Discussion
Unfortunately, it is difficult to interpret the accuracy of the groupings made during this study from the elemental ratios alone due to the low sample size represented (n=12). Even with a larger sample size, the significant overlap between trace element ratios amongst volcanos makes developing conclusions from these ratios alone difficult. Nonetheless, some notable patterns do emerge from this dataset. Groupings of the Cayambe identified tephra and the Quilotoa identified tephra roughly correspond to the Eastern and Western Cordillera groupings presented by Bablon et al. The Nb results presented in this study appear almost twice as high as the values produced by Bablon et al., either due to better recovery or actual variation between samples. Nonetheless, the orientation of the groupings seem to correspond well with Bablon et al.’s. A cluster of spots from samples identified as Quilotoa with high Ba/La to high Zr/Nb and high Zr/Yb to low La/Zr ratios may represent a yet unidentified tephra not considered in this study. It should be noted that these outlying samples come from tephra layers that were exposed and naturally weathered while the other distal Quilotoa samples with lower Ba/La to lower Zr/Nb and low Zr/Yb to high La/Zr ratios come from tephra layers that were buried by anthropogenic activities relatively quickly after deposition. It’s possible that this cluster of samples has undergone some form of post-depositional chemical weathering or alteration that may have influenced their ratios. Future additions to this study will include the incorporation of more samples, weight percent of Al2O3, SiO2, K2O, MgO, FeO, and Na2O acquired by electron microprobe, relative concentrations of rare earth elements, additional ratios of more and less fluid-mobile elements, and Sr-Nb-Pb isotopic ratios to better distinguish the geochemical signatures of the potential source eruptions.