Episodic continental arc magmatism: Tempos of the Peruvian arc

Pompe L.R.; Martínez Ardila A.M.; Clausen B.L.; Paterson S.R.; Poma O. · Journal of South American Earth Sciences (2026) · DOI: 10.1016/j.jsames.2026.106151

Resumen

The Phanerozoic American Cordillera provides an excellent opportunity to study processes contributing to the creation of continental crust. The rate of magma emplacement into the arc over time is non-steady, being composed of a series of high magma addition “flare-ups” against an intermittent and variable lower level of background magmatism, or “lulls”. We add new U-Pb ages for igneous bedrock samples and detrital zircons from sedimentary rocks to existing geochronological data to describe the magmatic history of the Peruvian arc. Detrital zircons from three sedimentary samples collected from locations in the west, center and east of the arc show across-arc magmatic variation patterns. Flare-ups in magmatism from segments of the Peruvian Coastal Batholith (PCB) and Eastern Cordillera (EC) are analyzed to estimate the volume and rate of mantle magma addition (MMA) to the crust. Average flare-up duration is longer for the EC than for the PCB at ∼57 vs ∼27 My. Flare-ups are found to have variable durations from ∼15 to ∼64 My with variable periodicity, thus being episodic in nature rather than cyclic. Magma volumes are calculated from map data, crustal thickness estimates based on element ratios, and an empirical study of tilted crustal sections. Total MMA volume added to the arc crust during flare-ups and lulls is estimated at ∼2500k km3 for the PCB and EC, a rate of ∼6500 km3 per My, assuming a mantle/crust ratio of 65/35. Impacts of high flux magmatism and implications of magma episodicity on the continental subduction system environment are considered.

Instituciones: Universidad Peruana Unión