Efficient Carbon Recycling at the Central‐Northern Lesser Antilles Arc: Implications to Deep Carbon Recycling in Global Subduction Zones

Abstract

Carbon recycling efficiency of arc (CREA) is an important parameter to assess the recycling of slab carbon into Earth's deep interior. Although previous studies observed variable degrees of recycled slab carbon at global arcs, the CREA value of any individual subduction zone has not been obtained due to the loose constraints on carbon budget in altered oceanic crust (AOC). Here, through estimates of carbon input by both sediments and AOC at DSDP Site 543 and recycled carbon output from major volcanoes in the Central-Northern Lesser Antilles, we show an extremely efficient carbon recycling case, with the CREA value reaching 100 ±27 %. Nearly complete slab carbon release at sub-arc depth implies little carbon has been lost in the forearc region or subducted into the deep mantle in this subduction zone. Our results highlight strongly variable CREA on a global scale, which must be considered in the modeling of global deep carbon cycle.Plain Language Summary Subduction zones are the major channel to deliver crustal carbon into the mantle. However, the fate of crustal carbon at a variety of depth (e.g., forearc, sub-arc, beyond arc) in the subduction channel is poorly quantified, which is an obstacle to our understanding of the deep carbon cycle. Here, we assessed the carbon recycling efficiency in the Central-Northern Lesser Antilles arc by comparing the carbon input flux (estimated from data of the subducting slab recovered by DSDP drillings) with carbon output flux (estimated based on volcanic emission data). We found that the subducted crustal carbon was nearly completely recycled by arc volcanism in the Central-Northern Lesser Antilles. This implies little carbon loss within the forearc region and little carbon subducted into the deep mantle in the Central-Northern Lesser Antilles, which differs from some other subduction zones (e.g., the Izu-Bonin-Mariana and Central America) that show low carbon recycling efficiencies. Our discovery highlights that the carbon recycling in subduction zone is highly variable on a global scale.

Pervasive subduction zone devolatilization recycles CO2 into the forearc

“…In addition, mantle corner flow could, perhaps, transport carbonated forearc mantle into the subarc melting region 8 . Consequently, we do not consider evidence of slab-derived CO 2 in volcanic arcs 45 , to be at odds with our observations. Regardless of whether the~2 Tmol CO 2 yr −1 is released by arcs or subducted deeper into the mantle, it is far less than recent estimates of mantle-derived CO 2 outgassing, totaling~5 tõ 7 Tmol CO 2 yr −1 3 .…”

“…In addition, mantle corner flow could, perhaps, transport carbonated forearc mantle into the subarc melting region 8 . Consequently, we do not consider evidence of slab-derived CO 2 in volcanic arcs 45 , to be at odds with our observations.…”

Cycling of CO2 and N2 Along the Hikurangi Subduction Margin, New Zealand: An Integrated Geological, Theoretical, and Isotopic Approach

“…It has been apparent for some time that volatile return efficiency at arcs is geographically variable, and single‐margin studies are therefore vital to improve understanding of subduction zone processes. The central America margin, for example, undergoes little to no C loss in the deep forearc and subarc (0.15%–5% loss, Freundt et al., 2014; see also Li & Bebout, 2005), while other margins could experience more extensive loss (∼100% for the Lesser Antilles proposed by Li et al., 2020). For the Central America margin, previous research has concluded that ∼100% of sediment‐bound N 2 is lost by subarc depths (Fischer et al., 2002; Snyder et al., 2003), a conclusion at odds with studies of exhumed metasedimentary rocks that indicate near complete forearc retention of N in white mica (Bebout et al., 2013; Busigny et al., 2003).…”

Magmatic–Hydrothermal Origin of Fe-Mn Deposits in the Lesser Khingan Range (Russian Far East): Petrographic, Mineralogical and Geochemical Evidence

“…Carbon isotopes are currently successfully used to trace deep carbon recycling and processing through various parts of the subduction and collision zones [153][154][155][156][157]. δ 13 C variations in explosive volcanic breccia (from −24.5 to −28.4‰), iron-manganese ore (from −25.2 to −29.4‰) and host Vendian-Cambrian carbonates (from −22.0 to −28.3‰) are similar to the isotopic δ 13 C signature of biogenic carbon, which average −25‰ over more than 3.8 Ga of the Earth's planetary evolution [158][159][160].…”