Department of Human Evolution
Natural archives: secondary carbonate deposits corals and spelothems , groundwaters, sea water. Pons-Branchu E. Questioning the Neanderthal origin of Spanish rock art. Journal of Archaeological Science. Cushing E. Engineering Geology, , Montaggioni L. New insights into the Holocene development history of a Pacific, low-lying coral reef island: Takapoto Atoll, French Polynesia.
A novel approach for construction of radiocarbon-based chronologies for speleothems
U-series dating and stable isotope records of speleothem records from the Scladina Cave Belgium. The Scladina cave, situated in the village of Sclayn Ardennes, Belgium at the southern bank of the Meuse, is famous for its Neanderthal fossils and artefacts. The infilling of the cave consists of a succession of flowstone layers interbedded with reworked loess sediment from outside the cave. The younger flowstone layers correspond to interglacials MIS 5 and the Holocene, while the reworked loess sediments represent cooler conditions.
By careful diagenetic screening, well-preserved speleothem material was selected for U-series dating and stable isotope analysis of calcite and fluid inclusions.
Radiometric dating methods are based on the radioactive properties of certain measurement of the U/Th ratio in speleothem calcite, for example, it is.
Carbonate speleothems that contain ppb-ppm levels of uranium can be dated by the UUTh and UPa disequilibrium techniques. Accurate ages are possible if the initial concentrations of Th and Pa are well constrained and if the system has remained closed to post-depositional exchange of uranium, thorium, and protactinium.
For many speleothems, particularly those composed of nearly pure calcite, initial Th may be trivial. Because Pa is more soluble than Th, Th is a poor analog for Pa. Therefore, initial Pa tends to be more significant than initial Th for young samples, although this problem becomes less significant or even insignificant with increasing age. Thermal ionization mass spectrometry TIMS and inductively coupled plasma mass spectrometry ICP-MS offer significant improvements in counting efficiency and sample throughput compared to traditional decay-counting techniques.
Materials as young as tens of years and older than , years are potentially dateable by the UUTh method. Springer Professional. Back to the search result list. Table of Contents. Hint Swipe to navigate through the chapters of this book Close hint. Authors: Jeffrey A. Dorale R. Lawrence Edwards E.
Speleothem climate records from deep time? Exploring the potential with an example from the Permian
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Lechleitner, F. Quaternary Geochronology , 35, 54 – Robust chronologies are crucial for the correct interpretation of climate proxy records and for detailed reconstructions of palaeoclimate. Stalagmites have garnered strong interest as recorders of past climate in part due to their amenability to U-series dating. Here, a novel 14C-based method for dating stalagmites is presented and discussed. The technique calculates a best-fit growth rate between a time-series of stalagmite 14C data and known atmospheric 14C variability.
The new method produces excellent results for stalagmites that satisfy four requirements: i the absence of long-term secular variability in DCF i.
Cave Deposits: Processes, Approaches and Environmental Significance
Uranium series dating of speleothems. N2 – Radioactive decay of Uranium and Thorium isotopes at constant rates provides a tool to determine the age of speleothems with high precision and accuracy. As with any dating method a fundamental prerequisite is the lack of post-depositional alteration, that is, no gain or loss of isotopes within the decay chain of interest.
Using state-of-the-art instrumentation this method allows dating speleothems between essentially zero and ca. Multiple age determinations are typically performed along the extension axis of a stalagmite in order to decipher its detailed growth history.
Due to the environmental challenges we currently face as a global community, understanding the trajectories of climate and environmental change is critical. There is an increasing emphasis in the literature on historic and prehistoric anthropogenic environmental impacts and the role climate change has played on the evolution, dispersal, adaptation and cultural development of hominin.
However, the links between climate and environmental change and human response are frequently no more than speculative arguments and will remain so until fundamental problems in our methodologies are addressed. The most pressing of these problems is the need to establish reliable and robust chronologies for palaeoenvironmental and archaeological records.
This thesis has two main objectives 1 develop a means of reliably and precisely dating archaeological and palaeontological deposits beyond the limits of the C14 dating method; and 2 Assess human-environment interactions during the Late Holocene through the integration of precisely dated archaeological, palaeontological and palaeoenvironmental records from limestone caves sites in western Flores, Indonesia.
Limestone caves are excellent repositories for palaeoenvironmental and archaeological information. As the discovery site of a new species of hominin, Homo floresiensis, and with detailed evidence for modern human occupation, Liang Bua is one of the most important sites for our understanding of hominin evolution, dispersal and culture change in Island Southeast Asian ISEA.
The paper provides a chronological and geomorphological context for future excavations of the sub-chamber and demonstrates that the site was never used as an occupation area but acted as a sink for Pleistocene aged archaeological and faunal material from Liang Bua main chamber. Following the development and application of the soda straw stalactite dating technique, we go on to assess human-environment interactions in Flores, Indonesia.
David A. Richards, Jeffrey A. Reviews in Mineralogy and Geochemistry ; 52 1 : — An increasing number of scientists recognize the value of speleothems 1 as often extremely well-preserved archives of information about past climate, vegetation, hydrology, sea level, nuclide migration, water-rock interaction, landscape evolution, tectonics and human action. Well-constrained data are required to document past changes, reconstruct past patterns and predict future responses of the Earth system at a wide range of spatial and temporal scales.
Speleothems are particularly useful in this regard because they can be found in many locations of the globe, sampled at high-resolution and reliably dated using high-precision uranium-series techniques.
Radiometric and lasers to allow dating calculations. Speleothems from the case of this way can be dated calcite speleothems, the method. Jon is asssigned by.
In this study, we advance information-extraction from speleothems in two ways. First, the limitations in dating modern stalagmites are overcome by refining a dating method that uses annual trace element cycles. This is of particular relevance to mediterranean regions that display strong seasonal controls on PCP, due to seasonal variability in water availability and cave-air p CO 2. Second, using the chronology for one stalagmite sample, trace elements and growth-rate are compared with a record of climate and local environmental change i.
Uranium series dating of speleothems
Abstract: U/Th dating method is usually employed to build precise and reliable chronologies for speleothems. However, for some speleothems.
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:. When the solution reaches a cave, degassing due to lower cave pCO 2 drives precipitation of CaCO 3 :. Over time the accumulation of these precipitates form stalagmites , stalactites , and flowstones , which compose the major categories of speleothems. Calthemites which occur on concrete structures, are created by completely different chemistry to speleothems.