Provenance and depositional processes of tephras and Tertiary volcaniclastic sandstones from IODP Expedition 322, Nankai Trough

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During IODP Expedition 322 at the Nankai Trough, sediments down to the early Miocene have been drilled which allow to constrain the physical, compositional and structural characteristics of the subduction input into the seismogenic zone. We will use our samples from this expedition and samples from other Nankai bore holes to establish a Nankai-wide tephrostratigraphy including correlations with deposits on land; to identify provenance sources comprising the Miocene to recent Japanese and Izu-Bonin arc segments; to determine temporal and spatial variations in volcanic glass compositions since the Miocene; to unravel depositional processes of the newly discovered middle Shikoku basin formation; and to investigate the element exchange during submarine alteration of volcanic glass. Our chronological framework will provide the basis for other on- and offshore volcanological, sedimentological and geophysical studies aimed to understand the role of input parameters in the Nankai Trough subduction processes.