Page 228 - Carbonate Platforms Facies, Sequences, and Evolution

set
facies
ment
these
1988).
Early
certainty
of
this region.
Glandasse
Hemipelagic
in
Barremian
the
sequences
(depositional
bioclastic
bioclastic
LIMESTONE
BIOCLASTIC
GLANDASSE
change
Vercors,
sequence
because of the vegetation,
is
Upslope (to the northwest),
limestone
BA1)
but it
laterally
parasequences
stone (Fig. 9; Arnaud, 1981, fig. 59).
to
and
can
made
on
Glandasse bioclastic limestone formation.
be
its
distinguished
up
the
by
hemipelagic equivalents. This lowstand wedge cor­
responds to a relatively narrow strip, several kilo­
at the base, a thin level of hemipelagic marly lime­
an offiap arrangement on the Borne bioclastic lime­
the onlap arrange­
Bi1 to Bi6, Arnaud-Vanneau et al., 1976) showing:
hemipelagic
of six
deduced
stone and marl, and at the top, bioclastic, oolitic or
coral limestone. Downslope (towards the southeast),
groups of shallowing-upward sequences (sequences
lateral
must have been located to the north of the Glandasse
plateau, not far from the first visible outcrops of the
deposition of a general lowstand wedge made up of
late
metres wide, occurring on and basinwards of the late
Hauterivian wedge. It was formed by a parasequence
The third stage, which is now only identified with
the
decreases rapidly towards the southeast, displaying
calcareous at the top (Arnaud, 1981; Ferry & Rubino,
cycles which are usually marly at the base and more
The thickness of parasequences Bi2 to Bi5
Hauterivian hemipelagic wedge is very rarely visible
indirectly from field data. It definitely exists on the
of
above
Grand
the
towards
etation,
northern
sufficient
mountain
spectively,
c c c c Late s L' INFERNET URGONIAN PAS DE The Jura and northern Subal pine chains
Glandasse
Barremian
the
very
to
-e:-
the
c c
data
on
c
slope
Goulets
Barremian
c c LIMESTONE
c
of
c
clear
wedge
prove
c
plateau.
c
remain
c c
is
the
c
(for location,
c c c
hemipelagic
northwest.
Hauterivian-Barremian
that
(central
c
c
base (ranging from region
Hauterivian
c
It
Except
Tete
c c
the
c
to
sketchy;
c c
marly
c
see Fig.
for
c c
c
Vercors)
early
Pelandre, central Vercors, Fig. 10).
c c
outstanding:
sedimentological
its
boundary
c
region
c
there
probably
c
hemipelagic
c c c PELANDRE SERRE
Chevaliere
is,
(1)
c
where
c c I
limestone
break
also
or
c
c c N DE 213
location
(Serre
the
of
Barremian
c
at
Barremian bioclastic or hemipelagic limestone,
c
hemipelagic facies observed below the Urgonian limestone unconformity is of basal early Barremian age (according to
c
Clave! et al., 1987). It then seems that, as in the 'La Montagnette' section, the maximum sea-level fall took place in the
hemipelagic marly limestone and 200-300m of bio­
dis­
de­
Given present erosion and the abundance of veg­
out­
the Lower Barremian deposits above the Hauterivian hemipelagic slope. In the Serre de Pelandre Mountain, the top of the
re­
bioclastic facies on the shallowest part of the low-
Fig. 10. Schematic section through the Lente Forest (southwestern Vercors) showing the probable onlap arrangement of
basal Barremian. MLL: Matheronites limentinus level. 1: Unknown, but possible position of a bioclastic lowstand wedge in
(northern
the
however,
Glandasse plateau), to the north of the Deux Soeurs
13) and near the
Urgonian limestone of the southern Vercors above
clastic limestone (Bi6 sequence) disappear towards
the north within< 7km (Fig. 10). The late Barremian
the Bi6 bioclastic limestone is then observed directly
appearance of several bioclastic toplaps is observed
occurs
throughout the southern Vercors where= 1000 m of
one observes
total thickness of which reaches 2000 m below the
de
posits correspond to a wedge = 10 km in width, the
side the Hauterivian hemipelagic wedge, the early
facies; (2) because of the substantial development of
the
pelagic
because