SUMMARY

The distribution of the well-developed sands which form the surface and near-surface deposits of both the Recent and late Pleistocene is diagrammatically shown in Figure 52. The alluvial and deltaic meander belt and straight channel sands shown in black trend approximately at right angles to the regional depositional strike. The deltaic sands bifurcate towards the coast.

The deltaic fringe sands are not shown in this figure, but their occurrences are indicated by the distributary patterns. The barrier island and transgressive beach sands, indicated by red, are parallel to the regional depositional strike. The marine sands are patchy, but their distributions are believed to be controlled by the underlying occurrences of deltaic and other shoreline sands.

As summarized in this report, the sequence in sedimentary features, grain size, sorting, fauna, and flora, and the geometry, associated facies, geological framework, and setting are criteria for the recognition of sand bodies similar to those formed in the depositional environments of the northwestern Gulf of Mexico. In many cases the SP log should be an important tool in determining the generalized sequences in grain size. In order to employ directional features such as cross bedding and grain orientation in the prediction of a sand trend, it is necessary to have a thorough understanding of the relationships between the directional features and the genesis, geometry, and framework of a similar Recent sand model.

The results reported herein represent a continuation of the investigation of the Recent Depositional Environments and Related Facies as reported in EPR Report 162 by R. J. LeBlanc.

The writers gratefully acknowledge the assistance and advice of R. J. LeBlanc, R. H. Nanz, E. H. Rainwater, and many others. Most of the text in this paper was presented at the January 1958 Production Geology Conference, Houston, Texas, and preliminary copies were printed and presented to the delegates of the May 1958 and Fall 1958 Seminars on Clastic Sediments.