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Methane-derived carbonates (MDCs) are common along modern and ancient continental margins, and the majority of such formations are associated with seafloor cold seeps. Here, we document petrographic, rare earth element+ yttrium (REE+ Y), carbonate clumped isotope temperature (T Δ47), and carbon-isotopic evidence from a shale succession in southern Tibet spanning a~ 28 my interval (ca. 113–85 Ma) that coincided with the mid-Cretaceous greenhouse event. At least nine limestone nodule-bearing horizons exhibit seep-associated sedimentary structures, including carbonate fabrics (eg, micritic crusts, crystal fans, and botryoidal textures) and 13 C-depleted isotopic compositions (δ 13 C carb<–32.3‰), which are indicative of methane-derived carbon sources. Along with sedimentary evidence, the patterns of T Δ47–δ 13 C carb–δ 18 O carb support precipitation of these MDCs over a large temperature …