Relationships between major sand body trends and facies distributions of the Cretaceous Gulfian Series in the Mississippi embayment and the Mississippian Chesterian 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, depositional strikes, and basin axes. Major sand bodies in the Gulfian and Chesterian Series have southwesterly trends that parallel the respective paleoslopes and basin axes, 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 Gulfian Series of the Mississippi embayment and the Chesterian Series of the Illinois basin. Both basins were open-ended to the south and sediments were introduced longitudinally at the northeastern end; the paleoslopes were to the southwest and parallel with the basin axes; the depositional strikes were east-west, normal to the basin axes; 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.
Figures & Tables
Geometry of Sandstone Bodies
This volume contains the eight papers presented as a symposium of the Research Committee of The American Association of Petroleum Geologists at the 1960 annual meeting in Atlantic City, New Jersey. One paper presented in the General Session at that meeting, one reprinted paper, and three other solicited papers are also included.
The choice of “Geometry of Sandstone Bodies” as a timely and pertinent subject lor the 1960 symposium was made after an extensive canvass of Research Committee members and about fifty other geologists vitally interested in research in petroleum geology. From a group of about 15 proposed subjects, this one was selected as first choice by almost all those canvassed. Partly because of this high level of interest, the decision was made to attempt publication of the symposium as a special volume of The American Association of Petroleum Geologists. The word geometry in the title probably had several different meanings among the selectors, and for this reason an attempt was made to define the term adequately in order to establish uniformity of communication among symposium participants.
The dictionary definition of the word “geometry” is the science of magnitudes in space. In applying the term to the symposium theme, some modification and interpretation of its formal meaning were needed, and the following definition was therefore proposed for use in this volume—
Geometry of Sandstone Bodies—Spatial relationships of sandstone deposits within the sedimentary framework.
As used in this book, the subject is more than just a three-dimensional study in which thickness is added to areal distribution.