subductionera

Subductionera is a term used in some geological discussions to denote a hypothetical geologic era characterized by pervasive subduction-driven plate tectonics. In this concept, oceanic crust is repeatedly recycled through subduction zones, giving rise to extensive trenches, mature volcanic arcs, accretionary prisms, and efficient crustal recycling that shapes continental growth and mantle dynamics. Subductionera is not an officially defined epoch in the geologic time scale, but appears in theoretical models of tectonic evolution and debates about the onset and longevity of modern-style plate tectonics.

Key features would include persistent subduction beneath multiple plates, widespread arc volcanism and related batholith formation, and large-scale formation of accretionary complexes and forearcs. Metamorphism associated with subduction zones, such as high-pressure/low-temperature belts, would be common, along with recycled crust signatures in mantle-derived magmas. The era would also involve significant volatile recycling and changes in mantle geochemistry driven by subduction input.

Evidence cited for subductionera includes preserved ophiolites, blueschist and eclogite facies rocks, and isotopic patterns in arc rocks indicating crustal recycling. Dating and global synchronization of subduction-dominated phases are debated and depend on definitional choices about what constitutes a subductionera.

In summary, subductionera is a conceptual framework used to discuss how sustained subduction could affect Earth's tectonic and geochemical evolution. It remains speculative and is not part of the formal geologic time scale.