GEOCHEMISTRY OF THE MAUNA KEA ADZE QUARRY COMPLEX AND THE IMPLICATIONS FOR STONE TOOL EXCHANGE IN HAWAI`I

The Mauna Kea Adze Quarry Complex on the island of Hawai`i is located on the south slope of the Mauna Kea volcano at elevations between 9,000 and 12,500 feet. The primary flows exploited for adze production are part of the Liloe Spring member of the Hamakua Volcanic Series. These lavas were erupted as a possible subglacial fissure ridge between 150,000 and 70,000 years ago and covered by magmatically evolved lavas of the Laupahoehoe Volcanic Series (Wolfe et. al., 1997). This quarry complex was used extensively from AD 1100-1800 and provided the source material for possibly hundreds of thousands of stone adzes (ko`i) as demonstrated by the enormous piles of chipping debris found scattered throughout the site. The quarry complex occupies a larger area and has a larger volume of debitage than all other known Hawaiian quarries combined.

We measured the trace element geochemistry of 43 geological samples and 820 archaeological flakes from the quarry site using energy dispersive x-ray fluorescence (EDXRF). The range of compositional values for the Hamakua Volcanics are: Rb 15-45 ppm; Sr 540-600 ppm; Y 30-60 ppm; Zr 270-360 ppm; and Nb 25-40 ppm, while corresponding values for the younger Laupahoehoe Volcanics are: Rb 45-50 ppm; Sr 1175-1275 ppm; Y 55-60 ppm; Zr 615-630 ppm, and Nb 60-65 ppm. This extensive sampling of stone tool quality material from the quarry complex indicates a subtle variation in trace element geochemistry within the Hamakua Volcanic Series across the large site (up to 7 square miles), and a significant difference between the geographically proximate Hamakua and Laupahoehoe Volcanic Series rocks. These evolved lavas have a distinct geochemical signature relative to other stone tool quarries in Hawaii. We are beginning to use this information to trace the distribution of stone tools from Mauna Kea on the island of Hawai`i and throughout the Hawaiian island chain.