Basin�f ill Comple xes
�
!0� cours� s�4Ut'nt.:t'
(base of)
01 0lC3 0
••
Fig. 9.25. Schematic summary of an alluvial suite contain�
ing up to seven marker tuff beds, showing the use of these
beds to provide a detailed subdivision of the succession.
Horizontal scale is arbitrary, but includes vertical proflles
mapped over a lateral distance of about 35 km. Vertical
years. These sequences are thought to refl ect the independent operation of tectonic mechanisms on two
time scales (Yoshida et al., in press; see Chap. 13).
Blair and Bilodeau (1988) reviewed a wide range
of literature on sedimentation and tectonics and
pointed out that large�scale cyclic successions of
271
Fig. 9.24. Schematic cross sections perpendicular to active
margin of A pull�apart, B rift, and C foreland basins, showing
tectonic cyclothems. Large�dot pattern, alluvial�fan and
braidplain deposits; small�dot pattern, fluvial, lacustrine,
and marine deposits. (Blair and Bilodeau 1988)
B -- murkt'r tuff
G
SB 2oo y��r.> ·
36 !00 years
E
27 000 years
D
16 800 years
c
12 ZOO years
B
9 SUO years
A
0 years
scale is proportional to time. Thickness of the succession
varies between about 13 and 27 m. Old Red Sandstone
(Lower Devonian), southwest Wales. (Allen and Williams
1982)
tectonic origin are common in the geological record,
in all types of tectonic setting (Fig. 9.24). They proposed the term "tectonic cyclothem" for these successions. Their tabulation shows cycles of 120 m to
more than 2 km in thickness and representing 2.5-15
million years of sedimentation.
�
!0� cours� s�4Ut'nt.:t'
(base of)
01 0lC3 0
••
Fig. 9.25. Schematic summary of an alluvial suite contain�
ing up to seven marker tuff beds, showing the use of these
beds to provide a detailed subdivision of the succession.
Horizontal scale is arbitrary, but includes vertical proflles
mapped over a lateral distance of about 35 km. Vertical
years. These sequences are thought to refl ect the independent operation of tectonic mechanisms on two
time scales (Yoshida et al., in press; see Chap. 13).
Blair and Bilodeau (1988) reviewed a wide range
of literature on sedimentation and tectonics and
pointed out that large�scale cyclic successions of
271
Fig. 9.24. Schematic cross sections perpendicular to active
margin of A pull�apart, B rift, and C foreland basins, showing
tectonic cyclothems. Large�dot pattern, alluvial�fan and
braidplain deposits; small�dot pattern, fluvial, lacustrine,
and marine deposits. (Blair and Bilodeau 1988)
B -- murkt'r tuff
G
SB 2oo y��r.> ·
36 !00 years
E
27 000 years
D
16 800 years
c
12 ZOO years
B
9 SUO years
A
0 years
scale is proportional to time. Thickness of the succession
varies between about 13 and 27 m. Old Red Sandstone
(Lower Devonian), southwest Wales. (Allen and Williams
1982)
tectonic origin are common in the geological record,
in all types of tectonic setting (Fig. 9.24). They proposed the term "tectonic cyclothem" for these successions. Their tabulation shows cycles of 120 m to
more than 2 km in thickness and representing 2.5-15
million years of sedimentation.