Estonian Tremadocian black-shales

Cross-section of a drill core from the Aseri deposit, showing alternation between beds of Tremadocian black shale , also known as ‘Graptolite Argilite’ and phosphorite-bearing sandstone.

The black shales are enriched with organic matter and are investigated for their V, Mo and U potentials. Also, they contain authigenic K-feldspars. This image represents the first horizons formed at the boundaries between the Kallavere Formation and the Türisalu Formation.

https://doi.org/10.1016/j.chemgeo.2023.121583