Date of Award

1959

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

Geological investigations in Bossier Parish, Louisiana, disclose exposures ranging in age from lower Eocene Wilcox to middle Eocene Cook Mountain. Subsurface data indicate that the Sabine uplift, on the northeast flank of which Bossier Parish is situated, is complicated by several local structures in this area. This investigation has produced the first detailed surface geological map of Bossier Parish. The Wilcox group of lower Eocene age is represented by 300 to 550 feet of sediments which are undifferentiated except for the uppermost sand unit, the Carrizo formation. In Bossier Parish the interval between the top of the Wilcox group and the base of the Claiborne Sparta formation is undifferentiated throughout most of the parish. The sediments of this interval, 220 to 300 feet of glauconitic sand and clay, are mapped in central and southeast Bossier Parish as "undifferentiated lower Claiborne". In northwest Bossier Parish, adjacent to the Red River, this interval is divided into three formations which have been correlated by electrical logs with the Reklaw, Queen City and Weches formations of East Texas. Overlying these units are the Sparta formation, 220 to 300 feet of sand and interbedded sand and clay; and the Cook Mountain formation, 250 feet of glauconitic clay, sand and ironstone. These formations crop out in a general northwest-southeast belt across the parish and dip northeast at a rate from 15 to 60 feet per mile.

Tifo Pleistocene formations have been mapped in Bossier Parish and a third formation possibly is present* The youngest formation, the Prairie, is the only one to which a formal name has been applied; the other deposits are mapped as "undifferentiated terrace deposits". The Prairie surface extends over a large portion of Bossier Parish and tends to surround the Tertiary highlands* This surface is found to be 10 to 16 feet lower along tributary streams than the level along trunk streams* The same relationship is found in some of the recent alluvial deposits and is considered a possible explanation for the formation of Lake Bodcau during the last century. The topographically higher, older Pleistocene deposits are difficult to map due to lithologic similarities to the Tertiary blanket sands.

The Bellevue dome in east central Bossier Parish and the Sligo dome in south central Bossier Parish represent deformation which occurred along the edge of the Sabine uplift during the Tertiary. The Bellevue dome, which has undergone some 1,500 feet of vertical uplift, is indicated by the presence of Wilcox sediments as an inlier within the Claiborne outcrop. This structure lies along the northeast extremity of the Sabine uplift and is complicated by numerous faults. The Sligo dome is situated on the Sabine uplift and has not experienced the degree of deformation undergone by the Bellevue dome. The structure is not as apparent as the Bellevue dome but is indicated by eastward dips on the base of the Carrizo formation in excess of the normal amount which is 30 to 40 feet per mile northeast.

In T22N, R14W, in the Gilmer Hill community of Bossier Parish, a series of northwest-southeast and northeast-southwest normal faults have been mapped. These faults have displacements ranging from about 10 feet to approximately 40 feet and may have resulted from a basement flexure in this area where subsurface contours indicate a change of strike of the Upper Cretaceous Annona formation from northwest to a more westerly direction.

This investigation was conducted under the auspices of the Louisiana Geological Survey.

Pages

141

DOI

10.31390/gradschool_disstheses.538

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