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A common precursor for global hotspot lavas
Matthijs A Smit1,2, Ellen Kooijman2
1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia Canada.
Nature Geoscience
|October 14, 2024
Summary
Global hotspot lavas show uniform parental melt compositions, suggesting a depleted mantle source enriched during the Archaean, not a heterogeneous deep mantle. This explains lava chemistry without primordial relics.
Area of Science:
- Geochemistry
- Petrology
- Mantle Dynamics
Background:
- Hotspot lavas display chemical heterogeneity, often attributed to diverse deep mantle sources.
- Directly characterizing primary melt compositions and mantle heterogeneity is scientifically challenging.
Purpose of the Study:
- To investigate a global dataset of hotspot lavas to determine the incompatible-element composition of their parental melts and sources.
- To constrain the origins of chemical variations observed in hotspot lavas.
Main Methods:
- Analysis of trace-element ratios in a global dataset of hotspot lavas.
- Comparison of elemental and isotopic compositions (radiogenic and noble-gas) of parental melts from various volcanic settings.
Main Results:
- Trace-element ratios indicate that observed heterogeneity in hotspot lavas is secondary, resulting from ascent processes, not primary mantle variations.
- Parental melts of hotspot lavas, kimberlites, and large igneous province basalts exhibit uniform elemental and isotopic compositions.
Conclusions:
- Hotspot melt parental sources are likely a depleted, outgassed mantle reservoir, enriched by Archaean material.
- This model reconciles observed lava compositions without necessitating a heterogeneous lower mantle or primordial Earth relics.
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