Carbon and hydrogen isotope constraints on degassing of CO₂ and H₂O in submarine lavas from the Pitcairn hotspot (South Pacific)

Cyril Aubaud (1) , Françoise Pineau (1) , Roger Hékinian , Marc Javoy (1)

1 IPGP - Institut de Physique du Globe de Paris

The analysis of CO₂-δ¹³C-H₂O-δD in vesicles of 35 submarine volcanic glasses reveals that open-system degassing, following closed-system degassing, is responsible for the observed variations in volatile concentration and isotopic ratios. The least degassed samples allow the assessment of minimum estimates for the flux of CO₂ and H₂O from the Pitcairn hotspot: 2.24 +/- 0.17 10⁴ tons C yr^-1 and 1.32 +/- 0.82 10⁵ tons H₂O yr^-1. The results also suggest that the carbon in the source of the Pitcairn hotspot may have a δ¹³C value around -6‰, 2‰ lower than the source of mid-ocean ridge basalts. This indicates either a possible contribution from the lower mantle or the possible involvement of decarbonated recycled materials with an unusual carbon isotopic signature.

Domaines: Planète et Univers [physics]

Cyril Aubaud, Françoise Pineau, Roger Hékinian, Marc Javoy. Carbon and hydrogen isotope constraints on degassing of CO₂ and H₂O in submarine lavas from the Pitcairn hotspot (South Pacific). Geophysical Research Letters, 2006, 33, ⟨10.1029/2005GL024907⟩. ⟨insu-03603151⟩