The latest Triassic to Early Jurassic interval was characterized by periods of sustained large igneous provinces (LIPs) activity and associated global carbon-cycle perturbations, as well as recurrent marine redox and sea-level changes. These coupled environmental changes would have strongly influenced marine biogeochemical cycling, yet their effects on the sulfur cycle remain insufficiently resolved, especially across the end-Triassic mass extinction (ETME) and the Sinemurian-Pliensbachian Boundary Event (SPBE). Here, we present a continuous carbonate-associated sulfate sulfur-isotope (δ³⁴S_CAS) record from the Prees 2C core (Cheshire Basin, UK), spanning the Triassic-Jurassic boundary to the lower Pliensbachian. The obtained record reveals a >10‰ positive δ³⁴S_CAS excursion across the ETME interval, indicating intensified marine deoxygenation and enhanced burial of ³²S-enriched reduced sulfur. The excursion peaks between the two recognized ETME extinction phases, suggesting substantial redox deterioration after the initial biotic crisis. Across the SPBE, δ³⁴S_CAS increases by ~6‰, closely matching the trends in coeval records from the eastern Tethys. Sulfur-cycle box modelling indicates that, under low Early Jurassic seawater sulfate concentrations (~1-1.5 mM), a ~1.5-fold increase in pyrite burial is sufficient to reproduce the observed isotopic shift. We propose that the SPBE sulfur-cycle perturbation was driven not solely by prolonged CAMP degassing-driven marine anoxia, but by the combined effects of volcanic forcing and tectono-eustatic induced shelf expansion, resulting in enhanced organic-matter and pyrite burial. Comparison with existing global records further reveals persistent regional δ³⁴S_CAS heterogeneity within the “low”-sulfate Early Jurassic Ocean, reflecting limited sulfate-reservoir buffering and regional differences in water-mass exchange and reduced-sulfur burial.

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