Page 112 - Carbonate Platforms Facies, Sequences, and Evolution

well
LST
The
Table 1.
tention
LST-1
TST-1
Dewey,
LST-2
TST-2
HST-1
HST-2
tensional
especially
in
subsidence
sedimentary
depositional
Depositional
1982;
systems tracts
(Figs 22 & 23).
and
close
facies variations
fills
IBERIAN RANGES
0
documented
formation
recent
tectonic
to
"•
the
of
(e.g.
in the
years,
Hubbard,
basin
form the Upper Muschelkalk.
environments
3
1
1
1
1
7
regimes
0.6
(Ma)
and
has
central
Duration
that
Sclater
deposition
1988;
and subsidence
ANGULAR UNCONF0At.41TY
margin
the
F.
&
of
sedimentary
not yet been studied by the authors,
x X">< >< 'X.>< 102
existed,
EBAO
Thorne
received
BASIN
faults.
x Ca/vet, M.E.
1989). The rifting phase is characterized
nature
coarse
basins
&
(m)
part of the
PYRENEES BASIN Tucker and J.M. Henton
50-95
10-25
the
20-40
Christie,
49- 107
of
50-300
50- 130
30- 116
Thickness
in
much
Rates
ex­
is also a car­
at­
clastics,
control, and at times a more open connection with
were a function of ramp geometry, some structural
water
circulation patterns and nutrient supply, all of which
Tethys to the east. The Imon Formation, which has
1980;
are very similar too in all domains. The dramatic
Upper
Watts,
bonate sequence of very uniform facies and thickness
Muschelkalk are a consequence of the great range of
their
by rapid
histories are now
subsidence depend on the amount of stretching and
of
of
but
Max.
y><
3
4
13
4
20
11
the
Triassic
2.5
higher rates
(em 1000yr- 1 )
sed. rate
! 100Km
sediment:
(e.g.
extensional
carbonate-evaporite
Pitman
unit
7
16
15
30
event
&
of cycles
result of lithospheric cooling.
Max. no.
(Rot
was
fanglomerates,
few em 1000yr- 1 over 20-30Ma.
a
typical values are the order of
northeast of Spain.
Andrews,
major
pending on the extent and duration of the
equivalent)
braidplain
Cycle
37 000
70 000
33 000
430000
in
periodicity
of the Triassic basin fills in the
of the Buntsandstein, the lutite-carbonate-evaporite unit, equivalent to the Rot of northwestern Europe. TST-1 and
Again rates vary de­
upward passage from fluvial clastics into the lutite­
Duration of depositional systems tracts, sedimentation rates and cycle periodicities in the Catalan Basin Triassic.
sand­
LST is the major part of the Buntsandstein. LST-1 , the first systems tract of Depositional sequence 1, is the uppermost part
HST-1 form the Lower Muschelkalk. In Depositional sequence 2, LST-2 is the Middle Muschelkalk, and TST-2 and HST-2
Fig. 23. Three-dimensional model
rapid subsidence during rifting is generally followed
1985). The
rifting,
by a much slower, regional thermal subsidence as a
(<50 km), heat loss during rifting can lead to even
a metre or more per 1000 years. For narrow basins
Now with regard to the Catalan Basin, the early
1000 years immediately after rifting, decreasing to a
a long period of subaerial erosion and for the nature
rifting
episode, accounting for the onset of deposition after
10-20 em per
sea-level, and the succeeding transgressive systems
the
stones and floodplain mudrocks (Marzo, 1980). The
width of the basin, but they are typically the order of
upper part of the Buntsandstein, deposited close to