Periods of significant environmental and climatic upheavals throughout Earth’s history are usually associated with increased faunal extinction rates. Therefore, these time intervals present unique opportunities to further our understanding of the link between environmental changes and the evolution of life on Earth. The latest Permian to Early Triassic (ca. 252 – 247.2 Ma) was one such interval, being characterized by significant environmental and climatic disturbances, as well as the largest mass extinction of the Phanerozoic, which was accompanied by several diversification and extinction cycles of marine faunas. While still the subject of much scientific debate, the environmental and climatic perturbations of this time are most attributed to Siberian Traps Large Igneous Province (STLIP) magmatism. This thesis aims to further our understanding of the causes, timing, and spatial distribution of marine environmental changes associated with the biotic events of the latest Permian to Early Triassic. This objective is approached using temporally calibrated geochemical and isotopic records from continental shelf and offshore marine sedimentary successions deposited in the Tethys Ocean and which are currently situated in South China and Oman, respectively. The results from this thesis indicate that mercury (Hg) concentration anomalies (a proxy for volcanism) associated with the Permian–Triassic boundary (PTB) in South China post-date the PTB mass extinction event in the studied sections and can be explained by regional subduction-related arc volcanism. Similarly, Hg concentration anomalies recorded in Smithian to Spathian (Olenekian, Early Triassic) strata vary in magnitude and age across different localities. These Hg anomalies derive from a combination of enhanced terrestrial Hg input to marine depositional environments, subduction-related arc volcanism and hydrothermal fluid activity in the Tethys region during the Early Triassic. An investigation of marine sulfur (S) cycle changes (a proxy for ocean-atmosphere oxygenation) across the Smithian – Spathian interval (ca. 251.2 – 247.2 Ma) indicates that the global ocean was characterized by relatively low dissolved oxygen levels between the middle and latest Smithian (ca. 250.4 – 249.3 Ma). This dissolved oxygen depletion, coupled with a low seawater sulfate reservoir, permitted geologically rapid sulfur cycle perturbations across the Smithian – Spathian interval. The oxygen depletion coincided with both climatic warming and cooling, as well as with increased faunal diversification and extinction alike. However, the Smithian–Spathian boundary (SSB, ca. 249.29 – 249.1 Ma) was associated with cooler seawater temperatures and water column oxygenation. Finally, NeoTethyan seawater likely had oxygen isotope compositions of around -1 ‰ VSMOW during the Early Triassic. Based on these results, it is concluded that Hg concentration anomalies associated with the PTB in South China cannot be unequivocally linked to STLIP magmatism, and that evidence for renewed STLIP magmatism during the Smithian – Spathian transition remains elusive. As such, subduction-related felsic and intermediate arc volcanism in the Tethys region likely played a bigger role in driving environmental changes during the studied interval than previously thought. Furthermore, the results argue against a direct causal link between marine redox or seawater temperature changes and faunal diversification/extinction during the middle Smithian to early Spathian. Consequently, Early Triassic marine biotic events were likely driven by a combination of various biotic and abiotic factors, and not by environmental changes alone.