Geology Reference
In-Depth Information
Pertuis
Savagnières
Gorges de Court
Hautes-Roches
Vorbourg
7
k
2
k
9
k
1
k
m
B
5
B
?
?
m
(d)
m
?
?
4
m
m
9
m M W P G F/R B
3
(c)
Facies
limestone with quartz
marls
peloids
oncoids
ooids
lithoclasts
brachiopods
echinoderms
benthic foraminifera
corals
bivalves
gastropods
serpulids
ostracods
dasycladacean algae
charophytes
plant fragments
m M W P G
Texture
marls
mudstone
wackestone
packstone
grainstone
floatstone / rudstone
boundstone
2
m
M
W
P
G
F/R
B
m M W P G
(b)
1
Sequence- and Cyclostratigraphy
20-kyr sequence boundaries
100-kyr sequence boundaries
20-kyr maximum floodings
100-kyr maximum floodings
Sedimentary Structures
birdseyes
bioturbation
cross-stratification
microbial mat
(a)
m M W P G B
m M W P G
Fig. 9.
Correlation of elementary (20-kyr) sequences that compose small-scale sequence 9 (Fig. 6). Only major facies ele-
ments and sedimentary structures are indicated in the lithological columns. a, b, c and d indicate time lines along which
the reconstructions in Fig. 10 have been made. For discussion see text.
not possible to distinguish between reactivation
surfaces and elementary sequence boundaries,
and the correlation is speculative. In the Gorges
de Court section, a thin interval with birdseyes
and microbial mats covers a coral reef. This is
attributed to the top of elementary sequence 4.
The sections of Pertuis and Savagnières display
only slight facies contrasts. The correlation of
the elementary sequence boundaries is therefore
guided by the most conspicuous bedding surfaces.
However, maximum-fl ooding surfaces may also be
expressed as bedding surfaces. This is explained
by the ponding of clays during fastest relative sea-
level rise, while the clays at sequences boundaries
are washed onto the platform as a result of rapid
sea-level fall (Strasser & Hillgärtner, 1998). As for
the small-scale sequences (Fig. 6), the correlation
at the level of the elementary sequences represents
a best-fi t solution.
CONTROLS ON FACIES DISTRIBUTION
The complex interplay of many factors controls
carbonate-producing ecosystems, sediment distri-
bution and the fi nal sedimentary record; however,
the most important parameters will be discussed
separately.
Sea-level change
Facies evolution in many small-scale sequences
clearly indicates that water depth, water energy
and/or marine infl uence have increased then
decreased during the deposition of one sequence
(Figs 6 and 8). In other small-scale sequences,
facies show a rather aggradational pattern, then a
rapid shallowing at the sequence boundary. The
fact that the boundaries and in some cases also the
maximum-fl ooding surfaces of these sequences
