Plio-Pleisatocene environmental changes in Java and hominind evolution and dispersion

爪哇原始人化石对于研究原始人的扩散，即“走出非洲”问题具有重要意义。然而，他们的年龄还没有确定，仍然存在争议。在这项研究中，我们重建了爪哇中部桑吉兰原始人类化石建造的古环境变化，并讨论了原始人类的分散与环境变化的关系。此外，还研究了一种新的古地磁测年技术，并尝试将其应用于爪哇古地磁地层资料。(1)首次将环境磁学技术应用于爪哇中部桑吉兰普昌干(Sangiran)组的黑色粘土中。结果，我们发现了一个大的环境变化，发生在T11凝灰岩地平线上方，与桑吉兰最早的直立人化石的出现相吻合。我们证实了该方法对生物化石含量较少的沉积物是有效的，如花粉或硅藻，常用于古环境研究。(2)花粉和硅藻化石含量低，很难进行详细的古环境研究，除了普苍干(桑吉兰)组的部分部分。(3)桑吉兰的磁层析数据表明，上奥杜瓦伊转换代表了多次地磁波动。在宝鸡、中国中南部的中国黄土中也观察到了同样的田间行为。从而证实了这是一种真实的地磁特征，并证实了Hyodo等人的地磁地层对比。(1992；1993；2002)是合理的。(4)我们利用大阪湾1700米的岩心揭示了松山-布鲁内斯极性转变的千禧年到亚千年尺度的特征。利用这些特征确定了桑吉兰的磁性地层对比。

Javan hominid fossils are important to study hominid dispersion, namely "Out-of-Africa" problem. However, their ages have not been established, and still disputed. In this study, we reconstructed paleoenvironmental changes from the Sangiran hominid fossil-bearing formation, central Java, and discuss the relationship between hominid dispersion and environment changes. In addition, a new paleomagnetic dating technique was studied, and tried to apply to the Javan paleomagnetic stratigraphy data. The following results were obtained:(1) A technique of environmental magnetism was first applied to the black clay of the Pucangan (Sangiran) Formation in Sangiran, central Java. As a result, we found a large environmental change that occurred just above the T11 tuff horizon, coincided with the occurrence of the earliest Homo erectus fossil in Sangiran. We confirmed the method was valid to the sediments with less content of biological fossils like pollen or diatom, often used for paleoenvironmental study.(2) Detailed paleoenvironmental study with pollen and diatom fossils is difficult because of poor content, except some parts of the Pucangan (Sangiran) Formation.(3) The magnetostratrigraphy data in Sangiran show that the Upper Olduvai transition represents a number of geomagnetic fluctuations. The same field behavior was observed in the Chinese loess in Baoji, south-central China. Thus we confirmed that it is a real geomagnetic feature, and that the magnetostratigraphic correlation by Hyodo et al. (1992; 1993; 2002) is reasonable.(4) We revealed millennial to submillennial-scale features for the Matuyama-Brunhes polarity transition using a 1700-m core from Osaka Bay. The features are utilized to confirm the magnetostratigraphic correlation in Sangiran.