Evidences of Widespread Cretaceous Deep Weathering and Its Consequences: A Review

摘要

This study highlights the effect of the Cretaceous greenhouse climate on weathering processes. Atmospheric CO2 level was relatively higher in the Cretaceous than it was in both the Jurassic and the Cenozoic. Consequently, temperature and humidity were higher in the Cretaceous than in the Jurassic and the Cenozoic. The interaction among the high levels of atmospheric CO2, extreme global warmth, and humidity in the Cretaceous resulted in widespread deep weathering. Cretaceous palaeo-weathering profiles are observed to occur at higher palaeolatitudes relative to the Jurassic and Cenozoic palaeo-weathering profiles. This implies the upward warming of the Cretaceous palaeolatitude, consistent with palaeotemperature estimates for the Cretaceous. The present thickness of weathering profiles in some selected tropical zones is approximately 200 m. During the greenhouse climatic condition in the Cretaceous, the thickness of weathering profiles at those areas could have been up to 4–5 times the present value. This suggests that many sediments were produced from the Cretaceous weathering events.