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Palaeodose Underestimation Of Heated Quartz In Red-TL Dating Of Volcanic Contexts

Richter D., Klinger P., Zöller L.

Geochronometria

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2015

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Vol. 42, no.1

182--188

EN

Thermoluminescence (TL) dating is a valuable tool for chronometric dating of heated minerals and has been shown to agree very well with independent age control. Comparison with argon dating of samples from identical events, however, revealed age underestimations of volcanic eruptions dated by orange-red TL (R-TL) of quartz extracts from some xenolith samples, while good agreement was obtained for others. The underestimation is attributed to an apparent signal loss (“anomalous fading”) which was experimentally observed for some, but not all samples investigated. The presence of significant amounts of feldspar or tridymite, which could be related to the observations, is excluded by IRSL (Infrared Stimulated Luminescence) and XRD analysis. While the data is not entirely conclusive, it leads to the current working hypothesis that exposure to high temperatures might be responsible for an effect similar to the anomalous fading phenomena observed for some feldspar luminescence. It therefore appears to be prudent not to sample xenoliths from high temperature context, like basalt dykes in volcanic context.

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Thermoluminescence age of quartz xenocrysts in basaltic lava from oninomi monogenetic volcano, northern Kyushu, Japan

Shitaoka Y., Miyoshi M., Yamamoto J., Shibata T., Nagatomo T., Takemura K.

Geochronometria

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2014

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Vol. 41, no. 1

30--35

EN

We determined the eruption age of basaltic rocks by application of thermoluminescence (TL) method, which is often used for TL dating, to quartz. Mafic magma only rarely includes quartz because of their mutual disequilibration. The basaltic lavas reported herein include quartz as xeno-crysts, as corroborated by their rounded or anhedral shape.The basaltic lava used for this study is from the Oninomi monogenetic volcano in northern Kyushu, Japan. The volcano eruption was estimated as occurring 7.3–29 ka because the lava exists between two widespread tephras: Aira-Tanzawa ash (26–29 ka) and Kikai-Akahoya ash (7.3 ka). We succeed-ed in collecting ca. 200 mg of quartz by decomposition of 30 kg of the lava samples. TL measure-ments for the lava indicate the eruption age as 15.8 ± 2.5 ka, which is fairly consistent with the strati-graphical estimation. Although the TL method has played a considerable part in constraining the timescale of Quaternary events, its application has been limited to silicic samples. The present result demonstrates the availability of quartz for dating even of mafic rock.

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Glacial and periglacial transformation of palaeokarst in the Lublin-Volhynia region (SE Poland, NW Ukraine) on the base of TL dating

Dobrowolski J., Fedorowicz S.

Geochronometria

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2007

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Vol. 27

41-46

EN

Distinctly diverse results of TL dating are obtained for the deposits with similar lithofacial features but filling morphologically differentiated karst palaeoforms (dolines, pipes, pockets). The infillings of dolines and pipes are mostly of the Saalian age. Based on sedimentological analysis, their formation conditions are related to sub- or/and terminoglacial environment. The age obtained for all infillings of pockets is underestimated in comparison with lithostratigraphic data. A close genetic relationship between these forms and periglacial conditions seems to indicate that the reduction of TL signal is mostly influenced by the disintegration of grains resulted from the repeated freezing and thawing of glaciogenic deposits. A considerable influence of frost weathering on the decrease of thermoluminescence intensity of mineral grains is indirectly confirmed by the results of experimental investigations consisting in the repeated TL measurements of pockets’ infillings after successive freeze-thaw cycles.

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Dependence of luminescence characteristics of irradiated quartz with the thermal treatment and consequences for TL dating

Roque C., Guibert P., Duttine M., Vartanian E., Chapoulie R., Bechtel F.

Geochronometria

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2004

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Vol. 23

1-8

EN

The dependence of luminescence properties of archaeological quartz pebbles with their thermal history is investigated and consequences for TL-dating are examined; the archaeological samples studied were collected from Solutrean layers at Laugerie Haute West rock shelter (Dordogne, France). This study is supported by a simulation experiment carried out on a natural quartz, using a combined approach by Cathodoluminescence (CL), Thermoluminescence (TL) and Electron Paramagnetic Resonance (EPR) techniques. The quartz grains used were given a high beta dose, then independent aliquots were annealed in air at a temperature varying from 300 degrees C to 900 degrees C. It has been observed that the TL growth with dose, after annealing and re-irradiation, evolved from a linear behaviour to a marked supralinear one according to annealing temperature linked respectively with a partial or a total thermal drainage of charges in deep traps. Consequently, during the TL-dating process of materials anciently heated at low temperature in the past (between 300 degrees C and 500 degrees C approximately), a special care has to be taken by adopting an annealing treatment that approaches the filling state of trapped charges that the samples had after the archaeological zeroing. This necessary new requirement strengthens accuracy and reliability of TL-dates obtained at Laugerie Haute.

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Divergence in the TL dating resulting from different methods of equivalent dose determination

Kusiak J., Łanczont M., Boguckyj A., Wojtanowicz J.

Geochronometria

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2002

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Vol. 21

27-32

EN

This paper focuses on problems connected with equivalent dose (ED) estimation. The ED results obtained by using two methods: regeneration (R) and total-bleach (TB) were compared. To this end, ten loess samples were taken from about 20 m thick Zahvizdja profile (western Ukraine). The obtained results show that the ED values are strongly dependent on the applied technique. When using the regeneration method, the maximum ED value observed is 1051š158 Gy. The total-bleach procedure gives considerably different results, because the gradual increase of ED values is recorded up to 2833š896 Gy. TL ages obtained by the TB method were confirmed by palaeomagnetic investigations.

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The parameters of traps in K-feldspars and the TL bleaching efficiency

Chruścińska A., Oczkowski H. L., Przegiętka K. R.

Geochronometria

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2001

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Vol. 20

15-20

EN

The fractional glow technique (FGT) applied to the investigation of optically bleached samples of K-feldspars extracted from sediments reveals the coexistence of various groups of traps which are active in the same temperature region over 300 °C. Significant differences between the trap parameters seem to explain the diversity of TL bleaching efficiency for different trap groups.

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The fractional glow technique as a tool of investigation of tl bleaching efficiency in K-feldspar

Chruścińska A.

Geochronometria

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2001

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Vol. 20

21-30

EN

The fractional glow technique was applied to the investigation of trap occupation in optically bleached K-feldspars separated from sediments. Various bleaching times and two spectra ranges of sunlight simulator were used. Three trap groups exhibit different sensitivities to bleaching. The influence of the spectrum range of the stimulation light on the bleaching efficiency is presented. Results of the fractional glow technique measurements simulations are presented for the case of second order kinetics.

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Chronostratigraphy of the Vistulian deposits in the southern part of the Lower Vistula region (north Poland) in the light of TL dating

Wysota Wojciech, Chruścińska Alicja, Lankauf Krzysztof R., Przegiętka Krzysztof R., Oczkowski Hubert L., Szmańda Jacek

Geologos

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2000

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Vol. 5

123--134

EN

Lithostratigraphy and chronostratigraphy of the Vistulian deposits in the southern part of the Lower Vistula region are presented. In detail, sedimento- logical investigations and thermoluminescence (TL) dating of thick glaciogenic and fluvial deposits exposing at Rzęczkowo and Łążyn sections in the southwest of the Chełmno Lakeland are described. In profile of the Vistulian deposits have been distinguished two glaciogenic formation: Łążyn (La) and Starogród (Sa) which are represented mainly by tills and glaciolacustrine lithofacies. Fluvial deposits of Rzęczkowo formation (Rz) separate these formations. Four samples (R-2, L-l, L-2, L-3) taken from fluvial sand and silts of Rzęczkowo formation and two samples taken from glaciolacustrine silts (R-l) and stratified diamicton (L-4) of Starogród formation were investigated by thermoluminescence method. Obtained TL dates especially for the samples R-2 - 49 ± 6 ka and L-3 - 50 ± 8 ka indicate that chronostratigraphic position of distinguished formations can be younger than it was previously expected. So far Rzęczkowo formation has been related to the Gniew Interstadial (the Early Glacial). It is suggested that Rzęczkowo formation can be related with the younger Grudziądz Interstadial (the Inter-pleniglacial).

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Gamma spectrometry in thermoluminescence dating

Oczkowski H. L., Przegiętka K. R., Lankauf K. R., Szmańda J. B.

Geochronometria

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2000

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Vol. 18

57-62

EN

The aim of this paper is to present in detail a method, adopted in our laboratory, for the determination of annual dose. In particular, an analysis is focused on the thermoluminescence dating of eolian sediments from Kępa Kujawska. The advantage of the presented method is that partial matrix doses for alfa, beta and gamma radiation are determined simultaneously from the high resolution gamma spectrometry measurements.

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Beta source calibration for thermoluminescence dating

Oczkowski H. L., Przegiętka K. R.

Geochronometria

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2000

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Vol. 18

53-56

EN

The results of calibration of the dose rate from the beta source, incorporated in the RISO TL/OSL SYSTEM TL-DA-12, are presented. The quartz grains, separated from sediments by a typical procedure applied for thermoluminescence (TL) dating were used as a dosymetric material. The stability of thermoluminescence sensitivity of the material was achieved by the sequence of irradiating and the subsequent annealing of the grains. The calibrated 60Co and 137Cs sources were applied for irradiation with reference gamma doses. The calibration performed in January 1998 confirms the result obtained in 1996 with respect to the decay of activity of the beta source in the meantime.