Abstract
This thesis investigates the eruptive history of Surtsey volcano, Iceland, through detailed textural and compositional analysis of a drill core extracted from its subaqueous diatreme. Surtsey, a UNESCO World Heritage Site formed during a 1963-1967 submarine eruption, provides a unique opportunity to study the complex interplay of magma, water, and geological structures in the formation of volcanic islands. While previous research has extensively explored Surtsey's surface geology and eruptive products, the subsurface record, particularly for the diatreme, remains understudied.
This study addresses this knowledge gap by examining the textural characteristics of the core, including grain size distribution, particle shape, sorting, and componentry. These analyses reveal distinct variations within the core, reflecting shifts in eruption dynamics, magma properties, and the degree of magma-water interaction during the volcano's early evolution. The core exhibits a complex record of transitions between submarine and subaerial eruptive phases, highlighting the dynamic nature of Surtseyan volcanism. The findings support a refined multi-stage eruption model, proposing a three-phase evolution: an initial submarine phase, intensified phreatomagmatic activity during emergence, and, though lavas were not sampled by coring, a transition to effusive activity.
The refined model challenges previous interpretations of Surtsey's early eruptive environment and provides new insights into the processes involved in diatreme formation. This research has significant implications for understanding the submarine growth phases of volcanic islands, the dynamics of explosive magma-water interactions, and the processes involved in diatreme formation. The high-resolution record preserved in the Surtsey core provides valuable insights for hazard assessment and the interpretation of similar volcanic systems globally.