Yorinao Shitaoka

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

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 Ghaggar 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 started or had already been completed by 15‐10 ka. Aeolian deposition was subdued by enhanced moisture 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.

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

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 xenocrysts, 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 measurements for the lava indicate the eruption age as 15.8 ± 2.5 ka, which is fairly consistent with the stratigraphical 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.

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

Although radiocarbon (14C) dating, uranium-series dating, and optically stimulated luminescence (OSL) dating have been conducted for Upper Palaeolithic sites in the Nihewan Basin, northern China, there is room for constructing a detailed chronological framework. In this study, loess sediments collected from two Upper Palaeolithic sites, Youfang site and Hutouliang site, were dated using the single-aliquot regenerative-dose (SAR) OSL protocol. OSL measurements for palaeodoses estimation 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, archaeological evidence and independent 14C ages.

Availability and Problem of Environmental Education Using Magma Formation Program; Comparative Analysis for Students Living with or without Volcanic Activity: ― 活動する火山が在る地域と無い地域での実践比較 ―

私たちの生活環境において、火山噴火はそれほ ど身近な現象として捉えられていないと思われ る。しかし、日本の地表のおよそ40%は火成岩 に覆われているため(村田・鹿野 1995)、日本の 環境教育において火山噴火を対象とした教材は不 可欠である。火山噴火が日常生活に与える影響は 正負両面において極めて大きい。正の影響では、 風光明媚な地形である富士山の世界遺産登録や日 本各地のジオパークへの登録、地熱活動による温 泉やエネルギーとしての地熱発電などが挙げられ る。これに対して、負の影響は、雲仙普賢岳や三 宅島、有珠山の火山噴火に見られるように物心両 面に及ぶ甚大な被害が想起される。火山噴火は台 風や豪雨現象などとは違って、数十年から数百年 単位の時間スケールで活動を繰り返すため、これ に備えるには長期的なスケールでの心構えが必要 であり、かつ突発的な活動に対処するためには、 日常的にそして継続的な教育活動が必要と考え る。 火山噴火をテーマとした教育を持続発展可能な 社会の形成のために用いるには、初等・中等の教 育現場における活動がまずは可能であろう。小学 校や中学校のカリキュラムにおける火山噴火に関 する学習としては、6年生理科の単元で「大地の つくりと変化」(文部科学省 2008a)、中学校理科 第2分野で単元「大地の成り立ちと変化」(文部 科学省 2008b)の項目が設けられている。しかし、 これらの授業で火山に関心を持ち、実感を持った 理解を目指した授業展開を可能にする教材は少な い。特に、小学校における「大地のつくりと変化」 単元において、児童が火山噴火を主体的な問題と して理解を深められる授業展開は難しい。火山噴 火を対象とした教材としては、映像によるものや キッチン火山実験などがある。また、廃油を用い 資 料 火山を主眼とする環境学習の有効性と課題