A quantitative link between recycling and osmium isotopes.

Area of Science:

• Geochemistry
• Isotope Geochemistry
• Petrology

Background:

• Recycled subducted ocean crust is a key component in mantle source regions.
• Previous studies have used elevated 187Os/188Os ratios and trace element compositions (high Ni, low Mn) to identify recycled crust.
• The link between these tracers and their implications for mantle sources remain debated.

Purpose of the Study:

• To investigate the relationship between osmium isotopes and trace elements in Icelandic lavas.
• To strengthen the model of recycled crust contributing to mantle sources.
• To estimate the osmium isotopic composition of recycled crust and mantle peridotite.

Main Methods:

• Analysis of Quaternary lavas from Iceland.
• Osmium (Os) isotope ratio measurements (187Os/188Os).
• Trace element analysis (Nickel, Manganese).

Main Results:

• Demonstrated a direct link between elevated 187Os/188Os and high Ni/low Mn contents in Icelandic lavas.
• Estimated the osmium isotopic composition of the recycled crustal component.
• Constrained the composition of the peridotitic end-member to resemble present-day oceanic mantle.

Conclusions:

• The findings strengthen the model of recycled ocean crust influencing mantle composition.
• Icelandic lavas are partly derived from an ancient crustal component (1.1–1.8 billion years old).
• The study provides insights into the long-term evolution of Earth's mantle.