About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

Rocky Mountain Section (SEPM)

Abstract


Mesozoic Systems of the Rocky Mountain Region, USA, 1994
Pages 273-298

Paleogeographic and Tectonic Controls on Some Lower and Middle Jurassic Erg Deposits, Colorado Plateau

Ronald C. Blakey

Abstract

Lower and lower middle Jurassic rocks on the Colorado Plateau are dominated by eolian deposition in large to regionally extensive ergs. Regional stratigraphic patterns were used to establish five major depositional sequences that are divided by major bounding unconformities. The sequences and their bounding unconformities consist of the following:

Sequence 1: J-0 unconformity, Wingate Sandstone and coeval Dinosaur Canyon Member of Moenave Formation;

Sequence 2: J-sub-k unconformity, sandy facies of Kayenta Formation and coeval Springdale Sandstone Member of Moenave Formation, silty facies of Kayenta Formation and coeval parts of Navajo Sandstone and overlying Navajo Sandstone;

Sequence 3: J-1 unconformity, Temple Cap Sandstone;

Sequence 4: J-2 unconformity, lower Carmel Formation and coeval parts of the Page Sandstone;

Sequence 5: J-s-up unconformity, transition member of Page Sandstone, upper Carmel Formation.

Analysis of the five sequences demonstrates that major portions of the eolian Wingate, Navajo, and Page Sandstones were flanked by coeval fluvial systems. In each fluvial-eolian system, eolian paleocurrents are opposed to fluvial paleocurrents. Sand, mud, and minor gravel was transported northwesterly by major river systems, some of which may have originated in the Ouachita System of west Texas. Northerly winds deflated fluvial plains to initiate major erg systems. Sand that escaped the ergs blew southward onto the fluvial plains and was then recycled northward. Sand that was transported by rivers northwest of the Colorado Plateau was blown back to the south.

Eolian deposition was frequently interrupted by fluvial and marine flooding and accompanying rise of the water table. The resulting bounding surfaces (super surfaces) reflect temporary demise of eolian deposition. In contrast, the sequence bounding unconformities reflect major tectonic, climatic, or eustatic events and mark the termination of the major eolian sequences.


Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24