Objective Following the mass extinction at the end of the Permian， microbialites were widely distributed in southern China， indicating a microbial bloom in the Lower Triassic following the cataclysm. However， microbialites generally exhibit low paleo-productivity， which seems to contradict the microbial explosion. This study analyzed the microbialites at the base of the Triassic Tianwan section in the Luodian area of Guizhou province， focusing on the petrological characteristics of micritic pellets and their thermal metamorphic evolution and sources of organic matter. The study clarifies the respective influences of microbially derived and seawater-trapped organic matter on pellet formation， with the aim of providing empirical evidence for exploring carbon cycling mechanisms in post-extinction microbialite systems. Methods In situ micro-area analytical techniques （optical microscopy， fluorescence microscopy， scanning electron microscopy （SEM） with energy-dispersive spectroscopy （EDS）， and laser Raman spectroscopy） were used to conduct a detailed analysis of various types of peloids within the microbialites from the Tianwan section. These reveal the distribution patterns and thermal metamorphic evolutionary characteristics of internal organic matter. Results Based on morphology and infill materials， the various peloids were classified into six types： type I （microbially-induced peloid， MIP）； type II （recrystallized microbially-induced peloid， RMIP）； type III （aggregated detrital peloid， ADP）； type IV （intraskeletal peloid， ISP）； type V （dolomitized peloid， DP）； and type VI （aggregated microbially-induced peloid， AMIP）. Raman spectroscopy-derived metamorphic roasting temperatures provide insights into the thermal history and transformation of these peloids. The organic matter in types I， II， IV and VI （MIP， RMIP， ISP and AMIP） shows thermal maturity similar to that found in primary cyanobacteria in microbialites and shell fragments， indicating a common diagenetic history and microbial origin. Of these， peloids I， II and VI exhibit low thermal maturation temperatures， with organic matter mainly derived from the photosynthetic and metabolic processes of primary cyanobacteria and other microorganisms within microbialite systems. Specifically， peloid VI formed when micritic particles wrapped around peloid I， linked to bioclastic micritization. peloid IV shows moderate thermal maturation temperatures， resulting from a mix of microbial micritization and siliceous clastic material. By contrast， peloids III and V （ADP and DP） evidenced significantly higher metamorphic temperatures， suggesting multiple thermal alteration events. Peloid III may have been formed by neomorphism； peloid V was primarily shaped by bioclastic micritization. Conclusions In summary， after the end-Permian mass extinction， microbial blooms， especially cyanobacterial photosynthesis， led to the generation of large amounts of dissolved organic carbon （DOC） in the oceans. Due to frequent fluctuations in seawater redox conditions and rapid temperature increases， the DOC was typically oxidized into CO₂ and released into the atmosphere， with only a small fraction being preserved as particulate organic carbon （POC） and deposited on the seafloor. Raman geothermometric analysis shows that most of the organic matter in the microbialite peloids， particularly in those associated with bioclastic peloidal envelopes， originated from the metabolic activity of primary cyanobacteria， which was the original organic matter in the microbialite system. A small portion of the organic matter may have been sourced from long-stored terrestrial organic matter in seawater， which underwent multiple diagenetic thermal alterations and shows higher thermal maturation temperatures. The thermal maturation of organic matter and mineral recrystallization during diagenesis had a significant impact on the efficiency of organic matter preservation， ultimately resulting in a low total organic carbon （TOC） content in the microbialites.