Contributions to Mineralogy and Petrology

, Volume 49, Issue 3, pp 233–257 | Cite as

Petrology of rodingites from the equatorial Mid-Atlantic fracture zones and their geotectonic significance

  • José Honnorez
  • Paul Kirst


Rodingites were dredged from fracture zones of the equatorial Mid-Atlantic Ridge along with serpentinized ultramafics, and fresh and metamorphosed basalts and gabbroids. These rodingites were generated by a metasomatic process at low temperature involving an enrichment in lime and water, and a loss of silica and alkalis. The parent rocks were gabbronorites which intruded ultramafic material as it ascended from the upper mantle to its present location in the upper oceanic crust. The gabbronorites were probably altered to rodingites while they were still in the lower oceanic crust. Since the rodingitization process appears to be concomitant, complementary and simultaneous with the serpentinization of the host ultramafic rocks, we infer that the serpentinization process also took place in the deeper part of the oceanic crust. These two simultaneous metasomatic processes thus predate the major phase of tectonic events which uplifted these blocks as cold, solid diapiric emplacements of ultramafic material and accompanying rodingites to their present positions along lines of weakness expressed as fracture zones.


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Copyright information

© Springer-Verlag 1975

Authors and Affiliations

  • José Honnorez
    • 1
  • Paul Kirst
    • 2
  1. 1.School of Marine and Atmospheric ScienceUniversity of MiamiUSA
  2. 2.Miami-Bade Community CollegeUSA

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