Introduction, principle, lab methods, measurements, and their applications will discussed from the following techniques:
provides a means for dating objects independently of stratigraphic or typological relationships and made possible a worldwide chronology, thus transforming archaeological investigation. Radiocarbon dating provides the most consistent technique for dating materials and events that occurred during the last 50,000 years on the surface of the Earth. Moreover, radiocarbon dating is also of significant use in other fields than archaeology, including environmental studies, ecology, geology, climatology, hydrology, meteorology, and oceanography.
(or tree-ring dating) is the scientific method of dating tree rings (also called growth rings) to the exact year they were formed in order to analyze atmospheric conditions during different periods in history. Dendrochronology is useful for determining the timing of events and rates of change in the environment (most prominently climate) and also in works of art and architecture, such as old panel paintings on wood, buildings, etc. It is also used in radiocarbon dating to calibrate radiocarbon ages and for wood provenance determination.
is the use of varve sequences to establish time lines in sedimentary sequences and for correlation. The advantage that varves have over other sediments is that they have tremendous precision of a year and in some cases down to the level of seasonal layers within a varve if intra-annual stratigraphy shows a consistent separation of seasonal features. Correlation of glacial varve records from place to place is generally based on the matching of the pattern of varve thickness change and not absolute thickness, which varies widely for a single varve year across a lake or region. In addition, correlations can sometimes be established by matching basin-wide lithologic changes in varve sequences if they represent isochronous events. Applications include, but are not limited to, the fields of paleoclimatology, flood history and human impact.
Speleothem dating possibilities are multiple: U/Th, U/Pb, 14C, 210Pb, ESR, TL, lamina counting. Those dating methods are all useful, with their advantages and disadvantages. The construction of an age model makes it possible to have a general chronology for the speleothem studied and the comparison with the sedimentary profile allows, with the stratigraphic order of the ages, to have a control on the ages obtained.
Cosmogenic nuclide dating.
In-situ produced and meteoric cosmogenic nuclides (e.g. 26Al, 10Be) allow to quantify rock exposure ages, soil residence times and long-term denudation rates. Cosmogenic nuclides are produced at a predictable rate in atoms at the Earth’s surface (in-situ) and in the atmosphere (meteoric). The accumulation of these isotopes can then be used as a cosmogenic clock that records the residence time of the material in the upper few meters of the Earth’s surface, and is also indicative for the accumulation or removal of soil particles at the surface as a result of erosion or deposition processes.
Electron spin resonance (ESR) dating
is based on the accumulation of radiation damage in geological materials due to radioactive decay of naturally occurring radionuclides in the surrounding matrix. Various geological events and processes can be dated using this technique, such as mineral formation, fault activity and sediment burial. Although methodological developments are rather slow due to the time-consuming nature of the method, ESR dating is contributing to our understanding of the Quaternary history of our planet for a couple of decades now. In this presentation the basic principles of the method will be explained, and several (un)successful case studies will be discussed.
Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) dating
work on the same principle as ESR dating, mainly differing in the way the radiation damage is detected. Luminescence dating is, at present, the second most widely used Quaternary radiometric method after radiocarbon. It has become an indispensable tool for those studying the most recent period in Earth’s history (such as Quaternary geologists, physical geographers, archaeologists and anthropologists). In its mainstream application, luminescence dating is used to establish deposition chronologies for sediments from a wide range of environments. In recent years, new methods have been developed that use luminescence signals to unravel the exposure and/or light history of consolidated rocks, opening whole new chapters in earth-scientific and archaeological research.
Radioactive imbalance-based methods in the uranium-238 family are useful for paleoclimatic studies. These methods give temporal constraints for the last 500ka and is mainly valid for carbonate sediments. The imbalance between the Th and the U, itself based on the radioactive imbalance between the 238U and its descendants 234U-230Th, covers the oldest periods. The method based on 226Ra (T1/2 = 1600 years) is the most suitable for the Holocene. For very recent periods (0-120 years), the method based on 210Pb (T1/2 = 22.6 years) is useful to date both carbonate and non-carbonate sediments. Here we will present some examples on lake and peat sediments. The causes of U-Th imbalances and examples of applications in archeology, oceanography, paleoclimatology and karst environment will be discussed.