Age modelling of late Quaternary marine sequences in the Adriatic: Towards improved precision and accuracy using volcanic event stratigraphy
Introduction
Accurate dating and correlation are essential for the construction of reliable models of sediment architecture and influx rates in marine basins, as well as for establishing the links between changes in sedimentation and palaeoenvironmental events. In recent years, the survey and analytical tools employed in the investigation of marine sequences have become more sophisticated, increasing the precision with which palaeoenvironmental records can be assessed. At the same time, analysis of Greenland ice cores (e.g Alley et al., 1993; Dansgaard et al., 1993; North Atlantic Ice Core Project Members, 2004; Rasmussen et al., 2005) has shown that environmental changes during the late Quaternary were much more abrupt than previously understood, with some marked changes in climate possible within a few decades. These developments have fuelled a demand for greater geochronological precision in the analysis of marine sedimentary sequences, to support better resolved palaeoenvironmental records. The question arises, however, as to whether available geochronological methods can deliver this increased precision.
The method most routinely employed to date marine fossils and sediments spanning the last ca. 50,000 years is radiocarbon dating. It is now evident that this method cannot normally provide age estimates for Holocene events at greater than a centennial precision, while true uncertainties of the order of millennia will commonly constrain dates for pre-Holocene events (see below). In this paper we explain why conventional procedures for the construction of radiocarbon-based age models are less secure than has been commonly assumed, and why the wider application of tephrostratigraphy, the basis of a regional Event Stratigraphy scheme, can yield more reliable results.
The discussions focus on records from the Adriatic Sea, as the views expressed here have emerged from workshop activities conducted within the EU-funded EURODELTA and EUROSTRATAFORM projects. The general bathymetric and geographical context of the study area, as well as locations of all cores and sites referred to in the text, are shown in Fig. 1. One of the key aims of these collaborative initiatives was the development of more robust age models to underpin precise correlations of marine sediment sequences in various sectors of the Mediterranean, including the Adriatic Sea. However, the recommendations developed below have much wider application to the dating of marine sequences in general.
Section snippets
Limitations of radiocarbon dating
Four general sources of uncertainty constrain the precision and accuracy of radiocarbon dates obtained from marine samples: (1) analytical (laboratory) precision; (2) factors affecting the geological (stratigraphical) integrity of dated materials; (3) marine reservoir errors; and (4) calibration procedures. Each of these is discussed in turn.
Scientific context
Tephra layers are widely encountered within late Quaternary sediment sequences in the Mediterranean, particularly in the central basins (e.g. Keller et al., 1978; Paterne et al., 1988, Paterne et al., 1990). They are routinely employed to date and correlate marine records (e.g. Calanchi et al., 1996, Calanchi et al., 1998; Siani et al., 2004). Some of them can also be traced to terrestrial sites, including lake basins, where they can be reasonably well dated. Of particular note in this respect
Conclusions
The key conclusions to emerge from the arguments presented in this paper are as follows.
- (1)
Radiocarbon-based age models for Holocene stratigraphical records cannot normally deliver better than centennial precision, unless a minimum of 24 radiocarbon dates is available to support the models. Age models for pre-Holocene periods are even less precise, with uncertainties commonly millennial in scale, mainly because of the limitations of currently available calibration models. Radiocarbon dating of
Acknowledgements
We gratefully acknowledge the following two main sources of funding support for the work reported in this paper:
- (1)
EURODELTA Concerted Action, a project dedicated to European Co-ordination on Mediterranean Prodeltas funded within the European Union's 5th Framework research programme entitled Energy, Environment and Sustainable Development (Contract No. EVK3-CT-2001-20001).
- (2)
EUROSTRATAFORM, a scientific research programme exploring the fate of sediment particles from their source in rivers through to
References (89)
- et al.
The North Atlantic atmosphere-sea surface 14C gradient during the Younger Dryas climatic event
Earth and Planetary Science Letters
(1994) - et al.
Radiocarbon calibration beyond 20,000 14C yr B.P. by means of planktonic foraminifera of the Iberian margin
Quaternary Research
(2004) - et al.
Cosmogenic nuclides during Isotope Stages 2 and 3
Quaternary Science Reviews
(2002) - et al.
A new and less destructive laboratory procedure for the physical separation of distal glass tephra shards from sediments
Quaternary Science Reviews
(2005) - et al.
Palaeomagnetism of Holocene and Late Pleistocene sediments from Lago di Mezzano and Lago Grande di Monticchio (Italy): initial results
Quaternary Science Reviews
(1999) - et al.
Abrupt environmental oscillations during the Early Weichselian recorded at Lago Grande di Monticchio, southern Italy
Quaternary International
(2000) - et al.
A novel approach to selecting samples for radiocarbon dating
Journal of Archaeological Science
(1998) - et al.
Tephra layers in Late Quaternary sediments of the central Adriatic Sea
Marine Geology
(1998) - et al.
Extending the radiocarbon calibration beyond 26,000 years before present using fossil corals
Quaternary Science Reviews
(2005) - et al.
Interaction between particles transported by fallout and surge in the deposits of the Agnano–Monte Spina eruption (Campi Flegrei, Southern Italy)
Journal of Volcanology and Geothermal Research
(2004)
Volcanism and deformation since 12,000 years at the Campi Flegrei caldera (Italy)
Journal of Volcanology and Geophysical Research
Marine reservoir age variability and water mass distribution in the Iceland Sea
Quaternary Science Reviews
High-resolution climate signals in the Bølling-Allerød Interstadial (Greenland Interstadial 1) as reflected in European tree-ring chronologies compared to marine varves and ice-core records
Quaternary Science Reviews
Surface reactivity of volcanic ash from the eruption of Soufrière Hills volcano, Montserrat, West Indies with implications for health hazards
Environmental Research
Marine and limnic radiocarbon reservoir corrections for studies of late- and postglacial environments in Georgia Basin and Puget Lowland, British Colmbia, Canada and Washington, USA
Quaternary Research
14C AMS wiggle matching of raised bog deposits and models of peat accumulation
Quaternary Science Reviews
Apparent radiocarbon ages of recent marine shells from Norway, Spitzbergen and Arctic Canada
Quaternary Research
Changes in the carbon cycle during the last deglaciation as indicated by the comparison of 10Be and 14C records
Earth and Planetary Science Letters
A high resolution late Holocene palaeo-environmental record from the central Adriatic Sea
Quaternary Science Reviews
Explosive activity of the south Italian volcanoes during the past 80,000 years as determined by marine tephrochronology
Journal of Volcanology and Geothermal Research
Fluctuations of the Campanian explosive volcanic activity (south Italy) during the past 190,000 years as determined by marine tephrochronology
Earth and Planetary Science Letters
The chemical correlation of microtephras: numerical analysis of geochemical data
Applied Geochemistry
Calibration of the 14C time scale to >40 ka by 234U-230Th dating of Lake Lisan sediments (last glacial Dead Sea)
Earth and Planetary Science Letters
Tephrostratigraphy study for the last 18,000 14C years in a deep-sea sediment sequence for the South Adriatic
Quaternary Science Reviews
All age-depth models are wrong: but how badly?
Quaternary Science Reviews
Implications for the precise dating of Wisconsinan (Weichselian) lateglacial events of systematic radiocarbon age differences obtained from terrestrial plant macrofossils from a site in SW Ireland
Quaternary Research
Major Δ14C excursions during the late glacial and early Holocene: changes in ocean ventilation or solar forcing of climate change?
Quaternary International
Devensian Lateglacial environmental changes in Britain: a multi-proxy record from Llanilid, South Wales, UK
Quaternary Science Reviews
Tephrochronology of the 100 ka lacustrine sediment record of Lago Grande di Monticchio (southern Italy)
Quaternary International
The Statistical Analysis of Compositional Data
The deglaciation of the Northern Hemisphere: a global perspective
Annual Review of Earth and Planetary Sciences
Abrupt increase in Greenland snow accumulation at the end of the Younger Dryas
Nature
Methodological approaches to determining the marine radiocarbon reservoir effect
Progress in Physical Geography
High-resolution Foraminifera biostratigraphy in the Central Adriatic basin during the Last Deglaciation: a contribution to the PALICLAS project
Memorie del’Istituto Italiano di Idrobiologia
Short-term climate changes during the Last Glacial–Holocene transition: comparison between Mediterranean records and the GRIP event stratigraphy
Journal of Quaternary Science
The 14C age of the Icelandic Vedde Ash: implications for Younger Dryas marine reservoir age corrections
Radiocarbon
Hydrological impact of Heinrich events in the subtropical northeast Atlantic
Science
A better radiocarbon clock
Science
Extremely large variations of atmospheric 14C concentration during the last glacial period
Science
Confidence intervals for age estimates and deposition times in late-Quaternary sediment sequences
The Holocene
Carbon-14 wiggle-match dating of peat deposits: advantages and limitations
Journal of Quaternary Science
Establishing Late-glacial and Holocene marine reservoir radiocarbon offsets in the northern North Atlantic: the potential for improving the chronology of Arctic archaeology
Physics in Canada
Bayesian analysis of radiocarbon chronologies: examples from the European Late-glacial
Journal of Quaternary Science
Cited by (101)
Coupling palaeobiology and geochemistry from the Holocene of the southern Adriatic Sea (Gulf of Manfredonia, Italy): Shelf facies patterns and eutrophication trends
2024, Palaeogeography, Palaeoclimatology, PalaeoecologyClimate evolution in the Adriatic Sea across the last deglaciation: A multiproxy approach combining biomarkers and calcareous plankton
2022, Palaeogeography, Palaeoclimatology, PalaeoecologyLate Pleistocene to Holocene glacio-eustatic history as recorded in the Pescara paleovalley system (Central Italy, Adriatic basin)
2022, Marine and Petroleum GeologyQuaternary marine tephrochronology of Rock Garden accretionary ridge, Hikurangi Subduction Margin, New Zealand
2022, Journal of Volcanology and Geothermal Research
- 1
Present address: BLOCKLEY & POLLARD: Research Laboratory for Archaeology, University of Oxford, Dyson Perrins Building, South Parks Road, Oxford OX1 3QY, UK.
- 2
Present address: IFREMER, DRO/GM BP 70, 29280 Plouzané, France [email protected] 33-298-224572.
- 3
Present address: Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, PO Box 7456, Austin, TX 78713, USA.