Page 227 - Carbonate Platforms Facies, Sequences, and Evolution

212
larly
-
drop
SE
in
erosion,
mentation
rapid
noticeable in
depth
BASINWARD
took
and
varying
Hemipelagic
bioclastic limestone).
in
had
marly limestone
form (Jura platform),
place
often
the Jura,
two
DEPOSITIONAL
along
rv
older than the basal Barremian.
the
100m
most or all of the late Hauterivian
unexplained
I
late
consequences.
RANCONNET
importance from one
DYNAMICS
The
deposits.
variations
area
Substantial drop in sea-level is in the northern Sub­
alpine chains, where outer-platform bioclastic sedi­
inner domain and the edge of the Hauterivian plat­
another, provides an understanding of the particu­
first,
Several stages can be identified (Figs 7 & 8). The
followed by the erosion of
highest levels of this sequence contain a microfauna
was the emergence of the
Hauterivian or at the base of the Barremian. This
first stage corresponds to the sudden drop, probably
in
to
thickness and facies at this level in the Vaudois and
Hauterivian
Neuchatelois Jura. The second consequence of the
This
of several decameters, in sea-level at the top of the
Fig.
8).
(Arnaud,
It
Barremian
A. Arnaud-Vanneau and H. Arnaud
PARASEQUENCE
1981).
Bi5
the Hauterivian (Fig.
was fed by
This
depositional
7),
of the Valanginian, in the =
bioclastic limestone formation.
(northern Subalpine chains, Fig.
sequence
I
submarine
PARASEQUENCE
(BAI
fan
Bi 4
LA MONTAGNETTE
can
plateau). Outcrop view offlap arrangement of bioclastic limestone (Bi4 and Bi5 parasequences, part of the Glandasse
NW
and below the initial levels of the Glandasse bio­
Fig. 9. Lower Barremian lowstand prograding wedge (or late highstand wedge) of the Montagnette (northern Glandasse
3), at the bottom
of the Hauterivian hemipelagic slope. In this region,
bioclastic limestone corresponds to an accumulation
hemipelagic slope. Located on a slope, but not seen
sequence,
surface responsible for the synsedimentary sliding of
the exact location of which are unknown, but which
shallow-subtidal sediments,
thus
at the Hauterivian-Barremian boundary, the Borne
a submarine fan in the eastern Diois and the Devoluy
of grain flows located geometrically to the southeast
30 km 2 region between
and even locally of a part
the source for the grain flows that led to the Borne
along a narrow, more or less unstable strip that was
in outcrops, these deposits must have accumulated
clastic limestone. It is found above a large truncation
be interpreted as being the first level of the early
The second stage corresponds to the deposition of
the Col de Menee and the Col de Ia Croix-Haute