火山岩類の熱ルミネッセンス年代測定の精度検証 -雲仙火山火砕流堆積物のβ線量精密補正年代- Verification of errors and reliability of thermoluminescence age for volcanic rocks -Precise beta-ray correction age of pyroclastic flow deposits of Unzen volcano, SW Japan-
Thermoluminescence (TL) age determination was carried out for 18 samples from four pyroclastic flow deposits(Mutsugi, Kureishibaru, Furue and Yugawachi) of Unzen volcano, SW Japan. The TL growth curve method was used for quartz phenocrysts to determine the ages. Major inaccuracy of TL dating is caused in annual dose evaluation, especially in determination of beta rays contributions. Therefore, the beta ray correction was done by measurement of quartz phenocryst diameter on thin sections.<br> The TL ages for Mutsugi, Kureishibaru, Furue and Yugawachi pyroclastic flow deposits indicated 4.9±0.4 ka, 23±1 ka, 23±1 ka and 77±6 ka, respectively, which are average of 3 to 6 samples collected from same outcrop each. These ages consistent with <sup>14</sup>C ages and stratigraphy identified by tephra.
- 岩鉱 : 岩石鉱物鉱床学会誌 : journal of mineralogy, petrology and economic geology
岩鉱 : 岩石鉱物鉱床学会誌 : journal of mineralogy, petrology and economic geology 94(4), 109-119, 1999-04-05
Japan Association of Mineralogical Sciences