尉迟寺遗址文化层铅的地球化学特征及原始冶金文明矿料示踪

GEOCHEMICAL CHARACTERISTICS OF Pb IN CULTURAL LAYERS OF YUCHISI SITE AND SOURCE TRACING OF PRIMITIVE METALLURGY IN CHINA

古遗址土壤形成物是研究古代人类活动的重要载体。通过对安徽蒙城尉迟寺遗址YC1剖面中Pb、Al等金属元素的分析,研究了Pb在5050cal a BP～4000cal a BP间剖面中的富集特征。结果表明,尉迟寺遗址文化层剖面中的铅富集系数变化范围为1·0～1·8左右,富集程度不是很高。但是随着时间的推移,从大汶口文化到龙山文化,Pb的富集系数有明显逐步上升的趋势,表明遗址剖面中的Pb很可能与原始社会中期发展起来的冶金活动有关。5050～4000cal a BP间,中国先后经历了石器时代、铜石并用时代,到最后进入青铜时代,这个过程中铜资源利用越来越多导致产生的大气粉尘铅越来越多,很可能是YC1剖面中Pb富集系数逐步增长的主要原因。此外,铅同位素结果表明,土壤206Pb/204Pb比值分布在18·3～19·8之间,平均为18·82;207Pb/204Pb比值分布在15·3～16·5之间,平均为15·76;208Pb/204Pb比值分布在38·0～41·0之间,平均为39·04。铅同位素示踪表明,土壤中的铅的来源自5050calaBP至4000calaBP有越来越广的趋势,并且很可能与出自中国南方地区的矿料有关,包括云南、四川、湖北、湖南或广东地区的矿料。

Paleosols and sediments are important archives for studying ancient human activities. A soil profile labeled as YC1 was located at Yuchisi, Mengcheng County, Anhui Province, where relics of the Dawenkou Culture and Longshan Culture were detected. Elemental concentrations, such as Pb, Al, as well as the lead isotopes, were analyzed in soil samples collected from Profile YC1. Pb enrichment in the soil layer from 5 050 cal a BP to 4 000 cal a BP, was characterized. Results show that Pb enrichment factors varied from 1.0～1.8 in the cultural layers, and were not quite high. However, with the history going on from the Dawenkou Culture to the Longshan Culture, the Pb enrichment factor displayed an obvious rising trend, which indicated that the Pb in the cultural layers was probably associated with the development of metallurgic activities in the middle stage of the primitive society. From 5 050 cal a BP to 4 000 cal a BP, China underwent Stone Age, Chalcolithic Age and Bronze Age in sequence. Pb dust in the atmosphere increased with intensifying utilization of copper resources, which was probably the main cause of the rising enrichment factor in the cultural layers. The measurements of lead isotope in the cultural layers show the ratio of 206Pb/204Pb varied from 18.3～19.8, with an average being 18.82; the ratio of 207Pb/204Pb from 15.3～16.5, with an average being 15.76; the ratio of 208Pb/204Pb from 38.0～41.0, with an average being 39.04. The tracing study shows the sources of lead in the various cultural layers multiplied from 5 050 cal a BP to 4 000 cal a BP, which was most likely related to ores from South China, including Yunnan, Sichuan, Hubei, Hunan or Guangdong Provinces.