Evolution of oceanic gabbros : in-situ and ancient examples

Magma Reservoir Formation and Evolution at a Slow-Spreading Center (Atlantis Bank, Southwest Indian Ridge)

“…Here the implication of RPF is clear from the textures presented above, and in order to test if RPF had also an impact on the chemistry of minerals, we hereafter compare the measured compositions with FC and AFC models. The AFC model of DePaolo (1981) has been commonly used for the study of lower oceanic crust samples as a simplified analogue to the complex RPF processes (Coogan et al, 2000;Kvassnes, 2003;Borghini and Rampone, 2007;Gao et al, 2007;Lissenberg et al, 2013;Sanfilippo et al, 2014;Ferrando et al, 2018). The novelty of our approach resides in our consideration of a sample suite interpreted as representative of an entire magmatic reservoir instead of individual samples, hence helping to better assess the impact of RPF on the differentiation process.…”

“…This led Godard et al (2009) to suggest that no significant fraction of evolved melt escaped the magmatic system sampled at Atlantis Massif. At Atlantis Bank, Dick et al (2000) and Kvassnes (2003) suggest that the average bulk composition of the cumulate sequence from ODP Hole 735B (and later from IODP Hole U1473A, Dick et al, 2019a) is too evolved with respect to the composition of primary MORB melts (bulk Mg# of 69.2 for Hole 735B and of 71 for Hole U1473A, Dick et al, 2000). Dick et al (2000) first infer the presence of a significant mass of "missing" primitive cumulates lying either out of the section or further deep in Atlantis Bank to account for this difference.…”

Hydrated Peridotite–Basaltic Melt Interaction Part II: Fast Assimilation of Serpentinized Mantle by Basaltic Magma

“…Ross andElthon, 1993, Nonnotte et al, 2005;van der Zwan et al, 2017) and in ophiolites, (Amri et al, 1996;Benoit et al, 1999;Clenet et al, 2010;Lange et al, 2013) suggest more complex mechanisms for the generation of oceanic magmas involving the assimilation of altered lithospheric material. Experimental and melt inclusion studies highlight the important role of basaltic melt-lithospheric rocks reactions on the chemical composition of both mantle rocks and silicate melts (e.g., Morgan & Liang, 2003;Kvassnes and Grove, 2008;France et al, 2010;Van den Bleeken et al, 2010;2011;Borisova et al, 2012a;. For example, Sr isotope diversity of basalts and mafic cumulates possibly related to assimilation of seawater-altered rocks is common in spreading environment (Michael and Cornell, 1998;Lange et al, 2013;van der Zwan et al, 2017).…”