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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 950

Last Page: 951

Title: Products and Processes of Ancient Arid Coastline: Lower Cutler Group (Permian), Southeastern Utah: ABSTRACT

Author(s): David B. Loope

Article Type: Meeting abstract


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In Canyonlands National Park, the Ceder Mesa Sandstone consists of 700 ft (213 m) of large-scale trough, cross-bedded, well-sorted sandstone. It conformably overlies 1,100 ft (335 m) of interbedded sandstone, limestone, and shale of the Elephant Canyon Formation. Sandstones of both formations, formerly interpreted as shallow marine, are here interpreted as eolian due to occurrence of: (1) subcritically climbing translatent strata produced by migrating wind ripples; (2) unimodal southeasterly dips; (3) rare vertebrate fossils and trackways; (4) gypsum sand crystal pseudomorphs; and (5) abundant calcified plant roots. In contrast, limestones, conglomeratic sandstones, and shales of the Elephant Canyon contain diverse marine body and trace fossil faunas, and dip directions are widely dis ersed.

Roots occur along twelve major bedding planes in the Cedar Mesa, several of which can be traced at least 16 mi (26 km). These planes are not channeled by overlying trough cross-beds. Planes do not climb downwind and are thus unrelated to migrating bedforms. Roots also occur along the planar tops of 15 eolian sandstone bodies in the Elephant Canyon, but are there overlain by fossiliferous marine carbonates. The planes are interpreted as eolian deflation surfaces resulting from decreased sand supply to a coastal dune field. A modern analogy is the Sabkha Matti south of the Persian gulf. Colonization by plants and growth of gypsum sand crystals was followed by transgression (Elephant Canyon) or by renewal of erg conditions (Cedar Mesa). Eustatic control of both sand supply and deflation s a strong possibility.

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