The Sequence Stratigraphy of Transgressive Black Shales
Published:January 01, 1993
Black shales are relatively deep-water facies that form in basin center locations in epicontinental settings. At times of rapid relative sea level rise, conditions in epicontinental basins can become sufficiently deep (even in marginal settings) for the accumulation of thin black shales in close association with shallow-water facies. Using examples from the British Lower Jurassic (the Jet Rock) and Upper Carboniferous (marine bands) these thin transgressive black shales are classified into two categories: (1) Maximum flooding black shales—which are usually condensed, and pass into considerably thicker nearshore facies. Condensed sections are separated from sequence boundaries by sediments of the transgressive systems tract. (2) Basal transgressive black shales—which are associated with the initial flooding surface across sequence boundaries. They show no lateral facies variation, and do not connect laterally with contemporary nearshore or shoreline facies.