赤道东太平洋C—C区硅质沉积物的磁性特征及细菌合成磁铁矿

Magnetic Properties of Siliceous Sediments from the Clarion-Clipperton Zone, Northeastern Equatorial Pacific, and the Occurrence of Bacterial Magnetite

对分布于赤道东太平洋克拉里昂和克里帕顿断裂带之间 (C—C区 )的硅质沉积物所作的环境磁学研究表明 ,沉积物的磁性特征由亚铁磁性矿物主导 ,亚铁磁性矿物颗粒以单畴 (SD)和超顺磁 (SP)为主。磁性参数和透射电镜(TEM )分析表明 ,该区沉积物中存在着细菌合成的磁铁矿 ,并观察到磁铁矿存在不同程度的溶解。这一发现是微生物参与C—C区铁元素循环的直接证据。不完整反铁磁性矿物在氧化性较强的西区沉积物中含量较高 ,且随着纬度升高而增加 ,显示随着远离赤道 。

It is indicated that ferrimagnetic minerals dominate the magnetic properties of surface siliceous sediments in the Clarion-Clipperton (C—C) zone, northeastern equatorial Pacific. The ferrimagnetic minerals are mainly single domain (SD) an d superparamagentic(SP) in size. Magnetic parameters, together with TEM analysis , reveal the presence of bacterial magnetite, which undergoes dissolution to var ying extent. Such a phenomena is indicative of an active iron cycle involving mi crobes. Imperfect anti-ferromagnetic minerals show a higher content in the sed iments of the western region of C—C zone, and increase toward high latitude. It is suggested that, with increased distance from the equator, sediments become m ore oxidized.