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Subduction

Subduction is the primary driver of plate tectonics and has provided a critical exchange of life-supporting elements between the biosphere and geosphere over Earth’s history. This collection and editorial showcase recent multidisciplinary advances in subduction science, under the themes of subduction dynamics, element and volatile cycles, and magmatic systems. These works highlight the complexity of the subduction system, providing a platform from which traditionally disparate research fields can continue to work together to bring new dynamics to subduction science.

Commentary

Subduction is the primary driver of plate tectonics, yet we still do not fully understand how subduction zones initiate or the budgets of life-supporting elements recycled via subduction. At Nature Communications, we advocate for more transdisciplinary initiatives and collaborative projects, which are essential if we are to continue to bring new dynamics to subduction research.

Editorial | Open Access | | Nature Communications

Despite numerous advances in our understanding of subduction since the theory of plate tectonics was established, the mechanisms of subduction zone initiation remain highly controversial. Here, the authors present a transdisciplinary and expandable community database of subduction zone initiation events in the last 100 Ma, which establishes a clear direction for future research.

Perspective | Open Access | | Nature Communications

The primary causes of dramatic variations in volcanic flux and composition along strike in subduction zones remain largely unknown. Here we use a promising new approach to show that along-strike volcanic variability in the Quaternary Cascades Arc is primarily due to variations in the flux of basalt into the base of the crust, rather than crustal magma storage.

Perspective | Open Access | | Nature Communications

Subduction dynamics

The motions of subducted slabs are expected to drive mantle flow around slab edges, however, evidence of deep mantle flow has so far remained elusive. Here, the authors present a Full Waveform Inversion 3-D anisotropy model which allows them to infer deep subduction-induced mantle flows underneath the Mid-Americas and the Caribbean.

Article | Open Access | | Nature Communications

Knowledge of shear-wave anisotropy is important to understanding the structure and dynamics of the subduction zone mantle wedge. Here, the authors find unambiguous evidence that forearc anisotropy resides in the upper-plate crust, while weak anisotropy in the most seaward part of the mantle wedge indicates decoupling from the slab

Article | Open Access | | Nature Communications

The rheology of the upper mantle is key to understanding how plate tectonics may evolve. Here, using GPS and tide-gauge measurements along the Sumatran subduction zone, the authors’ show that a bi-viscous rheology model is needed to explain the stress and strain evolution of the upper mantle following earthquakes.

Article | Open Access | | Nature Communications

The magmatic progression produced during the initiation of the Izu-Bonin-Marianas subduction zone took place rapidly over 1 million years, but it has been unclear why. Here, using numerical models, the authors show that subduction initiation was dominated by vertical forces, internal to the system itself, progressing to self-sustained subduction.

Article | Open Access | | Nature Communications

Retreating subduction zones are enabled by the development of faults at the edges of the slab, but the physical mechanisms controlling fault propagation remain debated. Here, the authors find that oceanic crust recycling is controlled by weakening of fractures forming at the edges of slabs.

Article | Open Access | | Nature Communications

Topography at active forearc margins is controlled by numerous competing tectonic and erosional processes acting at different timescales, yet separating their respective contribution remains a challenge. Here, the authors evidence Myr-scale, uplift-then-subsidence cycles controlled by transient accretion at the base of the forearc domain.

Article | Open Access | | Nature Communications

The dynamics of continental subduction is largely controlled by the rheological properties of rocks involved along the subduction channel. Here, the authors reveal a prominent, yet previously undetected, low-velocity body beneath the Western Alps, along the plate interface between the European slab and the overlying Adriatic mantle, which they interpret as a serpentinite layer.

Article | Open Access | | Nature Communications

Indian continental subduction can explain crustal deformation, magmatic activity and uplift of the Tibetan Plateau following collision, however, the nature of the Indian subducting slab beneath Myanmar and the related tectonic regime remain unclear. Here, the authors present direct structural evidence of present-day Indian continental subduction beneath Asia.

Article | Open Access | | Nature Communications

The India-Asia collision has formed the highest mountains on Earth and is associated with extensive intraplate deformation. Here, the authors present geodynamic experiments of continental deformation across Central, East, and Southeast Asia which suggest that the Pacfic and Sunda subduction zones played an active role during intraplate deformation.

Article | Open Access | | Nature Communications

The subducting plates can either penetrate straight into the lower mantle or flatten in the mantle transition zone, yet slab dynamics in the past remains unclear. Here, using subduction models, the authors predict that a hotter early Earth was probably more favourable to lower mantle slab penetration.

Article | Open Access | | Nature Communications

Feldspars are stable at pressures up to 3 GPa along the mantle geotherm, but they can persist metastably at higher pressures at colder conditions. Here, above 10 GPa the authors find  new high-pressure polymorphs of feldspars that could persist at depths corresponding to the Earth’s upper mantle, potentially influencing the dynamics and fate of cold subducting slabs.

Article | Open Access | | Nature Communications

Element and volatile cycles

Geological sources of H2 and abiotic CH4 have had a critical role in the evolution of life and sustainability of the deep subsurface biosphere, yet the origins of these sources remain largely unconstrained. Here the authors show that deep serpentinization (40–80 km) during subduction generates significant amounts of H2 and abiotic CH4, potentially providing energy to the overlying subsurface biosphere.

Article | Open Access | | Nature Communications

Sulfur is one of the key volatiles in Earth’s chemical cycles; however, sulfur speciation, isotopic composition, and flux during the subduction cycle remain unclear. Here, the authors provide direct constraints on subduction zone sulfur recycling from high-pressure rocks and explore implications for arc magmatism.

Article | Open Access | | Nature Communications

Trace amounts of water dissolved in minerals play an important role in global tectonics through changing the density, viscosity and melting behaviour of the Earth’s mantle. Here, the authors identify the presence of molecular hydrogen in nominally anhydrous ecolgite minerals from the Kaapvaal and Siberian cratons, indicating that the storage capacity of H in the mantle may have been underestimated.

Article | Open Access | | Nature Communications

The authors here perform experiments to investigate the dihedral angle of olivine-H2O and olivine-H2O-NaCl systems. The observed effect of NaCl to decrease dihedral angles allows fluids to percolate through forearc mantle wedge and to accumulate in the overlying crust, accounting for the high electrical conductivity anomalies in forearc regions.

Article | Open Access | | Nature Communications

Sulphur isotopes track recycling of subducted crustal material, yet few igneous rocks preserve these signals over Earth history. Here, the authors investigate a billion-year-old alkaline province in Greenland and are able to reconstruct a recycled mantle source, thus alkaline rocks can be used to reveal crustal recycling through geological time.

Article | Open Access | | Nature Communications

The early Earth’s atmosphere had very low oxygen levels for hundreds of millions of years, until the 2.4 Ga Great Oxidation Event, which remains poorly understood. Here, the authors show that reducing Archean volcanic gases could have prevented atmospheric O2 from accumulating, and therefore mantle oxidation was likely very important in setting the evolution of O2 and aerobic life.

Article | Open Access | | Nature Communications

Magmatic systems

Porphyry copper and gold deposits are the dominant natural suppliers of these metals to our society, yet the large variations in metal endowments of porphyry Cu–Au deposits remain obscure. Here, the author shows that Cu-rich porphyries require large amounts of magma and water to be formed, while Au-rich porphyries are the result of a better efficiency of Au precipitation.

Article | Open Access | | Nature Communications

Hydrous and alkali rich magmas rise through the lithosphere and may host gold-rich ore deposits – a poorly understood process. Here, the authors present new chalcophile element data across a metallogenic section of the lithosphere and suggest a continuous or staged ascent of magmatic-hydrothermal settings from mantle to upper crust.

Article | Open Access | | Nature Communications

The oxidised nature of arc magmas is either attributed to recycling from the slab or magma differentiation. Here, the authors show that oxidised iron and sulfur, respectively in sub-arc mantle spinel and glass inclusions with elevated U/Th, Pb/Ce, Sr/Nd and δ34S, trace dehydration products of slab serpentinites.

Article | Open Access | | Nature Communications

The composition and tectonic affiliation of Earth's earliest crust remains disputed. Here, the authors find that Archean Jack Hills zircons crystallized from melts with compositions similar to andesite formed in modern subduction settings, which they suggest is consistent with an early onset of modern-style plate tectonics on Earth.

Article | Open Access | | Nature Communications

The permeability of a dome exerts a control on the outgassing efficiency of the underlying magma. The authors investigate the role of hydrothermal alteration on this process in the laboratory and use these data to model whether the overpressures generated are capable of promoting explosive behaviour.

Article | Open Access | | Nature Communications

Volatiles such as water play a key role in magma ascent and ultimately triggering explosive eruptions. Here, the authors show that water-rich melts with water concentrations of 6–9 wt.% can ascend rapidly to the surface over the timescales of hours to days with very short warning times.

Article | Open Access | | Nature Communications