长沙铜官窑遗址剖面地球化学元素特征与物源变化

Geochemical Element Characteristics and Provenance Changes at Tongguanyao Site Section in Changsha

使用HR-ICPMS对长沙铜官窑遗址石渚坪(SZP)剖面的地球化学元素进行测定,分析了遗址剖面地球化学含量变化特征,揭示其沉积环境演变及其物源变化。结果表明,元素的含量变化特征显著,元素Ti、Cr、Co、V、Ni等在80~230 cm逐渐升高出现峰值,230~310 cm逐渐降低至谷值。Pb、Zr、Mn等分布趋势与其相反。其中,Ti含量最高,平均值达5 405.8μg/g;最低的是Mo,平均值为0.9μg/g。含量均值由大到小为:Ti>Mn>Ba>Zr>Rb>Zn>Li>Cr>V>Pb>Sr>Cu>Y>Ni>Th>Cs>Co>Sc>Sn>Hf>U>Be>Mo。SZP剖面记录了一个近1 300年来的沉积环境变化过程:风尘堆积—石渚湖形成—河漫滩沉积—石渚湖再次形成—石渚坪。物质来源也发生相应变化:310 cm以下来源为末次冰期风尘堆积;310~230 cm(年代为1 288~1 094 a B.P.)地层中含大量瓷片,物源主要是铜官窑瓷器煅烧过程中金属矿物开采及冶炼产生的废料;230~80 cm(年代为1 094~380 a B.P.),下层物源是湘江输入的泥沙,主要是上游的石灰岩沉积,上层是中下游地区砂岩的风化侵蚀和水流搬运沉积;80 cm以上(年代为380 a B.P.以来)与人类活动有关,主要为人工垫土和坡地周边风化侵蚀堆积。

High-resolution inductively coupled plasma mass spectrometry(HR-ICPMS)was applied to determine the geochemical element content in sediments from the Shizhuping(SZP)profile of the Tongguan kiln site in Changsha,Hunan province,China.The variation of geochemical content was analyzed to reveal environmental evolution and provenance change.The content varies significantly.The elements Ti,Cr,Co,V,Ni,etc.gradually increase at depths from 80 cm to peak at 230 cm,then decrease from 230 cm to 310 cm to the lowest value s;Pb,Zr and Mn show the opposite trend.Of these,Ti content is the highest(average 5405.8μg/g).The lowest is Mo,with an aver⁃age of 0.9μg/g.The order of the average content from higher to lower is Ti>Mn>Ba>Zr>Rb>Zn>Li>Cr>V>Pb>Sr>Cu>Y>Ni>Th>Cs>Co>Sc>Sn>Hf>Be>Mo.The SZP section has recorded the changes in the sedimentary environment over the past 1300 years:loess sediment⁃SZP lake formation⁃flood plain sediment⁃SZP lake reformed⁃SZP terrace.Correspondingly,the provenance of the section has changed significantly.The source below 310 cm is dust accumulated in the most recent glacial period.The formation at 310⁃230 cm depths(1288⁃1094 a B.P.)con⁃tains a large number of ceramic tablets,and the sediments are mainly the waste products of mining and smelting of metal minerals in the calcination process of Tongguan kiln porcelain.From 230 cm to 80 cm(1094⁃380 a B.P.),the lower sediment source is from the Xiangjiang River;the upper sediment is weathering erosion and water transport of sandstone in the middle-to-lower reaches.Above 80 cm(380 a B.P.to present)the sediments are related to human activity,comprising mainly an artificial soil cushion and weathering erosion accumulation around the slope.