Depositional History of the Cretaceous Cliff House Sandstone, San Juan Basin, New Mexico

TEMPLET, PAUL L., and DAG NUMMEDAL, Louisiana State University, Baton Rouge, LA

The basal portion of the Cliff House Sandstone (A, B, and C benches and lowermost La Ventana) in northwestern New Mexico records a major regional transgression (third order sea-level fluctuation). Retrogradational parasequence stacking reflects this overall transgression. Parasequence development during an overall transgression is probably due to fourth order sea-level fluctuations. A measured section through benches A and B (lowermost Cliff House) contains two complete parasequences. Part of a third parasequence is observed

before reaching the end of the section. At the base, a flooding surface separates fluvial deposits from a complete regressive shoreface sequence. A second flooding surface precedes deposition of a coarsening-upward parasequence consisting of marine shale, inner shelf transition strata, and finally lower shoreface strata. A flooding event again precedes deposition of a shelfal marine shale/inner shelf transition deposit. The next overlying sandstone unit is found translated at least 16 km, and up to 50 km landward of the previously described section. This unit consists of the C bench and its correlative, the lowermost portion of the La Ventana tongue. A vertical section through the lowermost La Ventana encounters the following succession: a flooding surface separates fluvial deposits f om 8 m of overlying back-barrier strata. Above the back-barrier strata is a 9 in. transgressive lag deposited by marine ravinement processes. Above the transgressive lag is a coarsening-upward succession of inner shelf transition strata overlain by lower shoreface sands. Finally, a flooding surface separates the lower shoreface sands from inner shelf transition strata.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)