Publication Date:
2023-04-26
Description:
We report on a total of 1005 samples analyzed for major and trace element compositions from marine sediments drilled along the Hikurangi subduction zone and within the incoming Pacific plate. The samples are from International Ocean Discovery Program Expeditions 375 and 372; Integrated Ocean Drilling Program Expedition 329; Ocean Drilling Program Leg 181; and Deep Sea Drilling Project Leg 90.
All 1005 samples, resulting in a total number of ~20,200 individual measurements, were analyzed for major element compositions with the electron microprobe. A subset of 419 samples, resulting in a total number of ~1820 individual glass shard analyses, were analyzed for trace element compositions using the laser ablation-inductively coupled plasma-mass spectrometer. In total, ~640 samples were identified as primary ash layers based on their homogeneous geochemistry, visual appearance in the core pictures, and high amount of volcanic glass. Based on the biostratigraphy presented in the cruise reports and subsequent work, we can distinguish between Quaternary- and Neogene-derived tephras. The tephra layers of Quaternary age are mostly of rhyolitic composition with occasional andesitic, dacitic, and trachytic glass shards. The Neogene tephras are mostly of basaltic andesite, andesitic, and rhyolitic composition, with a few basaltic and trachytic tephras. Tephras of both age groups follow the calc-alkaline series trend with a tendency to shift into the high-K calc-alkaline series for tephras with 〉70 wt% SiO2.
Type:
Book chapter
,
NonPeerReviewed
,
info:eu-repo/semantics/bookPart
Format:
text
Format:
archive
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