Special issue: Advances in understanding and applying speleothem climate Research article 23 Oct A fundamental problem in paleoclimatology is to take fully into account the various error sources when examining proxy records with quantitative methods of statistical time series analysis. Records from dated climate archives such as speleothems add extra uncertainty from the age determination to the other sources that consist in measurement and proxy errors. These records carry regional information about past changes in winter precipitation and temperature. The timescale error influences on centennial- to millennial-scale trend estimation are not excessively large. We find a “mid-Holocene climate double-swing”, from warm to cold to warm winter conditions 6. Our analyses cannot unequivocally support the conclusion that current regional winter climate is warmer than that during the MWP. Annales Geophysicae.
The age of flowstones and their spatial distribution within the cave prove that the upper storey of the cave was dewatered before ka. At that time the lower storey also existed and was able to carry the whole water flowing through the cave. It suggests that ka ago the water-table was at similar level as it is at present. Hence, one should accept that the valley bottom was then also at the present level.
During at least a part of the MIS 6 the growth of speleothems was possible in the cave. It suggests that the cave was located outside the permafrost zone then.
Given the ability of speleothems to provide high resolution and very precisely dated records of past terrestrial climate, speleothem records from.
All publications more feeds DOI: BibTeX file. Gravitational mass movements landslides have been one of the most efficient processes contributing to the morphogenesis of the Outer Carpathians formed of flysch, siliciclastic-clayey rocks. Such processes often produce non-karst caves in sandstones. Dating of calcite speleothems developed in caves hosted by sandstone with calcareous cement seems to be a suitable method to reconstruct phases of slope evolution in this region.
The paper discusses the usefulness of radiocarbon 14C and U-series dating of speleothems in non-karst caves in the reconstruction of mass movement chronology and evaluates possible reasons for discrepancies between both methods. The obtained speleothem age data are used to improve the existing knowledge on the chronology of mass movements during the Late Glacial and Holocene in the flysch Carpathians.
U-Th and radiocarbon dating of calcite speleothems from gypsum caves (Emilia Romagna, North Italy)
The U-series laboratory focuses on development and application of U-series dating techniques to provide a robust chronological framework for palaeoclimatology, archaeology and human evolution. The U-series disequilibrium method is based on the radioactive decay of radionuclides within the naturally occurring decay chains. There are three such decay chains, each starts with an actinide nuclide U, U, Th having a long half live and ultimately ends with different a stable isotope of lead.
U-Th dating can be applied to secondary calcium carbonate formations like speleothems , travertine or corals.
; Edwards et al., ), its successful application to dating speleothems. (Li et al., ; Baker et al., ), and evidence that oxygen isotope ratios.
Hennig G. Absolute age determinations of calcite formations in caves as e. Because the growth speed of stalagmites should be low or even zero during the ice ages, paleocl imatical informations may also be obtained from the frequency distribution of speleothem ages determined so far. In order to check the reliability of uranium series ages we also applied other absolute dating techniques.
Because prehistoric men frequently used limestone caves as their domicile or shelter, today many remains of their life are covered by subsequently precipitated calcite formations. Such “speleothems” are usually regarded to be a most suitable material for dating purposes, and they are not altered as is bone material after long times of storage. Uranium series dating seems to be a most reliable and rather frequently used technique to determine the formation age of such speleothems.
A few other methods have been applied, but of these only C, thermoluminescence and electron spin resonance proved to be quite successful as well. Out of the three very long lived daughter nuclides of the U-decay series the isotope Th is commonly believed to be the most useful one for dating via radioactive disequi- libria.
Thorium, however, is tightly adsorbed by clay minerals always present in the hair-cracks and crevices of the roof limestone. It is for that reason that in the members of the U series fig. This raising ratio can be seen on figure 3, which also demonstrates a certain influence caused by the initial a- activity ratio of the uranium isotopes U to U, shortly called “ro”.
Each single growth zone is then dissolved in HC1 or HNO3, and the trace amounts of uranium and thorium are separately isolated by means of a specially developed chemical procedure fig. Artificially produced isotopes U and Th are added as tracers for the different uranium and thorium yields.
U-series and U-Pb carbonate geochronology
Until the s, information contained within cave sediments was thought to be limited to just:. Archaeological deposits such as animal and human remains. Information gleaned by visual examination of the stratigraphy of sedimentary layers.
The earliest speleothem dating involved the use of radiocarbon methods to verify annual layering in a flowstone entombing a human thighbone (Broecker et al.
Climate change. Geology of Britain. U-series and U-Pb capability for carbonate geochronology has been developed in the geochronology and tracers facility to support NERC climate research, benefitting from extensive knowledge transfer from our U- Th -Pb geochronology facility. Sea floor geochronology and tracers is a recently developed but rapidly growing area for the facility. This science area is focused on the chronology of sea floor deposits that can be dated by U-Th methods e.
An issue with such projects is access to samples, and we are working with partners in Norway and the US to build collaboration and access to unique sample sets, and to include other UK interested parties. Press Office. Online shops. Recent publications.
The antiquity of Nullarbor speleothems and implications for karst palaeoclimate archives
Speleothems typically form in limestone or dolomite solutional caves. The definition of “speleothem,” in most publications, specifically excludes secondary mineral deposits in mines, tunnels, and other man-made structures. More than variations of cave mineral deposits have been identified. Calcareous speleothems form via carbonate dissolution reactions. As the lower pH water travels through the calcium carbonate bedrock from the surface to the cave ceiling, it dissolves the bedrock via the reaction:.
Abstract. 14C ages of speleothems are usually younger than the Uranium-Series ages. The difference is often explained by changes of atmospheric radiocarbon.
Lawrence Edwards. To date, there is a lack of information regarding the dating potential of calcite speleothems that have grown in such gypsum karst environment e. High-resolution U-Th dating, aimed at establishing if these speleothems can provide robust radiometric age sequences, is first presented. These outliers are best explained by post-depositional diagenetic processes affecting the U-Th system rather than anything specific to gypsum karst environment conditions.
Consequently, radiocarbon measurements were undertaken, and combined with the U-Th ages to build an age-model. Soils were considered the main source of carbon, because bedrock dissolution acted predominantly under open-system conditions, and soil organic matter SOM turnover rate appears above average compared to sites studied elsewhere. Earth Sciences. Overview Fingerprint.
Dating of Cave Sediments and Speleothems Attracts Press
Shah, C. Morrill, E. Gille, W. Gross, D. Anderson, B. Bauer, R.
In cave-mouth deposits, windblown detritus is also present, as well as cultural materials to which ages can be assigned by dating of speleothem. Lacustrine.
Some features of this site are not compatible with your browser. Install Opera Mini to better experience this site. The first pieces of evidence for climate change came from the land itself, from the misplaced boulders scattered across much of the Northern Hemisphere, though there were other signs as well.
A homogeneous, fine yellow soil covered more than one million square miles of Europe, Asia, and North America. The soil was as thick as 3 meters 10 feet in some places, and nearly nonexistent in others. As the ice melted, water swept the dust out from under the glaciers into streams along the edge of the ice. When water levels dropped, the dust blew across the land, leaving an uneven layer of fine, homogeneous soil.
By mapping the loess and the trail of rock debris left by the glaciers, scientists determined that the ice sheets had once stretched down over the familiar bowls of the Great Lakes in North America and across the British Isles and Scandinavia. Thick glaciers, far larger than those that currently cap the mountain peaks, covered the Alps.