Page 218 - Carbonate Platforms Facies, Sequences, and Evolution

the
and
late
204
four
late
main
Rl, Les Rimets.
European
stages
Jurassic-early
may
margins and continental
continental
be
Cretaceous
Cretaceous-Tertiary
collision.
margin,
southeast (Lemoine, 1984; Lemoine et
to
distinguished:
subsidence
which
NEUCHATE�
Fig. 1. Map of France shows the position of the area
northern Subalpine chains (dotted area) and the Jura
convergence
of
of the Triassic platform during the rifting period.
c}
a!., 1986).
studied (in black). Larger map shows the position of the
Lower Cretaceous deposits described here belong,
Triassic platform, Liassic and Middle Jurassic rifting,
mountains: CH, La Chambotte; LT, La Tailla I borehole;
passive margin and onset of the seafloor spreading,
During the Trias and particularly in the Lias, the
and the Apulian-Adriatic continental block to the
Cretaceous shelves were derived from the break-up
prerift
rift structures were all normal faults, some of which
domain of the Alps and in the Jura, the Jurassic and
of
the
In the external
Considering the main sedimentological features of
the
of
of
foot.
fault.
more
where
trench
tinued
marine
margin
basinal
Tucker,
the NW
three
Subalpine
deposition
and
Dauphinais
thin
Dauphinais
These
stable
During
of
part
located
or
large
A. Arnaud-Vanneau and H. Arnaud
deep-marine
platform located
of
in
the
chains)
Jura
were
sediments
of the Isere fault,
Basin,
to
thick
From the Dogger
deposits
the late Hauterivian,
the
the
corresponded
by
domain where
facies
differences
to
domains
rather
occur.
along
in
Vocontian
show
the
platform
was
into a rimmed shelf (Read,
thick
in
centre
locally
which are often considerable
Berriasian,
the
few
Known liassic palaeofaults have
hemipelagic
and
to
Basin
Dauphinais
the
the southeast
hemipelagic
seafloor
a
Isere
deposited
small
series of tilted blocks (Lemoine, 1984).
and
lateral
Palaeofaults
shallow-marine environments extended
strongly affected by sea-level variations.
represents
Basin
relief
shallow-marine
and laterally
margin
a
southeastern
bypass
fault
sequences
are
over
there.
sequences
1985) with reefs.
in
throws;
along the Menee fault (Fig.
were
deeper­
con­
into the NW part of the unstable and rapidly sub­
re­
(Fig. 2): (1) the Jura-Bas Dauphine platform situ­
the outer edge of this hemi­
variations.
Haute-Provence
scarp,
may have a certain strike-slip component (Lemoine,
1984). The interplay of two groups of fault (namely
the N-S to NE-SW faults) allows the delineation
France
another earlier major structure which runs in the
1),
pelagic sediment ramp was located 40 km to the SE
of the Durance
moved. The former shelf margin was obliterated and
domains
a ramp developed in the Hauterivian (Read, 1985;
ated to the northwest of the Cevennes faults and the
Isere fault (Vialon, 1974); (2) the Haute-Provence
areas. On the platform margins, sedimentation was
From the end of the Jurassic to the early Aptian
(Figs 3 & 7), many palaeogeographical changes took
The
platform were subjected to reduced subsidence, and
large
place, including progradation of the platform facies
(Read, 1985), with an accumulation of breccia at the
The
evolved
siding Dauphinais Basin (Arnaud, 1988). The shelf
margin
the
domain) was subsiding rapidly and a thick sequence
shelf was gradually drowned. The gradual filling of
found
the early Valanginian to the early Hauterivian, the
variable
(3)
Languedoc
(northern
late Jurassic (onset of
brought about a gradual filling of this marine domain
the spreading stage), the Dauphinais Basin (central
and decreasing of the outer slope of the shelf. From
wherever Liassic rocks crop out. They have throws
and which delimit a
1985) sloping steadily towards the SE. In