Print this pageP. N. Johannessen1 and D. Nummedal2
1Geological Survey of Denmark and Greenland (GEUS),
Copenhagen, Denmark
2Institute for Energy Research, University of
Wyoming, Laramie, WY, USA
ABSTRACT: Sequential Development of Paralic and Shallow Marine Sediments of the Upper Cretaceous Dakota Sandstone, San Juan Basin, USA: A Surface and Subsurface Study
The Late Cretaceous San Juan Basin is part of a foreland basin developed by loading of the lithosphere by thrust plates from the Sevier Orogenic Belt to the west, delivering sediment to the foreland basin. The study area is located within a large, Cenomanian embayment, the Seboyeta Bay.
The Dakota Sandstone in the western part of the Western Interior, San Juan Basin, New Mexico, consists of three backstepping shoreface sandstones; the Cubero Sandstone, the Paguate Sandstone and the Twowells Sandstone. Each of these shoreface sandstones can be followed in to the non-marine sediments of the Dakota Main Body towards west.
The study was based on 25 outcrop sections and 40 wells with gamma logs situated at a distance of 5 to 125 km from the outcrops. The outcrop sections and wells are distributed over an area of about 200 km x 200 km. A detailed sedimentological and sequence stratigraphic study was carried out on the Middle Cenomanian Paguate Sandstone and the Dakota Main Body. The development of the Paguate Sandstone is very similar to the Cubero and Twowells Sandstones. The combination of many outcrops and wells covering a large area makes it possible to construct detailed palaeogeographic maps for each of the three sandstone tongues.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado