Page 153 - Carbonate Platforms Facies, Sequences, and Evolution

=
of
to
the
be
Tethys,
western
described
(Gaetani,
established
by
Margaritatus).
strong
Tyrrhenian Sea
Algeria
and wide swells.
1975),
consistent
physiography
On the contrary,
biostratigraphic
can
Macrocephalus) and
during the
with
(Elmi,
Bosworth
some
13
tectonic
along
central
Differences
been similar to that of the
this
the
only a few direct indications.
are poor. Discontinuities nos.
evidence:
early Mesozoic sedimentation.
1981) .
are
of the
(1986)
(middle
control
Red Sea (Monienat et al., 1986).
CONCLUSIONS
end
early rifting:
model.
Apennines
has
more
from
These
Ardeche
nuities are very attenuated in Ardeche.
of
The
the
documented in western France and the no.
been
also furnish a valuable
early
the
unclearly defined Progracilis Zone is abandoned; 5 =
margin.
(Fazzuolli
noticeable
equivalent to the poorly defined Aspidoides Zone; 4 =
Authors often call on similar en­
Gracilis) disconti­
11 (pre­
and between the Carixian and the Domerian (pre­
&
Sguazzoni, 1981; Farinacci et al., 1981; Elmi, 1981),
modern
A
pattern of Ardeche during the early Mesozoic seems
During late Triassic to early Callovian times, strong
complicated pattern developed of small sub-basins
southern Alps
clearly
Around the western
Recent African Rift as
model
However, there are
5, 6, 7, 9 and 14 are
been identified in western France because of a lack
stages
Hettangian, early Sinemurian (Semicostatum Zone)
Gregory Rift. The multidirectional palaeostructural
vironments to explain perturbations sustained by the
local, tectonic movements led to a segmentation of
However, strike-slip was probably active in the
western Tethys and the structural pattern may have
early
may be comparable with the recent history of the
unconformities well established in Ardeche have not
Kenyan
in
where they cannot be separated from each other.
coeval with strong instability on the Ardeche border
discontinuities and
the early Callovian as the pre-Gracilis event is not
to
with
data,
water
Purser
J.L.
also be
history.
Crevello
carbonate
and Scilla
Colorado).
(University
Institutions
appearance
environment
of
is
Wilson
especially
facies
deduced
circulation.
Lyon,
which
Late Triassic and Jurassic platf orms, France
the
(Marathon
(Montenat
such
climatic changes.
from
(New
have
&
as
the
France)
Oil
Oceanic
The
interpreted
cussed the initial manuscript.
weathering of the landmasses.
given
to
Falciferum Zone. Main sources of data: Elrni & Mouterde (1965), Elrni (1967), Elmi et al. (1987).
the well-cores
has
Barrier,
Braunfels,
me
helpfully reviewed the manuscript.
physiographic
have
I wish
'grumeleux'
chemical
prove the conclusions on the controls.
Company,
1985).
ACKNOWLEDGEMENTS
disappearance
access
Texas)
A
Fig. 29. [Opposite] Biochronostratigraphical chart of the major unconformities of the Jurassic sequence along the
of
to
changes
(lumpy)
corrected and
Fallaciosum Zone which is considered in France as the lower subdivision of the Insigne Zone; 7 = equivalent to the
and
developed
France (Centre-Ouest) (vertical column B) and with the major cycles defined by Haq et al. (1987) (vertical column C).
dis­
after the beginning of the Cretaceous. The physio­
'Ammonitico Rosso' facies, as rapidly lithified deep­
the sedimentation. One striking result was the dis­
from abundant files and varied sources and to im­
noteworthy disappear­
boundaries, black arrows = supercycle boundaries. Biostratigraphical comments: 1 = during the Coronatum Zone, the gap
Oblique lines = gaps, dotted = reduced sequences, circled crosses = lenticular beds; column C: white arrows = megacycle
began after the end of the earliest Obductum Subzone; 2 = equivalent to the Calloviense Zone of northwestern Europe; 3
considered as full zones (continental usage); 6 = equivalent to the
141
physiography is also known in the Messina Straits
washed by strong currents active between Charybde
where strong dipping slopes and deep plateaus are
to thank the
from the Recent (Boccaletti & Manetti, 1978). Steep
similar
(Societe Nationale
which previously obstructed the balance of the ocean
changes in the climate as well as modification of the
fragmentation
P.
The English text has been greatly improved thanks
and
graphic evolution must have been interdependent
water limestones do not seem to be well documented
can
Vivarais-Cevennes (vertical column A). Correlation with the discontinuities recognized by Gabilly et al. (1985) in western
some
(University Paris Sud-Orsay, France) have
R. Ross (Denver, Colorado) and B.H.
many parts of the Jurassic Tethys during its early
G. Dromart
Littleton,
the Morrisi 'Zone', considered here as a subzone; the poorly and
At the end of the Jurassic, changes took place all
around the Tethys and led to strong modifications of
in
remarks have led me to complement the data selected
ance of oolitic iron ore was probably influenced by
their
Their editorial