大荔人遗址黄土-古土壤序列

本文划分了大荔人化石层位上部的黄土-古土壤序列,对黄土进行了磁化率测量,并将结果与附近位于黄土塬上的垣雷剖面以及典型黄土洛川剖面的地层和磁化率曲线对比,认为大荔人化石地点地层上部黄土-古土壤序列包括S₀、L₁、S₁、L₂、S₂.大荔人化石位于黄土层以下约20 m处的河流相砾石层中,因此大荔人化石的年代大于S₂的轨道调谐年龄,即0.247 Ma B.P..根据动物化石和孢粉指示的环境以及化石层位上堆积较厚的河流相地层,推测大荔人生活在S₃古土壤形成时期.

STUDY ON LOESS-PALEOSOL SUCCESSION OF THE DALI MAN SITE

Since Dali man Site discovered in 1978, much research has been done for the strata, the palaeolithic, the mammalian fossils etc., however no agreement has been made on the age of the fossil Dali-man. The main reason lies in not only there being no consolidate dating method, but also in how researchers dealing with the lithostratigraphy of the loess-paleosol successions overlying fluvial deposits bearing Dali man fossil. In this paper,the stratigraphic section is analyzed, the magnetic susceptibility of the loess-paleosol measured. Our results show the strata of Dali man section consisting of two kinds of sediments from the top to the bottom: the loess-paleosol succession and fluvial deposits. The former, in thickness about 17m, includes S₀, L₁, S₁, L₂ and S₂, so the age of the Dali-man should be older than 0.247 Ma B.P. according to the Orbit-Tuning Mode which gives S₂ an age of 0.247 Ma. Since the sporopollen and mammilla fossil suggested a more-humid period than that of today, it could be inferred that Dali man lived in an interstadial period. Together with the fact that the horizon bearing the fossil Dali man is more-than 20 m below the loess-paleosol succession, an age span of 0.28～0.33 Ma B.P. when S₃ developed is suggested for the Dali man fossil.