腾冲温泉中Li-U-Au异常富集特征及其成因浅析

Characteristics and causes of Li-U-Au abnormal enrichment in Tengchong hot spring

关键词:  腾冲  温泉  锂、铀、金富集特征  地核  地幔柱

Key words:  Tengchong  Hot spring  Characteristics of Li-U-Au abnormal enrichment  Earth’s core  Mantle plumes

摘要:

综合滇西腾冲1974年以来的调查研究文献资料发现，该区正在发育国内外罕见的现代热泉型铀、金、砷、锑、稀土、锂、汞、钨、氢等元素的异常富集系统。为总结温泉中锂、铀、金战略性金属元素异常富集特征，探索其共生富集机制，本文统计了腾冲57个温泉近50年报道的320个地球化学数据，初次系统梳理出温泉中锂、铀、金元素具以下典型特征：（1）3种金属元素集中在部分泉水中异常富集。锂、金主要富集于大滚锅，铀主要富集于珍珠泉和叠水河碳酸泉，温泉中锂和铀含量高于全省绝大多数温泉。（2）锂元素含量稳定、富集效率高、资源潜力大。热海地区温泉锂含量变异系数均低于30%，指示半个世纪来锂含量波动幅度小，锂“流而不衰”；有学者初步测算出全区温泉年溢出锂金属量达532.9吨，20年流失量即可超过一个小型锂矿。此外，381砂岩型铀矿床还存在铀“采而不尽”的现象，可能与泉水中新生铀的持续补给有关。在前人研究成果基础之上，新提出温泉中锂、铀、金的共生富集可能主要是在地核或其局部富集的此类元素沿“腾冲现代地幔柱”自下往上迁移，在地表温泉及其沉积物中不断聚集的结果，即“核源—地幔柱”成因。

Abstract:

Based on the investigation and research results since 1974 in Tengchong, Western Yunnan Province, it is found that there is a rare modern hydrothermal enrichment system of uranium, gold, arsenic, antimony, rare earth, lithium, mercury, tungsten, hydrogen and other elements. To summarize the anomalous enrichment characteristics of strategic metal elements of lithium, uranium and gold in hot springs and explore their symbiotic enrichment mechanism, we collected 320 geochemical data from 57 hot springs reported over the last 50 years through regional data collection and integration. Then we firstly systematically combed out the following typical characteristics of lithium, uranium and gold elements in hot springs: (1) Three kinds of metal elements are anomalously enriched in some springs. Lithium and gold are mainly enriched in the Dagunguo spring, uranium is mainly enriched in Zhenzhu spring and Dieshuihe carbonated spring. The hot springs in this area contain higher levels of lithium and uranium than most in the province. (2) Lithium element has the characteristics of stable content, high enrichment efficiency and great resource potential. The variation coefficients of lithium content in hot springs in Rehai area are all lower than 30%, indicating that the fluctuation range of lithium content is small in the past half century. It is estimated that the annual overflow of lithium from hot springs in the region amounts to 532.9 tons, and the loss in 20 years can exceed that of a small lithium mine. In addition, the 381 sandstone-type uranium deposit also has the phenomenon of “inexhaustible exploitation” of uranium, which may be related to the continuous replenishment of new uranium from the spring. On the basis of previous research results, it is proposed that the co-accumulation of lithium, uranium and gold in hot springs may be mainly caused by the migration of such elements in the core or its local areas along the “Tengchang modern mantle plume” from bottom to top, and the continuous accumulation in the surface hot springs and their sediments, that is, the origin of “Earth’s core source-Mantle plume”.