Access Restriction

Author Bach, Wolfgang ♦ Paulick, Holger ♦ Garrido, Carlos J. ♦ Ildefonse, Benoit ♦ Meurer, William P. ♦ Humphris, Susan E.
Source Hyper Articles en Ligne (HAL)
Content type Text
Publisher American Geophysical Union
File Format PDF
Language English
Subject Keyword ODP ♦ sdu ♦ Sciences of the Universe [physics]/Earth Sciences
Abstract The results of detailed textural, mineral chemical, and petrophysical studies shed new light on the poorly constrained fluid-rock reaction pathways during retrograde serpentinization at mid-ocean ridges. Uniformly depleted harzburgites and dunites from the Mid-Atlantic Ridge at 15°N show variable extents of static serpentinization. They reveal a simple sequence of reactions: serpentinization of olivine and development of a typical mesh texture with serpentine-brucite mesh rims, followed by replacement of olivine mesh centers by serpentine and brucite. The serpentine mesh rims on relic olivine are devoid of magnetite. Conversely, domains in the rock that are completely serpentinized show abundant magnetite. We propose that low-fluid-flux serpentinization of olivine to serpentine and ferroan brucite is followed by later stages of serpentinization under more open-system conditions and formation of magnetite by the breakdown of ferroan brucite. Modeling of this sequence of reactions can account for covariations in magnetic susceptibility and grain density of the rocks.
ISSN 00948276
Educational Use Research
Learning Resource Type Article
Publisher Date 2006-01-01
e-ISSN 19448007
Journal Geophysical Research Letters
Volume Number 33
Issue Number 13