OSL chronology of traditional zinc smelting activity in Yunnan province, southwest China

Accepted Manuscript OSL chronology of traditional zinc smelting activity in Yunnan province, southwest China AnChuan Fan, ZhengYao Jin, YingYu Liu, ShengHua Li, YingZi ZhangSun, YouJin Wu PII:

S1871-1014(15)30024-8

DOI:

10.1016/j.quageo.2015.05.011

Reference:

QUAGEO 690

To appear in:

Quaternary Geochronology

Received Date: 5 November 2014 Revised Date:

7 May 2015

Accepted Date: 11 May 2015

Please cite this article as: Fan, A., Jin, Z., Liu, Y., Li, S., ZhangSun, Y., Wu, Y., OSL chronology of traditional zinc smelting activity in Yunnan province, southwest China, Quaternary Geochronology (2015), doi: 10.1016/j.quageo.2015.05.011. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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OSL chronology of traditional zinc smelting activity in Yunnan

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province, southwest China 1

AnChuan Fan, 1ZhengYao Jin, 1YingYu Liu, 2ShengHua Li, 1YingZi ZhangSun, 1

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YouJin Wu

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Archaeometry Laboratory, University of Science and Technology of China, Hefei 2

Department of Earth Sciences, The University of Hong Kong, Pokfulam Road,

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Hong Kong Abstract

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The production of zinc has played an important role in both the technological and

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the economic history of ancient china. However, the lack of studies on zinc smelting

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remains with convincing chronology limits our understanding on the history of zinc

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production.

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Our recent field survey in Yunnan province, southwest china, has discovered

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zinc-smelting sites in Qiaojia County. The location is in the Jinsha River Valley,

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which has abundant lead, zinc, copper and mineral coals. Large numbers of crucible

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and slags were excavated, which indicates a large scale of zinc production in the

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region. A profile of 10 layers containing slag pellets altered with fluvial sediments

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presents clear evidence of a series of zinc smelting events. The ages of both the

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fluvial sediment and slag layers have been obtained using luminescence dating.

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Detailed chronology indicates that large scale of zinc production in this area can be

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traced back to late Qing Dynasty (AD 1854).

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Keyword

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Zinc production, OSL dating, smelting slag, southwest China

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1, Introduction

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Zinc (Boiling temperature: 907˚C) was a difficult and enigmatic metal in the antique

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world. It immediately volatilizes and reoxidizes when people attempt to reduce the

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zinc ore in an open furnace. The earliest use of zinc is to make brass, an alloy of zinc

ACCEPTED MANUSCRIPT and copper. Brass was manufactured by heating zinc-bearing copper ore and

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charcoal to 1000˚C in a sealed crucible to directly dissolve zinc vapor into the

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copper (Craddock, 1978). Regular production of unalloyed zinc occurred relatively

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late in metallurgical history. In China, smelting of zinc was achieved based on the

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principle of distillation by ascending vapors (Hu and Han, 1984; Mei, 1990; Zhou,

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1996). Recent studies suggest that regular zinc production in China is known to have

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begun in the16th Century AD in the Chongqing region (Zhou, 2007; Zhou et al,

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2012). Zinc was mainly used for making brass coins and copper-bearing artefacts in

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the late Ming (AD 1368-1644) and Qing (AD 1644-1911) Dynasties (Zhou, 2012).

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The Chinese mining and smelting of zinc have a significant impact not only on the

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domestic economy, but also on European industrial production via exporting

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(Craddock and Hook, 1997).

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Early studies by historians of metallurgy, mainly based on historical records and

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analyses of brass coins, provide us a time outline since the late Ming Dynasty

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(Zhang, 1925; Zhao, 1984; Zhou and Fan, 1993; Zhou, 2001). A recent case study of

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ancient zinc smelting sites in Chongqing analyzed production remains directly

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relates to older zinc smelting with an established chronology (Zhou et al., 2012). A

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brief outline of general temporal and regional distribution of zinc production is

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provided. Geological surveys focusing on traditional zinc production since the early

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20th century have identified several zinc smelting sites in in Hezhang, Guizhou, in

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1954 (Xu, 1986); in Huize, Yunnan, in 1939; in Weining, Guizhou, in 1940; and in

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Huili, Sichuan, in 1941 (summarized in Mei 1990). The sites documented by

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historians and geologists are mostly located in the Chuan-Dian-Qian region, a

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triangle-shaped area surrounded by Sichuan, Yunnan and Guizhou Provinces. The

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region is known to have an abundance of zinc and lead ores, coal, and other

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resources for zinc production (Zhou, 1997). However, lack of studies on zinc

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smelting sites with convincing chronology limit our understanding on the history of

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zinc production in this region. This paper presents the results of our recent survey to

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explore the history of traditional zinc smelting in this area.

59 2, Sampling

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The sampling site is in Qiaojia County, located about 310 kilometers south of

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Kunming city in Yunnan (Figure 1a), southwest China. The mountain region has

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abundant resources of various ores, including copper, zinc, lead and coal mines,

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which support the mining and smelting activities. Our archaeological survey led to

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the discovery of several zinc-smelting sites close to the Jinsha River, including

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buried slags and hundreds of ceramic crucibles showing large-scale smelting

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activities in the past (Figure 1b). The traditional local smelting process of zinc is still

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practiced in some villages in Qiaojia County. This makes this site an ideal region to

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investigate the production of zinc in more detail.

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A profile containing soil horizons with slag pellets alternating with fluvial sediments

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was excavated at the Laoqianchang site (Figure 1c). The top of the deposits is a

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modern soil layer (~40cm thick), which shows clear evidence of bio-turbation.

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Beneath the modern soil five slag layers (dark gray) and five fluvial sediment layers

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(yellow) were identified. The fluvial sediment layers consist of fine-grain clay and

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coarse-grain sands. The slag layers are made of coarse-grain sands mixed with slag

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pellets (mostly around 1mm or less in diameter). The deepest slag layer ends at a

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depth of 1.80m followed by a thick soil layer. The bottom of the soil layer was not

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reached at a depth of 2.2m. Lightproof tubes were horizontally driven into each

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fluvial sediment layer and slag layer to extract OSL samples.

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3, Methods

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The tubes of OSL samples were opened under subdued red light in the laboratory.

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Surface samples at both ends of tubes were used for measurements of water content,

ACCEPTED MANUSCRIPT radionuclide concentrations and other proxies. Only the central part of the sediment

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was used for OSL dating to avoid any incidental exposure to light during sampling

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and transportation. Chemical treatments using 10% hydrochloric acid and 10%

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hydrogen peroxide solution were employed to remove carbonates and organic

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materials respectively in raw samples. Quartz grains (90-150µm) were extracted

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using a sodium polytungstate solution (density: 2.58, 2.62 and 2.75 g/cm3). The

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separated grains were etched with 40% HF for at least 40 min prior to mounting on

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9.7mm-diameter aluminum discs. Small aliquots (less than 200 grains) and medium

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aliquots (500-1000 grains) were used for equivalent dose (De) determination of

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quartz samples extracted from slag layers and fluvial sediment layers respectively.

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The absence of K-feldspar contamination was then checked with IR stimulation on

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the aliquots (Aliquots showing any significant IRSL signals compared with the

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background were not included in subsequent measurements).

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Equivalent doses measurements were carried out using a Risø automated TL/OSL

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system (TL-DA-20) with a single-grain attachment in the Archaeometry laboratory

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at University of Science and Technology of China (USTC). The OSL stimulation

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units contain blue light-emitting diodes (LEDs, 470±20 nm) and IR LEDs (870∆80).

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The total power delivered by the blue LEDs to the sample position is about

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45mw/cm2 (Bøtter-Jensen et al., 2003). The OSL signals were measured through

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three 2.5 mm-thick U-340 filters with a bialkali EMI 9235QB photomultiplier (PM)

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tube. Beta irradiation was performed using a

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Gy/s to grains loaded on aluminum discs. The single aliquot regeneration (SAR)

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protocol formalized by Murray and Wintle (2000) was used for De determination.

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Internal checks of the validity of the SAR method were performed to quartz grains

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extracted from sample ZY-YNQJ6 from the profile prior to De measurements. The

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aliquots were first bleached at 125 °C, which is followed by a laboratory irradiation

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of 1.778 Gy. Such a dose was then measured as an “unknown” dose using the same

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Sr/90Y beta source delivering 0.127

ACCEPTED MANUSCRIPT SAR procedure. It was found that the SAR protocol could successfully recover the

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artificially given dose (recovery ratio: 1.05±0.10). Preheat plateau tests were

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performed to determine the most appropriate experimental conditions (Figure 2). As

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a result of the tests, a preheat procedure of 10s at 200°C prior to measurements of

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the natural and regenerative doses was adopted. Totally six regenerative points (D=0,

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0.381, 0.762, 1.143, 1.905 and 0.762 Gy) were used to construct growth curves. The

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initial 0.2s OSL subtracted by the following 0.2s signal (early background

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subtraction, EBG) are used to minimize the contribution from the slow component

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to the net signal.

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Environmental dose rates were derived from measured radioactive element

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concentrations and radioactivities (Guérin et al., 2011). The U and Th contributions

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from their decay chains were obtained using thick source alpha counting (Aitken,

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1985) at the Luminescence Dating Laboratory of the University of Hong Kong.

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Potassium content was measured using X-ray florescence (XRF-1800) at the USTC

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Instruments’ Center for Physical Science. The results show that radio isotopic

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contents strongly vary between the slag and fluvial sediment layers in the profile.

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The gamma dose-rates as a function of distance from the interface between layers

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are calculated as shown in Table S1. The gamma contribution from the layer above,

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the layer below and the layer itself are calculated separately based on the model and

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fractional factors given in Appendix H (Aitken, 1985). The measured water contents

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obtained from the tube surface samples are assumed to represent the long-term

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average during the period of burial. The value was incorporated in later calculations

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for attenuation effects by moisture. Beta dose attenuation of quartz grains was also

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taken into consideration (Mejdahl, 1979; Fain et al., 1999). Cosmic ray contributions

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were calculated from the depth, altitude, latitude and longitude of the samples

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(Prescott and Hutton, 1994). The detailed information concerning the OSL

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chronology is summarized in Table 1.

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ACCEPTED MANUSCRIPT 4, Results and discussion

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The samples showed good behavior in OSL measurements, with good recycling ratios

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and dose recovery. This suggests that samples in the study site are suitable for OSL

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dating. The obtained OSL ages, together with the De values, environmental dose rates

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and other data used for age calculations are summarized in Table 1. The OSL ages in

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the profile are in stratigraphic order within the errors. Ages are calculated using the

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weighted mean of all aliquots of each sample and data is converted to calendar year in

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the following discussion.

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148 Environmental dose rate and Luminescence sensitivity

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At the Qiaojia site, the environmental dose rates for fluvial sediments are from 4.36

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to 5.85 Gy/ka. In contrast, the dose rates for slag layers are from 4.51 to 9.39 Gy/ka,

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with an average value of 7.40 Gy/ka. In comparison, dose rate for Aeolian and

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fluvial deposits in China is usually within the range between 1 to 4 Gy/ka.

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Controlling factors of the environmental dose rate are mainly radioactive elements,

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cosmic rays, and water attenuation effects. For our slag sediments, it is the high

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concentration of U and Th that contributes most to the abnormally high dose rates in

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the slag layers, as indicated by the alpha counting data in Table 1.

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Apart from great variations in environmental dose rates, another significant

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difference is the change in luminescence sensitivity between the stacked slag layers

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and fluvial sediment layers. Figure 3c shows the OSL response of quartz grains of

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each layer after bleaching and beta irradiation (12.7 Gy). It can be seen that grains

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from the slag layers are about 3-4 magnitudes brighter than the average obtained for

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samples in the fluvial deposits. Small aliquots (less than 200 grains) and medium

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aliquots (500-1000 grains) were then adopted for De measurements of slag and

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fluvial sediment layers respectively to ensure adequate OSL signals (Figure S1). The

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effect of luminescence sensitivity is also manifested in the obtained OSL age errors

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(Figure 3a), with average relative errors of 18.5% and 45.1% for slag layers and

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fluvial sediment layers, respectively. The differences can be mainly explained by the

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strong luminescence signal of the quartz grains sensitized by direct or indirect

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heating of the slag deposits during zinc smelting.

172 OSL Chronology and implications for zinc production in southwest China

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The bottom layer of the profile dates back to AD 1717, corresponding to the

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Yongzheng regime in the late Qing Dynasty (AD 1678-1735). The age sets an upper

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estimate on the initial of ancient smelting activity. Based on the OSL age of eleven

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samples of slag and fluvial sediment layers, a time span of 177 years for zinc

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production is established for the Qiaojia site. As shown in the age-depth plot (Figure

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3a), OSL ages of five slag-rich stratigraphic sections fall into two periods. The early

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period is from 1852 to 1896. The late period is from 1917 to 1964, consistent with

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historical records of ancient utilization of zinc ores in Chuan-Dian-Qian region

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1940s (Mei, 1990). Although the low sensitivity and consequently large errors in

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ages of the fluvial sediments limit their use in precisely constraining the duration of

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zinc production, the data is consistent with the ages of the slag layers. It implies that

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the fluvial sediment is readily bleached prior to deposition. Considering the

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thickness of the slag layer and the slight age difference of adjacent slag layers within

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the same period, the duration that each slag layer represents is not long (less than a

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decade), which is less than the error of the OSL ages.

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Considering possible denudation or human reworking, age gaps between sediment

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layers much be taken into account. Thus, OSL ages of certain slag layers should be

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interpreted as the youngest age of each zinc production event. The Qiaojia profile

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demonstrates that traditional zinc production in the Qiaojia region lasted at least one

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and a half centuries with several interruptions by flooding, as indicated by the slag

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layers interrupted by the fluvial sediment layers. Our results provide important

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information on the spatial and temporal distribution of zinc production in China.

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Further analyses of production remains (e.g. crucibles and smelting installations) are

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necessary to reconstruct detailed history of Zinc production in the region.

199 Acknowledgements

201 202 203 204 205 206 207 208 209 210

The authors are grateful to Professor James Burton for the help in improving the manuscript. The research was supported by National Natural Science Foundation of China (Grant No. 41073004 and Grant No. 41303080) and China Postdoctoral Science Foundation (Grant No. 2013T60618 and Grant No. 2012M521236). We thank the anonymous reviewer, who provided very helpful commentary and suggestions that improved the manuscript.

211 212 213

Botter-Jensen, L., Andersen, C. E., Duller, G. A. T. Murray, A. S., 2003. Developments in radiation, stimulation and observation facilities in luminescence measurements. Radiation Measurements 37, 535-541

214 215 216

Craddock, P. T., 1978. The composition of the copper alloys used by the Greek, Etruscan and Roman Civilisation 3: the origins of early use of brass. Journal of Archaeological Science 5, 1-16

217 218 219 220

Craddock, P.T., Hook, D.R., 1997. The British Museum collection of metal ingots from dated wrecks. In: Redknap, M. (Ed.), Artefacts fromWrecks: Dated Assemblages from the Late Middle Ages to the Industrial Revolution. Oxbow Books, Oxford, 143-154

221 222 223

Fain, J., Soumana, S., Montret, M., Miallier, D., Pilleyre, T. and Sanzelle, S., 1999. Luminescence and ESR dating - Beta-dose attenuation for various grain shapes calculated by a Monte-Carlo method. Quaternary Geochronology 18, 231-234

224 225

Guérin, G., Mercier, N., Adamiec, G., 2011. Dose rate conversion factors: update. Ancient TL 29, 5-8

226 227

Hu, W. L, Han, R. F., 1984. Ancient Chinese zinc smelting technology seen from traditional zinc smelting. Chemistry 7, 59-61

228 229

Mei, J. J., 1990. Modern Chinese traditional zinc smelting. China Historical Materials of Science and Technology 11, 33-37

230 231

Mejdahl, V., 1979. Thermoluminescence dating; beta-dose attenuation in quartz grains. Archaeometry 21, 61-73

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Reference

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Aitken, M. J., 1985. Thermoluminescence Dating, Oxford University Press

ACCEPTED MANUSCRIPT Murray, A. S. and Wintle, A. G., 2000. Luminescence dating of quartz using an improved single-aliquot regenerative-dose protocol. Radiation Measurements 32, 57-73

235 236 237

Prescott, J. R. and Hutton, J. T., 1994. Cosmic ray contributions to dose rates for luminescence and ESR dating; large depths and long-term variations. Radiation Measurements 23, 497-500

238 239

Xu L., 1986. Investigation of traditional zinc smelting technology in the Guma District of Hezhang County. Studies in the History of Natural Sciences 5, 361-369

240 241 242 243

Zhou, W. R., 2007. The origin and invention of zinc-smelting technology in China. In:S. La Niece, D. Hook and P. T. Craddock (eds.), Metals and Mines: Studies in Archaeometallurgy. London: Archetype in association with the British Museum, 179-186

244 245 246

Zhou, W.L., 2012. Distilling Zinc in China: The Technology of Large-Scale Zinc Production in Chongqing During the Ming and Qing Dynasties (AD 1368-1911). Unpublished PhD thesis, University College London

247 248 249

Zhou, W.L., Martinón-Torres, M., Chen, J. L., Liu, H. W., Li, Y. X., 2012. Distilling zinc for the Ming Dynasty: the technology of large scale zinc production in Fengdu, southwest China. Journal of Archaeological Science 39, 908-921.

250 251

Zhang, H. Z., 1925. Further discussion on the origin of the use of zinc in China. Science 9, 1116-1127

252 253

Zhao, K. H., 1984. Further discussion on the origin of zinc in China. China Historical Materials of Science and Technology 5, 15-23

254 255

Zhou, W. R. and Fan, X. X., 1993. A study on the development of brass for coinage in China. Bulletin of the Metals Museum 20, 35-45

256 257

Zhou, W. R., 1996. Chinese traditional zinc-smelting technology and the history of zinc production in China. Bulletin of the Metals Museum 25, 36-47

258 259 260

Zhou, W. R., 1997. Traditional zinc-smelting technology in Yun-Gui region and the history of zinc production in China. China Historical Materials of Science and Technology 2, 86-96

261 262

Zhou, W. R., 2001. The emergence and development of brass-smelting techniques in China. Bulletin of the Metals Museum 34, 87-98

263 264 265 266

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Table Table 1．Luminescence dating results for the Qiaojia profile

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a

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counts per kilo seconds.

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b

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The ages have been calculated using values prior to rounding.

Table S1. Gamma contribution from the U, Th and K of the layer above, the layer below and the layer itself. a

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Fractional factors of gamma dose are from Table H1. Gamma Dose in Radioactive Soil Adjacent to Inert Soil (Aitken, 1985). All the calculation results are rounded to 3 decimal places. b ZY-YNQJ01 and ZY-YNQJ02 are from the same layer. Their above layer is 70cm-thick soil. The radioactivity contents of the above layer is estimated using the average of the soil layers in the profile. c The bottom of ZY-YNQJ11 is no reached at a depth of 2.2. The gamma contribution is from its above layer and itself.

Figure captions

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Figure 1. Sampling location: (a) the zinc-smelting site. The inset indicates the

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location of Qiaojia County in China; (b) smelting remains: slags and ceramic

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crucibles for traditional zinc production; (c) the sampling profile.

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Figure 2. (a) Preheat tests on sample ZY-YNQJ6 of temperature ranging from

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160°C to 260°C. The equivalent dose presented is the result of at least 6 aliquots. (b)

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The average recycling ratio (filled squares) and recuperation ratio (filled diamonds)

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measured at each preheat temperature.

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Figure 3. The results of (a) OSL ages (converted to calendar year); (b)

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Environmental dose rates and (c) OSL sensitivity versus depth graph (meter).Data

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were taken from Table 1. Horizontal bar indicates error of age.

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308 Figure S1. The OSL decay curves from one slag layer sample (YNQJ01) and one

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fluvial sediment layer sample (YNQJ03). Small aliquots (less than 200 grains) and

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medium aliquots (500-1000 grains) were then adopted for De measurements of slag

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and fluvial sediment layers respectively. Please note the luminescence signal is in

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log scale.

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ZY-YNQJ0 4 ZY-YNQJ0 5 ZY-YNQJ0 6 ZY-YNQJ0 7 ZY-YNQJ0 8

Fluvial sediment layer 4 Slag layer 4 Fluvial sediment layer 3 Slag layer 3 Fluvial sediment layer 2 Slag layer 2

(%)

(%)

Beta

Gamm a

61.07±0.6 1 68.89±0.6 4

1.96±0.0 2 1.18±0.0 1

7.56

4.89

3.77

4.17

5

4.13

Cosmi c ray

8.92±0.4 4 9.39±0.4 8

OSL ageb

Calendar year

(Gy)

(a)

(a)

0.57±0.12

64±14

1936-1964

0.74±0.17

79±19

1917-1954

26

0.70

30

0.80

23

24.95±0.3 7

1.23±0.0 1

12.73

2.17

3.14

0.26

5.57±0.6 0

0.27±0.16

48±29

1936-1995

0.95

25

59.18±0.5 7

1.24±0.0 1

4.48

4.44

3.93

0.25

8.62±0.4 4

0.64±0.16

74±19

1921-1959

1.05

24

31.08±0.4 1

1.17±0.0 1

18.87

2.31

3.29

0.25

5.85±0.5 6

0.39±0.18

67±31

1916-1979

1.30

25

55.46±0.5 5

1.13±0.0 1

2.16

4.25

3.75

0.24

8.24±0.4 3

0.72±0.07

87±10

1917-1936

1.40

30

25.33±0.3 2

1.02±0.0 1

20.63

1.89

2.57

0.24

4.70±0.4 6

0.55±0.22

117±4 8

1849-1945.

1.50

29

25.62±0.3 2

0.99±0.0 1

8.17

2.16

2.11

0.24

4.51±0.2 7

0.65±0.07

144±1 8

1852-1888

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0.26

Total

Equivalen t dose

0.70

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ZY-YNQJ0 3

Slag layer 5

Counts/ks

Dose rate (Gy/ka)

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ZY-YNQJ0 1 ZY-YNQJ0 2

Water conten t

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(cm)

K content

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Remarks

Number of aliquots

α counting rate a

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Dept h

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29.56±0.3 5

0.99±0.0 1

17.81

2.15

2.24

1.75

33

25.97±0.3 2

0.93±0.0 1

2.97

2.27

2.25

1.95

30

26.74±0.4

1.29±0.0 1

22.39

2.09

2.05

Table 1．Luminescence dating results for the Qiaojia profile. a

0.23

The alpha counting rate is for a 42mm diameter ZnS screen and is given in units of counts per kilo seconds.

b

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The ages have been calculated using values prior to rounding.

4.62±0.3 0

0.65±0.35

141±7 6

1797-1950

4.75±0.2 9

0.66±0.09

139±2 1

1854-1896

4.36±0.2 4

1.05±0.24

241±5 7

1717-1830

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ZY-YNQJ1 1

1.65

0.23

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ZY-YNQJ1 0

Fluvial sediment layer 1 Slag layer 1 Fluvial sediment layer 0

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ZY-YNQJ0 9

0.22

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ZY-YNQJ01 ZY-YNQJ02 ZY-YNQJ03 ZY-YNQJ04 ZY-YNQJ05 ZY-YNQJ06 ZY-YNQJ07 ZY-YNQJ08 ZY-YNQJ09 ZY-YNQJ10 ZY-YNQJ11

5 5 5 7.5 5 7.5 5 5 7.5 5 10

5 5 7.5 5 7.5 5 5 7.5 5 10 N/A

From layer aboveb K U+Th 0.060 0.390 0.060 0.390 0.065 1.006 0.046 0.283 0.068 1.008 0.041 0.332 0.063 0.969 0.047 0.367 0.038 0.304 0.047 0.440 0.029 0.241

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From layer below

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From layer above

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Sample No.

Gamma (Gy/ka)a From layer Total From layer itself c below Gamma Dose K U+Th K U+Th 0.062 0.390 0.242 2.627 3.772 0.062 0.390 0.151 3.073 4.126 0.050 0.730 0.160 1.125 3.137 0.055 0.458 0.176 2.909 3.926 0.047 0.702 0.144 1.321 3.289 0.047 0.367 0.165 2.796 3.748 0.052 0.419 0.111 0.958 2.573 0.035 0.319 0.135 1.211 2.114 0.052 0.449 0.123 1.269 2.236 0.033 0.205 0.144 1.382 2.250 N/A N/A 0.223 1.553 2.046

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Distance (cm)

a

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Table S1. Gamma contribution from the U, Th and K of the layer above, the layer below and the layer itself.

AC C

Fractional factors of gamma dose are from Table H1. Gamma Dose in Radioactive Soil Adjacent to Inert Soil (Aitken, 1985). All the calculation results are rounded to 3 decimal places. b ZY-YNQJ01 and ZY-YNQJ02 are from the same layer. Their above layer is 70cm-thick soil. The radioactivity contents of the above layer is estimated using the average of the soil layers in the profile. c The bottom of ZY-YNQJ11 is no reached at a depth of 2.2. The gamma contribution is from its above layer and itself.

AC C

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TE D

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