oa Glacio-Eustatic Influences on Sedimentation and Diagenesis in Organic-Rich Fine-Grained Sediments of the Cariaco Basin

This study explores the complex interactions between sedimentological processes and early diagenetic transformations in the Cariaco Basin, a Neogene fault-bounded depression on Venezuela’s northern continental shelf. The basin, known for its anoxic conditions and high organic carbon content, has been a focus of scientific interest since the 1950s. The research highlights how factors like facies mineralogical composition, petrography, organic content, and texture influence early diagenetic processes in fine-grained sediments.

The Cariaco Basin’s unique conditions, including high sedimentation rates and extended periods of anoxia, have resulted in a sedimentary series with distinct textures and mineralogical compositions. The study analyzed three core sections from ODP 1002D, identifying seven lithofacies grouped into three facies associations. These findings were compared to sea-level fluctuations to develop an integrative depositional model.

Glacio-eustatic sea level changes significantly impact anoxic conditions in the basin, with lowstands leading to oxygenated conditions and highstands promoting anoxia due to increased nutrient input and productivity. Additionally, early diagenetic modifications, such as the formation of authigenic carbonates and pyrite, were observed, suggesting a correlation with organic matter presence.