肃北战国-汉代古采矿遗址（群）软玉：深部地质过程响应及其对丝绸之路华夏早期玉石文明的影响

Kunlun-Qilian orogenic belt was considered as the most important nephrite mineralization belt in China. Two groups of historic mining sites of nephrite jades in the Warring States to Han dynasty, including over 100 mining pits, were discovered along north branch of ancient silk road in North Mountain region and Dunhuang block, inferring that there occurred intensive mineralization of nephrite jades in geology and important mining activity of jade materials in Chinese history. This project aims at studying the relationship between the mineralization of nephrite jades and geological tectonics through geochemical methods including major & minor elements and isotopes (e.g. Si,O,Sr,Li) of nephrites and associate granite rocks and metamorphic basement rocks, U-Pb dating and Hf isotopes of zircons/sphenes in relation to mineralization, in order to reveal the forming condition and mechanism of nephrites and their response to deep geological process, and finally to explore the temporal and spatial relation between the mineralization of nephrites and the collision and subduction of the Paleo-Asiatic/Tethystectonic domains. Moreover, we will conduct comprehensive petrochemical and isotopic analyses on nephrite materials from these historic mining sites by means of modern micro-probe analysis techniques such as EMPA,LA-(MC)-ICPMS and SIMS, for setting up their geochemical fingerprints. Finally, these results will be compared and contrasted with unearthed jadewares and jade materials from other locations in order to trace the spreading path and influence of the nephrite materials from these historic mining sites on traditional supply system of jade materials in central China at that time, and provide constraints on the birth and development of early civilization on the ancient silk road.

昆仑-祁连山造山带是我国最重要软玉成矿带，申请人和合作者在甘肃北部古丝绸之路北线（北山地区和敦煌地块）发现我国战国-汉代古老玉矿采矿遗址群，厘定出100多个采坑并发现大量古玉料。本项目拟对新发现玉矿（料）成矿岩石、相关花岗质岩石及基底变质岩进行系统元素地球化学，Si-O-Sr同位素地球化学，锆石/榍石U-Pb年代学和Hf同位素等的综合研究，揭示古玉（矿）形成物理化学条件、形成机制，软玉形成与古亚洲洋构造域板块俯冲拼贴过程时空联系及深部地质过程响应；利用现代微区微束分析技术(EMPA, LA-(MC)-ICPMS和SIMS等)对新发现古玉料进行系统岩石地球化学和同位素组成测试，建立其地球化学“指纹”，并通过与新疆及丝绸之路一带中原出土古玉（软玉）的对比，追溯其迁徙路径，揭示汉代以前该区玉料工业对中原传统古玉供应体系的影响，为反演我国古代丝绸之路早期玉石文明的形成与演化提供新的约束。

甘肃肃北古玉矿采矿遗址的发现为中国史前玉料来源乃至文明流变研究提供了重要的机会。国自然基金项目（41673032）对肃北发现古玉矿玉料、围岩进行了系统岩石矿物地球化学的测试分析，无损/微损系统分析测试了大汶口-龙山文化遗址（约4000BC～2000 BC）、石峡遗址（约2900BC～2700 BC）、下靳遗址（约2300BC～2000 BC）、石峁遗址（2300 BC～1800 BC）、金沙遗址（1200 BC～600 BC）、徐州汉墓（西汉早期）等十几个史前遗址（含汉代遗址）上千件的古玉器。主要取得如下重要结果：1）合作发掘、研究了敦煌旱峡玉矿遗址，发现距今4000年（14C同位素）中国最古老的透闪石玉矿遗址，结合对多个考古及文博单位出土玉器测试，给出了玉料东传中原的重要证据，合作成果获得2019年中国十大考古新发现；2）对肃北古玉矿成矿相关的花岗质岩石和基底变质岩进行了元素地球化学、同位素地球化学、锆石U-Pb年代学和Hf-O同位素分析测试，确认矿床的形成与加里东构造岩浆活动有重要关联，有交代（R型）和热液（P型）两类玉料，为大理岩型接触变质交代矿床，根据透闪石石墨包裹体碳同位素组成可区分马鬃山与新疆玉料，敦煌旱峡玉矿遗址采矿工具石锤的材料主要来源于玉矿附近；3）根据对十多个现代玉矿大量的野外调研、采样和测试，初步建立了玉器溯源的数据库和微量元素溯源模型；4）确认距今5500年前大汶口文化部分蛇纹石质玉器材料就近来源于泰山玉；5）证实金沙遗址出土玉器主要为就地取材于四川龙溪玉，但有外来玉料来源；6）探索了不同玉料的溯源技术，发现新的无损测试溯源技术组合。项目成果为探索北山和敦煌地块古生代软玉形成与古亚洲洋构造域板块俯冲拼贴过程时空联系、突破困扰考古文博界的古玉器无损检测技术瓶颈约束、揭示中国黄河流域古玉资源开发、玉文化演化及史前跨区域经济文化交流提供了新的重要材料/技术方法。