Black shales and other deposits that were enriched in organic matter on the continental margins in the early to late Paleozoic

Epochs of the predominance of the relatively cold climate conditions in the Paleozoic alternated with epochs of a warm or hot climate. The cooling climate intervals were accompanied by glaciation of some zones of Gondwana and a significant decrease in the sea-water level. These events are recorded in the structure of sedimentary formations that are enriched in organic matter (OM), which are called black shales; these are widespread along the margins of the Laurentia, Baltic, North and Southern China continental blocks. The sediments with a high content of sapropel organics are characteristic of the epoch of a hot climate, while they continued to accumulate in the intervals of drastic cooling. As a result, the area of black-shale distribution is sharply reduced within the continents and on continental margins, while they accumulated mainly in rift troughs and foredeeps, as well as on the outer shelf and adjacent areas of the continental slope. After the Carboniferous–Permian conquest of the land by higher plants organic matter that transformed into humus became dominant in sedimentary formations. © 2015, Allerton Press, Inc.