Page 193 - Carbonate Platforms Facies, Sequences, and Evolution

SW
the
sea-level
in Table 1.
this
(in
slope
I
#2
wells
ALDEIA
basinward
both
does
to
break
basi n
to
its
tectonic flexure (Fig. 7).
grai nstones
the
not
allochthonous
southwestward
was
form
limestone
O + o
_ me _ tr _ e _ s _ - . - -- - 4 GRANDE �1 400l MONTEJUNTO (U.OXFORDIAN) shown by the Cabas;os formation. thick; basinal ammonitic lime mudstones are only = 200m exploratory not reach the underlying Cabas;os formation. Other #1 well penetrated 500 Away from the Serra de Montejunto, the Praganca tectonics. in Fig. monoclinal flexures between the facies blocks shown ably continued over the shelf. while shallow-water carbonate sedimentation prob­ breccias and
_
slumps
tTojiera mb.l
the
®
shallow-
contain
located
southwest
thinning
fm.
small scale?
breccias
and
Caba<;:os
any
Tojeira
over
show
trend
a
is
that
-,
slope
deep-water
The steep dips and
member,
5 are probably related to Tertiary inversion
m into the buildup, but did
into a fault scarp at the end of the late Oxfordian
did develop
gentle
also
- 0 ' oo
the
limestone
- ------ -- ---- - - turbiditic
sand
pack stones
cv
The
I
after
shoals
shelf
. break
buildup.
the
presumed
Oxfordian
coral
to
Lourinha
biostrome
shallow
middle
and
Ota buildup is
Portugal
Cabas;os
extend
lagoon
I
Torres
situated
ROCHAFORTE
Oxfordian,
formation
=
eastwards
PRAGANCA
but
160m thick
restricted
& packstones
5 km
tural relationship between the two is
@
under
pebbles
(Fig.
shallow ,mai nly
a
nerineid wackstones
lagoon
before
8),
S-SE
& wackstones
Vedras formations.
the
NE
within
lime mudstones
@
cover
with
Montejunto buildup (see Fig. 3), though the struc­
Tertiary sediments. In places the Lourinha formation
of the
As Ota is cut by deep quarries and natural valleys,
on its western side by a N-S trending fault and is
obscured by
Fig. 7. Interpretative cross-section across the Montejunto buildup showing distribution of the facies associations described
exposed part of the Ota buildup is some 6 km long,
The
lateral facies relationships are much better displayed
179
rests unconformably on the karstified surface of the
of
block of Cabas;os formation situated to the northeast
Ota limestones indicates the uplift of a nearby region
late
Kimmeridgian. It is possible that the fault-bounded
the
than those at Montejunto. The presence of middle
a
tectonic dip a few degrees to the east. It is bounded