Burial estimates constrained by clumped isotope thermometry: example of the Lower Cretaceous Qishn Formation (Haushi-Huqf High, Oman)

Accurate determination of the thermal history of sedimentary basins is critical to constrain the timing of diagenetic processes. Here, clumped isotope palaeothermometry is used to estimate minimum burial depth of the Lower Cretaceous Qishn Formation in east central Oman. Fossil oysters were collected in a soft argillaceous unit, thin-sectioned, and studied under petrographical and cathodoluminescence microscopy, revealing a variable state of shell preservations with early silica replacement of carbonate and late-stage calcite cementation. Clumped isotopes values varied from 0.602 to 0.666‰, with the best-preserved oyster shell yielding a temperature of 37 ± 4°C and a calculated oxygen isotope ratio in seawater (δ18Oseawater) compatible with Cretaceous seawater having experienced moderate evaporation (1.0–1.5‰ VSMOW). The new minimum estimates for the burial depth of the Qishn Formation is 1.0–1 …