[SVC43-P09] Major element chemistry of volcanic glass from tephras around Pacayal Volcano in the eastern El Salvador, Central America
Keywords:tephrochronology, WDS, major element analysis
1) By the difference in major element chemistry, the tephras in the area can be distinguished from other tephra originating Coatepeque Caldera in western El Salvador, or Ilopango Caldera in central El Salvador.
2) Major element chemistries of the tephras in the area were concentrated to four clusters, as shown in fig. 2. Most of the tephras belong to Cluster I that shows relatively K2O poor and FeO and CaO rich chemistry. The Twin/Las Gemelas tephra and the Unit/Unidad-A tephra compose Cluster II, slightly higher in K2O and lower in FeO and CaO than the chemistry of the Cluster I. The chemistry of the Blanca Rosa tephra and the Jucuapa-4 tephra forms Cluster III, plotted in the area where K2O is higher and FeO and CaO is lower than the Cluster II. Only the Pacayal-1 tephra belongs Cluster IV that shows clearly unique chemistry of lower FeO and higher SiO2 than other tephras while the K2O value is similar to that of the Cluster III.