Identifying the sediment source of the Lower Cenomanian Maness ShaleShow full item record
|Identifying the sediment source of the Lower Cenomanian Maness Shale
|Davidson, Joshua Escobedo
|The Maness Shale is a clay-rich mudrock that marks the transition from a carbonate platform to a siliciclastic-dominated shelf at the inception of the Woodbine succession within the east Texas region of the Gulf Coast Basin. Although the Maness has not traditionally been regarded as a hydrocarbon source or reservoir rock within a lithostratigraphic context, using a sequence stratigraphic approach reveals the possibility of the Maness interval serving as both a source and reservoir rock in specific areas. Prior research investigated the Maness Shale within the vicinity of the San Marcos Arch, the East Texas Basin, and up to the western flank of the Sabine Uplift. However, none of these studies extended to the south of the Sabine Uplift, nor did they definitively identify the sediment source. Therefore, this study aimed to identify the sediment source of the Maness and to evaluate its potential as a source rock based on organic matter content. Identifying the sediment source involved the analysis of 338 raster well logs spanning nine counties (Rusk, Cherokee, Anderson, Houston, Trinity, Tyler, Polk, Angelina, and Nacogdoches) and the correlation of four horizons (Top of the Buda, Top of the intra-Maness, Top Maness, and Base of the Austin Chalk). The results yielded two structural maps, four isochore maps, three net sandstone maps, and one isochore map that combined the results from this and previous studies of the Maness. The maps indicate that the upper Maness interval, which was previously referred to as the lower Woodbine in studies by Ambrose et al. (2009), is dominated by a coarsening upwards sand package just west of the Sabine Uplift, suggesting a deltaic depositional environment. They also reveal pro-deltaic muds west of the Sabine Uplift in the East Texas Salt Basin, a bypass zone between the Houston Arch and the Lower Cretaceous shelf margin, and sand-rich slope deposits near the shelf margins. Conversely, the lower Maness interval is mainly characterized by shale, which drapes over the Buda Limestone throughout the study area. The results suggest that the sediment source for the lower Maness is located to the north of the study area, whereas the upper Maness has a deltaic sediment source just west of the Sabine Uplift but a primary source to the north, possibly originating from the Ouachita Highlands. Passey's ¿ log R method was applied to estimate organic richness in 5 wells using a sonic/resistivity overlay. TOC wt.% values were estimated by using the local geothermal gradient to estimate effective heating time and the Level of Organic Metamorphism (LOM). The findings indicate some potential within the Maness interval, yet they do not offer sufficient evidence to categorize the Maness as a viable source rock in the examined wells.
This item appears in the following Collection(s)
- Masters Theses