Thermoluminescence dating of the orkutsay loess section in Tashkent region, Uzbekistan, Central Asia

Zhou, Liping; Dodonov, A.E.; Shackleton, N. J.

doi:10.1016/0277-3791(95)00056-9

Cited by 57 publications

(24 citation statements)

References 23 publications

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“…Until 1996, most of the luminescence age estimates for Chinese loess had been obtained by multiple aliquot thermoluminescence (TL), and some by infraredstimulated luminescence (IRSL), dating methods applied to polymineral fine grains (Lu et al, 1987(Lu et al, , 1988(Lu et al, , 1999Forman, 1991;Musson et al, 1994;Frechen, 1999;Zhao, 2003). The Quaternary Research 67 (2007) 152 -160 www.elsevier.com/locate/yqres precision and accuracy of TL and IRSL ages beyond 50 ka has been questioned (e.g., Wintle, 1990;Zhou et al, 1995;Prescott and Robertson, 1997). However, luminescence dating has undergone many innovations in methodology in the past decades, especially with the development of Optically Stimulated Luminescence (OSL) dating (Huntley et al, 1985).…”

Section: Introductionmentioning

confidence: 99%

“…The critical disadvantage is that if any sensitivity changes occur between measurements of the natural and regenerative OSL signals, the age obtained will be inaccurate. Zhou and Wintle (1994) and Zhou et al (1995) considered that most of the TL age estimates obtained by the regeneration method on polymineral loess samples were underestimated, and they attributed this mainly to sensitivity changes induced by the laboratory optical bleaching prior to laboratory irradiation.…”

Section: Introductionmentioning

confidence: 99%

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A new OSL chronology for dust accumulation in the last 130,000 yr for the Chinese Loess Plateau

2007

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A sensitivity-corrected Multiple Aliquot Regenerative-dose protocol has been developed for fine-grained quartz OSL dating of Chinese loess. Its reliability has been assessed on the basis of the methodology and by dating reference samples of known age close to the transition from the last interglacial paleosol (S 1 ) to the last glacial loess (L 1 ), which corresponds to the Marine Oxygen Isotope Stage (MIS) 5/4 transition. On the basis of the fine-grained quartz OSL-age estimates for 33 loess samples from the upper part of the Luochuan profile, a detailed chronostratigraphy of continuous dust accumulation in the past 130 ka has been proposed. Changes in the accumulation rate occurred during the last glacial period (MIS 4 to MIS 2); unexpectedly, high accumulation rates were found in the weakly developed L 1-2(S) paleosol of the last interstadial (MIS 3), rather than in the classic L 1-1 and L 1-3 loess of the cold-dry glacial condition (MIS 2 and 4). The OSL ages show some disagreement with the previous numerical chronology for the loess-paleosol sequence based on correlation of variations in grain size with sedimentation rate; the latter method resulted in an almost constant accumulation rate from 72 to 12 ka.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A new OSL chronology for dust accumulation in the last 130,000 yr for the Chinese Loess Plateau

2007

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“…In recent years, international Quaternary geologists have paid much attention to the loess sediments in Tajikistan and southern Kazakhstan, which are situated in the southern part of Central Asia [17][18][19][20][21][22][23][24]. Previous studies show that paleoenvironment information recorded in south Central Asia loess sediments is very comparable with that recorded in Chinese loess.…”

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confidence: 99%

Loess magnetic properties in the Ili Basin and their correlation with the Chinese Loess Plateau

Song

Shi

Fang

et al. 2010

Sci. China Earth Sci.

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Over the past two decades, magnetoclimatological studies of loess-paleosol sequences in the Chinese Loess Plateau (CLP) have made outstanding achievements, which greatly promote the understanding of East Asian paleomonsoon evolution, inland aridification of Asia, and past global climate changes. Loess magnetic properties of the CLP have been well studied. In contrast, loess magnetic properties from outside the CLP in China have not been fully understood. We have little knowledge about the magnetic properties of loess in the Ili Basin, an intermontane depression of the Tianshan (or Tien Shan) Mountains. Here, we present the results of rock magnetic measurements of the Ili loess including mass magnetic susceptibility (χ) and anhysteretic remanent magnetization (ARM), high/low temperature dependence of susceptibility (TDS) and hysteresis, as well as X-ray diffraction (XRD) for mineral analysis. Based on the comparison with loess-paleosol sequences in the CLP (hereafter referred to as the Chinese loess), we discuss the possible magnetic susceptibility enhancement mechanism of the Ili loess. The results show that 1) the total magnetic mineral concentration of the Ili loess is far lower than that of the Chinese loess, though they have similar magnetic mineral compositions. The ferrimagnetic minerals in the Ili loess are magnetite and maghemite, and the antiferromagnetic mineral is hematite; XRD analysis also identifies the presence of ilmenite. The ratio of maghemite is lower in the Ili loess than in the Chinese loess, but the ratios of magnetite and hematite are higher in the Ili loess than in the Chinese loess.2) The granularity of magnetic minerals in the Ili loess, dominated by pseudo-single domain (PSD) and multi-domain (MD) grains, is generally much coarser than that of the Chinese loess. Ultrafine pedogenically-produced magnetic grains have a very limited contribution to the susceptibility enhancement. Rather, PSD and MD particles of magnetite and maghemite are the main contributors to the enhancement of susceptibility in the Ili loess. 3) The susceptibility enhancement mechanism for the Ili loess is complicated and superimposes both a wind velocity/vigor model (Alaskan or Siberian model) and the in situ ultrafine grain pedogenic model; the former might play an important role in the Ili loess. 4) Magnetic susceptibility enhancements of the Ili loess are related not only to the eolian input of the source area, but also to the local climate, landform, and geological background. Therefore, great care should be taken when reconstructing paleoclimate using magnetic susceptibility data from the Ili loess. loess, magnetic property, magnetic susceptibility, the Ili Basin, the Chinese Loess Plateau Citation: Song Y G, Shi Z T, Fang X M, et al. Loess magnetic properties in the Ili Basin and their correlation with the Chinese Loess Plateau.

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“…While this may well have been true in 1985, it is arguable now. Zhou et al (1995) present TL ages for the Orkutsay loess section in the Tashkent region of central Asia, speci®cally relating it to earlier work from the same region. This appears to be the ®rst direct comparison of ages obtained by contemporary protocols with early work from the then USSR, and with other regions.…”

Section: Loessmentioning

confidence: 61%

Sediment dating by luminescence: a review

Prescott

Robertson

1997

Radiation Measurements

137

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AbstractÐIn the present article we review applications of luminescence methods for the determination of the age of sediments for Quaternary Earth science.``Sediment'' is taken to include any mineral particles transported by wind, water and/or ice and subsequently deposited. Methodology is not discussed per se but appears in context. The emphasis is on recent work and is illustrative rather than exhaustive. Applications in archaeology are mentioned only brie¯y. Successful dating requires that the luminescence signal has been zeroed by sunlight at the time the sediment was laid down. Dune sands and loess transported in full daylight usually satisfy this condition and have been dated by both traditional thermoluminescence and by optical methods. Optical dating is advantageous for less well-bleached sediments, such as are found in colder climates and those laid down by¯uvial and glacial processes, although the prospects for dating the latter are shown to be poor. Among less common contexts are volcanic eruptions, earthquake faults and tsunami deposits. The dating of very young sediments, less than 2 ka, is demonstrated and the factors limiting the dating of very old sediments, 500 ka to 1 Ma, are discussed. Validation of any dating method by comparison with other methods is necessary; luminescence ages have been successfully compared with ages obtained by, for example, 14 C, U±Th series and d 18O isotope ratios. The most dicult problems encountered in dating quartz, feldspars and undierentiated ®ne grain mixtures include: anomalous fading (which leads to underestimates of age), incomplete zeroing (which gives overestimates) and sample inhomogeneity. Methods devised to minimise these eects include preheating regimes, selection of observing wavelengths and of stimulating wavelengths for optical dating, the use of single aliquot and single grain measurements. The use of appropriate data analysis procedures is also important. Advice on current best practice on procedures for obtaining reliable ages is oered and, in all applications, there are suggestions as to where further research might be directed. #

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Thermoluminescence dating of the orkutsay loess section in Tashkent region, Uzbekistan, Central Asia

Cited by 57 publications

References 23 publications

A new OSL chronology for dust accumulation in the last 130,000 yr for the Chinese Loess Plateau

A new OSL chronology for dust accumulation in the last 130,000 yr for the Chinese Loess Plateau

Loess magnetic properties in the Ili Basin and their correlation with the Chinese Loess Plateau

Sediment dating by luminescence: a review

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