RESEARCH FIELD
This proposal aims to facilitate an ESF Research Network Programme that brings together the European and pan-European specialists in the Research Field of developing and improving the Geological Timescale. It results from a successful ESF sponsored Exploratory Workshop, held in April 2007. Knowledge and understanding of detailed ages and durations of events, and therefore rates of processes, are the fundamental basis for Earth System Science in general, and crucial for tackling current challenges such as driving forces and feedbacks at the global scale and understanding abrupt or extreme changes in the Earth System in particular. We plan an ongoing exchange between the refinement and development of detailed age scales with direct applications to elucidate, e.g., mechanisms of climatic change. This Network Programme fits directly into most EU national science funding agencies’ key challenges and strategies.
SCIENTIFIC CONTEXT
The need for much improved knowledge of the durations and ages of climatic and geological events, such as the Palaeocene-Eocene Thermal Maximum (~55 million years ago), has become urgent within the Earth science and climate modelling communities. The exact dating and timing of fluxes into and out of the marine carbon reservoir can differentiate between competing hypotheses of climatic change. Highly detailed reconstructions of Earth history allow us to assess whether past climatic change can be used as an analogue for the current and future change of ocean acidification and climate. The Earthtime project, and this RNP application, are an international effort with the goal to further this quest for a well calibrated and stable time scale that will allow more precise dating of rock layers and minerals (Kuiper et al., 2008).
Radioisotopic dating methods have a small but significant error that hinders our ability to assess geologically short-lived climate events. For instance, the most widely used method for the Cenozoic era is 40Ar/39Ar, which has an error of up to 2.5% and few tie points of known age. Yet, over the last two decades much progress has been made in exploiting the imprint of Earth’s orbital variations in palaeoclimatic records. This has dramatically increased the potential age resolution of approaches like cyclecounting and pattern matching, to less than 40,000 years throughout much of Cenozoic time (the past ~66 million years, Pälike & Hilgen, 2008).
Unfortunately, there have been a number of inconsistencies and discrepancies between ages and durations derived from radioisotopic and astronomical dating. What is now needed is a more systematic and co-ordinated approach to provide a detailed intercalibration of radioisotopic clocks (U-Pb, Ar-Ar methods), the rock standards that are used for these methods, and geological tie-points with astronomical ages. At the same time, Cenozoic palaeoclimatic compilations need to be improved by closing existing gaps, verifying data from single sites, and supplementing the database of magneto- and biostratigraphy so we can improve the accuracy of existing age calibrations.
For all Earth Science applications time is a fundamental, essential for the integration of disparate datasets, unravelling cause and effect relationships (not only in the climate context), and for the quantification of rates and durations of geological processes. Temporal relationships are often the key to causality arguments in Earth Sciences, for example between environmental and biological change during mass extinction events. The Geological Time Scale (GTS) is instrumental for the quantification of geological time. However, published time scales are commonly based upon a limited number of geochronological tie-points of variable quality, and derivative age models that are of different and widely disparate quality. The accuracy and resolution of such time scales are also variable, generally in the order of 1 to 0.5% at best. Large uncertainties - on the order of several millions of years - still exist in our estimates for the age and duration of key geological intervals. The integration of revised numerical ages with key stratigraphic information requires a concerted and coordinated approach at the European level to tackle these important research questions, and we thus seek a broad collaborative effort through workshops, outreach and scientific exchange activities.
OBJECTIVES AND ENVISAGED ACHIEVEMENTS
The principal scientific objective of the network is to link the much improved numerical calibration of the GTS that comes out of the ITN to other stratigraphic disciplines (bio-, magneto-, chemo-, and cyclostratigraphy) in order to arrive at a fully integrated GTS for the last 100 million years. Such a time scale, with its stratigraphic underpinning, underlies all fields in the Earth Sciences. The broader stratigraphic community that will work on the integration can also directly start to apply the new time scale. Thus biostratigraphers can have a much more precise look at evolution and the influence of environmental changes, magnetostratigraphers are interested in reversal history and frequency, sequence stratigraphers in the potential link to eccentricity, cyclostratigraphers at the possible orbital control on sequence stratigraphy and longperiod hypothermals and ocean anoxic events, astronomers are eager to find out about the expression of the chaotic behaviour of the Solar System. To achieve both objectives, Earthtime-EU will bring together acknowledged expertise in all subdisciplines of time scale calibration techniques found within the European Earth Science community, with a strong cross-disciplinary character including astronomers, the radioisotopic dating community, the wider stratigraphic community as well as climate scientists, industry, and the Integrated Ocean Drilling Program and similar initiatives. This European-centred effort (http://www.earthtime-eu.eu), which will be closely linked to a broader international initiative EARTHTIME (www.earth-time.org), focuses on (1) the integration and intercalibration of these techniques in order to exploit both their strengths and to address their weaknesses, and specifically (2) a major effort to intercalibrate different bio-, magneto- and cyclostratigraphic efforts under a strategic umbrella. Increased communication and cooperation between the different communities will result in a fundamental change in the approach Earth scientists take in quantifying geological time. The achievements are planned to be supported through several different strands:
- Training of a new generation of PhDs and PostDocs is envisaged within the framework of a Marie Curie ITN (FP7-PEOPLE-2007-1-1-ITN, submitted
proposal “GTSnext”, currently in Stage 2 of evaluation). - A broader networking component of stratigraphers is envisaged under this RNP proposal, involving principal investigators, key collaborators, and the PhD and Postdoc cohort, all from the wider science community (open calls). This will provide integration and synthesis of the results from (1), and result in applications such as better understanding of climatic changes for the past and future. This proposed effort will be made wholly in concert with the continuously ongoing work by IUGS/ICS to improve the GTS.
Supported by these programmes, geochronologists will be fully capable to apply and evaluate the various state-of-the-art dating techniques for the first time.
