Optically stimulated luminescence osl dating
Optically stimulated luminescence osl dating - Sex Chat
Following the natural zeroing event and subsequent burial, the natural minerals begin luminescence acquisition afresh from the ionizing radiation (alpha, beta and gamma) constantly provided by the decay of radioactive elements (U238, Th232, K40, Rb) present in the sediments and also from the cosmic rays.For calculating the age, the radiation energy stored in the mineral (known as Paleodose) and the annual radioactivity rate (annual dose) from the surrounding sediments has to be calculated.
For calculating the annual dose rate, the elemental concentration of U, Th and K (by XRF or ICP-MS) in the sediment and water content in the sediment are required.Luminescence dating provides absolute ages and has very important application in Quaternary geology and archaeology.The following events can be dated by luminescence technique i) The most recent sun bleaching (application in sediment dating) ii) The most recent thermal event (application in archaeology, baking by lava flows, fusion crust of meteorites) iii) Crystallization event (application in travertine's in caves) Sediment sample should be collected in steel pipe to avoid any exposure to sun light. In the lab (under sub-dued red light condition), chemical treatment, sieving and mineral extraction will be carried out.Both coarse- and fine-grained material can be used for dating.Optically stimulated luminescence (OSL) dates are reported for silts and very fine sands believed to be loessic sediments from northwest England.At three sites loessic sediments were initially interpreted as primary aeolian deposits, and at two other sites as loess incorporated into the matrix of cemented scree.
However, the results of OSL dating indicate a more complex pattern of accumulation than originally hypothesized and have prompted reconsideration of these materials.
Whatever the process(es) and underlying cause(s), it is evident that significant amounts of soil erosion occurred on the limestone uplands earlier than previously thought.
A) Optically Stimulated Luminescence (OSL) Dating a) Blue Light Stimulated Luminescence (BLSL) Dating using Blue light emitting diodes b) Infra-red Stimulated Luminescence (IRSL) Dating using infrared diodes Luminescence dating is based on the principle that certain naturally occurring minerals (e.g.
quartz, feldspar), which are previously exposed to ionizing radiation, will emit light (luminescence) when they are thermally or optically stimulated.
Depending on the type of stimulation source, the phenomenon is termed thermally stimulated luminescence (TL) or optically stimulated luminescence (OSL).
The OSL is further divided, based on the colour (wavelength) of the excitation light source, into Blue Light Stimulated Luminescence (BLSL) and Infrared Stimulated Luminescence (IRSL)Luminescence dating requires a proper resetting of the previously acquired (pre depositional) luminescence in the natural minerals into a very low level (natural zeroing event), either by exposure to sun light during pre-depositional transportation (by wind, water etc.) or by a thermal event (pottery making, baking by lava, fusion crest of meteorites), before deposition.