The Cyclostratigraphy Intercomparison Project (CIP): consistency, merits and pitfalls

Cyclostratigraphy is an important tool for understanding astronomical climate forcing and reading geological time in sedimentary sequences, provided that an imprint of insolation variations caused by Earth’s orbital eccentricity, obliquity and/or precession is preserved (Milankovitch forcing). Numerous stratigraphic and paleoclimate studies have applied cyclostratigraphy, but the robustness of the methodology and its dependence on the investigator have not been systematically evaluated. We developed the Cyclostratigraphy Intercomparison Project (CIP) to assess the robustness of cyclostratigraphic methods using an experimental design of three artificial cyclostratigraphic case studies with known input parameters. Each case study is designed to address specific challenges that are relevant to cyclostratigraphy. Case 1 represents an offshore research vessel environment, as only a drill-core photo and the approximate position of a late Miocene stage boundary are available for analysis. In Case 2, the Pleistocene proxy record displays clear nonlinear cyclical patterns and the interpretation is complicated by the presence of a hiatus. Case 3 represents a Late Devonian proxy record with a low signal-to-noise ratio with no specific theoretical astronomical solution available for this age. Each case was analyzed by a test group of 17-20 participants, with varying experience levels, methodological preferences and dedicated analysis time. During the CIP 2018 meeting in Brussels, Belgium, the ensuing analyses and discussion demonstrated that most participants did not arrive at a perfect solution, which may be partly explained by the limited amount of time spent on the exercises (∼4.5 hours per case). However, in all three cases, the median solution of all submitted analyses accurately approached the correct result and several participants obtained the exact correct answers. Interestingly, systematically better performances were obtained for cases that represented the data type and stratigraphic age that were closest to the individual participants’ experience. This experiment demonstrates that cyclostratigraphy is a powerful tool for deciphering time in sedimentary successions and, importantly, that it is a trainable skill. Finally, we emphasize the importance of an integrated stratigraphic approach and provide flexible guidelines on what good practices in cyclostratigraphy should include. Our case studies provide valuable insight into current common practices in cyclostratigraphy, their potential merits and pitfalls. Our work does not provide a quantitative measure of reliability and uncertainty of cyclostratigraphy, but rather constitutes a starting point for further discussions on how to move the maturing field of cyclostratigraphy forward

The Generation R Study: design and cohort update 2010

The Generation R Study is a population-based prospective cohort study from fetal life until young adulthood. The study is designed to identify early environmental and genetic causes of normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on four primary areas of research: (1) growth and physical development; (2) behavioural and cognitive development; (3) diseases in childhood; and (4) health and healthcare for pregnant women and children. In total, 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. General follow-up rates until the age of 4 years exceed 75%. Data collection in mothers, fathers and preschool children included questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome wide association screen is available in the participating children. Regular detailed hands on assessment are performed from the age of 5 years onwards. Eventually, results forthcoming from the Generation R Study have to contribute to the development of strategies for optimizing health and healthcare for pregnant women and children

Modeling of negative Poisson’s ratio (auxetic) crystalline cellulose Iβ

Energy minimizations for unstretched and stretched cellulose models using an all-atom empirical force field (Molecular Mechanics) have been performed to investigate the mechanism for auxetic (negative Poisson’s ratio) response in crystalline cellulose Iβ from kraft cooked Norway spruce. An initial investigation to identify an appropriate force field led to a study of the structure and elastic constants from models employing the CVFF force field. Negative values of on-axis Poisson’s ratios nu31 and nu13 in the x1-x3 plane containing the chain direction (x3) were realized in energy minimizations employing a stress perpendicular to the hydrogen-bonded cellobiose sheets to simulate swelling in this direction due to the kraft cooking process. Energy minimizations of structural evolution due to stretching along the x3 chain direction of the ‘swollen’ (kraft cooked) model identified chain rotation about the chain axis combined with inextensible secondary bonds as the most likely mechanism for auxetic response

Proxy evidence for state-dependence of climate sensitivity in the Eocene greenhouse

Despite recent advances, the link between the evolution of atmospheric CO2 and climate during the Eocene greenhouse remains uncertain. In particular, modelling studies suggest that in order to achieve the global warmth that characterised the early Eocene, warmer climates must be more sensitive to CO2 forcing than colder climates. Here, we test this assertion in the geological record by combining a new high-resolution boron isotope-based CO2 record with novel estimates of Global Mean Temperature. We find that Equilibrium Climate Sensitivity (ECS) was indeed higher during the warmest intervals of the Eocene, agreeing well with recent model simulations, and declined through the Eocene as global climate cooled. These observations indicate that the canonical IPCC range of ECS (1.5 to 4.5 °C per doubling) is unlikely to be appropriate for high-CO2 warm climates of the past, and the state dependency of ECS may play an increasingly important role in determining the state of future climate as the Earth continues to warm

Multiproxy analysis of paleoenvironmental, paleoclimatic and paleoceanographic changes during the early Danian in the Caravaca section (Spain)

After the Chicxulub impact and mass extinction at the Cretaceous-Paleogene boundary (K-PgB), ecosystems haltingly recovered under unstable conditions. An early Danian (65.9 Ma) perturbation of the carbon cycle known as Dan-C2, which includes two carbon isotopic excursions (CIEs), has been ascribed to inputs of greenhouse gases through large-scale volcanism of the Deccan Traps. However, the relationship between Dan-C2, volcanism and environmental and climatic changes during the early Danian remains ambiguous. Based on stable isotopes, calcium carbonate content, magnetic susceptibility and planktic foraminifera, we present a paleoenvironmental, paleoclimatic and paleoceanographic reconstruction of the early Danian from the Caravaca section, Spain, one of the most complete and continuous K-PgB sections worldwide. The paleobiological response of planktic foraminifera suggests very volatile environmental conditions during the first 230 kyr of the Danian, as reflected in the rapid succession of opportunistic/generalist blooms and episodic high occurrences of aberrant specimens. According to our age model, the Dan-C2 has been identified at the Caravaca section from 65.92 to 65.74 Ma. No evidence of strong carbonate dissolution through ocean acidification was observed in the Dan-C2 interval or the rest of the studied section, excluding the K-PgB clay bed. We find that blooms of highly eutrophic Chiloguembelitria and increases in aberrant planktic foraminifera coincided with a major early Danian eruptive episode of Deccan Traps (Ambelani Formation), occurring before the Dan-C2. Conversely, during both Dan-C2 CIEs, less opportunistic taxa thrived, indicating changes in the upper part of the water column. This study demonstrates that the relationship between marine biota and climate change was very complex and rapidly changing during the early Danian. In addition, we propose that the Deccan volcanism had adverse effects on marine plankton, mostly through strong eutrophication, while an increased water column stratification during the Dan-C2 event resulted in a transient boost in the recovery of ecosystems