东北太平洋东部CCB53孔沉积物Mn元素活化、迁移和沉淀与沉积环境演化的统一

本文引用地质矿产部“七五”东北太平洋CCB53孔柱状沉积物（＜63μm）的元素地球化学分析数据，采用“标准元素对比值法”定量分离Mn元素在不同物源（陆源、生物源、热液源和自生源）中的绝对含量，确定Mn元素地球化学本底，提取CCB53柱状沉积物中Mn元素的正、负异常。据此讨论了Mn元素发生活化、迁移和再沉淀的时间演化规律，即从沉积物的底部到顶部（22．42～0Ma），Mn元素经历了四个活化、迁移和沉淀旋回，分别为840～320、320～170、170～120和120～0。Mn元素的正、负异常分布与自生源组分和氧化还原环境的变化对比分析表明，Mn元素正、负异常分布与自生源组分的高→低变化规律和氧化还原条件的周期振荡紧密相关。早期成岩过程中发生的氧化还原环境的振荡是元素发生活化、迁移和沉淀的动因。

THE UNITY BETWEEN THE REMOBILIZATION,MIGRATION,DEPOSITION OF Mn AND THE EVALUATION OF SEDIMENTARY ENVIRONMENT RECORDED BY THE CCB53 SEDIMENT CORE IN NORTHEASTERN PACIFIC OCEAN

Applying geochemical data of the CCB53 sediment core in northeastern Pacific Ocean, obtained by MGMR during the "Seventh Five-Year Plan" in China, and using the "method of prognosis", the Mn concentration of the CCB53 sediment core is partitioned according to its source and Mn geochemical background value is determined, from which the positive/negative anomalies of Mn element are recognized. From the above,the laws of temporal evaluation of Mn remobilization, migration and deposition are discussed, i. e., Mn element has experienced four cycles from the bottom to the top (840- 320cm, 320- 170cm, 170- 120cm and 120- 0cm, respectively). By contrasting Mn positive/negative anomalies with the distribution of authigenic Mn concentration, and with cyclical changs of redox environment, it is illustrated that Mn positive/negative anomalies correspond to Mn high/low authigenic concentration and to oxidative/reductive environment, implicating that the reductive environment is favourable to Mn remobilization and migration, and the oxidative environment to Mn deposition. Therefore, it is concluded that the dynamic factor affecting Mn remobilization, migration and deposition is the oscillation of oxidative/reductive environment in the course of early diagenesis.