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Relationships between major sand body trends and facies distributions of the Cretaceous Gulf series in the Mississippi embayment and the Mississippian Chester series in the Illinois basin have been investigated. This study indicates that trends of major sand bodies in these two depositional basins are intrinsically related to their paleoslopes and depositional strikes. Major sand bodies in the Gulf and Chester series have southwesterly trends that parallel the respective paleoslopes, and that are normal to depositional strikes. Studies of directional properties enhance the predictability of these trends.
An impressive similarity exists between the sediments in the Gulf series of the Mississippi Embayment and the Chester series of the Illinois basin. Both basins were open-ended to the south and sediments were introduced longitudinally at the northern end; the paleoslopes were to the southwest and parallel with the basin axis; the depositional strikes were northwest-southeast, normal to the basin axis; sediment transport directions were to the southwest; and the depositional patterns are those of deltaic deposition in the north, becoming increasingly marine to the south.
Based on the parallelism exhibited by these features, a depositional model has been developed for this type of sedimentation in an intracratonic basin. Within the model, trends of major sand bodies are oriented parallel to the basin axis, paleoslope, and sediment transport direction; are normal to the depositional strike; and are the result of a deltaic pattern of sedimentation.
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