The morphology of ash particles from the tephra allows an understanding of the eruptive dynamics of the eruptions and provides insight into the eruptive history of Erebus volcano.Īn extensive tephrostratigraphy for Antarctica has been established using tephra layers found in ice cores, exposed blue ice areas, and sedimentary deposits throughout the continent (Smellie, 1999). As the tephra are preserved in stratigraphic order we are also able to examine changes in the magma composition with time. Chemical compositions and statistical correlation help determine Erebus to be the source for all of the tephra. Tephra contained in glacial ice on the flanks of and adjacent to Mount Erebus and at several locations along the Transantarctic Mountains provide insight into the explosive eruptive history of Erebus volcano (Fig. Trace element analyses of bulk tephra samples show slight differences that reflect varying feldspar contents. The glasses show subtle trends in composition, which correlate with stratigraphic position. The phonolite compositions of glass shards confirm Erebus volcano as the eruptive source. Clustered and rare single xenocrystic analcime crystals, undifferentiated zeolites, and clay are likely accidental clasts entrained from a hydrothermal system present prior to eruption. A budding ash morphology results from small spheres quenched during the process of hydrodynamically splitting off from a parent melt globule. Glass droplets in some tephra indicate that these shards were produced in both phreatomagmatic and Strombolian eruptions. Two tephra deposited on the East Antarctic ice sheet, ~ 200 km from Erebus, resulted from Plinian and phreatomagmatic eruptions. Tephra having mixed phreatomagmatic–Strombolian origins are common. Scanning electron microscope images of the ash morphologies help determine their eruption mechanisms The tephra resulted mainly from phreatomagmatic eruptions with fewer from Strombolian eruptions. Tephra from Erebus were collected from glacial ice and firn.

A tephrostratigraphy for Erebus volcano is presented, including tephra composition, stratigraphy, and eruption mechanism.

Atlas erebus