tivity on the carmel faul

The plots illustrated in Figures 17 and 18 may serve as indicators for sample clusters,
which could lend statistical reliability to speleo-seismite ages from Denya Cave, yet with
no precise dating the uncertainty of these results is very large. Using the results from
these plots, which indicate age clusters, an age cluster analysis was made (see below).
4.2 Age cluster analysis
Another way to calculate sample ages is by using equation [2] according to Broecker
(1963), based on isotopic ratios of 230 Th/ 238 U and 234 U/ 238 U. Those ages can be plotted on
a U-series evolution diagram with isochron lines and initial 234 U/ 238 U evolution curves
(Fig. 19).
Adding a third axis (z= 232 Th/ 238 U) to the evolution diagram, age calculations can be
presented using a regression for an isochron line in three dimensions. The x-y plane
intercepts of this 3-D isochron define the ratios used to calculate a 230 Th/U age and initial
234 U/ 238 U (Ludwig and Titterington, 1994). Age calculations were done using Isoplot3.7,
where one age was calculated for all samples which plotted reasonably well on a three
dimensional isochron plot. The isochron plots were calculated for all samples of similar
uncorrected ages (as indicated by Figs 17 and 18) and then modifications were made
according to the criteria elaborated above (see ch. 3.3.3- Cluster dating). These isochron
age calculations (elaborated in Figs. 20-28), are termed sample age clusters and
considered to be indicators of seismic events that affected Denya Cave.
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