From marine sediments to explosive eruption record: A case study from New Zealand and a revised methodical approach

The investigation of marine tephra records allows the establishment of most complete long-term eruptive sequences of volcanoes, volcanic centres, and arc systems. These eruptive sequences enable further research of systematic changes, including potential links to external forcing, over entire life cycles of volcanic systems which is a major goal of this thesis. Five deep ocean drilling campaigns targeted the marine sediments offshore New Zealand [...] covering the marine environment towards the East and Southeast of New Zealand [...]. The recovered sediments comprised several intercalated volcanic deposits (i.e. tephra) and therefore enabled the investigation of the marine tephra record from New Zealand’s volcanic arc systems. The result of this investigation is a most complete marine tephrochronostratigraphy of New Zealand’s volcanism reaching back to the Neogene. The marine tephra record is continuous until c. 12 Ma and therefore complements and extends the volcanic onshore record of New Zealand’s volcanoes, which is considered to be well-established until ≤61 ka. [...] This cumulative thesis is based on four independent manuscripts. The first three contributions present the marine tephrochronostratigraphy of New Zealand’s volcanism [...]. The fourth contribution presents a methodical approach designed for marine tephra studies and optimised for large sample quantities and can be used as a “core to correlation” - recipe. [...] The major findings of this thesis are: 1) a continuous marine tephrochronostratigraphy for New Zealand’s volcanic arcs for the last 12 Myr [...], 2) temporal geochemical variations and trendswithin and between the two arc systems, 3) insights into the dispersal, depositional processes and overall preservation of tephra in the marine environment, 4) first estimates of tephra volumes and equivalents [...], and 5) eruption frequencies and repose times [...]