Table 2. Representative XRD analyses for three samples that demonstrate the effectiveness of the aragonite concentration protocol.
|
Sample
|
Sediment
type
|
Depth
(mbsf) |
LMC
(%) |
HMC
(%) |
ARAG
(%) |
|---|---|---|---|---|---|
| 3-2 | Bulk sediment | 14.40 | 6.5 | 0.9 | 92.6 |
| Fine fraction (<63 µm) | 14.40 | 6.4 | 0.7 | 92.8 | |
| 63- to 250-µm aragonite separate | 14.40 | -1.1 | -1.5 | 102.6 | |
| 3-5 | Bulk sediment | 36.72 | 18.9 | 5.5 | 75.5 |
| Fine fraction (<63 µm) | 36.72 | 29.6 | 5.4 | 65.0 | |
| 63- to 250-µm aragonite separate | 36.72 | -0.6 | -0.8 | 101.4 | |
| 6-2 | Fine fraction (<63 µm) | 5.05 | 6.7 | 7.0 | 86.3 |
| 63- to 250-µm aragonite separate | 5.05 | -1.3 | -2.0 | 103.3 |
Notes: LMC = low-Mg calcite, HMC = high-Mg calcite, ARAG = aragonite. Percentages were calculated using peak areas and standards of known composition (Fig. 2). 63- to 250-µm aragonite separates have undergone the sieving and heavy liquid protocols described in the text.