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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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OSL dating using quartz fine grains extracted from loess in Upper Palaeolithic sites of Nihewan Basin, northern China

Shitaoka Y., Nagatomo T.

Geochronometria

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2013

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Vol. 40, no. 4

311--316

EN

Although radiocarbon (14C) dating, uranium-series dating, and optically stimulated lumi-nescence (OSL) dating have been conducted for Upper Palaeolithic sites in the Nihewan Basin, north-ern China, there is room for constructing a detailed chronological framework. In this study, loess sed-iments collected from two Upper Palaeolithic sites, Youfang site and Hutouliang site, were dated us-ing the single-aliquot regenerative-dose (SAR) OSL protocol. OSL measurements for palaeodoses es-timation used fine-grained quartz samples extracted from loess. OSL dating results were obtained as 10-17 ka. These OSL ages were consistent with the related stratigraphy of Palaeolithic sites, archaeo-logical evidence and independent 14C ages.

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Quartz OSL dating of sand dunes in Ghaggar Basin, northwestern India

Shitaoka Y., Maemoku H., Nagatomo T.

Geochronometria

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2012

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Vol. 39, no. 3

221-226

EN

Several studies have used luminescence dating to investigate sand mobilization activity in extreme western areas and the southern margin of the Thar Desert, India. However, room exists for a chronology of sand profiles for the northern margins of the Thar Desert. The Ghaggar River flood plain at Rajasthan, northwestern India, in the northern margin of the Thar Desert, is bordered by sand dunes. Elucidation of the environmental changes of the Ghaggar Basin requires knowledge of many aspects of sand dune formation. We measured optically stimulated luminescence (OSL) using the single aliquot regenerative-dose (SAR) protocol for sand of eight palaeo-dunes and two flood silts of both sides of the present Ghag-gar Basin and Chautang Basin flood plains. Their OSL ages were obtained respectively, as 15-10 ka or 5 ka, and 9-8 ka. Results of this study reinforce the hypothesis that sand dune deposition had start-ed or had already been completed by 15-10 ka. Aeolian deposition was subdued by enhanced mois-ture during 9-8 ka. Our interpretation is that, at least since 5 ka, the scale of the flood plain of the Ghaggar River has remained equivalent to that of the present day.