太平洋富钴结壳中碲元素的地球化学特征及其富集机制探讨

Geochemical characteristics and enrichment mechanism of tellurium in Co-rich crusts from Pacific Ocean

文章通过对采自太平洋海域不同海山上68个结壳样品中Te元素地球化学特征的研究，探讨了富钴结壳中控制Te元素富集的古海洋氧化还原环境及其富集机制。分析表明，太平洋海域中大多数结壳的w（Te）变化于13．4×10^-6～115．8×10^-6，平均50×106，是海水训（Te）的10’倍；结壳中叫（Te）与Mn／Fe比值呈正相关，相关系数为0．51；与Fe呈负相关，相关系数为-0．61，显示结壳中Te与Co有类似的地球化学特征。古海水氧化还原环境的改变是控制结壳中Te元素含量变化的重要因素；能反映古海水氧化还原环境的＆异常与结壳中Te含量基本呈同步变化趋势，Te含量具有随古海水氧化程度减弱而降低的特征。结壳中Te元素的富集主要受控于其内的Mn／Fe比值。Te元素的富集机制除被海水中带微弱正电荷的FeOOH胶体以库伦静电吸附外，还可能与δ-MnO2表面上以一种表面络合物方式的富集机制有关。Te进入结壳的存在形式及其在不同古海洋环境中的富集机制还有待进一步研究和探讨。

In order to explore the effect of the paleoredox environment change on Te concentration and the enrichment mechanism of Te in Co-rich crusts, the authors studied the geochemical characteristics of 68 crust samples from different geographic locations and different seamounts in the Pacific Ocean. The results show that Te content of the crusts varies from 13.4 ×10^-6 to 115.8 ×10^-6 with a mean content of 50 ×10^-6. Te exhibits a positive cor- relation with Mn/Fe with a correlation coefficient of 0.51, a negative correlation with Fe with a correlation coef- ficient of - 0.61, and similar geochemical features to Co. It is found that the change of paleoredox environment is an important factor which controls Te content variation in the crusts. Ce anomaly which reflects the change of paleoredox environment varies with Te content simultaneously, and Te content will decrease with the reductionof oxidation extent. Based on systematic research and analysis, the authors consider that the enrichment mecha- nism of Te in the crusts is mainly controlled by the Mn/Fe ratio of the crusts, and the enrichment mechanism of Te in the crusts would be related to a kind of surface complexes mode on δ-MnO2 in addition of the absorption of Te on the slightly positively charged FeOOH colloid in seawater. It is also held that the modes of occurrence of Te-dominant species that enter the crusts and their enrichment mechanism in different paleo-oceanographic envi- ronments should be further studied.