AN AMAZON-SCALE DRAINAGE SYSTEM IN THE EARLY PENNSYLVANIAN OF CENTRAL NORTH-AMERICA

This study compares Morrowan conglomeratic sandstones from three basins in the central North American craton: Central Appalachian Basin (eastern Kentucky), Eastern Interior Basin (Illinois, Indiana, western Kentucky, and lateral extensions in Arkansas), and Hugoton Embayment (Kansas and Colorado) to develop realistic analogues for Morrowan fluvial systems and to compare the relative effects of tectonic subsidence, eustacy, and paleoclimate on sedimentation. Based on paleogeographic reconstruction, the paleodrainage for the Central Appalachian Basin is estimated to have ranged from 1,337,100 km(2) to 2,854,300 km(2), and for the Eastern Interior Basin from 1,568,600 km(2) to 4,011,500 km(2). These sizes are comparable in scale to the modern Amazon River drainage area. Paleodrainage for the Hugoton Embayment was considerably smaller, estimated at 128,600 km(2) to 282,900 km(2). Comparing the varying effects of tectonic, eustatic, and paleoclimatic controls, the Central Appalachian Basin and Hugoton Embayment were particularly affected by ongoing regional tectonism, whereas the Eastern Interior Basin was affected to a much lesser extent. Eustatic changes influenced the development of sandstones, particularly within the Hugoton Embayment and the Eastern Interior Basin: Effects of climate were much more difficult to estimate, but the low-latitude position of the eastern basins had significant effects on the maturity of the sandstones and on the sizes of the fluvial systems. Degree of seasonality affected styles of fluvial sedimentation and paleosol development.