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1. Expedition 381 Preliminary Report: Corinth Active Rift Development

   https://doi.org/10.14379/iodp.pr.381.2019  

   Shillington, D.J.; McNeill, L.C.; Carter, G.D.O. (February 2019, Preliminary report)

   null (Ed.)

   The primary objective of International Ocean Discovery Program Expedition 381 was to retrieve a record of early continental rifting and basin evolution from the Corinth rift, central Greece. Continental rifting is fundamental for the formation of ocean basins, and active rift zones are dynamic regions of high geohazard potential. However, the detailed spatial and temporal evolution of a complete rift system needed to understand rift development from the fault to plate scale is poorly resolved. In the active Corinth rift, deformation rates are high, the recent synrift succession is preserved and complete offshore, earlier rift phases are preserved onshore, and a dense seismic database provides high-resolution imaging of the fault network and of seismic stratigraphy around the basin. As the basin has subsided, its depositional environment has been affected by fluctuating global sea level and its absolute position relative to sea level, and the basin sediments record this changing environment through time. In Corinth, we can therefore achieve an unprecedented precision of timing and spatial complexity of rift-fault system development, rift-controlled drainage system evolution, and basin fill in the first few million years of rift history. The following are the expedition themes: • High-resolution fault slip and rift evolution history, • Surface processes in active rifts, • High-resolution late Quaternary Eastern Mediterranean paleoclimate and paleoenvironment of a developing rift basin, and • Geohazard assessment in an active rift. These objectives were and will be accomplished as a result of successful drilling, coring, and logging at three sites in the Gulf of Corinth, which collectively yielded 1645 m of recovered core over a 1905 m cored interval. Cores recovered at these sites together provide (1) a longer rift history (Sites M0078 and M0080), (2) a high-resolution record of the most recent phase of rifting (Site M0079), and (3) the spatial variation of rift evolution (comparison of sites in the central and eastern rift). The sediments contain a rich and complex record of changing sedimentation, sediment and pore water geochemistry, and environmental conditions from micropaleontological assemblages. The preliminary chronology developed by shipboard analyses will be refined and improved during postexpedition research, providing a high-resolution chronostratigraphy down to the orbital timescale for a range of tectonic, sedimentological, and paleoenvironmental studies. This chronology will provide absolute timing of key rift events, rates of fault movement, rift extension and subsidence, and the spatial variations of these parameters. The core data will also allow us to investigate the relative roles of and feedbacks between tectonics, climate, and eustasy in sediment flux and basin evolution. Finally, the Corinth rift boreholes will provide the first long Quaternary record of Mediterranean-type climate in the region. The potential range of scientific applications for this unique data set is very large, encompassing tectonics, sedimentary processes, paleoenvironment, paleoclimate, paleoecology, geochemistry, and geohazards. 

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2. Corinth Active Rift Development

   https://doi.org/10.14379/iodp.proc.381.2019  

   McNeill, L.C.; Shillington, D.J.; Carter, G.D.O. (February 2019, Proceedings of the International Ocean Discovery Program)

   null (Ed.)

   The primary objective of International Ocean Discovery Program Expedition 381 was to retrieve a record of early continental rifting and basin evolution from the Corinth rift, central Greece. Continental rifting is fundamental for the formation of ocean basins, and active rift zones are dynamic regions of high geohazard potential. However, the detailed spatial and temporal evolution of a complete rift system needed to understand rift development from the fault to plate scale is poorly resolved. In the active Corinth rift, deformation rates are high, the recent synrift succession is preserved and complete offshore, and earlier rift phases are preserved onshore. Additionally, a dense seismic database provides high-resolution imaging of the fault network and seismic stratigraphy around the basin. As the basin has subsided, its depositional environment has been affected by fluctuating global sea level and its absolute position relative to sea level, and the basin sediments record this changing environment through time. In Corinth, we can therefore achieve an unprecedented precision of timing and spatial complexity of rift-fault system development, rift-controlled drainage system evolution, and basin fill in the first few million years of rift history. The following are the expedition themes: 1. High-resolution fault slip and rift evolution history, 2. Surface processes in active rifts, 3. High-resolution late Quaternary Eastern Mediterranean paleoclimate and paleoenvironment of a developing rift basin, and 4. Geohazard assessment in an active rift. These objectives were and will be accomplished as a result of successful drilling, coring, and logging at three sites in the Gulf of Corinth, which collectively yielded 1645 m of recovered core over a 1905 m cored interval. Together, these cores provide (1) a long rift history (Sites M0078 and M0080), (2) a high-resolution record of the most recent phase of rifting (Site M0079), and (3) the spatial variation of rift evolution (comparison of sites in the central and eastern rift). The sediments contain a rich and complex record of changing sedimentation, sediment and pore water geochemistry, and environmental conditions from micropaleontological assemblages. The preliminary chronology developed by shipboard analyses will be refined and improved during postexpedition research, providing a high-resolution chronostratigraphy down to the orbital timescale for a range of tectonic, sedimentological, and paleoenvironmental studies. This chronology will provide absolute timing of key rift events, rates of fault movement, rift extension and subsidence, and the spatial variations of these parameters. The core data will also allow us to investigate the relative roles of and feedbacks between tectonics, climate, and eustasy in sediment flux, basin evolution, and basin environment. Finally, the Corinth rift boreholes will provide the first long Quaternary record of Mediterranean-type climate in the region. The potential range of scientific applications for this unique data set is very large, encompassing tectonics, sedimentary processes, paleoenvironment, paleoclimate, paleoecology, geochemistry, and geohazards. 

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3. PREHISTORIC BRONZE AGE RADIOCARBON CHRONOLOGY AT POLITIKO- TROULLIA , CYPRUS

   https://doi.org/10.1017/RDC.2022.99  

   Falconer, Steven E; Ridder, Elizabeth; Pilaar Birch, Suzanne E; Fall, Patricia L (February 2023, Radiocarbon)

   ABSTRACT Politiko- Troullia has generated the largest radiocarbon ( 14 C) dataset from a Prehistoric Bronze Age settlement on Cyprus. We present Bayesian modeling of 25 calibrated AMS ages, which contributes to an emerging multi-site 14 C chronology for Cyprus covering most of the Prehistoric Bronze Age. Our analysis places the six stratified phases of occupation at Troullia between about 2050 and 1850 cal BCE, in contrast to a longer estimated occupation inferred from pottery analysis. We provide a rare 14 C determination for the transition from Prehistoric Bronze Age 1 to 2 just after 2000 cal BCE, associated with a major architectural dislocation at Politiko- Troullia in response to local landscape erosion, possibly due to increased regional precipitation. We present a regional 14 C model for Prehistoric Bronze Age Cyprus combining the chronology for Politiko- Troullia with modeled 14 C ages from Sotira Kaminoudhia and Marki Alonia , which is bolstered by individual ages from five other settlements on Cyprus. Through the Prehistoric Bronze Age, agrarian villages on Cyprus developed the foundations for the emergence of urbanized settlement and society during the ensuing Protohistoric Bronze Age. Politiko- Troullia , in conjunction with other key settlements on Cyprus, provides a significant independent contribution to increasingly robust Bronze Age 14 C chronologies in the Eastern Mediterranean. 

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4. Recalibrating the Devonian time scale: A new method for integrating radioisotopic and astrochronologic ages in a Bayesian framework

   https://doi.org/10.1130/B36128.1  

   Harrigan, Claire O.; Schmitz, Mark D.; Over, D. Jeffrey; Trayler, Robin B.; Davydov, Vladimir I. (November 2021, GSA Bulletin)

   Abstract The numerous biotic, climatic, and tectonic events of the Devonian cannot be correlated and investigated without a well-calibrated time scale. Here, we updated the calibration of the Devonian time scale using a Bayesian age-depth model that incorporates radioisotopic ages and astrochronology durations. We used existing radioisotopic ages collected and harmonized in the last two geologic time scale compilations, as well as new U-Pb zircon ages from Emsian {Hercules I K-bentonite, Wetteldorf, Germany: 394.290 ± 0.097(0.21)[0.47] Ma} and Eifelian K-bentonites {Tioga B and Tioga F K-bentonites, Fayette, New York, USA: 390.82 ± 0.18(0.26)[0.48] Ma and 390.14 ± 0.14(0.23)[0.47] Ma, respectively}. We anchored floating astrochronology stage durations on radioisotopic ages and chained astrochronologic constraints and uncertainty together to extrapolate conditioning age likelihoods up or down the geologic time scale, which is a new method for integrating astrochronology into age-depth modeling. The modeling results in similar ages and durations for Devonian stages regardless of starting biostratigraphic scaling assumptions. We produced a set of rescaled biostratigraphic zonations, and a new numerical calibration of Devonian stage boundary ages with robust uncertainty estimates, which allow us to evaluate future targets for Devonian time scale research. These methods are broadly applicable for time scale work and provide a template for an integrated stratigraphic approach to time scale modeling. 

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5. Bayesian ages for pollen records since the last glaciation in North America

   https://doi.org/10.1038/s41597-019-0182-7  

   Wang, Yue; Goring, Simon J.; McGuire, Jenny L. (September 2019, Scientific Data)

   Abstract Terrestrial pollen records are abundant and widely distributed, making them an excellent proxy for past vegetation dynamics. Age-depth models relate pollen samples from sediment cores to a depositional age based on the relationship between sample depth and available chronological controls. Large-scale synthesis of pollen data benefit from consistent treatment of age uncertainties. Generating new age models helps to reduce potential artifacts from legacy age models that used outdated techniques. Traditional age-depth models, often applied for comparative purposes, infer ages by fitting a curve between dated samples. Bacon, based on Bayesian theory, simulates the sediment deposition process, accounting for both variable deposition rates and temporal/spatial autocorrelation of deposition from one sample to another within the core. Bacon provides robust uncertainty estimation across cores with different depositional processes. We use Bacon to estimate pollen sample ages from 554 North American sediment cores. This dataset standardizes age-depth estimations, supporting future large spatial-temporal studies and removes a challenging, computationally-intensive step for scientists interested in questions that integrate across multiple cores. 

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