Page 137 - Carbonate Platforms Facies, Sequences, and Evolution

Fig.
are
126
and
block
Rosso
sitional
existed
facies
Millimetre-scale.
coccoliths
widespread
in
REGIONAL
over
can
suite' form a
be
the
the
(Middle
Northern Tethyan margin
found.
largest
JURASSIC
part
Oxfordian;
of
particular kind of
'Lumpy'
western Mediterranean region (Chanell et
(a) and small and angular quartz (b). Riou-Petit
'Marly-Calcareous
Formation (Upper Sandy-Calcareous series). Late
slope
SETTING
Bourseau
sorted grains: large multi-crystalline and rounded quartz
18. Biomicritic packstone to wackestone with poorly
tran­
Toarcian. ARD 14 Well (COGEMA) near Privas (144 m).
('calcaires grumeleux') belonging to the 'Ammonitico
&
S.
Elmi, 1981; Dromart & Elmi, 1986; Dromart, 1986).
a!. , 1979;
Laubscher & Bernoulli, 1977; Winterer & Bosellini,
limestones
At the beginning of the Jurassic, a wide continental
the present
Series'
1981). Several attempts to reconstruct the opening
Elmi
et
of
for
the
the
and
(see
early
been
They
ward,
The
trends
basins.
(Massif
the
present
Lister et
External
Apulian)
structural
commonly
Dercourt et
Wernicke's
detachment
to
internal
basement
limited
strip
brian�onnais'
These
Jurassic
support
Cevennes
kinematics
Bernoulli
changed
margin)
on
of
Central)
Subalpine
Alps
&
margin
and
model
the
Brian�onnais Zone.
Crystalline
massifs
prevailed
sedimentary history.
the
times,
and
crops out in the west
area).
which
structure
and
from
European
a
Basin
which
(1981)
can
east
outcrop.
both
The
was
Palaeostructural framework
have
is
(Piemont
of
time
Lemoine,
be
by
on
within
Massifs).
(French
slightly deformed fringe
(Lemoine,
to
cratonic
tectonic
'Brian�onnais'
evolved
been
the
the
1980,
Zone)
palaeostructural
located
related
time
Transverse
obliquely
into
for
tilting
zones,
are
to
affecting the same continental basement.
pre-Triassic
a
Zones.
detachment
Transition
basin
a 'marginal
a
east
a
cut
external
of
involved
the
1983; Elmi,
trends
extension of the European basement leading
of
during
in
by
faults
areas
to
'Sub­
folded zone (Subalpine Chains) and a narrow west­
given in Fig. 21. Cartographic, structural and strati­
review;
of so-called oceanic sub-basins have been presented
1980,
evolution began by the opening of many elongate
has been an attractive model but it cannot explain all
Mesozoic
deformation and uplift of the Mesozoic continental
margins. In a wide area stretching from African (or
were related to extensional stresses
crustal thinning with some Triassic volcanism in the
basement
Cristallins Externes) fits well with the adaptation of
to
well as in the east ('Massifs Cristallins Externes' or
'Massif Central') as
the
complex
blocks
(Ardeche-Vivarais
a/. , 1985). The opening of the Atlantic
Through
(Massifs
by
margin
Thickness data and isopach maps, published by Elmi
situated between two detachment systems. A similar
plateau'
a/. (1986). The rifted basin appears to have
the
eastern parts of the basin. Moreover, the occurrence
main structures are oriented SSW-NNE (N10 E to
graphical data also have been extensively used. The
vary
N20 E; longitudinal 'Cevenol' trend), parallel to the
a/. (1984, 1987) are summarized in Figs 19 & 20.
a
general
interpretation
the
from WNW-ESE to WSW-ENE. The role of these
the