344
Chapter 7 Sequences, Minor Cycles, and Event Stratigraphy
a MARINE FLOODING OF ALLUVIAL PLAINS
(UMITED TERRIGENOUS SEDIMENT SUPPL V)
SEA lEVEL
HIGH SS
_~rGH_-_-~~-;::;~::;;~~!~;,~j: ' _ _ - ~_ ---SED ,
- LOW - - .. :.:.:,..~"w~ - - - - - - - - - - - - - - - - - - - - - - - - - - • ~ <)U
, -
9.::: ; : : ::;:::!.;;;t~Mr-/;;;·'" SLOW SUB
r-- A ~ )0
A
B
± REGR. LAG AND/OR SOlL
. MATERIAL
r;:,;~~~a--- FLUVIAL
f- LONG PHASE OF
\1
~§ .... ± REGR. LAG AND/OR SOlL
SHORT OR MISSING PHASE
F MARINE DEPOSITION
Fig. 7.29. a Marine
flooding of coastal
plains with limited
sediment supply: reduced or missing
barrier-lagoon system. Note difference
in time available for
marine sediment
buildup, SED, between locations A and
B (at B no subsidence). b Marine
flooding of lowland
lake or lagoon. The
effects of irregular
lake-level fluctuations may become
overprinted by those
of sea-level highstands
I MARINE DEPOSITION
6
TS ± SOlL
SS = SEDIMENT SUPPL Y
b MARINE INGRESSION INTO LOWLAND LAKE, LAGOON
BRACKISH TO MARINE SED
(INCL. CARBONATES)
FRESHWATER LAKE
SEDIMENTS ( ± COAL)
7.6.4 Economic Aspects of Incised Valleys and
Flooded coastal Plains
The marine and coastal fills of major incised valleys
often have lengths in the order of 100 km, widths of 20
km, and thiclmesses of some 20 m. This means that the
volume of one valley fill may reach about 40 km 3 • Under specific conditions, co al seams fonned within
these sedimentary bodies. The facies associations of
such valley fills include coastal and deltaic sand bodies
(reservoir rocks) and lagoonal and shelfal muds (seal
rocks). They therefore favor the accumulation of hydrocarbons and groundwater. If 1 % of the total sediment volume of 40 km 3 is filled by extractable oil, this
amounts to about 0.4 km 3 or approximately 400 million
tons of oil. For this and other reasons discussed in
Chapter 14, incised valley fills are an important target
in hydrocarbon exploration. In North America, for example, a significant part ofthe hydrocarbon production
comes from Cretaceous incised valleys ofthe Western
Interior foreland basin (e.g. Dolson et al. 1991).
UMITED SS -MP..RINE EVAPORITES
AND DOLOMITES
SHALES ± CONT.
EVAPORITES
In the case of groundwater, the storage capacity of
young valley fills is much higher than that for hydrocarbons and may be in the order of 5%. Assuming the
same total volume of one individual valley fill as
above, ab out 2000 million m 3 of water can be stored.
When part of the initial marine or brackish porewater
has been replaced by fresh water, this water body constitutes an important reservoir for groundwater extraction.
Many widely extended coal beds are associated with
the marine flooding of coastal plains and marine deltas. Examples are the extensive Perrnian coal seams of
northeastern China and the Carboniferous coal
cyclothems of North America and the Ruhr Basin in
northwestern Gerrnany (see above).
Chapter 7 Sequences, Minor Cycles, and Event Stratigraphy
a MARINE FLOODING OF ALLUVIAL PLAINS
(UMITED TERRIGENOUS SEDIMENT SUPPL V)
SEA lEVEL
HIGH SS
_~rGH_-_-~~-;::;~::;;~~!~;,~j: ' _ _ - ~_ ---SED ,
- LOW - - .. :.:.:,..~"w~ - - - - - - - - - - - - - - - - - - - - - - - - - - • ~ <)U
, -
9.::: ; : : ::;:::!.;;;t~Mr-/;;;·'" SLOW SUB
r-- A ~ )0
A
B
± REGR. LAG AND/OR SOlL
. MATERIAL
r;:,;~~~a--- FLUVIAL
f- LONG PHASE OF
\1
~§ .... ± REGR. LAG AND/OR SOlL
SHORT OR MISSING PHASE
F MARINE DEPOSITION
Fig. 7.29. a Marine
flooding of coastal
plains with limited
sediment supply: reduced or missing
barrier-lagoon system. Note difference
in time available for
marine sediment
buildup, SED, between locations A and
B (at B no subsidence). b Marine
flooding of lowland
lake or lagoon. The
effects of irregular
lake-level fluctuations may become
overprinted by those
of sea-level highstands
I MARINE DEPOSITION
6
TS ± SOlL
SS = SEDIMENT SUPPL Y
b MARINE INGRESSION INTO LOWLAND LAKE, LAGOON
BRACKISH TO MARINE SED
(INCL. CARBONATES)
FRESHWATER LAKE
SEDIMENTS ( ± COAL)
7.6.4 Economic Aspects of Incised Valleys and
Flooded coastal Plains
The marine and coastal fills of major incised valleys
often have lengths in the order of 100 km, widths of 20
km, and thiclmesses of some 20 m. This means that the
volume of one valley fill may reach about 40 km 3 • Under specific conditions, co al seams fonned within
these sedimentary bodies. The facies associations of
such valley fills include coastal and deltaic sand bodies
(reservoir rocks) and lagoonal and shelfal muds (seal
rocks). They therefore favor the accumulation of hydrocarbons and groundwater. If 1 % of the total sediment volume of 40 km 3 is filled by extractable oil, this
amounts to about 0.4 km 3 or approximately 400 million
tons of oil. For this and other reasons discussed in
Chapter 14, incised valley fills are an important target
in hydrocarbon exploration. In North America, for example, a significant part ofthe hydrocarbon production
comes from Cretaceous incised valleys ofthe Western
Interior foreland basin (e.g. Dolson et al. 1991).
UMITED SS -MP..RINE EVAPORITES
AND DOLOMITES
SHALES ± CONT.
EVAPORITES
In the case of groundwater, the storage capacity of
young valley fills is much higher than that for hydrocarbons and may be in the order of 5%. Assuming the
same total volume of one individual valley fill as
above, ab out 2000 million m 3 of water can be stored.
When part of the initial marine or brackish porewater
has been replaced by fresh water, this water body constitutes an important reservoir for groundwater extraction.
Many widely extended coal beds are associated with
the marine flooding of coastal plains and marine deltas. Examples are the extensive Perrnian coal seams of
northeastern China and the Carboniferous coal
cyclothems of North America and the Ruhr Basin in
northwestern Gerrnany (see above).