Volcanic Processes in the Sedimentary Record: When Volcanoes Meet the Environment
CONTAINS OPEN ACCESS

This book brings together research, review and methodological papers that provide an updated view on the sedimentary record of volcanism, spanning diverse processes and environments. It aims to bridge the gap between volcanological and sedimentological approaches to the investigation of processes governing the generation, dispersion and accumulation of volcaniclastic deposits.
Volcaniclastic deposits and sedimentation processes around volcanic ocean islands: the central Azores Available to Purchase
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Published:April 13, 2023
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CitationYu-Chun Chang, Neil C. Mitchell, Thor H. Hansteen, Julie C. Schindlbeck-Belo, Armin Freundt, 2023. "Volcaniclastic deposits and sedimentation processes around volcanic ocean islands: the central Azores", Volcanic Processes in the Sedimentary Record: When Volcanoes Meet the Environment, A. Di Capua, R. De Rosa, G. Kereszturi, E. Le Pera, M. Rosi, S. F. L. Watt
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Abstract
Geological histories of volcanic ocean islands can be revealed by the sediments shed by them. Hence there is an interest in studying cores of volcaniclastic sediments that are particularly preserved in the many flat-floored basins lying close to the Azores islands. We analyse four gravity cores collected around the central group of the islands. Three sedimentary facies (F1-F2a, F2b) are recognized based on visual core logging, particle morphometric and geochemical analyses. F1 is clay-rich hemipelagite comprising homogeneous mud with mottled structures from bioturbation. F2a and F2b are both clay-poor volcaniclastic deposits, which are carbonate-rich and carbonate-poor, respectively. More biogenic carbonate in F2a reflects the incorporation of unconsolidated calcareous material from island shelves or bioturbation. Within F2a and F2b we identify deposits emplaced by pyroclastic fallout, primary or secondary turbidity currents by combining multiple information from lithological composition, sedimentary structures, chemical composition of volcanic glass shards and morphometric characteristics of volcanic particles. Primary volcaniclastic sediments were found in all four cores, echoing activity known to have occurred up to historical times on the adjacent islands. These preliminary results suggest that greater details of geological events could be inferred for other volcanic islands by adopting a similar approach to core analysis.
- Atlantic Ocean Islands
- Azores
- biogenic structures
- bioturbation
- C-13/C-12
- carbon
- chemical composition
- cores
- currents
- fallout
- glasses
- grain size
- igneous rocks
- isotope ratios
- isotopes
- lithofacies
- mineral assemblages
- morphometry
- nitrogen
- organic carbon
- organic compounds
- organic nitrogen
- pyroclastics
- sedimentary structures
- sedimentation
- sediments
- stable isotopes
- thickness
- total organic carbon
- turbidite
- turbidity currents
- volcanic glass
- volcanic rocks
- volcaniclastics