REE AND TRACE ELEMENT ANALYSES OF ASH USED BY THE ANCIENT ANDEAN CIVILIZATION OF TIWANAKU

Even though archeologists consider geological materials such as obsidian, sandstone, and basalt as raw materials for tool-making for humans, traditionally they have disregarded volcanic ash as having any technological importance. Therefore, the discovery of several layers of volcanic ash at an archaeological site on Lake Titicaca’s Taraco Peninsula in Bolivia, studied as part of the Iwawi Project, could not be easily explained. Stratigraphic analysis and radiocarbon dating suggest that the ash was deposited in between A.D. 550-750. Early analyses of the ash layers indicate that these layers were brought in by people to the location where they were found, indicating that the ash may have served some technological purpose.

In order to determine whether the ash was brought in from a single source or multiple sources, we chemically analyzed 13 samples collected from the Iwawi Project for Rare Earth Elements (REE) and trace elements. We used an Inductively Coupled Plasma Optical Emissions Spectrophotometer at UW Whitewater campus for our analyses. Preliminary results show that the ash samples contain Lu, Th, Yb, Sm, La, Nd, Ce, Y, and Sc, and that Th is very abundant in each sample. Also, Ce varies greatly between samples. Chondrite-normalized plots for REE indicate that sample 8 probably originated from a different source than the rest of the samples. In this poster we present the data from our chemical analyses and their archeological implications.