Lacustrine coquinas and spherulites associated with Mg-rich silicates constitute extensive and important reservoirs in the Early Cretaceous Pre-Salt rift basins of Brazil and West Africa. Understanding what factors control the origin, deposition and distribution of these facies is challenging, especially as few good analogues occur at outcrop. Many aspects, such as coquina ecology and taphonomy, the precise genetic relationship between spherulites and Mg-rich silicates, and the diagenesis of Mg-rich silicates are poorly understood. This study utilizes analogue examples from China and Scotland to address these questions.
Early Jurassic lacustrine coquinas in the Sichuan Basin, China.
- The facies, architecture and depositional environments of the coquinas will be assessed to identify the processes responsible for the formation of coquinas.
- The coquina ecology and taphonomy will also be investigated in order to understand factors controlling molluscan productivity and growth in a lacustrine environment.
- The diagenetic trends within the coquina limestones will be studied to understand their effects on reservoir properties.
Origins of carbonate spherulites: examples from Early Carboniferous alkaline lacustrine sediments (East Kirkton, Scotland) and laboratory experiments.
- The mechanisms that initiate spherulite precipitation.
- The precise genetic relationship between spherulites and Mg-rich silicates.
- The lake conditions necessary for spherulite creation, and the interplay with volcanics on depositional systems.
Project length: 24 months from November 2017.
Contact: Li Guo