Episodic zircon age spectra mimic fluctuations in subduction

Area of Science:

• Geochronology
• Plate Tectonics
• Petrology

Background:

• Zircon age distributions exhibit episodic patterns on billion-year timescales, often linked to supercontinent lifecycles.
• Dominant models propose fluctuating magmatic productivity or selective zircon preservation during continental assembly.
• These processes have profound implications for crustal growth, plate tectonics, and mantle outgassing.

Purpose of the Study:

• To investigate the physical processes driving zircon age episodicity.
• To analyze Phanerozoic zircon ages within global plate tectonic models extending to the mid-Paleozoic.
• To test the relationship between subduction flux and zircon age distributions along active margins.

Main Methods:

• Analysis of a large collection of Phanerozoic zircon ages.
• Application of global, full-plate tectonic models.
• Scrutiny of zircon age distributions along two long-lived active margins.
• Correlation of zircon age peaks with regional subduction flux and length.

Main Results:

• A clear relationship exists between regional subduction flux and zircon age distribution along active margins.
• Zircon age peaks consistently follow intervals of high subduction flux with a ~10-30 million-year time lag.
• Subduction flux demonstrates a stronger correlation with zircon age distributions than subduction length.

Conclusions:

• The findings suggest an intrinsic delay within the subduction-related magmatic system.
• Convergence rates, reflected in subduction flux, significantly influence melting volumes in subduction zones.
• This has direct implications for regulating crustal growth over geological timescales.