Rare gas systematics on Lucky Strike basalts (37°N, North Atlantic): Evidence for efficient homogenization in a long-lived magma chamber system?

Manuel Moreira (1) , Javier Escartin (1) , Eric Gayer (1) , Cédric Hamelin (1) , Antoine Bézos (2) , Fabien Guillon (1) , Mathilde Cannat (1)

1 IPGP - Institut de Physique du Globe de Paris
2 LPGN - Laboratoire de Planétologie et Géodynamique de Nantes [UMR 6112]

We present rare gas data in fresh glasses from the Lucky Strike segment located on the Mid Atlantic Ridge (∼37.3°N), close to the Azores plateau. We analyzed the helium and neon isotopes in 28 samples by melting as well as He‐Ne‐Ar‐Kr‐Xe isotopes in 9 samples by crushing. Samples were collected during the Graviluck06, MOMAR08, and Bathyluck09 cruises over a ridge length of ∼13 km (mean sample spacing of ∼500 m), and at depths ranging from 1550 m to 2174 m. The helium isotopic ratio varies between 84,410 and 88,235 (R/Ra between 8.19 and 8.56). The samples having the “most” primitive helium isotopic ratio are the enriched samples (e.g. high K2O/TiO2) although the difference to the depleted samples is small. It appears that all of our samples derive from the same and well‐homogenized magma chamber. Neon isotopes clearly show the influence of the Azores hotspot, which is not seen with helium because of lower 3He/22Ne in the plume source compared to the MORB source.

Domaines: Géochimie

Manuel Moreira, Javier Escartin, Eric Gayer, Cédric Hamelin, Antoine Bézos, et al.. Rare gas systematics on Lucky Strike basalts (37°N, North Atlantic): Evidence for efficient homogenization in a long-lived magma chamber system?. Geophysical Research Letters, 2011, 38 (8), pp.L08304. ⟨10.1029/2011GL046794⟩. ⟨hal-02330261⟩