INTERPRETATION OF MIOCENE SURFACE WATER TEMPERATURE BASED ON DIATOM TEMPERATURE INDEX

基于硅藻温度指数的中新世地表水温解释

• 批准号: 07640618
• 负责人: MARUYAMA Toshiaki
• 金额: $ 1.15万
• 依托单位: Yamagata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640618/
• 关键词: DIATOM; NEOGENE; MIOCENE; PALEOCEANOGRAPHY; BIOSTRATIGRAPHY; MICRO FOSSIL; 年代決定

Diatom analyzes were made on exogenetic rock samples collected from the Neogene strata, which contain sea cow fossils and fossil whale bones discovered in Yamagata Prefecture. Dating of the lithostratigraphic unit and reconstruction of the depositional environment were the basic purposes of this investigation, however, precise paleontological resolution could not be obtained because the diatom assemblages have almost gone out. Most of the diatom fossils were completely dissolved by silica diagenesis, making the corroded valves impossible to identify. As other biosiliceous sediments as well as diatom skeletons seem to remain out of the opal-A facies.Upper Miocene deposits distribute well in the hills on the western margin of Yamagata Basin in Yamagata Prefecture. Because, that their lithofacies are quite similar, that only a few key beds are available and that their lithology remarkably change lateraly, the lithostratogrphic division and the geographical distribution have not been defin … More ed properly. Based on the extensive geologic survey, the strata are divided into five formations. Two of those namely, the Hashikami Formation and the Kuzusawa Formation are a contemporaneous heterotopic facies. According to the diatom fossil analyzes under this new lithologic division, the Kuzusawa Formation is correlated to the Denticulopsis dimorpha Zone. In addition, it is possible that the Hashikami Formation may also correspond to the D.dimorpha Zone or to underlying the Thalassiosira yabei Zone.During the last dicade, Neogene diatom biostratigraphy has been advanced in the North Pacific region. Most of these biozones and datum levels were correlated to the geomagnetic polarity time scales of Berggren et al. (1985) or Cande and Kent (1992). In this study most applicable Neogene diatom zones and events in the middle-to-high latitudes of the Northwest Pacific have been evaluated and recalibrated to the geomagnetic time scales of Cande and Kent (1992,1995). Several planktonic taxa indicating paleotemperature can be selected from diatom assemblages based on their distributional patterns, which are drawn characteristically by fossil frequencies in time and space, and then a diatom temperature index (Td index) reflecting the extent of paleo-isotherm is defined as Td=W+T-C,where W,T and C are frequencies in percentage of warm, temperate and cold water species respectively. Less

对采自新近纪地层的外生岩石样品进行了硅藻分析，其中包括山形县发现的海牛化石和鲸鱼化石。岩石地层单位的测年和沉积环境的重建是本次调查的基本目的，但由于硅藻组合已基本消失，无法获得精确的古生物分辨率。大多数硅藻化石被硅质成岩作用完全溶解，使得被腐蚀的阀门无法识别。由于其他生物硅质沉积物以及硅藻骨架似乎留在蛋白石-A面之外。上中新统沉积很好地分布在山形县山形盆地西缘的山丘上。由于它们的岩相十分相似，可利用的关键层很少，岩性在横向上变化明显，因此尚未明确…的岩性地层划分和地理分布。更适当的教育。在广泛地质调查的基础上，将地层划分为5个组。其中Hashikami组和Kuzusawa组为同生异位相。根据在新的岩性划分下的硅藻化石分析，库祖萨泽组与双形态金线藻带相对应。此外，Hashikami组还可能对应于D.dimora带或Thalassiosira yabe带的下伏。在最后一次大讨论中，北太平洋地区新近纪硅藻生物地层学已经向前推进。这些生物带和基准面大多与Berggren等人的地磁极性时间尺度相关。(1985)或坎德和肯特(1992)。在这项研究中，对西北太平洋中高纬度地区最适用的新近纪硅藻带和事件进行了评估，并根据Cande和Kent(1992,1995)的地磁时间尺度进行了重新校准。根据化石频率在时间和空间上的分布特征，从硅藻组合中选出指示古温度的几个浮游类群，并定义了反映古等温线程度的硅藻温度指数(Td指数)为Td=W+T-C，其中W、T和C分别为暖水、温水和冷水物种的频率。较少

项目成果

I.Motoyama, et al.: "Neogene diatom and radiolarian biochronology for the middle-to-high latitudes of the Northwest Pacific region : Calibration of the Cande and Kent's geomagnetic polarity time scales (CK92 and CK95)." Jour.Geol.Soc.Japan. 104 (3), (in p

I.Motoyama 等人：“西北太平洋地区中高纬度地区的新近纪硅藻和放射虫生物年代学：Cande 和 Kent 地磁极性时间尺度（CK92 和 CK95）的校准。”

R.Nomura, et al.: "Cenozoic paleoceanography in the Indian Ocean : Paleoceanographic biotic and abiotic changes before the development of monsoon system." Jour.Geol.Soc.Japan. 103 (3). 280-303 (1997)

R.Nomura等人：“印度洋新生代古海洋学：季风系统发展前的古海洋生物和非生物变化。”

本山 功: "中・高緯度北西太平洋地域における新第三紀珪藻・放散虫化石年代尺度" 地質学雑誌. 104・3(印刷中). (1998)

Isao Motoyama：“西北太平洋中高纬度地区的新近纪硅藻和放射虫化石年龄尺度”，《地质杂志》104, 3（出版中）。

M.Lyle, et al.: Proceedings of the Ocean Drilling Program, Initial Reports, 167.Ocean Drilling Program, College Station, TX, 1378 (1997)

M.Lyle 等人：海洋钻探计划论文集，初始报告，167。海洋钻探计划，德克萨斯州大学城，1378 (1997)

本山 功: "青森県津軽半島中西部の新第三系の層序と放散虫・珪藻化石" 地質調査所月報. 46・7. 333-374 (1995)

Isao Motoyama：“青森县津轻半岛中西部的新近纪地层学和放射虫和硅藻化石”地质调查月报46・7（1995）。