We numerically model the influence of an arc on back-arc extension. The arc is simulated by placing a hot region on the overriding plate. We investigate how plate ages and properties of the hot region affect back-arc extension and present regime diagrams illustrating the nature of back-arc extension for these models. We find that back-arc extension occurs not only in the hot region but also, surprisingly, away from it, and a hot region facilitates extension on the overriding plate.

The late Mesozoic igneous rocks in the South China Block exhibit flare-ups and lulls, which form in compressional or extensional backgrounds. The ascending of magma forms a mush-like head and decreases crustal thickness. The presence of faults and pre-existing magmas will accelerate emplacement of underplating magma. The magmatism at different times may be formed under similar subduction conditions, and the boundary compression forces will delay magma ascent.

Magnesium isotope ratios of arc lavas have been proposed as a proxy for serpentinite subduction, but uncertainties remain regarding their utility. Here we show that bulk serpentinite Mg isotope ratios are identical to the mantle, whereas the serpentinite mineral brucite is enriched in heavy Mg isotopes. Thus, Mg isotope ratios may only be used as serpentinite subduction proxies if brucite is preferentially mobilized from the slab at pressures and temperatures within the arc magma source region.

We use uncrewed-aerial-system-derived optical and infrared data, mineralogical and geochemical analyses of rock samples, and surface degassing measurements to analyze degassing and hydrothermal alteration at the fumaroles of the La Fossa cone, Vulcano island, Italy. We give a detailed view of associated structures and dynamics, such as local alteration gradients, diffuse active units that significantly contribute to the total activity, or effects of permeability reduction and surface sealing. 

A rapid quantitative identification criterion based on the basic chemical composition combination rules of red beds has been established, taking into account the correlation between red bed geomorphic characteristics, mineral compositions, and chemical compositions. The research results can also be applied to the quantitative identification of red beds in other fields, such as resources, ecology, environment, energy, and materials.