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Fig. 1
Location map of the study area with the geomorphological map of the Kaveri delta showing various geomorphological features. The easternmost VKI core has been undertaken for the present study. White circles depict the borehole sites for a few more core samples for future studies.
Fig. 2
(a) Chronostratigraphic cross-section of the VKI core, taken along the NS trending palaeo beach ridge parallel to the present coast. (b) Depth vs sand (%) graph showing a distinct change in the sediment type down the core. (c) Depth vs organic matter (%) graph showing variation in the total organic matter content down the core.
Fig. 3
(a) Preheat plateau test of VKI 12 shows 220°C as optimal preheat temperature (b) Laboratory generated dose growth curve; (inset) BSL shine down curve of VKI 12. (c, d) Dose recovery tests of VKI 4 and VKI 13 respectively (RD = Recovered doses), R1, R2, R3 are the regenerated laboratory doses shown in different colours for 5 different aliquots, laboratory doses given are shown in red. (e, f) Frequency histograms of VKI 4 and VKI 13 showing < 40% overdispersion. (g,h) radial plots of the measured doses of samples (VKI 4, VKI 12) respectively.
Summary of sea level fluctuations over the last 150 ka. The black bars represent durations of deposition in the core. The depositional periods in the core matches closely with sea level highs. The grey line depicts the present sea level. (Modified after Gibling et al., 2005; Waelbroeck et al., 2002; Singhvi et al., 2012).
OSL age table of samples analysed from VKI core showing various parameters for age calculations.
S. No
Sample
Depth
U
Th
K
Dose Rate
Dose
Age
No. of Discs
Name
(m)
(ppm)
(ppm)
(%)
(Gy/ka)
(Gy)
(ka)
1
VKI 2
2.6
0.68 ± 0.02
5.17 ± 0.03
1.46 ± 0.01
1.72 ± 0.12
5.81 ± 0.13
3.4 ± 0.2
22
2
VKI 3
4.4
0.55 ± 0.01
9.28 ± 0.07
0.64 ± 0.02
1.24 ± 0.08
6.14 ± 0.19
5.0 ± 0.4
27
3
VKI 4
5.8
1.48 ± 0.03
12.86 ± 0.19
1.50 ± 0.06
1.80 ± 0.23
11.34 ± 0.30
6.3 ± 0.8
30
4
VKI 5
8.0
1.94 ± 0.02
9.30 ± 0.09
1.23 ± 0.07
1.52 ± 0.20
8.90 ± 0.33
5.9 ± 0.8
32
5
VKI 6
9.9
1.41 ± 0.01
11.63 ± 0.22
1.35 ± 0.01
1.55 ± 0.21
No signal
-
-
6
VKI 7
11.9
1.98 ± 0.04
9.24 ± 0.07
1.31 ± 0.01
1.57 ± 0.21
14.34 ± 0.37
9.1 ± 1.2
21
7
VKI 8
13.8
0.69 ± 0.01
9.62 ± 0.18
0.55 ± 0.01
1.17 ± 0.08
67.05 ± 3.57
58 ± 5
25
8
VKI 10
16.9
1.07 ± 0.01
12.84 ± 0.01
0.62 ± 0.01
1.44 ± 0.10
117.50 ± 7.17
82 ± 7
13
9
VKI 11
19.4
0.93 ± 0.01
14.48 ± 0.16
0.41 ± 0.01
1.33 ± 0.09
117.90 ± 5.82
89 ± 7
30
10
VKI 12
20.8
1.48 ± 0.02
12.66 ± 0.12
0.50 ± 0.01
1.40 ± 0.09
143.50 ± 5.28
102 ± 8
33
11
VKI 12F
21.2
1.48 ± 0.02
12.66 ± 0.12
0.50 ± 0.01
1.37 ± 0.10
166.60 ± 10.19
121 ± 11
20
12
VKI 13
22.8
1.07 ± 0.01
4.67 ± 0.03
0.60 ± 0.01
0.96 ± 0.07
134.38 ± 7.52
140 ± 12
21
13
VKI 14
24.7
1.04 ± 0.02
7.05 ± 0.16
0.59 ± 0.01
1.08 ± 0.07
153.97 ± 6.66
143 ± 11
16
Table showing relative abundance of foraminifera: benthic, planktic and stress markers down the VKI core.