地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
総説
氷河編年研究の展望
―南半球・アジア山岳地域の最近の事例―
奈良間 千之
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ジャーナル フリー

2012 年 121 巻 2 号 p. 215-234

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 Establishment of a continuous, detailed glacial chronology based on radiocarbon (14C) dating has been hindered by the difficulty of collecting organic matter in cold and arid mountainous regions. The development of other numerical dating methods, such as terrestrial cosmogenic nuclide (TCN) and optically stimulated luminescence (OSL) dating, has recently made it possible to establish a detailed glacial chronology and to compare local glacial chronologies with recent climate proxy data of ice cores obtained from polar and alpine glaciers, and of deposits from sea floors and lake bottoms. This paper reviews recent studies on the glacial chronology of the Southern Hemisphere and high mountains of Asia (Himalayas, Tibet, and Central Asia). There are three main outcomes. (1) Glacial advances from the Late Glacial to Holocene in New Zealand and Patagonia were mostly synchronized with cold periods identified in Antarctic ice cores, while glaciers in the Peru Andes fluctuated oppositely but similarly to the North Atlantic. (2) Differences and similarities between local glacial chronologies in the Himalayas and Tibetan Plateau originated from the Indian monsoon and westerlies. For example, some researchers have proposed that the presence of early Holocene moraines and absence of moraines deposited in the Last Glacial Maximum (LGM) indicate an enhanced monsoon in the early Holocene because a stronger summer monsoon brings more snow to the Himalayan ranges. (3) The glacial chronologies during the Last Glacial in Central Asia, which is not influenced by the Indian monsoon, differ from those in the Himalayas. The glacier changes agree with climate proxy records from lacustrine deposits and mountain ice cores in Central Asia during the last 1000 years, which indicates the change of precipitation in the area.

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© 2012 公益社団法人 東京地学協会
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