Catuneanu Principles Seq Stratigraphy book[1]
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Catuneanu Principles Seq Stratigraphy book[1]


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however, inde-
pendent time control may be required to find the actual
position of unconformities, which are not necessarily
placed at the base of the fining-upward successions but
rather within the underlying fine-grained facies (Sweet
et al., 2003, 2005; Catuneanu and Sweet, 2005).
In spite of the potential limitations, the observation
of grading trends remains a fundamental and useful
method of emphasizing cyclicity in the stratigraphic
record. As long as data are available, i.e., access to
outcrops or core, plots reflecting vertical changes in
grain size can be constructed by careful logging and
textural analysis. The actual vertical profiles may
reflect the absolute, bed-by-bed changes in grain size,
or smoothed out curves that show the overall statistical
changes in grain size (e.g., moving averages of overlap-
ping intervals). The latter method is often preferred
because it eliminates abnormal peaks that may only
have local significance. The technique of constructing
vertical profiles can also be adapted as a function of
case study. The grain size logs may be plotted using an
arithmetic horizontal scale, where fluctuations in grain
size are significant, or on logarithmic scales where the
succession is monotonous and the differences in grain
size are very small. The latter technique works best in
fine-grained successions, where logarithmic plots
enhance the differences in grain size, but is less efficient
in coarser deposits (D. Long, pers. comm., 2004).
The construction of grain size logs is generally a
viable method of identifying cycles in individual
A-Kaolinite: B-Palygorskite/Smectite: C-Glaucony:
Kaolinite
Increasing abundance
CoalPB
Foreshore
Upper shoreface
Middle shoreface
Lower shoreface
PB
PB
Backshore
Coal
Fluvial deposits
Backshore
Foreshore
Upper shoreface
Middle shoreface
Lower shoreface
Kaolinite
Kaolinite
PB
PB
PB
Lagoonal
deposits
Intertidal
sands
Intertidal
marine deposits
Paleosol horizon
Supratidal
Lagoonal
deposits
Intertidal
sands
Intertidal
marine deposits
Palygorskite
Palygorskite
Smectite
Smectite
PB
PB
PB
M Si S
Inner
shelf
Outer
shelf
Inner
shelf
Outer
shelf
Glaucony
Increasing abundance
Clay mineral
Increasing abundance
10-15
vol%
40
vol%
5-10
vol%
DEPOSITIONAL ENVIRONMENT
NONMARINE TO SHOREFACE SHELF
1. Semi-humid to humid climate 2. Arid climate
FIGURE 2.8 Predictive distribution of early-diagenetic clay minerals in a succession of fluvial to shallow-
water regressive lobes (\u2018parasequences\u2019) separated by flooding surfaces (redrafted and modified from Ketzer
et al., 2003a). A\u2014kaolinite content increases toward the top of parasequences where continental facies are
exposed to extensive meteoric water flushing under semi-humid to humid climatic conditions. Kaolinite
content increases in the presence of unstable silicates and organic matter, as the degradation of the latter facil-
itates the formation of acidic fluids; B\u2014palygorskite content increases toward the top of parasequences
capped by evaporitic deposits, under arid climatic conditions; C\u2014in fully marine successions, autochthonous
glauconite is most abundant at the parasequence boundary, and decreases gradually toward the top of the
parasequence. Abbreviation: PB\u2014parasequence boundary.
FACIES ANALYSIS: OUTCROPS, CORE, AND MODERN ANALOGUES 23
FIGURE 2.9 Predictive distribution of diagenetic clay minerals in a sequence stratigraphic framework
(redrafted and modified from Ketzer et al., 2003a). Abbreviations: MFS\u2014maximum flooding surface; TS\u2014
transgressive surface; SB\u2014sequence boundary; HST\u2014highstand systems tract; TST\u2014transgressive systems
tract; LST\u2014lowstand systems tract.
Fluvial/estuarine sandstones
Coastal sandstones and mudstones
Marine mudstones
Marine sandstones
Condensed section deposits
Peat/coal deposits
Deep water turbiditic sandstones
Diagenetic clay minerals:
Kaolinite
Infiltrated clays
Berthierine
Glaucony (autochthonous)
Glauconitized mica
Mud intraclast (pseudomatrix) Parasequence
SB/TS
MFS
1
2
3
4
5
6
1 2 3 4
5
6
TST MFS
TS
SB
LST
 Present-day sea level
Re
tro
g.
 p
s. 
se
t.
TS
T
Re
tro
g.
 p
s. 
se
t.
TS
T
Re
tro
g.
 p
s.
 s
et
.
TS
T
Retrog. ps. set.
TST
Pr
og
. p
s.
 s
et
.
HS
T
Pr
og
. p
s.
 s
et
.
HS
T
Pr
og
. p
s.
 s
et
.
HS
T
Re
tro
g.
 p
s. 
se
t.
TS
T
Pr
og
. p
s.
 s
et
.
HS
T
Pr
og
. p
s.
 s
et
.
HS
T
Pr
og
. p
s.
 s
et
.
HS
T
SB/TS
MFS
SB/TS
MFS
SB/TS
MFS
MFS
TS
SB
MFS
TS
SB
SB
TS
MFS
Basin-floor fan
Slope fan
Lowstand
wedge
Condesed
section
Facies:
LS
T
TS
T/
HS
T
Dickite
M VcCLAY CFSILT Vf
Sandstone
Conglomerate
Up
pe
r C
oa
lsp
ur
 F
or
m
at
io
n
Paskapoo
Formation
0 m
12 m
24 m
36 m
48 m
50 m
62 m
74 m
clast-supported, crudely
bedded gravel
coalsandstone, very fine to coarse
massive sandstone,
fine to coarse
silt, mud
coaly shale
2
1
1
3
10µm
2
3
Illite
Smectite
Illite
1µm
1µm
Dickite
Dickite
Kaolinite
SU
SU
Kaolinite/Dickite
Increasing abundance
SU
FIGURE 2.10 Pattern of change in the distribution of kaolinite/dickite in a fluvial sequence stratigraphic
framework (from Khidir and Catuneanu, 2005). Kaolinite/dickite content increases gradually toward the top of
the sequence, and decreases abruptly across the sequence boundary. Abbreviation: SU\u2014subaerial unconformity.
outcrops or core, but matching such trends across a
basin, solely based on the observed grading trends, 
is not necessarily a reliable correlation technique.
Changes in sedimentation patterns across a basin due
to variations in subsidence and sediment supply make
it difficult to know which cyclothems are age equiva-
lent when comparing vertical profiles from different
sections. Under ideal circumstances, the availability 
of age data (biostratigraphic, magnetostratigraphic,
radiometric, marker beds) represents the perfect 
solution to this problem. Often, however, such age
data are missing, especially in the study of older
successions, and in the absence of time control other
sedimentological observations have to be integrated
with the petrographic data in order to constrain
geological interpretations. Paleocurrent measurements,
derived from unidirectional flow-related bedforms,
are particularly useful as a complement to petro-
graphic data, as they provide a record of the tectonic
tilt in the basin and changes thereof. The documenta-
tion of such changes helps us to infer events in the
evolution of the basin, commonly reflected by
sequence-bounding unconformities in the rock record,
providing additional criteria to enhance correlations
across the basin.
Paleocurrent Directions
The major breaks in the stratigraphic record are
potentially associated with stages of tectonic reorgani-
zation of sedimentary basins, and hence with changes
in tilt direction across sequence boundaries. This is
often the case in tectonically active basins, such as
grabens, rifts, or foreland systems, where stratigraphic
cyclicity is commonly controlled by cycles of subsi-
dence and uplift triggered by various tectonic, flexural,
and isostatic mechanisms. Other basin types, however,
such as \u2018passive\u2019 continental margins or intracratonic
sag basins, are dominated by long-term thermal subsi-
dence, and hence they may show little change in the
tilt direction through time. In such cases, stratigraphic
cyclicity may be mainly controlled by fluctuations in
sea level, and paleocurrent measurements may be of little
use to constrain