In the early Proterozoic - around 2.4 billion years ago - photosynthetically active microorganisms (cyanobacteria) began to produce oxygen. The accumulation of oxygen in the atmosphere and oceans are among the most significant events in the history of the Earth. The international and interdisciplinary project GOE-DEEP (Gabon and Oxygenation of Earth - Drilling Early Earth Project) is aiming to improve our understanding of these important events and to place them in the context of the Earth's history more than two billion years ago.

In the course of a drilling campaign by the ICDP (International Continental Scientific Drilling Program), eleven drill cores are recovered from the Franceville Basin in Gabon, central Africa. This area is considered to be one of the world's best preserved archives of sedimentary rock from this period. Those cores are intended to establish a new knowledge base in the fields of sedimentology, palaeontology, geochronology and geochemistry.

Scientists at LIAG analyze the borehole data

LIAG is responsible for the evaluation and interpretation of geophysical borehole measurements. These are used to generate a stratigraphic model of the Franceville Basin and to establish a better chronological classification of the drilled sections. As well as measurements that record the physical and chemical properties of the sediments, additional techniques are used to detect possible groundwater aquifers in the subsurface.

To complement these activities, a detailed petrophysical investigation program is being conducted. The aim is to systematically determine the porosity, permeability and rock density of the drilled sediments in order to gain an integrative understanding of their hydrogeological and sedimentological properties. The project also aims to investigate complex electrical properties of the sediments, such as frequency-dependent conductivity and polarization characteristics. In combination with the geochemical and geophysical borehole data, they could provide new, high-resolution insights into the diagenetic processes and oxygen availability during the Earth's early history.

The research carried out by LIAG will help to reduce uncertainties in the interpretation of geochemical signals and to reconstruct the original environmental conditions in this important phase of the Earth's history.