ABSTRACT
A sediment core from the salt marsh fringing Loch Duart, NW Scotland, UK, containing Lateglacial to Holocene sediments, was analysed using a multi‐element geochemical approach to elucidate ...the relative sea level (RSL) and palaeoenvironmental changes associated with the deglaciation of the British and Irish Ice Sheet. Elemental and isotopic measurements of rhenium, osmium, carbon and nitrogen, X‐ray fluorescence scanning, radiocarbon dating, and foraminiferal analysis produced a suite of data that complements the existing biostratigraphic framework. This suite of bio‐, litho‐ and chemostratigraphic analyses permits discussion of RSL changes that reflect the interplay between post‐glacial eustatic rise and glacio‐isostatic adjustment. The osmium‐isotope (187Os/188Os) data, coupled with a new age–depth model, depict an RSL fall between 16.8 and 14.1 ka cal
bp at an average rate of 2 mm a−1. Falling RSL culminates in basin isolation and is followed by subsequent marine inundation from 11.6 ka cal
bp. This RSL record preserves the local interaction between glacial isostatic adjustment and glacio‐eustatic sea‐level change, a relationship that is reflected in the sediment's 187Os/188Os signature. This is the first known application of the osmium isotope system in an isolation basin that is shown to be a viable proxy for RSL change, a technique that could be applied to glacially influenced isolation basins globally.
後期白亜紀の年代モデルは，主に北米Western Interior Seawayの地層において，各種化石・同位体比・サイクル層序と凝灰岩の放射年代を組み合わせることにより構築されてきた．一方，前期白亜紀のタイムスケールについては，層序学的研究が盛んにおこなわれてきたヨーロッパ地域の地層に凝灰岩がほとんど挟まらないため放射年代が得られず，各ステージ境界の年代値については不確定要素が高い（Gale ...et al., 2020）．とりわけ，Aptian階の基底の年代については，Malinverno et al. (2012)の年代モデルとGradstein et al. (2012)の年代モデルの間に500万年近くの差が生じている（Erba et al., 2015）． 北海道中軸部に露出する白亜系蝦夷層群は，全層厚が10,000mにも達する前弧海盆堆積物で，保存良好な化石が多産するとともに，多くの層準で流紋岩質凝灰岩を挟む．近年，各種化石層序と炭素同位体比・オスミウム同位体比層序を統合することにより，欧米にある白亜系各ステージのGSSPと蝦夷層群の間での高精度の層序対比が可能となった（e.g., Du Vivier et al., 2015; Takashima et al., 2019）．このことから，蝦夷層群における凝灰岩の年代測定は，白亜紀のタイムスケールの精度向上に大きな貢献ができる可能性が高い． 本研究はJSPS国際共同研究ＢおよびNSF-NERSの支援を受けた共同プロジェクトとして，蝦夷層群最下部の地層を用いて，Aptian/Barremian境界およびOAE1a層準の年代モデルの構築を目指した．北海道芦別地域中天狗沢の蝦夷層群最下部には，層厚約800mの泥岩ないし珪質泥岩からなる地層中に211枚もの珪長質凝灰岩層が挟まる．この区間の地層からおよそ層厚25㎝～50cm間隔で合計2000試料の泥岩・珪質泥岩試料，150試料の凝灰岩試料を採取し，炭素同位体比，オスミウム同位体比，ジルコンのCA-ID-TIMSによるU-Pb年代測定を実施した．その結果，蝦夷層群において，バレミアン/アプチアン境界およびOAE1a層の区間が明瞭に特定することができ，バレミアン/アプチアン境界に挟まる凝灰岩からは121.20±0.23 Ma，OAE1a層準の基底に挟まる凝灰岩からは119.63±0.14 Ma，OAE1a最上部の層準の凝灰岩からは118.84±0.13 Maの年代を得ることができた．これらの結果は，Geologic Time Scale 2020で示された年代よりも2~30万年ほど若く，最近提案された天文年代較正に基づくアプチアンのタイムスケール（Leandro et al., 2022）より2，30万年古い年代を示すことが明らかとなった．引用文献Erba et al., 2015. The Geological Society of America Special Paper 511, 271-303. Gradstein et al., 2012. The Geologic Time Scale 2012, 793-854. Malinverno et al., 2012. Geophys. Res., 117, B06104, DOI:10.1029/2012JB009260. Du Vivier et al., 2015. EPSL, 428, DOI:10.1016/j.epsl.2015.07.020. Takashima et al., 2019. Newsletters on Stratigraphy, DOI:10.1127/nos/2019/0472.Gale et al., 2020. Geologic Time Scale 2020, 1023-1086. Leandro et al., 2022. Nature Com. https://doi.org/10.1038/s41467-022-30075-3
The Paleocene/Eocene boundary and attendant Paleocene-Eocene Thermal Maximum (PETM) marks a time of rapid global climatic change. New Jersey shelf sediments of the Marlboro Formation record the PETM ...with exceptionally thick preservation (up to ∼15 m at Wilson Lake) during the period of global low carbon isotopic values ("the core") which requires minimum sedimentation rates near 10 cm/kyr. Rhythmic layers have previously been reported from both Wilson Lake & Millville, NJ (IODP Leg 174AX). These structures, dubbed 'couplets', consist of semi-periodic, 1-2 mm thick, raised laminations separated by typically homogenous sediment layers of varying width averaging 1.27 cm at Medford as opposed to nearly 2 cm at Wilson Lake and Millville. Previous studies have dismissed these structures as artifacts ('drilling biscuits') produced by drilling mud.I report here on a series of shallow (<65 ft; ∼19.81 m) auger cores drilled without using drilling fluid along a downdip transect at Medford, NJ. These cores show similar couplets on the ∼1 - 2 cm scale, indicating that they are in fact primary depositional features. The mm-width laminae in the auger cores experienced remarkable swelling within minutes of splitting. XRD, XRF, bulk carbonate geochemistry, and grain size analysis were measured throughout the Medford auger cores. I analyzed differences in these parameters between the laminae and interspersing bulk material, and then made comparisons with data collected at other sites along the New Jersey Coastal Plain (NJCP). I find no uniform discernible difference in lithology between laminae and beds, other than a higher percentage of kaolinite in some laminae.In general, the Marlboro Formation at this updip location consists of micaceous, lignitic, silty clay (mean size < 2 μm) with occasional organic debris indicating proximal deposition in a prodelta setting. A paleodepth of ∼40 m is estimated from a paleoslope model and normal marine salinities are inferred from the presence of common, though not abundant, planktonic foraminifera. I propose a model of deposition for the Marlboro Formation as being driven by fluid mud (near-bed suspension flows) transport associated with the "Appalachian Amazon", implying that the extremely fine-grained Marlboro Clay was deposited at Medford as part of a sigmoidal shaped subaqueous clinoform. The clinoform model explains the differential preservation of the Vincentown Formation, transitional units, and the CIE onset, "core", recovery, and overlying units along a dip transect across the paleoshelf. The laminations discussed here have analogs in modern environments characterized by muddy continental shelves and are associated with episodic or possibly quasi seasonal events of increased riverine discharge and the attendant migration of the benthic salinity front.
The COVID-19 pandemic has been a catastrophic event that has seriously endangered the world's population. Governments have largely been unprepared to deal with such an unprecedented calamity, ...partially due to the lack of sufficient or adequately fine-grained data necessary for forecasting the pandemic's evolution. To fill this gap, researchers worldwide have been collecting data about different aspects of COVID-19's evolution and government responses to them so as to provide the foundation for informative models and tools that can be used to mitigate the current pandemic and possibly prevent future ones. Indeed, since the early stages of the pandemic, a number of research initiatives were launched with this goal, including the PERISCOPE (Pan-European Response to the ImpactS of COVID-19 and future Pandemics and Epidemics) Project, funded by the European Commission. PERISCOPE aims to investigate the broad socio-economic and behavioral impacts of the COVID-19 pandemic, with the goal of making Europe more resilient and prepared for future large-scale risks. The purpose of this study, carried out as part of the PERISCOPE project, is to provide a first European-level analysis of the effect of government policies on the spread of the virus. To do so, we assessed the relationship between a novel index, the Policy Intensity Index, and four epidemiological variables collected by the European Centre for Disease Control and Prevention, and then applied a comprehensive Pan-European population model based on Multilevel Vector Autoregression. This model aims at identifying effects that are common to some European countries while treating country-specific policies as covariates, explaining the different evolution of the pandemic in nine selected countries due to data availability: Spain, France, Netherlands, Latvia, Slovenia, Greece, Ireland, Cyprus, Estonia. Results show that specific policies' effectiveness tend to vary consistently within the different countries, although in general policies related to Health Monitoring and Health Resources are the most effective for all countries.
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