Stable isotopes of carbon and oxygen in modern sediments of carbonate platforms, barrier reefs, atolls and ramps: patterns and implications - Perspectives in Carbonate Geology - page 66

2

Non-skeletal facies
Halimeda facies
Mollusc facies
Coral facies
Mud facies

Coral grainstone
Mollusc wackestone
Mudstone

− 0.5

Mollusc packstone

− 1 1

Mollusc-foraminifera packstone

13 C (‰)

− 1.5

2 0 2 4 6

−

0

− 2

1

−

− 2.5

2

−

− 2 0 2 4 6

− 3 13 C (‰)

3

−

− 3.5

Fig. 6. C-O-isotope plot of sediments from Maldive atolls.
Note the overlap of isotopic composition of facies.

Fig. 5. C-O-isotope plot of sediments from Belize Barrier
Reef. Samples from different facies largely overlap with the
exception of the non-skeletal facies.

Table 5. Correlation matrix of Belize Barrier Reef data. Bold numbers indicate statistically signifi cant correlation ( p < 0.05).

18 O 13 C

Depth ARA Mollusc Halimeda Coral Red algae Nonskel Mud

Depth 1

ARA .003 1

18 O

.214 − .463 1

13 C

.112 .123 .463 1

Mollusc .117 .123 .026 .089 1

Halimeda .089 − .376 .549 .340 .047 1

Coral .261 .433 − .205 .065 − .442 − .397 1

Red algae .002 .299 − .533 − .387 .112 − .476 .015 1

Nonskel .069 .086 .073 .057 − .300 .154 .181 .322 1

Mud .040 .232 − .477 − .480 .099 − .450 .079 .402 .157 1

In Rasdhoo Atoll, a number of signifi cant
correlations are seen between

examples, carbonate facies have characteristic
isotope compositions.
There are statistically signifi cant correlations
between

18 O and the
abundance of Halimeda , mollusc and foramin-
ifera (Table 6). The

13 C,

13 C values also correlated
with aragonite content and water depth. In Ari
Atoll, no statistically signifi cant correlations can
be detected between

18 O and the abundances of almost
all constituent particles, with the fi ne grain-size
fraction and with aragonite content (Table 8). The

13 C,

18 O, abundance of
constituent particles, fi nes, aragonite content and
water depth (Table 7).

13 C, 13 C pattern is also statistically correlated with

water depth.

Kuwait Ramp, Arabian-Persian Gulf DISCUSSION

Among surface sediment samples and constitu-
ent particle end-members,

Patterns and comparisons

13 C values range from

18 O from 13 C ( c . +1 to +5‰)

is comparable among the sites studied, bulk

0 to +4.5‰ and 2.1 to +1.5‰ (Fig. 7).

Unlike in the barrier reef, atoll and platform

Whereas the range of bulk

18 O