Xing Gao, Shuangquan Zhang, Yue Zhang, and Fuyou Chen
June 28, 2017
Introduction from the paper:
Zhoukoudian (ZKD, also Choukoutien or Chou-kou-tien in early literature) Locality 1, close to Beijing, has been well known since the 1920s because of the discovery of Sinanthropus (Homo erectus pekinensis) fossils, stone artifacts, and evidence of hominin-controlled use of fire (Black 1926, 1931; Pei 1934). Deposits at the site have been divided into 13 stratigraphic layers (fig. 1), with Layer 4 referred to as the “Upper Cultural Horizon” and Layer 8–9 the “Lower Cultural Horizon” (Jia 1959; Pei and Zhang 1985). With respect to the time frame of hominin occupation at the site, fission-track dating was employed in the early 1980s, which determined that the formation of Layer 10 probably took place 462 ± 45 kya while Layer 4 was deposited approximately 299 ± 55 kya (Guo et al. 1980, 1991). Thermoluminescence dating was also applied at the site, generating an age of 417–592 kya for Layer 10 and 292–312 kya for Layer 4 (Pei et al. 1985). Uranium-series (U-series) dating on animal teeth produced an age range of 230–256 kya for Layers 1–3 and an indefinite date of >300 kya for Layer 8 (Zhao et al. 1985b). The detailed chronology of ZKD Locality 1 established by early investigations was reviewed by Zhao et al. (1985a) and Goldberg et al. (2001). Shen et al. (2001) published older ages for key horizons at the site using mass spectrometric U-series dating of intercalated calcite samples: 400 kya for Layers 1–2, 500 kya for the upper part of Layer 5, and 600 kya for the middle and lower parts of Layer 5. In 2009, Shen et al. used 26Al/10Be burial dating to determine the age of the lower component of the deposits (Layers 7–10) yielding an estimate of 770 kya (Shen et al. 2009).
Section on hematite detection at Zhoukoudian, Locality 1, Layer 4:
Research on Magnetic Susceptibility and Color Measurements
Another series of analyses carried out recently at ZKD Locality 1 involved detailed measurements of magnetic susceptibility, color, and diffuse reflectance spectra of sediments in the area newly exposed during recent excavations in Layer 4 (Zhang et al. 2014). Magnetic analysis and color measurements have been proven to be effective methods for detecting the presence of heated areas in archaeological sites (e.g., Carrancho and Villalain 2011; Jordanova, Petrovsky, and Kovacheva 2001). In order to analyze the sedimentary features of the excavation pits and determine the extent of the potentially burned areas, systematic sampling was employed in three zones identified as possible burned areas or “hearths” as well as apparently unburned areas in the same level. A total of 405 samples were collected. Magnetic susceptibility was measured with an Agico MFK1-FA Kappabridge magnetic susceptibility meter at frequencies of 976 Hz (vLF) and 15,616 Hz (vHF). Redness was measured with a Konica Minolta CM-700d spectrophotometer. Following magnetic susceptibility and redness measurements, some samples were then selected for DRS and high-temperature magnetic susceptibility measurements (fig. 4). The results indicate that the magnetic susceptibility and redness of sediments taken from the hypothetical “hearths” were markedly higher than those from other areas in the same level (up to 22 times greater for magnetic susceptibility and three times more for redness), and fine-grained magnetite and hematite grains contributed significantly to the distinctly high values of magnetic susceptibility and redness in these “hearth” sediments. High-temperature magnetic susceptibility measurements demonstrated that the thermally altered sediments were heated to above 700°C. Those changes in low-frequency magnetic susceptibility and redness cannot result from natural fires (Zhang et al. 2014).