--> Late Campanian Coal-Bearing and Tidally Influenced Strata of the Neslen Formation, Book Cliffs, Utah and Colorado, by M. A. Kirschbaum, R. D. Hettinger, and P. J. Mccabe; #90986 (1994).

Datapages, Inc.Print this page

Abstract: Late Campanian Coal-Bearing and Tidally Influenced Strata of the Neslen Formation, Book Cliffs, Utah and Colorado

Mark A. Kirschbaum, Robert D. Hettinger, Peter J. Mccabe

The 80-120-m thick Neslen Formation crops out along 100 km of the Book Cliffs. The formation contains coal beds, up to 2 m thick, interbedded with siliciclastic strata. In the west, lenticular sand bodies, up to 5 m thick, have cross-beds with unidirectional paleocurrent indicators, and contain Teredolites. These sand bodies are interpreted as fluvial channel deposits that experienced some tidal influence. The sand bodies grade downstream into inclined heterolithic units that contain cross lamination, mud drapes that extend all the way down the inclined surfaces, and a diverse trace-fossil assemblage. The inclined units are interpreted as the fills of tidal channels. Farther east, wavy-bedded and burrowed sandstones and fossiliferous shales interfinger with cross-bedded sandstones tha have multiple reactivation surfaces and bidirectional paleocurrent indicators. These units are interpreted as lower estuarine deposits.

In the east, the Neslen Formation is interbedded with hummocky and swaley cross-stratified beds of the Corcoran and Cozzette sandstones, which are interpreted as shoreface deposits. Erosion surfaces, with up to 20 m of relief, cut into the shoreface strata and are, in turn, overlain by estuarine and coal-bearing strata. The erosion surfaces can be traced over distances of 30 km and are interpreted as sequence boundaries cut during lowstands of relative sea level. Although previous studies suggested a delta-top setting for coal deposition, the coals apparently formed within valleys during times of relative sea level rise.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994