The EBL 10-027 drill hole goes through the 2.94 Ga top of the Ball assemblage of the Red Lake greenstone belt, northwestern Ontario. It reveals a succession of chemical sediments and siliciclastics that shows, for the most part, a progression from a hydrothermal signature with the formation of sulphides close to the bottom of the sequence to chemical sediments reflecting the influence of seawater at the top. The stratigraphy is dominated by sulphides, i.e. pyrite and pyrrhotite, carbonaceous slate, magnetite iron formation and chert. The chert varies from units roughly mixed up with siliciclastics and sulphides to chert that is nicely layered with sulphides and contorted to finely layered carbonate with dolomite crystals.
The drill hole has a true thickness of about 280 metres which allows the bottom sediments to reflect the geochemistry of deeper water hydrothermal activity with fluids rich in iron and manganese while the top is composed of carbonates that reflect the chemistry of a shallow, continental shelf environment.
The evident europium (Eu) anomaly present in the sample signifies the effect of the leaching of basalt which is interlayered with carbonate iron formation at the lowest point of the sequence.