Clumped Isotope Thermometry of Subsurface Carbonate Reservoirs, Central Oman

S.A. Al Balushi¹, K. Bergmann², J. Grotzinger², and J. Eiler²

Abstract

Clumped isotope thermometry is a relatively new geochemical technique that potentially can be used to estimate absolute paleotemperatures of carbonate minerals precipitation and recrystallization. This can be achieved based on measurements of 13C and 18O degree of ordering (“clumping”) into bonds with each other, making the 13C18O16O2−2 ion group in lattices of carbonate crystals. Temperature estimates are always accompanied by a measurement of carbonate σ18O, and this can be used to calculate the oxygen isotopic composition of the liquid that the carbonate minerals precipitated from or equilibrated with. However, there is a significant uncertainty on how burial processes have modified the isotopic composition. There is evidence that both recrystallization and solid-state diffusion within crystal lattices are important processes. Therefore, there is likely a time-depth dependency to these processes, though the details of these dependencies are currently poorly constrained.

AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain