Publisher: Bachudo Science Co. Ltd

Major and Trace Elemens (+ SR ISOTOPJC) Geochemical Characteristics of The Mid-Atlantic Ridge Peridotites and, The Nature of The Upper Mantle

M. Loubet, U. A. Lar
KEYWORDS: Lherzolites, herburgites, MAR, mantle, serpentinization


A geochemical study (major and trace elements 87Sr/86Sr isotopic composition) of peridotites collected during ODP Leg 109 drilling on the flanks of the Mid Atlantic Ridge "(M.A.R.) (23° 10' N), is presented. Like most. abyssal peridotites, the samples have suffered variable degrees of serpentinization. Analysis of the data permits one to. d1stengu~sh. at least two stages of serpentinization. The first one was induced by a 87Sr/86Sr isotopically enriched fluid interpreted .as low temperature 1.1nevolved sea water. The fluid corresponding to the second stage was less 87Sr/86Sr isotopic enriched, and could correspond to high temperature seawater evolved through fluid/rock interactions. The data support a residual nature of ~these mantle periodtities, with compositional characteristics intermediate between slightly depleted organic therzolites and highly depleted ophiolitic harzburgites. 

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