Contrasting slab decarbonation patterns control deep carbon cycling efficiency in hot vs. cold subduction zones.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42525748.
- Also identified by DOI 10.1126/sciadv.aee3217 and PMC identifier 13418749.
- Licence recorded as CC BY-NC.
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Abstract
Subducting slabs play a crucial role in deep Earth carbon cycling, yet the carbon-cycling efficiency of different subduction zones remains debated. Here, we systematically compare decarbonation characteristics in the extremely cold Tonga and hot Colombia subduction zones using observation-constrained thermo-petrological modeling, integrated with volcanic degassing and arc geochemistry. Two contrasting slab decarbonation patterns are identified: efficient "focused" decarbonation in hot subduction zones versus sluggish "diffuse" decarbonation in cold subduction zones. Hot Colombia exhibits a high decarbonation efficiency >15%, dominated by metamorphic carbon release within a narrow depth range of ∼75-115 km and supplemented by partial melting-induced decarbonation. In contrast, cold Tonga shows a much lower decarbonation efficiency of ∼1% by dissolution-dominated carbon removal over a broad depth range of ∼75-310 km. These findings suggest a contrasting efficiency of different subducting slabs for deep carbon cycling and volcanic degassing in present-day and ancient subduction systems.