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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 57 (1973)

Issue: 9. (September)

First Page: 1823

Last Page: 1823

Title: Depositional and Directional Features of Braided-Meandering Stream: ABSTRACT

Author(s): J. W. Shelton, R. L. Noble, H. R. Burman, Jr.

Article Type: Meeting abstract

Abstract:

The Cimarron River in north-central Oklahoma shows characteristics intermediate between typical braided and meandering streams. The gradient is 1.8 ft/mi. at Perkins; the sinuosity is 1.5; the monthly average discharge ranges from 2 to 17,800 cu ft/second; and average channel depth at bankful stage is 15 ft.

The deposits are generally fine- to medium-grained, well-sorted sand, with scattered quartz and intraformational pebbles and thin beds of coarse-grained sand. Several clay drapes are present as thin discontinuous layers. Medium-scale crossbedding, horizontal bedding, and small-scale crossbedding are the dominant sedimentary structures. Compositionally the sand is an arkose, which suggests the Wichita uplift and the southern Rocky Mountains as ultimate source areas.

Irregularities and discontinuities in the sand deposits are due primarily to channel shifts during times of major floods and secondarily to deposition of clay during recession of high-water stages. The irregularities resulting from dissection of transverse dunes and superposition of ripples on dunes are thought to be of minor significance in causing reservoir variations.

Crossbedding, parting lineation, and grain orientation all define the sand trend very well and indicate that directional features in this type of sand deposit are useful in estimating reservoir trend. Directional imbibition parallels the dip of the crossbeds and grain orientation (and parting lineation) in horizontal beds.

Compared with typical meandering-stream deposits, the Cimarron River sand is thinner and contains less fine-grained clastics in the upper part of the sequence and as clay interbeds. It is finer grained than typical braided-stream sands, and current indicators show a wider directional range. The type of deposit represented by the Cimarron River sand may be similar to certain Pennsylvanian alluvial sandstones which were deposited as the gradient was reduced during the initial stages of eustatic rise in sea level.

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