Recovering Missing Continental Crust to Understand Paleozoic Tectonic Evolution in East Asia

Plate tectonics describes Earth’s lithosphere as a mosaic of rigid plates whose interactions drive volcanism, seismicity, mountain building, and crustal recycling. While oceanic crust is continuously created and destroyed as a conveyor belt, continental crust is commonly viewed as buoyant and long-lived. However, global geochemical estimates reveal a major imbalance between continental crust production and preservation, implying that large volumes of continental material have been recycled into the mantle throughout Earth’s history. The lack of direct geological evidence for this loss represents a key gap in our understanding of long-term Earth’s tectonic evolution.

Here, we address this problem using the record of NE Japan, a long-lived subduction system that preserves sedimentary and magmatic archives linked to arc processes. We analyze magmatic and detrital zircon U–Pb ages, Hf isotopes, and trace element (TE) geochemistry from forearc (sedimentary) and arc (igneous) units. Detrital zircon populations define age peaks at ~430, 360, 270, 184, 112, and 7 Ma, accompanied by a progressive loss of older zircon components through time. Hf isotopic data show three major shifts in crustal contribution that coincide with changes in the dominant age populations. In addition, REE systematics in igneous zircons indicate significant changes in magmatic redox conditions. Igneous zircon U/Yb ratios shift from enriched mantle/crustal values in 450–430 Ma samples to mantle values in ~270 Ma samples, documenting replacement of continental lithosphere with juvenile material. Ti-in-zircon temperatures show thermal pulses at ~430 Ma and ~270 Ma, supporting episodic magmatic flare-ups.

The sedimentary record reveals episodic magmatic flare-ups combined with sustained tectonic erosion, leading to the progressive removal of older crustal sources. A major Late Carboniferous event marks the complete loss of Precambrian crust beneath the arc, while we interpret that Cretaceous melting of the Permian arc crust might be linked to mid-ocean ridge subduction. These observations indicate cryptic continental loss beneath the NE Japan forearc. The igneous record corroborates the forearc sedimentary signal and provides additional constraints on the origin and evolution of individual crustal blocks. Together, the results are consistent with a Late Cambrian–Ordovician arc collision and help constrain the mechanisms responsible for large-scale continental loss beneath the NE Japan forearc during the Carboniferous, which should be accounted for in tectonic and paleogeographic reconstructions.