Table 2. Oxide/element compositions.
ICP–AES data for the ten common rock-forming elements (as weight % oxides) from the Walton bed (Unit 4, Flora 4) of the Visean sequence at Loch Humphrey Burn. The relatively unconsolidated reworked tuff containing compression fossils is compared with enclosed, diagenetically generated concretionary nodules containing permineralised plants. SiO2 is used as a notional constant in order to estimate the relative degrees of concentration of other oxides in the nodules containing anatomically preserved plants, and CO2 is given as CaCO3 equivalent by acid digestion. Also given are values (ppm) of selected minor elements totalling 0.03–0.04% of each sample. LOI, loss on ignition; NA, not applicable (see also Bateman, 1999).
| Oxide | Sediment | Concretion | Change (%) |
|---|---|---|---|
| H2O | 5.1 | 2.8 | NA |
| LOI | 5.5 | 6.1 | NA |
| CO2 | ca 0.5 | 28.2 | NA |
| CaO | 1.90 | 24.22 | +1628 |
| MgO | 2.46 | 3.02 | +66 |
| FeO | 10.52 | 7.25 | −7 |
| Na2O | 0.45 | 1.69 | +409 |
| K2O | 1.42 | 0.91 | −13 |
| P2O5 | 0.24 | 0.22 | +24 |
| MnO | 0.10 | 0.37 | +402 |
| Al2O3 | 15.28 | 12.70 | +13 |
| TiO2 | 2.47 | 1.55 | −15 |
| SiO2 | 65.16 | 48.07 | 0 (fixed) |
| Zn | 123 | 78 | −14 |
| Pb | <25 | <25 | NA |
| Cu | 41 | 42 | +39 |
| Ni | 83 | 60 | −2 |
| Cr | 131 | 83 | −14 |
| Cd | 7 | 4 | −22 |
| Co | 29 | 17 | −20 |
| Mo | <1 | <1 | NA |