Also known as volcanic ash chronology. A geological chronology method that uses tephra. Tephra accumulates over a wide area in a very short geological time due to volcanic eruptions. Therefore, it is extremely useful as a key layer for comparing strata. In Japan, tephrochronology has been used to investigate Quaternary systems and archaeological sites throughout the country since the research on the Kanto Loam layer in the 1950s. Furthermore, since the late 1970s, widespread tephra such as AT volcanic ash has been discovered, making it possible to compare sediments not only within Japan but also in neighboring areas and on the seabed, greatly improving the accuracy of Quaternary chronology. Source : Heibonsha Encyclopedia About MyPedia Information |
火山灰編年学とも。テフラを利用した地質学的編年法。テフラは火山噴火によって地質学的時間としてはごく短時間に広範囲に降り積もる。そのため地層対比の鍵層(かぎそう)としてきわめて有効である。日本では1950年代の関東ローム層の研究を契機として,日本各地の第四系や遺跡の調査にテフロクロノロジーが利用されてきた。さらに1970年代後半以降はAT火山灰に代表されるような広域テフラが見出され,日本国内だけでなく近隣の地域や海底の堆積物との対比が可能となり,第四系の編年の精度が大きく向上した。
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