Figure F66. Major element compositional variations for Site 1139 compared with Kerguelen Archipelago alkalic volcanic series. The archipelago rocks are divided into three groups based on K-Ar ages: a lower Miocene alkalic basalt to trachyte series (~22 Ma), an upper Miocene basanite to tephrite series (6-10 Ma), and the Mount Ross stratovolcano (<1 Ma), which is the youngest edifice on the archipelago (Weis et al., 1993; Weis et al., 1998). The least-altered Unit 18 and 19 samples are indicated in bold.