Stratigraphy and distribution of widespread Quaternary tephras in Chugoku and Kinki district, west japan

日本西部中国和近畿地区广泛分布的第四纪火山灰的地层和分布

• 批准号: 61540559
• 负责人: OKADA Shomei
• 金额: $ 1.41万
• 依托单位: Tottori University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61540559/
• 关键词: Wide spread tephra; Ferromagnetic minerals; Curie point; Aso-4 ash; フィッショントラック年代; 大山火山灰層; 阿蘇4火山灰; 三瓶木次軽石

1. In this study, for identify and correlate the Quaternary tephra layers the thermomagnetic analysis of ferromagnetic minerals in tephra is performed. The thermomagnetic balance was improved to computer controlled system in advance of the measurement.2. It is already reported that the widespread tephras(Ah,AT,Aso-4,K-Tz) which originated from Kyushu are distributed in Chugoku and Kinki district. The thermomagnetic measurements by the above mentioned system reveal that the ferromagnetic minerals in Ah, Aso-4 and K-Tz have distinctly different properties from those in tephras from the Daisen and the Sanbe volcanoes. By this difference, Aso-4 ash which is not distinguishable in the field because its thin thickness and progressive weathering was discriminated from the tephras of Sanbe at the site of Yasue, Akagichou, Shimane Prefecture.3. Both the phenocryst assemblage and the thermomagnetic property of Sanbe Kisugi Pumice(K_3) are so unique in the Daisen tephra formation that k_3 is good horizon marker around the Daisen volcanic area.4. Four pumice fall deposits(Arata pumice 2:DAP_2, Arata pumice 1:DAP_1, Hiruzenbara pumice:HiP and Okutsu pumice:DOP in descending order) erupted from Daisen volcano were newly described and named in the present study. Of them, DOP shows widespread distribution having ESE trend from Daisen.5. The fission track dating on DOP and h_1 pumice was made. The latter one is an upper member of the Daisen Lowest Tephra Formation. The results show 86,000<plus-minus>7,000 and 81,000<plus-minus>7,000y.B.P. respectively. Both dates indicate that DOP and h1 was erupted in late stage of the last interglacial or early stage of the last glacial age.

1。在这项研究中，为了识别和关联第四纪tephra层，进行了tephra中铁磁矿物的热磁性分析。在测量之前，将热磁性平衡提高到计算机受控系统。2。据报道，起源于九州的广泛的Tephras（ah，at，ASO-4，K-TZ）分布在Chugoku和Kinki区。通过上述系统的热磁测量表明，AH，ASO-4和K-TZ中的铁磁矿物质与雏菊和Sanbe火山的Tephras具有明显不同的特性。通过这种差异，ASO-4在田间无法区分的ASO-4灰分，因为其薄的厚度和进行性风化与Shimane县Akagichou所在地的Sanbe的Tephras区分开。3。 Sanbe Kisugi Pumice（K_3）的表晶组合和热磁特性在Daisen Tephra组中都是如此独特，以至于K_3在Daisen火山区域周围是良好的地平线标记。4。四个Pumice秋季沉积物（Arata Pumice 2：DAP_2，Arata Pumice 1：DAP_1，Hiruzenbara Pumice：Hip和Okutsu Pumice：Dop以降序下降的顺序）在本研究中被新地描述为Daisen Volcano。其中，DOP显示出具有daisen的ESE趋势的广泛分布。5。进行了DOP和H_1浮力的裂变轨道日期。后一个是雏菊最低的Tephra组的上部成员。结果显示86,000 <plus-minus> 7,000和81,000 <plus-minus> 7,000y.b.b。分别。两个日期都表明，DOP和H1在最后一个冰川时代的最后一次或早期阶段爆发。

项目成果

Shomei Okada: "On two pumice fall beds discovered in the Daisen Lower Tephra Member" Jour. Fac. Education, Tottori Univ., Natural Science. 35. 33-42 (1986)

Shomei Okada：“在大山下 Tephra 段发现的两个浮石落床上”Jour。

岡田昭明: 鳥取大学教育学部研究報告 自然科学. 35. 33-42 (1986)

冈田秋明：鸟取大学教育学部研究报告自然科学。 35. 33-42 (1986)

岡田昭明: 鳥取大学教育学部研究報告 自然科学. 37. (1988)

冈田秋明：鸟取大学教育学部研究报告自然科学 37。（1988）

Shomei Okada: "Thermomagnetic properties of ferromagnetic minerals in the Quaternary tephra layers distributed in San'in district" Jour. Fac. Education, Tottori Univ., Natural Science. 37. (1988)

Shomei Okada：“山阴地区第四纪火山灰层中铁磁矿物的热磁特性”，Jour。