Page 97 - Carbonate Platforms Facies, Sequences, and Evolution

as
88
a
(Fig.
They
close
to
9).
are
decimetre
Paleokarsts
cavities are
the
The
Domain has the
angular
Sedimentary model
main
developed
(Andreu et al. , 1987).
most
surface
interpreted
in
blocks
as
Olesa bioclastic limestones
the
are
from
paleokarst
caves
prominent
low-energy broadly tidal-flat
F.
meteoric phreatic environment (Fig.
morphology
is
limestones
10).
lagoonal
cave-roof
deposit
of
horizons.
developed
paleokarsts,
in
the
smooth
Calvet, M.E.
and silts, red to brown in colour, with centimetre­
Brull, Olesa and Vilella Baixa U_nits, and their oc­
The Vilella Baixa Unit represents a general trans­
(1967), Ramon (1985) and Ramon & Calvet (1987).
Paleokarsts are a feature of the Lower Muschelkalk
domains. The eastern part of the Gaia-Montseny
currence and degree of development vary in different
and they have been described by Gottis & Kromm
than 3m in height and from a few metres to more
than 100 m in length. The cavities are filled by clays
collapse
horizontal cavities from a few centimetres to more
and
to
they are associated with Pb-Zn-Ba mineralization
angular. A vuggy porosity occurs in the carbonates
the
El
The El Brull laminated carbonates are interpreted
The main paleokarst level has a morphology of
and the
deposits.
the lower part of this unit to the shallowing-upward
These
gressive sequence from the lagoonal mud banks of
(Fig.
relief
cycles
whole
ments.
of
transition
Tucker and J.M.
Domains:
carbonates
shelf
Lower
disconformity,
the
and
from
and high-energy
sequences of the
is
Henton
a
UPPE R
(Brady
the
an
sand
middle
&
gradual
Muschelkalk,
belt,
part
The model proposed
Gaia-Montseny,
upper part.
Middle
11). The Colldejou Unit,
to
Rowell,
dolomites' (d).
these
the
deposit of a broadly regressive nature.
transition
Prades
three
1976)
MUSCHELKALK
is similar to
front' of the massive 'grey
Muschelkalk
and
(over
Lower Muschelkalk filled by
units
and
the
angular blocks. The line (arrow)
On a large scale, the Lower Muschelkalk carbo­
corresponds to the 'dolomitization
shallow-ramp environ­
homoclinal-ramp barrier-bank type of Read (1985).
On the scale of the
clastics and evaporites into the Upper Muschelkalk
above the regional
metres) from the carbonates into overlying Keuper
intertidal-supratidal/sabkha
Muschelkalk varies from around 100m in the north
In the Catalan Ranges, the thickness of the Upper
fluvial
to more than 140m in the south. There is a rapid
mud-shoal
low
the sand shoals at the top of the Vilella Baixa Unit
(1973), Read (1985) and Tucker (1985), with all the
deposits (El Brull Unit) to lagoonal facies (Olesa) to
form a broad, transgressive sequence from peritidal
various facies deposited in the protected inner ramp
some
the
also
nates belong to the ramp sedimentary model of Ahr
Baix
evaporitic, mostly sulphate facies. Like the Lower
Muschelkalk, the Upper Muschelkalk occurs in three
Ebre- Priorat, bounded by major faults (Fig. 2), but
Fig. 9. Paleokarst cavern (b) in the