Polyphase Laramide tectonism and sedimentation in the San Juan Basin, New Mexico
Steven M. Cather

Abstract:

Laramide tectonic subsidence in the San Juan Basin occurred in three discrete phases, and produced three episodes of sedimentation divided by basin-scale unconformities. Laramide deformation began 80–75 Ma as shown by thickness variations in the Lewis Shale and Pictured Cliffs Sandstone, and by apatite fi ssion-track cooling data in adjacent Laramide uplifts. The fi rst phase of rapid Laramide subsidence in the San Juan Basin culminated during late Campanian and early Maastrichtian time (~74–67 Ma) in the northwest part of the basin, and is represented stratigraphically by the Kirtland and Fruitland formations. Following a 6–8 My interval of basin-wide non-deposition or erosion, a second phase of subsidence occurred in late Maastrichtian to early late Paleocene time (~67–61 Ma), primarily in the northeast part of the basin. Resulting deposits consist of the Ojo Alamo Sandstone (Naashoibito and Kimbeto members) and the Nacimiento Formation. A second period of non-deposition or erosion, possibly basin-wide, ensued in the late Paleocene. The third phase of rapid subsidence and accommodation began in the early Eocene, also in the northeast part of the basin, and caused deposition of the San Jose Formation. Nearly one kilometer of post-San Jose deposits of middle Eocene–early Oligocene age were present in axial part of the the San Juan Basin, but were subsequently stripped.


Citation:

  1. Cather, Steven M., 2003, Polyphase Laramide tectonism and sedimentation in the San Juan Basin, New Mexico, in: Geology of the Zuni Plateau, Lucas, Spencer G.; Semken, Steven C.; Berglof, William R.; Ulmer-Scholle, Dana S., New Mexico Geological Society, Guidebook, 54th Field Conference, pp. 119-132.

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