Long-term provenance supply records of the Emeishan large igneous province: implications for the extreme climate of the Early Triassic

The spatial-temporal climate and environmental effects triggered by the weathering of basaltic magmas after a large igneous province (LIP) eruption are not well known. Here, we present geochemical data from numerous sedimentary sites with a near-global distribution to explore the effects of juvenile basalt weathering of the low-latitude Emeishan large igneous province (E-LIP, ~260 Ma). These data show the weathering of basalt dominantly contributed to siliciclastic materials in proximal basins (> 6 × 10⁶ km²) at a timescale of up to ten million years. Our data thus provide evidence that, besides the gases released during the eruption, release of (metal) elements via weathering of basalt at low latitudes plays a significant role in surface geochemical cycling. The release of these elements likely facilitated the flourishing of tropical wetland flora in southwestern China during the Late Permian, resulting in the widespread formation of coal seams. Moreover, increased erosion rates, sharply reduced Chemical Index of Alteration (CIA), and exponentially increased bulk accumulation rates suggest a shift in the weathering regime of basaltic landscapes under the extreme climate conditions of the Early Triassic. This shift, characterized by intensified physical weathering, enhanced erosion in source areas but limited sediment transport, potentially resulting in the rapid disappearance of basalt weathering records in southwestern China.