Native aluminium in metalliferous sediments from the East Pacific Rise axial zone (21°S)

• Published in: Marine geology 1995-03, Vol.123 (1), p.87-103
• Main Authors: Dekov, Vesselin M., Mandova, Elena D., Dimitrov, Kalin B., Rekkalov, Krassimir N.
• Format: Article
• Language: English
• Subjects: Marine
• ISSN: 0025-3227; 1872-6151
• DOI: 10.1016/0025-3227(95)80006-W

An endogenous model of the formation of small amounts of > 100 μm metallic aluminium particles from the metalliferous sediments of the East Pacific Rise (21°S) is proposed on the basis of a detailed study of their morphology, chemical composition, X-ray data, spatial and temporal distribution. According to this model native aluminium is formed as an accessory mineral during the process of the pre-chamber evolution of basic and ultrabasic systems in the spreading zones, under high P—T and low ƒO 2 conditions, as well as during the later serpentinization of basites and ultrabasites from the second and third oceanic layer. As a result of the active tectono-magmatic processes in the rift zones the native aluminium particles are carried upwards into the seafloor water layer by the upwelling vent fluids of the hydrothermal circulation cells. During periods of high hydrothermal activity, the number of Al° particles carried upwards increases. The spatial distribution of the particles depends on the energy of the hydrothermal system and the direction and energy of the seafloor currents. The thin oxyhydroxide, silicate and chloride crusts formed on the surface of the Al° particles, as well as a monoatomic oxide film, prevent further alteration of the particles.