In the Saar-Nahe Basin, at the turn of Carboniferous to Permian, lacustrine organic matter-rich mudstone (paper shales), algal limestone (biostromes and bioherms), and deltaic sandstone accumulated in lakes, ponds, and flood basins under a tropical climate. Lakes were probably interconnected frequently by lowland meandering rivers to form more or less continuous waterways with rich plant and animal life.

The paper shales provide key insights into paleoclimatic conditions and their relation to sediment supply in this fluvial-lacustrine system. Lamination was formed by varying input of suspended sediment to the lakes of equatorial Central Europe. During the wet season (summer), silt-rich suspensions were swept out into the lakes, driven by heavy rainfall after depositing coarser grained sediment at the lake margin. During the dry season (winter), floods were infrequent, and siliciclastic suspension input to the lakes was minimal. During the entire year, the biological production that formed organic matter-rich dark clay layers of the laminites was more or less constant. This seasonality of clastic input resulted in a variable thickness of intervals of delicate light/dark laminite couplets that are attributed to storm or flood events (weather-bedded).

These strata demonstrate that hydrocarbon reservoir and source-prone lithofacies can accumulate in relatively close proximity. In this system, shales with significant amounts of organic matter are genetically related to profundal limestones as well as to algal bioherms and biostromes forming in the same lake or pond. Interbedded organic matter-lean siltstone resulted from the same floods that carried coarse clastics from rivers into flood-plain ponds and lakes, forming lacustrine deltas. The fine-grained strata can be quite useful for understanding the distribution of hydrocarbon play elements as they contain a relatively complete record of depositional conditions that is integrated across the entire alluvial landscape.