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Site U1592 (proposed Site CSK-09A) is located ~10 km southeast of Anhydros Island in the Anafi Basin at 693 meters below sea level (mbsl) (Figure F1). The aim at the site was to penetrate the entire volcano-sedimentary fill as far as the Alpine basement to reconstruct the evolution of the Anafi Basin: history of subsidence, presence of volcanic event layers in the basin sediments, and links between volcanism and crustal tectonics. We drilled to a maximum recovery depth of 519.8 meters below seafloor (mbsf) in two holes (U1592A and U1592B), terminating in limestone basement (all depths below seafloor [mbsf] are given using the core depth below seafloor, Method A [CSF-A], scale, except in Operations where the drilling depth below seafloor [DSF] scale is used). Average core recoveries were 71% (Hole U1592A) and 50% (Hole U1592B). The Anafi Basin potentially recorded the full volcanic history of Santorini (and any older centers) since rift inception, but it was envisaged to probably also contain few eruptive products from Kolumbo. Drilling enabled reconstruction of the volcanic, sedimentary, and tectonic histories of the Anafi Basin, allowing us to compare its evolution with that of the Anhydros Basin. The site was also chosen to develop a core-log-seismic integration stratigraphy and compare it with the recently published seismic stratigraphy for the basin (Preine et al., 2022a, 2022b) and the paleotectonic reconstruction of the region (Nomikou et al., 2016, 2018). The site transects six seismic packages of the Anafi rift basin, as well as the onlap surfaces between them (Nomikou et al., 2016, 2018; Preine et al., 2022a) (Figure F2). The Anafi Basin is crossed by many seismic profiles obtained in campaigns between 2006 and 2019, many of them multichannel (Hübscher et al., 2015; Nomikou et al., 2016, 2018). It is included within the area of the 2015 PROTEUS seismic tomography experiment, during which subbottom profiling, gravity, and magnetic data were also recorded (Hooft et al., 2017). The basin bathymetry had been studied in several marine campaigns, and fault distributions and throws had been mapped (Nomikou et al., 2016; Hooft et al., 2017). Previously published analyses of the seismic data suggested the following possible interpretations (from the bottom up; Preine et al., 2022a, 2022b): Units U1 and U2: sediment packages predating Santorini and Kolumbo volcanism; Unit U3: sediments and the products of the early Kolumbo volcanism and some of the Kolumbo cones; Unit U4: sediments associated with a major rift pulse; and Units U5 and U6: sediments and the products of Santorini activity, some of the Kolumbo cones, and the later eruptions of Kolumbo including the 1650 Common Era (CE) eruption. Units U3–U6 were believed to be of Pleistocene age, and Units U1 and U2 were believed to be possibly Pliocene. The site enabled us to test these interpretations by using the cores to reconstruct a near-complete volcanic stratigraphy consistent with both onshore and offshore constraints and pinned by chronological markers from biostratigraphy, magnetostratigraphy, and sapropel records. Benthic foraminifera from fine-grained sediments provided estimates of paleowater depths and, through integration with seismic profiles and chronologic data, of time-integrated basin subsidence rates. Coring at Site U1592 in the Anafi Basin addressed scientific Objectives 1–4 and 6 of the Expedition 398 Scientific Prospectus (Druitt et al., 2022). It was complemented by Site U1589 in the Anhydros Basin because each basin taps a different sediment distributary branch of the Christiana-Santorini-Kolumbo volcanic system.
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This content will become publicly available on June 13, 2026
Data report: core-seismic integration and time-depth relationships at IODP Expedition 398 Hellenic Arc Volcanic Field sites
We present seismic two-way traveltime depth relationships for all sites drilled by the International Ocean Discovery Program Expedition 398, Hellenic Arc Volcanic Field, using high-resolution multichannel seismic and core data. First, we filter and interpolate P-wave velocity and density data taken from (1) whole-round cores and (2) discrete measurements on half-round cores. We establish the reliability of shipboard density measurements by comparing them with in situ logging data. Using these validated measurements, we estimate acoustic impedance and synthetic seismograms. By correlating synthetic seismograms with those extracted from multichannel seismic profiles at each site, we establish time-depth relationships. We assess the quality of these relationships by examining the alignment of major lithologic boundaries with prominent unconformities or correlated conformities in the reflection seismic data. The results of this report facilitate the mapping of core data onto the multichannel seismic profiles at each site, allowing for spatial tracing of core data across the Christiana-Santorini-Kolumbo volcanic field.
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- PAR ID:
- 10600288
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- International Ocean Discovery Program
- Date Published:
- Journal Name:
- Proceedings of the International Ocean Discovery Program Expedition reports
- Volume:
- 398
- Issue:
- 201
- ISSN:
- 2377-3189
- ISBN:
- 978-1-954252-91-2
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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