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The Neogene history of environmental change in the Kenya Rift : Contribution to deciphering of evolution from ape to early hominid

肯尼亚裂谷的新近纪环境变化史：对破译从猿到早期原始人类进化的贡献

基本信息

批准号：
14253006
负责人：
SAWADA Yoshihiro
金额：
$ 20.97万
依托单位：
Shimane University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

The research results of the project are summarized as follows ;(1)On the basis of K-Ar ages and magnetostratigraphy, the Lukeino Formation (Fm) which yielded the earliest hominid Orrorin tugenensis accumulated between 6.0Ma and 5.7Ma.(2)The anorthoclase K-Ar ages from tuff layer yielding Nacholapithecus are 16.36±0.37Ma to 15.27±0.47Ma. Combined K-Ar ages and magnetostratigraphy of the Aka Aiteputh and Namurungule Fms in Samburu Hills, indicates that the hominoid fossil Sambrupithecus kiptalami occurs in the normal polarity zone, which is correlated with C4Ar.2n (ca.9.6Ma).Drastic environmental change occurred around 10Ma between the Aka Aiteputh Fm phase and subsequent Namurungure Fm phase which is sharply recorded in the sediment succession.(3)The age of lahar deposit layer yielding Kenyapithecus in the Fort Ternan area was dated 13.7 Ma based on the anorthoclase K-Ar and ^<40>Ar-^<39>Ar ages from phonolite lavas which sandwiched the fossil layer.(4)Earliest Late Miocene hominoid, which is very important for understanding on the evolution from great ape to human, and mammalian fossils were discovered from the lahar deposits of the Nakali Fm. The Nakali Fm consists mainly of lake and fluvial deposits with tuff and lapilli tuff beds including volcanic mud flow and pyroclastic flow deposits. Combined with the ^<40>Ar-^<39>Ar ages and magnetostratigrapy, the age of the Nakali Fm ranges from 10.1Ma to 9.8Ma (within Chron C5n.2n to C5n.1n).(5)Research of middle Miocene trachyte-phonolite flood volcanism in the whole Kenya rift ; geology, K-Ar age determination with magnetostratigraphy, petrography and geochemical characteristics.(6)Comparative geochemical studies on modern lacustrine sediments from the five lakes in the Kenya rift, and sedimentary rocks 16 to 5Ma.(7)Publications to journals and book (20 papers). The symposium was held at the annual meeting of Geological Society of Japan.

本项目的研究成果概括如下：(1)根据K-Ar年龄和磁性地层学资料，图根山最早形成原始人的鲁凯诺组(FM)在6.0 Ma~5.7 Ma之间积累。(2)产Nacholapithecus凝灰岩层的斜长石K-Ar年龄为16.36±0.37 Ma~15.27±0.47 Ma。结合K-Ar年龄和Namurungule FMS的K-Ar年龄和磁性地层学研究表明，Sambrupithecus kiptalami类人化石产于正极性带，与C4Ar.2n(约9.6 Ma)相关。Aaka Aiteputh FM相与随后的Namurungure FM相之间发生了10 Ma左右的剧烈环境变化，这在沉积序列中得到了明显的记录。(3)特尔南堡地区产Kenyapithecus的拉哈尔沉积层的年龄为13.7 Ma。(4)在纳卡利组火山岩沉积中发现了最早的中新世晚期类人猿化石和哺乳动物化石，这对了解类人猿向人类的演化具有重要意义。纳卡利组主要由湖泊和河流沉积组成，凝灰岩和火山灰凝灰岩层包括火山泥流和火山碎屑流沉积。结合^&lt；40&gt；Ar-^&t；39&gt；Ar年龄和磁性地层学，Nakali FM的年龄范围为10.1 Ma到9.8 Ma(在C5n.2n到C5n.1n内)。(5)肯尼亚整个裂谷中中新世粗面岩-响岩洪水火山作用研究；地质学，K-Ar年龄测定，磁性地层，岩石学和地球化学特征。(6)肯尼亚裂谷五个湖泊现代湖泊沉积和沉积岩16~5 Ma的对比地球化学研究。(7)期刊和书籍(20篇)。这次研讨会是在日本地质学会年会上举行的。

项目成果

期刊论文数量（126）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

The age and geological background of Nacholapithecus, Samburupithecus and Orrorin tugenensis, Kenya.

肯尼亚 Nacholapithecus、Samburupithecus 和 Orrorin tugenensis 的年龄和地质背景。

DOI：
发表时间：
2006
期刊：
Human Origins and Environmental Backgrounds (eds.Ishida, H.et al.)(Springer)
影响因子：
0
作者：
Sawada;Y;Sakai;T.;Itaya;T.;Hyodo;M.et al.
通讯作者：
M.et al.

Half graben filling processes in the early phase of continental rifting : The Miocene Namurungule Formation of the Kenya Rift

大陆裂谷早期的半地堑充填过程：肯尼亚裂谷的中新世 Namurungule 地层