Flat-Slab Subduction, the Laramide Orogeny, Uplift of the Colorado Plateau and Rocky Mountains: Paleocene and Eocene: Ca. 65–35 Ma

Abstract

The end of the Cretaceous gave way to the Paleogene Period, which includes the Paleocene, Eocene and Oligocene Epochs. At the dawn of the Paleogene (previously called the Early Tertiary), rapid sea floor spreading was occurring at the mid-Atlantic ridge, pushing fast-paced subduction at the western margin of the Cordillera (Fig. 9.1). Most of the continent was emergent during this interval with marine deposition limited only to the eastern seaboard, the Gulf of Mexico and the narrow fringes of the Pacific Borderland (Fig. 9.2). The accretionary prism of the Franciscan assemblage was still piling along the Coast Ranges but deposition of the Great Valley Sequence was superseded by several individual partitioned basins within the Central Valley. No large terranes arrived at the edge of North America during the Paleocene or Eocene Epochs.