Chapter 4 - The Appalachian and Black Warrior Basins: Foreland Basins in the Eastern United States

Abstract

The Appalachian and Black Warrior basins represent only two of the more than 200 sedimentary basins that have developed across the North American landmass, but these basins have probably had more influence than many others in understanding the interplay between sedimentation, structure, and tectonics. This is especially true for the Appalachian Basin, which is a composite, retroarc/peripheral foreland basin that formed during five orogenies. In many ways, the Appalachian Basin is the “type” foreland basin and the “type area” for the Wilson cycle. Our understanding of the basin, and others like it worldwide, is largely the legacy of a single observation by James Hall in 1857, an observation that also effectively established the framework for the later plate-tectonic paradigm, not to mention major framework developments in structure, tectonics, isostasy, flexural modeling, stratigraphy, sedimentation, paleoclimate, and paleogeography. As preserved today, the basin is about 2050km long with an area of nearly 536,000km2, extending from southern Quebec in Canada to northern Alabama in the United States; it reflects the structural influence of earlier Grenvillian convergence and Rodinian dispersal, as well as the paleoclimatic, paleogeographic, eustatic, and tectonic history of eastern Laurentia/Laurussia from latest Precambrian to early Mesozoic time. The associated Black Warrior Basin, on the extreme southwest margin of the Appalachian Basin, is a peripheral foreland basin that developed during a single orogeny. It is a more local basin, and as preserved today, it is about 383km long by 313km wide and encompasses an area of nearly 63,900km2. During latest Precambrian to Early Ordovician time, the recently formed, southern to southeastern Appalachian margin of Laurentia, which now includes both basins, experienced mainly synrift and postrift, passive-margin sedimentation, largely controlled by local structure, regional climate and eustasy. However, by Cambrian time, on some of the more distal outboard parts of the Laurentian margin, the initial tectonic reorganization that would ultimately produce these basins had already begun.