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Evolutionary History of Mammalian Fauna and Paleoenvironments-Late Cenozoic Eurasia and North America-

哺乳动物动物群和古环境的进化史-晚新生代欧亚大陆和北美-

基本信息

批准号：
04041077
负责人：
NAKAYA Hideo
金额：
$ 5.12万
依托单位：
Kagawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04041077/
关键词：
Late Cenozoic Paleoenvironment Sedimentary environment Climatic change Mammal Microfossil Eurasia Northern China 微石化

项目摘要

The purpose of this research is to interpret the paleoenvironments and biostratigraphy of Late Cenozoic mammalian fauna heretofore undescribed for the Eastern Eurasia.In 1993, the Japanese and Chinese joint expedition conducted stratigraphical, sedimentological and paleontological survey in the Leijiahe Formation of Lingtai County, Gansu Province, China. The field work was done during the end of August and the first part of September 1993. Paleontologists excavated Locality 4 in detail, and collected small mammalian fossils from Locality 4 and 6 by screen and washing method.The following conclusions are reached :1. stratigraphic structure of the Leijiahe Formation consists conglomerate bodies and interbeded mudstone. Sedimentological data indicate that the sedimentological environment of the Leijiahe Formation is meandering river system and its flood plain.2. About 2,200 fossils are excavated from the Leijiahe Formation. Mammalian fossil evidence suggests that the Leijiahe Formation is Pliocene in age.3. Taphonomy of mammalian fossils from the Locality 4 of the Leijiahe Formation indicate that mammalian fossils were not transported from far away.4. Paleomagnetic data from the Locality 6 by Dr.Cheng of the Institute of Geology, Academia Sinica indicate that the Leijiahe Formation ranges in age during 3 million years.5. Paleoenvironmental analysis by microfossils is not yet finished. However, preliminary result of pollen analysis shows that the paleoenvironment of Leijiahe Formation is mixed forest and openland.From available evidences, it is concluded that the paleoenvironment of Leijiahe Formation is alluvium sedimentary basin under the dry climate.

1993年，中日联合考察队在甘肃灵台县雷家河组进行了地层、沉积和古生物调查。实地工作是在1993年8月底和9月上半月进行的。古生物学家对4号地点进行了详细的发掘，并采用筛洗法在4号和6号地点采集了小型哺乳动物化石。雷家河组地层结构为砾岩体与泥岩互层。沉积学资料表明，雷家河组的沉积环境为曲流河及其泛滥平原.雷家河组出土化石约2,200件。哺乳动物化石证据表明雷家河组的时代为上新世.雷家河组4号地点哺乳动物化石的埋藏学研究表明，哺乳动物化石并非由远距离搬运而来.根据中研院地质研究所郑博士在第六地点所作的古地磁资料，雷家河组的年龄约为三百万年。微体化石的古环境分析尚未完成。然而，花粉分析的初步结果表明，雷家河组的古环境为混交林和开阔地，综合现有证据，认为雷家河组的古环境为干旱气候条件下的冲积沉积盆地。