Research into the origin and geological history of the Lake Hamana

滨名湖的起源和地质历史研究

• 批准号: 60300012
• 负责人: IKEYA Noriyuki
• 金额: $ 10.5万
• 依托单位: Shizuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Co-operative Research (A)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60300012/
• 关键词: Hamana Lake; Brackish water lake; Holocene deposits; Boring Core; Core sediments; Sedimentary environments; 古環境

In order to elucidate the depositional process of the Holocene sediments distributed in and around Hamana Lake, we have started a multidisciplinary research project. As a part of this project, four boring core samples were collected from four sites in the lake. Cores of 85H-1(-12m in depth), 85H-2(-5m in depth), 85H-3(-5m in depth), and 86H-4(-3m in depth) are 16.45m, 41.46m, 50.45m and 23.96m long, respectively. The coredd sediments are all Holocene age, and the bottoms of all four holes reached the boundary between Holocene and Pleistocene.The lithofacies of the boring core samples were described in detail. The geological age of the samples were determined by tephrochronological and 14C methods.Oki volcanic ash (ca.9,300 yr BP) was found with thickness of 30mm in 44.58m(H-3). Ah volcanic ash (ca.6,300 yr BP) was also found in 8.98m(H-2), 14.25m(H-1) and 15.75m(H-4) with 10 to 15mm in thickness.A pair of tephras, Os scoria (ca.2,800 yr BP) and Kg pumice (ca.3,000 yr BP) was observed in 6.52 - 6.57m(H-1) and 4.86 - 4.95m(H-4).By using the AMS (Accelerator Mass Spectrometry) technique, many radiocarbon dates were obtained from very small shell fragments and wood chip samples in the core sediments. The 14C data for the bottom of the H-1 core is 7140 140 yr BP at a depth of 28.15m, and for the H-2 core is about 10,000 yr BP at a depth of 46.4m.These data suggest that during the early Holocene there was not just one but two discrete marine transgressions, first before about 8,500 to 8,000 yr BP and the second after 8,000 to 7,000 yr BP, and the marine regression after the highest sealevel occurred rapidly from 4,000 to 3,500 yr BP.

为了阐明分布在滨名湖及其周围的全新世沉积物的沉积过程，我们启动了一项多学科研究项目。作为该项目的一部分，从湖中的四个地点采集了四个钻孔岩心样本。 85H-1（-12m深）、85H-2（-5m深）、85H-3（-5m深）和86H-4（-3m深）的核心长度分别为16.45m、41.46m、50.45m和23.96m。岩心沉积物均为全新世时代，四个孔的底部均达到全新世与更新世的交界处。对钻孔岩心样品的岩相进行了详细的描述。采用年代学法和14C法测定了样品的地质年龄。在44.58m(H-3)中发现隐木火山灰(距今约9,300年)，厚度为30mm。在 8.98m(H-2)、14.25m(H-1) 和 15.75m(H-4) 中还发现了 Ah 火山灰（距今约 6,300 年），厚度为 10 至 15mm。在 6.52 - 6.57m(H-1) 和 4.86 - 4.95m(H-4)。通过使用AMS（加速器质谱）技术，从岩心沉积物中非常小的贝壳碎片和木片样品中获得了许多放射性碳年代。 H-1 核心底部的 14C 数据为距今 7140 140 年，深度为 28.15m，而 H-2 核心的 14C 数据为距今 10,000 年，深度为 46.4m。这些数据表明，在全新世早期，不仅发生了一次，而且发生了两次离散的海侵，第一次是在大约 8,500 至 8,000 年 BP 之前，第二次是距今 8,000 到 7,000 年之后，海洋 距今 4,000 至 3,500 年间，最高海平面之后的回归迅速发生。

项目成果

Ikeya,N., Wada,H. and Ohmori, M.: "On the Boring Core Sediments from Hamana Lake." Geosci. Repts. Shizuoka Univ.No. 13. 67-111 (1987)

池谷，N.，和田，H.

大塚謙一: 静大地研報. NO.13. 113-145 (1987)

大冢宪一：静冈地震研究报告第 13-145 号（1987 年）。

Matsushita,M. and Sanukida,S: "Holocene Vegetation History Around Lake Hamana on the Pacific Coast of Central Japan" The Quaternary Res.(1988)

松下，M.

Abe,Y. and Wada, H.: "Clay Minerals in the Surface Sediments of Hamana Lake, Central Japan." Geosci. Repts. Shizuoka Univ.No. 13. 147-155 (1987)

阿部，Y.

池谷仙之: 静岡大学地球科学研究報告. 11. 171-179 (1985)

S. Ikeya：静冈大学地球科学研究报告。11. 171-179 (1985)。