Developed in the last two decades, carbonate clumped isotope approach (Δ47) is suitable for temperature reconstruction of the (re)crystallization (TΔ47) of all carbonate phases (Ghosh et al., 2006; Eiler, 2007). Unlike traditional oxygen isotope (δ18O) thermometers, clumped isotopes do not depend on the δ18O of the fluid from which the carbonate minerals developed (Eiler, 2007). This has significant implications for diagenesis and thermal history reconstruction of carbonate rocks in sedimentary basins.
In this study, geological samples were used as a natural laboratory which provides a testing ground to understand the behaviour of clumped isotope-exchange reactions through burial–exhumation complexity. The objectives are to investigate the robustness of clumped isotope thermometers to archive thermal history in recrystallized carbonates and to add more constraints on processes associated with the thermal history of a formation using several carbonate species (calcite and dolomite). First, a new approach was developed to safely cleans samples contaminated by organic matter and hydrocarbons. Using subsurface carbonate samples, the recrystallization and clumped isotope-thermal resetting of different limestone components work were then assessed. Finally, investigation of the kinetic differences between minerals in recrystallized limestone and dolostone at various stages of the burial process were conducted across a regional orogeny in Oman.
The results of this thesis indicate that different carbonate fabrics recrystallize at different water/rock ratios and with different susceptibility to thermal resetting with respect to clumped isotopes. Fine-grained matrix continues to recrystallize even at a low water/rock ratio during the deep stage of burial and records a wide range of temperatures, suggesting continuous and probably partial recrystallization. Here the evidence of cessation of dissolution and re-precipitation reactions during burial are stopped by oil emplacement was found, extending the application of clumped isotope analyses to petroleum migration studies. This thesis also confirms for the first time in a natural environment that calcite and early dolomite record a different clumped isotope history when subjected to the same thermal history. Finally, this thesis demonstrates that more geological phenomena can be discovered using calcite and early dolomite at the same sampling point, which offers additional constraints on the burial model.