in
Cretaceous
Bay
region.
Mondejar, 1979), which culminated with the forma­
(Garcfa­
SW-NE trend. A northward displacement of depo­
occurred: (1) at the beginning of the Aptian (Garcia­
the Aptian and Albian (e.g. Figs 21 & 24) (Garcfa­
formities (Fig. 28; Garcfa-Mondejar, 1979; Garcfa­
as they created local uncon­
was a second type of tectonic control on sedimen­
The most important tectonic movements that af­
most important of all, as they created local discon­
one
inferred
major faults of Hercynian age. During the Albian
series of tectonic movements which created a mobile
36), and brought about
It
angular unconformities
Tertiary (Soler et al. , 1981), it is clear that it was a
early in the Aptian and followed block-faulting in
Subsequent
early-late
of a
Aptian transition; (3) in the early Lower Albian; (4)
important
285
eastward
sedimentation
in the middle Albian; (5) in the middle-late Albian
kinesis of Upper Triassic clays and evaporites
and high fluvial gradients. Slight N -S compressional
The movements at the beginning of the late Albian
centres of some of the troughs is discernible during
areas or rejuvenation of the existing ones,
major
effects in the west of the region have been described
in association with this episode (Garcfa-Mondejar,
subordinate
of the
pre-existing
migration
Cretaceous
Albian movements were perhaps the
and
tion of the Black Flysch trough in the northeast of
well-defined
new
of
other studies it became very