新疆和田墨玉中石墨包裹体碳同位素组成研究

张存; 马楠; 王婉琦; 陈淑祥; 吴煜; 刘金海

新疆和田墨玉中石墨包裹体碳同位素组成研究

张存^1,,
马楠¹,
王婉琦¹,
陈淑祥¹,
吴煜²,
刘金海^1, ,

1.
齐鲁工业大学(山东省科学院)材料科学与工程学院，山东济南 250353
2.
新疆中鉴珠宝玉石检测研究院，新疆乌鲁木齐 830018

基金项目:

齐鲁工业大学(山东省科学院)科教产融合试点工程基础研究类项目 11240455

自然资源部黄河上游战略性矿产重点实验室开放课题 YSMRKF202304

详细信息

作者简介:
张存(1991-)，男，博士，主要从事矿物学(含宝石矿物学)、岩石学、同位素地球化学等领域的教学和研究工作。E-mail: gemzhangc@qlu.edu.cn

通讯作者:
刘金海(1973-)，男，副教授，主要从事宝石学、地球化学等领域的教学和研究工作。E-mail: ljhai@qlu.edu.cn

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出版历程
- 收稿日期: 2024-07-14
- 刊出日期: 2024-10-30

Carbon Isotopic Composition of Graphite Inclusion in Black Nephrite Jade from Xinjiang

1.
School of Materials Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
2.
Gemological Inspection Institute of Xinjiang Zhongjian, Urumchi 830018, China

摘要

摘要:
新疆地区是中国最重要的和田玉成矿区带，赋存大量优质原生和次生和田玉矿床。其中，新疆和田墨玉可以划分为两种典型类型，一种以阳起石为主要矿物，另一种则主要以透闪石和石墨为主要矿物，后者颜色通常由石墨包裹体导致。众所周知，石墨在有机和无机碳循环过程中发挥重要作用，对科学揭示地球深部碳循环具有重要科学指示意义，而和田墨玉中石墨包裹体则是研究新疆地区复杂背景下碳聚集、固定及循环的有利对象。但以往的研究重点关注了和田墨玉成因类型、形成机制等方面，针对石墨包裹体的碳质来源，尚未被厘定，不利于和田玉成矿规律和构造演化的完整科学认识。因此，本研究采用显微岩相学、电子探针、碳稳定同位素等技术手段，对新疆和田墨玉样品的矿物组成、石墨包裹体碳同位素特征进行了系统研究。结果表明，新疆和田墨玉的主要矿物组成为透闪石，副矿物或次要矿物组成为石墨、方解石、透辉石和磷灰石等；石墨碳稳定同位素揭示，新疆和田墨玉中石墨包裹体的δ¹³C_PDB处于-21.3‰~-8.5‰，平均值为-13.76‰，具有相对较重的碳同位素组成，指示石墨碳质来源具有有机和无机双重成因。结合区域地质环境，我们认为在古生代中酸性岩浆侵入到前寒武纪白云石大理岩过程中携带幔源重同位素碳，导致石墨和透闪石共同结晶或沉淀。本文研究为和田玉矿床成矿过程及地球深部碳循环方面提供独特视角。
- 和田墨玉 /
- 成矿过程 /
- δ¹³C稳定同位素 /
- 岩浆热液 /
- 新疆
Abstract:
Xinjiang is the most important metallogenic belt of nephrite jade in China, with a large number of high quality primary and secondary nephrite jade deposits. Two typical types of black nephrite jade from Xinjiang are classified. One is mainly composed of actinolite, and the other one is mainly composed of tremolite and graphite with its colour generally caused by graphite inclusions. It is well known that graphite plays an important role in the processes of organic and inorganic carbon cycle, which exhibits important scientific significance for the deep carbon cycle of the Earth, and the graphite inclusion is acted as a favorable object for the study of carbon accumulation, fixation and cycling under the complex background of Xinjiang. However, previous studies mainly focused on the genetic types and formation mechanisms of nephrite jade, and the carbon sources of graphite inclusions have not been determined, which is not conducive to the complete scientific understanding of the metallogenic regularity and tectonic evolution of nephrite jade. In this study, the mineral components and carbon isotope characteristics of graphite inclusions in black nephrites from Xinjiang were studied by means of microscopic petrography, electron probe microscopy, and carbon stable isotopes. The results show that the main mineral component of black nephrite jade is tremolite, and the accessory or secondary minerals are graphite, calcite, diopside, and apatite, etc. The carbon stable isotopes in graphite reveal that the δ¹³C_PDB values of graphite inclusions in black nephrite jade range from -21.3‰ to -8.5‰, with the average value -13.76‰. The δ¹³C_PDB of graphite inclusions exhibits relatively heavy carbon isotopic compositions, indicating that the carbon sources of graphite are both organic and inorganic. Combined with the regional geological environments, we infer that the relative heavy isotopic carbon derived from the mantle source was carried during the processes of intrusion of the Paleozoic intermediate-felsic magma into the Precambrian dolomite marble, leading to the crystallization or precipitation of graphite and tremolite. This study provides a new perspective for the ore-forming processes of the nephrite jade deposits and deep carbon cycle of the Earth.
- black nephrite jade /
- ore-forming processes /
- δ¹³C stable isotopes /
- magmatic-hydrothermal processes /
- Xinjiang

HTML全文

图 1 山东昌乐类达碧兹蓝宝石原石切片，修改自参考文献[7]

Figure 1. Trapiche-like sapphire slices from Changle, Shandong Province, modified from reference[7]

下载: 全尺寸图片幻灯片

图 1 代表性和田墨玉手标本(a-b)和偏光镜下岩相学观察(c-d)

Figure 1. Representative black nephrite jade samples (a-b) and petrographic observation using polarizing microscope (c-d)

Gr-Graphite; Tr-Tremolite

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图 2 自然界中δ¹³C分布情况及本研究中δ¹³C值

Figure 2. Natural distributions of δ¹³C values and the δ¹³C values in this study

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参考文献(12)

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