Date of Award

1967

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

C. O. Durham

Abstract

The Lake Bistineau Structural Bridge, an anticlinal subsurface feature extends between the Monroe and Sabine uplifts, trends east-west through Bienville Parish flanked north and south by the Minden and Winnfield basins, respectively. The bridge separates the basins, and probably reflects the presence of a deep basement arch. This arch influenced the thickness of overlying strata, such as the Louann Salt. Salt thickness and flow greatly influence bridge structure through time. Salt deformation was less on the bridge crest than the flanking basins because the salt is thinner on the crest. The bridge crest may reflect the basement arch crest. The basement arch may resemble the Triassic grabens of the southern Appalachians, bounded by similar graben faulting. The earliest documentation of the bridge is upper Jurassic. Mesozoic rocks show the bridge to be topographically higher than the basins, with lesser subsidence rates. This pattern persists from upper Jurassic through Cretaceous Taylor beds, although reduced in Taylor and Navarro time. The structural configuration of the bridge in Bienville Parish can be divided into the stable portion, in the central western third of the parish, and the deformed portion to the east of the stable bridge. The stable bridge joins the Sabine uplift immediately west of the parish and is less modified by salt flow. Bridge modification during its evolution were caused by salt flow beneath its flanks into piercement domes of the basins. Domal salt supply areas are synclinal "arms", extending from the basins onto the bridge flanks. These linear synclinal areas reveal the basin and bridge growth method. The bridge is a complex anticline dipping north into the Minden basin and south into the Winnfield basin. The basins are not structurally connected across the bridge demonstrating an independent growth history for each. Independent growth histories indicate the "North Louisiana Syncline" is not an adequate description of the area between the Sabine and Monroe uplifts. This report suggests that the term "North Louisiana Syncline" should be replaced by "Minden basin," "Lake Bistineau Structural Bridge," and "Winnfield basin," which form the most important geological features between the Sabine and Monroe uplifts.

Pages

255

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