Tracing carbonate-silicate interaction during subduction using magnesium and oxygen isotopes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 25367068.
- Also identified by DOI 10.1038/ncomms6328.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Subduction of carbonates and carbonated eclogites into the mantle plays an important role in transporting carbon into deep Earth. However, to what degree isotopic exchanges occur between carbonate and silicate during subduction remains unclear. Here we report Mg and O isotopic compositions for ultrahigh pressure metamorphic marbles and enclosed carbonated eclogites from China. These marbles include both calcite- and dolomite-rich examples and display similar O but distinct Mg isotopic signatures to their protoliths. Their δ(26)Mg values vary from -2.508 to -0.531‰, and negatively correlate with MgO/CaO ratios, unforeseen in sedimentary carbonates. Carbonated eclogites have extremely heavy δ(18)O (up to +21.1‰) and light δ(26)Mg values (down to -1.928‰ in garnet and -0.980‰ in pyroxene) compared with their protoliths. These unique Mg-O isotopic characteristics reflect differential isotopic exchange between eclogites and carbonates during subduction, making coupled Mg and O isotopic studies potential tools for tracing deep carbon recycling.