again established on the Marion plateau except at two
places, Marion reef on the extreme northeastern edge
and Suarez reef in the extreme southeast. This likely
occurred in the Pliocene as it did on the Queensland Plateau (Figure 5c). This phase of growth substantially
contracted on the Queensland Plateau by a third phase of
subsidence at 3.7 Ma, drowning much of the plateau and
in the north probably initiating further eastern migration
of the reefs at Pandora. This pulse probably also
established the main shape of the Australian continental
shelf. However, the third phase of reef growth – the Great
Barrier Reef – did not establish at this time; it occurred
much later.
Establishment of the Great Barrier Reef
The Great Barrier Reef, as we know it, started in the late
Pleistocene, much later than had been previously thought,
and very much later than when the main architecture of the
shelf had been established. The evidence for this is in the
drill holes from Ribbon 5 and ODP 820 (Figure 11a).
These data are summarized as follows
0
40
80
120
160
200
240
280
320
360
400
440
480
Distance (Km)
0
1
2
3
4
5
6
7
Ribbon 5
a
25 m
50 m
75 m
Caves
at 120 m
Caves at
160 m
Depth (M) below sea floor
Boulder reef
b
c
0
50
80
ODP 820
Simplified lithology
0
50
100
150
Depth(M)
mbsf
R1
R2
R3
R4
R5
R6
R7
R8
Rd3
Rd2
Rd1
Rd4
M
M
M
L
L
L
L
L
M
M
Mb
Mb
Mb
Mb
Mb
Mb
Mb
Mb
M
M
L
L
L
L
L
Lithology
Reef unit
Coral Ass
R1
R2
R3
R4
R5
R6
MUD
MUD
MUD
MUD
B2
B2
In-situ coral
framework
Mud and
coral rubble (Fac
Mud, clay with
minor sand (Faci
6C
275ka
B1
B2
C
465ka
A
0+2C
Hiatus
Grainstone/Packstone
Great Barrier Reef: Origin, Evolution, and Modern Development, Figure 11 Stratigraphy defined for (a) Ribbon Reef 5. Ribbon 5
data also shows the reef front morphology and its correlation with ODP 820 (b) Boulder Reef, and (c) ODP Site 820.
520
GREAT BARRIER REEF: ORIGIN, EVOLUTION, AND MODERN DEVELOPMENT