西藏曲龙遗址塞拉钦波普地点M2出土饰品的科学分析

Scientific Analysis of Ornaments Unearthed From M2 of Sailaqinbopu Locus,Qulong Site,Tibet

曲龙遗址位于西藏自治区阿里地区,是一处延续时间极长且遗存类型丰富的人类活动遗迹。所研究的饰品出土于曲龙遗址塞拉钦波普地点2号墓(M2),距今约2700~2400年。由于制作时的加工打磨和长期地下埋藏所遭受的风化侵蚀,已无法单从外观上判断8个饰件的原料,因此该研究通过使用超景深显微分析、傅里叶变换红外光谱技术(FTIR)、X射线衍射实验分析(XRD)、热分析技术(TGA-DSC)、X射线荧光光谱分析(XRF)、扫描电子显微镜(SEM)以及多孔材密度、孔隙率、吸水率测试等多种分析方法不仅确定了饰品的化学成分和原料来源,而且对其微观形貌、形制特点、保存状况等也进行了科学全面的分析。结果表明:8个穿孔饰件的原料来自于不同种类淡水贝贝壳的珍珠层,其主要化学成分是文石型碳酸钙,也残留有少量有机物及Fe,Ba,Cr和Cu等微量元素;饰件表面均有打磨痕迹,钻孔方式为对钻,且较厚饰件的穿孔为双面桯钻而成;饰件总体上风化严重,光泽不再且均有一定程度的酥粉,开孔孔隙率及吸水率远高于现代贝壳,出现这些病害的主要原因是有机物流失所导致的贝壳珍珠层文石板片松散杂乱。研究结论一方面为西藏西部地区象雄时期的饰品选材、形制、制作工艺等研究提供了重要信息,反映了当时社会的用贝情况和审美内涵,另一方面也为此类出土文物后续的保护修复提供了有益的参考。

The Qulong Site,located in Ngari Prefecture of Tibet Autonomous Region,is a relic of human activities with a long duration and rich types of remains.The ornaments studied in this paper were excavated from tomb No.2(M2)of Sailaqinbopu Locus,the Qulong Site,dating back to about 2700~2400 years ago.Due to the processing and grinding during production and the weathering and erosion suffered by long-term underground burial,it is impossible to judge the raw materials of the eight ornaments only from their appearance.Therefore,ultra-depth of field microscopic analysis,Fourier transform infrared spectroscopy(FTIR),X-ray diffraction experimental analysis(XRD),thermal analysis(TGA-DSC),X-ray fluorescence spectrometry(XRF),Scanning electron microscopy(SEM)and porous material density,porosity,water absorption test were used not only to determine the chemical composition and raw material source of ornaments,but also to scientifically and comprehensively analyze its microscopic morphology,shape and structure characteristics and preservation condition.The results show that the raw materials of eight ornaments come from the pearl layer of different freshwater shellfish shells,and the main components are aragonite calcium carbonate,with a small amount of organic matter and trace elements such as Fe,Ba,Cr,Cu;there are grinding marks on the surface of the ornaments,and the drilling method is drilling from both sides,and holes of thicker ornaments are drilled with a bit;the overall weathering is serious,luster is no longer and all have a certain degree of crisp powder,porosity and water absorption rate of the open holes are higher than the modern shell,and the main reason for these diseases is the loose and disorderly shell pearl layer aragonite plates caused by loss of organic matter.On the one hand,the above research conclusions provide important information on the material selection,shape and production technology of ornaments in the Xiangxiong period in western Tibet,and reflect the situation and aesthetic connotation of shellfish use in society at that time.On the other hand,they also provide valuable reference materials for the subsequent protection and restoration of such unearthed cultural relics.