Geology Reference
In-Depth Information
Table 1. Weight percentages of calcium carbonate, organic matter, average, maximum and standard deviation of
sedimentation rate for sediment reference markers; weight percentages of calcium carbonate and organic matter for several
cores. Location of sediment reference markers in Fig. 8.
Sediment
reference marker
Calcium
carbonate (%)
Organic
matter (%)
Accumulation
rate (cm yr −1 )
Maximum accumulation
rate (cm yr −1 )
Standard deviation
of accumulation rate
47
70
19
4.4
9.8
4.7
48
73
15
5.1
7.6
2.4
49
66
26
3.7
3.8
1.4
58
68
27
5.8
5.8
-
59
71
24
6.2
8.3
2.3
60
70
18
6.7
6.7
-
61
70
26
4.7
8.1
2.9
77
69
29
5.4
9.4
3.6
78
73
21
3.6
5.0
1.5
79
66
22
4.0
5.3
1.2
80
65
24
3.8
4.3
0.5
81
55
28
5.3
7.2
1.7
86
71
23
4.2
7.2
2.4
87
68
17
3.7
4.6
0.9
88
61
22
4.1
6.3
1.5
89
67
28
2.5
2.8
0.7
90
63
32
95
-
-
3.1
3.3
0.3
102
72
27
5.1
6.2
1.6
104
73
29
9.9
12.9
2.9
107
73
26
10.7
12.5
4.1
107A
71
24
6.0
7.0
1.4
109
65
26
2.5
2.5
-
112
67
25
5.9
7.7
1.2
116
75
17
13.8
13.8
-
117
77
16
11.5
13.6
2.9
Core #
30
61
34
34
63
30
37
7
89
39
51
31
49
65
26
the expansion of juvenile mangroves on the oldest
delta part are interpreted to refl ect a reduction of
accommodation space.
During the deployment of the sediment refer-
ence markers from May 2004 until January 2005,
four large hurricanes (Charley, Frances, Ivan and
Jeanne) hit south Florida, but Cape Sable was not
directly affected by any of them. The processes
responsible for the high measured sedimentation
rates are therefore thought to be entirely tidally
driven.
carbonate and organic; in fact, less than 10% of
the sediment is non-carbonate, including sponge
spicules, diatoms, pollen grains, spores, detrital
dolomite and quartz silt (cf. Gebelein, 1977).
Sediment in the collapsed freshwater marsh has
TOM values ranging between 31 wt% at 10 cm
depth (number 39, Fig. 8b) to 85 wt% at the
surface (number 37, Fig. 8b). On the intertidal
mudfl ats of Lake Ingraham, the Southern Lakes
and along ECC the calcium carbonate content of
most surface samples is between 55 and 75 wt%
and TOC values range from 15 to 35 wt%
(Table 1; Fig. 8b). Lake Ingraham accumulates
sediment with the highest percentage of organics
in the area, whereas the shallowing banks along
ECC (#numbers 116, 117, 107 and 107A in Fig. 8b)
accumulate more carbonate-rich sediments.
Sediments in the study area display a trimodal
grain-size distribution (Fig. 9). The mean grain
Sediment characteristics
Akin to the differences in patterns and rates of
accumulation, the relative abundance of the two
main sediment components, calcium carbonate
and organic material, varies considerably around
the area (Table 1). The majority of sediment is
 
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