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Data from: Innovative ochre processing and tool-use in China 40,000 years ago

Citation

Deng, Chenglong (2022), Data from: Innovative ochre processing and tool-use in China 40,000 years ago, Dryad, Dataset, https://doi.org/10.5061/dryad.9s4mw6mj0

Abstract

These data were generated to determine the anthropogenic hematite grains resulted from ochre processing at the Xiamabei site in the Nihewan Basin, northern China. Four samples were selected for sediment analyses, including Raman spectroscopy, X-ray diffraction (XRD), high-temperature magnetic susceptibilities, and/or magnetic component analysis of coercivity distributions. Two sediment samples (X1 and X2) come from the red stained area on which the ochre fragments OP1 and OP2, stone slab LS and quartzite cobble QC were found; two samples (X3 and X6) were retrieved in the same layer but at ~2 m distance from the stained area. All of the samples consist of flood plain silts.

The Raman spectra unambiguously identify hematite in red particles abundantly present in samples X1 and X2. The XRD measurements clearly show that hematite is abundant in samples X1 and X2. However, hematite is not detectable in samples X3 and X6. The volume percent for hematite is 0.9% in sample X1 and 1.7% in sample X2. The high-temperature magnetic susceptibility measurements suggest that hematite dominates the magnetic mineralogy of samples X1 and X2. Magnetic component analyses of coercivity distributions show distinct assemblages of magnetic minerals in samples X1 and X2, which have three components with low, middle and high coercivities. The low-coercivity component with median acquisition field of 40-62 mini Tesla (mT) is interpreted as magnetite and/or maghemite. The middle-coercivity component with median acquisition field of 100-166 mT is interpreted as partially-oxidized coarse-grained magnetite. The high-coercivity component with median acquisition field of up to 575 mT is interpreted as single domain hematite, because the single domain threshold grain size of hematite is considerably larger than 15 micrometers, and even up to 100 micrometers. This kind of hematite grains with high coercivities up to several hundreds of mT is usually of detrital origin, and is documented as evidence for the earliest ochre processing in east Asia. The new findings provide new insights into the expansion of Homo sapiens.

Methods

Raman spectra were obtained with a Witec alpha300R confocal-Raman spectrometer equipped with a solid-state continuous-wave laser emitting at 532 nm, and diffraction gratings of 300 grooves mm^-1. A piece of single-crystal silicon was used to calibrate the wavenumbers of the shifts. Laser focusing and sample viewing are performed through a Zeiss microscope fitted with an EC Epiplan 50x objective lens (NA = 0.75). The spot size is less than 1 micrometer and the resolution is 4.8 cm^-1. The laser power impinging on the hematite single crystal was 0.40 mW. A spectra acquisition time of 30 s and total spectra with 20 accumulations were collected for each measurement.

XRD analyses were carried out using a Netherlands PANalytical X’PerPRO diffractometer with the following parameters: Ni-filtered Cu-K_alpha/40kV/40mA, scattering slit of 0.0625 degree, receiving slit of 5 millimeters, continuous scan mode, scanning speed of 0.049884 degree/second, and a scanning step of 0.0167113 degree. Bulk minerals were identified based on the following peaks: quartz, 4.26 angstrom; anorthoclase, 3.21 angstrom; albite, 3.18 angstrom; rutile, 3.189 angstrom; calcite, 3.03 angstrom; dolomite, 2.89 angstrom; Hematite, 2.70 angstrom; Koninckite, 8.42 angstrom; and clay minerals smectite/chlorite, 14.1 angstrom; illite, 10.0 angstrom. The relative proportions of the identified minerals were approximately determined using their peak intensities by measuring the heights of the main reflections with PANalytical X’pert HighScore software (Version 2.2e): (https://www.malvernpanalytical.com/en/products/category/software/x-ray-diffraction-software/highscore/).

High-temperature magnetic susceptibilities were measured by continuous exposure of samples through temperature cycles from room temperature to 700 degree Celsius and back to room temperature with a ramping rate of 2 degree Celsius per minute, using an AGICO MFK1-FA equipped with CS-3 temperature control system. To minimize the possibility of oxidation, the samples were heated and cooled in an argon atmosphere. For each sample, we subtracted the contribution of the sample holder and thermocouple to the magnetic susceptibility. The data were analyzed with Cureval (https://www.agico.com/text/software/cureval/cureval.php).

Isothermal remanent magnetizations (IRMs) were imparted from 0 to 1.5 Tesla using a MicroMag 3900 Vibrating Sample Magnetometer (VSM) (Princeton Measurements Corp., USA). Derivatives of the IRM acquisition curves are used to illustrate the coercivity distributions. Magnetic component analyses of coercivity distributions were analysed using the IRM-CLG program of Kruiver et al. (Kruiver PP, Dekkers MJ, Heslop D. Quantification of magnetic coercivity components by the analysis of acquisition curves of isothermal remanent magnetization. Earth and Planetary Science Letters 189, 269-276, 2001).

Usage Notes

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Funding

National Natural Science Foundation of China, Award: 41888101