Tracing carbonate-silicate interaction during subduction using magnesium and oxygen isotopes
Shui-Jiong Wang1, Fang-Zhen Teng2, Shu-Guang Li3
11] State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China [2] Isotope Laboratory, Department of Earth and Space Sciences, University of Washington, Seattle, Washington 98195, USA.
Nature Communications
|November 5, 2014
Summary
Carbonate and carbonated eclogite subduction recycles carbon into Earth's mantle. Mg and O isotopes reveal distinct exchanges between these rocks during subduction, aiding deep carbon cycle studies.
Area of Science:
- Geochemistry
- Isotope Geology
- Petrology
Background:
- Subduction transports carbon into the deep Earth via carbonates and carbonated eclogites.
- The extent of isotopic exchange between carbonates and silicates during subduction is not well understood.
Purpose of the Study:
- To investigate Mg and O isotopic compositions of ultrahigh pressure metamorphic marbles and carbonated eclogites.
- To understand isotopic exchange processes between carbonate and silicate during subduction.
Main Methods:
- Analysis of Mg and O isotopic compositions.
- Examination of ultrahigh pressure metamorphic marbles and enclosed carbonated eclogites from China.
Main Results:
- Marbles show similar O but distinct Mg isotopic signatures compared to their protoliths.
- Carbonated eclogites exhibit significantly heavier O and lighter Mg isotopes than their protoliths.
- A negative correlation between δ(26)Mg and MgO/CaO ratios was observed in marbles.
Conclusions:
- Differential Mg-O isotopic exchange occurs between eclogites and carbonates during subduction.
- Coupled Mg and O isotopic studies are valuable tools for tracing deep carbon recycling.
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