interconc

INTERPRETATIONS/CONCLUSIONS

GEOCHEMISTRY

Semi-Quantitative Analysis (See appendix 5)

With and accuracy of only approximately 20% the results of this analysis only have limited use. Certain abundances are extremely high, including Ca, Mg and Si which will obviously be found in large amounts in a dolomitic conglomerate. The results showed that there were significant amounts of REE that could be analysed. Certain elements had to be ignored due to previous experiments on the machine creating an excess on the mass spectrometer. There are no outstanding identical results that san be drawn from these analyses and any that could are subject to experimental error. Peaks are always found at 82Pb though actual amounts vary. 66Zn is high in the Rhyolitic control unlike the other controls.

Quantitative graphs (See appendix 6)

It is important to look at trends rather than each individual element in turn though in every comparison there are good matches with abundances of 60Tm and to a lesser extent 62Sm. The 69Tm is always a negative value. Overall there tends to be goo correlation between controls 1 and 3 and the samples.

1. Comparison of all controls.

Trends are the same in LREE but the rhyolitic sample is notably richer in all of these. It has a particularly high peak of 58Ce. The megalithic control is consistently lowest in REE except 63Eu. 2. Comparison of all samples. Trends are consistent except sample D which has a peak in 50 Pr. Samples C and D both peak at 67Ho. 3. Sample A compared to all controls. An almost perfect correlation is seen between control 1 and A. The LREE signature of sample A is a much better fit to the sedimentary controls than the igneous control. 4. Sample B compared to all controls. Similar result to sample A. The HREE signature is good for sedimentary signatures but not as good a fit as sample A. The LREE show a better fit to the sedimentary signatures than the igneous signature. 5. Sample C compared to all controls. There are no conclusive patterns seen in this comparison. There is no correlation between LREE and controls. The HREE fit compared to Control 1 is disrupted by enrichments in 67Ho, 70Yb and 71Lu. 6. Sample D compared to all samples. D also has no conclusive patterns. The fit between the HREE and the sedimentary controls is disrupted by enrichment in 67Ho. 7. Control 1 and Control 3. There are relatively good trends of LREE and HREE between the silicified and unsilicified conglomerates but is disrupted by a peak in 67Ho. The rhyolite is not as distinct from the control samples as hoped. It is more likely the odd nature of this stone is due to it being an extremely sandy layer within the conglomerate having been silicified rather that it being an igneous rock of any sort. The REE analysis has not completely ruled this possibility out but it has not confirmed it either.

There are always greater abundances of the LREE in all the samples and controls. This may point to a segregation of the LREE by hydrothermal fluid actions, though it is more likely that the original conglomerate already has this signature (McLennan, 1989). McLennan states that the most interesting feature of sedimentary rocks is the high LREE and fairly flat HREE signatures. This same pattern has been noted in all of the experiments in this study. He also points out that 63 Eu is associated with ubiquitous anomalies.