Endolithic bloom linking with volcanic activities and biocrisis at the onset of the Guadalupian–Lopingian (Permian) extinction

Large-scale volcanism has been implicated in causing Phanerozoic mass extinctions, but little direct evidence of the effects of volcanism on microbiota interaction exist. Here we report abundant endolithic microboring traces from the Guadalupian–Lopingian (G–L; Permian) mass extinction transition in South China. Microanalyses using scanning electron microscopy (SEM), Raman spectroscopy, and nanoscale secondary ion mass spectrometry (NanoSIMS) reveal microborings comprising organic carbon, anatase, calcite, quartz, and clay minerals. Large amounts of organic carbon exhibit Raman spectrum peaks at ∼1366 cm‾¹ and ∼ 1603 cm‾¹, along with intense signals of ¹²C‾ and ¹²C¹⁴N‾ in NanoSIMS ion maps are interpreted as remnants of endolithic organisms or residues of their metabolic products. Well-crystallized quartz crystals, which can be assigned to α-quartz of volcanic provenance, are regularly aligned along microboring margins, reinforced by strong signals of ²⁸Si⁺ in NanoSIMS ion maps, suggesting that microbial adsorption of volcanic material during endolithic activity. Stratigraphic peak abundances of microborings and microbiota coincide with initial eruption phase of the Emeishan volcanism, implying that volcanic activity may have stimulated an endolithic bloom at the onset of the G-L mass extinction.