Abstract: Lithostratigraphy vs. Sequence Stratigraphy

Art D. Donovan

Traditional lithostratigraphy utilizes facies boundaries, pebble lags, and/or transgressive surfaces as the basis for regional correlations and the subdivision of sedimentary rocks. This methodology provides an excellent framework for mapping, defining, and naming stratigraphic units.

In contrast, sequence stratigraphy utilizes stratal surfaces (bed, bedset, parasequence, parasequence-set, and sequence boundaries) as the basis for regional correlations. Stratal surfaces separate older rocks below from younger strata above, and therefore have chronostratigraphic significance. Since stratal surfaces typically cross lithostratigraphic boundaries and have chronostratigraphic significance, they can be used to subdivide the rock record into genetically related packages of strata (bed, bedsets, parasequence, parasequence set, sequence) that are inherently different from traditional lithostratigraphic units (group, formation, member, bed). Thus, sequence stratigraphy provides geologists with an alternative methodology to subdivide the stratigraphic record, and evaluate the temporal and spatial distribution of facies.

The role of sequence stratigraphy in providing new insights into stratigraphic relationships will be illustrated using selected examples from the Cretaceous of North America. In these examples, sequence stratigraphy offers a more predictive framework to explain the distribution of reservoir-quality sandstones and stratigraphic traps than traditional lithostratigraphic frameworks.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994