The chlorine isotope composition of Earth's mantle | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  The chlorine isotope composition of Earth's mantle

Type de publication:

Journal Article

Source:

Science, Volume 319, Ticket 5869, p.1518-1520 (2008)

ISBN:

0036-8075

Numéro d'accès:

WOS:000253943800036

Mots-clés:

Physico-chimie des fluides géologiques ; Géosciences marines ; N° Contribution : 2342, UMR 7154

Résumé:

Chlorine stable isotope compositions ( delta Cl-37) of 22 mid- ocean ridge basalts ( MORBs) correlate with Cl content. The high-delta Cl-37, Cl- rich basalts are highly contaminated by Cl- rich materials ( seawater, brines, or altered rocks). The low-delta(37) Cl, Cl- poor basalts approach the composition of uncontaminated, mantle- derived magmas. Thus, most or all oceanic lavas are contaminated to some extent during their emplacement. MORB- source mantle has delta(37) Cl <= -1.6 per mil (%), which is significantly lower than that of surface reservoirs (similar to 0 parts per thousand not equal). This isotopic difference between the surface and deep Earth results from net Cl isotopic fractionation ( associated with removal of Cl from the mantle and its return by subduction over Earth history) and/ or the addition ( to external reservoirs) of a late volatile supply that is Cl-37- enriched.