2020/01/03 by Ananya Mallik, Mallik, Ananya, Sarah Lambart +3 · 1 citation
Earth and Planetary Sciences · #Chemical Physics (physics.chem-ph) #FOS: Physical sciences #Geological and Geochemical Analysis #Geophysics (physics.geo-ph) #High-pressure geophysics and materials #earthquake and tectonic studies
paper · pdf · doi:10.48550/arxiv.2001.00928
openalex publication_date 2020/01/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
This contribution reviews the effects of source heterogeneities, melt-rock\nreactions and intracrustal differentiation on magma chemistry across mid-ocean\nridges, intraplate settings and subduction zones using experimental studies and\nnatural data. We compare melting behaviors of pyroxenites and peridotites and\ntheir relative contributions to magmas as functions of composition, mantle\npotential temperatures and lithospheric thickness. We also discuss the fate of\nchemically distinct melts derived from heterogeneities as they travel through a\nperidotitic mantle. Using nearly 60,000 natural major element compositions of\nvolcanic rocks, melt inclusions, and crystalline cumulates, we assess broad\npetrogenetic trends in as large of a global dataset as possible. Consistent\nwith previous studies, major element chemistry of mid-ocean ridge basalts\n(MORBs) and their cumulates favor a first-order control of intracrustal\ncrystal-liquid segregation, while trace element studies emphasize the role of\nmelt-rock reactions, highlighting the decoupling between the two. Ocean island\nbasalts (OIB) show a larger compositional variability than MORB, partly\nattributed to large variations of pyroxenite proportions in the mantle source.\nHowever, the estimated proportions vary considerably with heterogeneity\ncomposition, melting model and thermal structure of the mantle. For arcs, we\nhighlight current views on the role of the downgoing slab into the source of\nprimary arc magmas, and the role of the overriding lithosphere as a magmatic\nchemical filter and as the repository of voluminous arc cumulates. Our approach\nof simultaneously looking at a large database of volcanic + deep crustal rocks\nacross diverse tectonic settings underscores the challenge of deciphering the\nsource signal versus intracrustal/lithospheric processes.\n