| dc.description.abstract | A high-resolution sequence and geomechanical stratigraphic investigation was conducted on one of the most prolific formations in the Delaware Basin: the Permian, Leonardian aged, shelf to proximal slope Bone Spring formation, Shumard Canyon, Guadalupe Mountain National Park. This work incorporates a detailed X-Ray Fluorescence survey with outcrop observations to analyze a 5th- order sequence, the Leonardian 5 (L5) high-frequency cycle (HFS), and establish a 6th- order sequence framework for the classic Leonardian aged Bone Spring formation of Shumard Canyon in Guadalupe Mountain National Park. This location offers access to the stratigraphically highest units of the Bone Spring Formation which represent the updip portion of these basin fed systems, which laterally grades into the up-dip Victorio Peak Formation. Two detailed outcrop sections along slope and basin sections reveal that the L5 is divided into at least nine 6th order system tracts. Depositional settings and paleoenvironments sensitive to oscillations in sea level show pronounced differences in the study area. A hierarchical cluster analysis of 25 different elements shows seven major clusters, or chemostratigraphic packages, which served a major role in the detailing of the 6th order sequences. Redox proxies were used in order to determine that the foreslope was mostly developed under oxic to suboxic environments whereas toe-of-slope and basinal sections were mostly developed under suboxic to anoxic environments. The changes in redox conditions were mainly associated with relative sea level changes and circulation access to the Panthalassa Sea by the Hovey Channel.
In addition to geochemical data, geomechanical data were recorded along the two sections using a SilverSchmidt N-type Schmidt rebound hammer by Proceq. These data provided an opportunity to compare changes in the mechanical properties of the changing lithologies. These mechanical properties were tied to the 6th order sequences delineated with the geochemical data. This method is possible since the sedimentological changes that occurred in response to fluctuations in sea level result in varying lithologies. Using the 6th order sequence, a prediction of a unit’s brittleness is possible. In general, increased siliciclastic material results in more brittle lithology owing to the higher Young’s Moduli of quartz, while increased carbonate and clay can result in more ductile lithology. The TST and HST deposits identified in this study show lower overall hardness values than the LST and RST deposits. This change in mechanical properties is due to the high levels of carbonate material and lower amount of silica being transported into the basin, and results in a more ductile lithology. There are, however, higher amounts of chert present in the TST and HST deposits, which show very high hardness values and are very brittle due to the high silica content. The LST deposits identified in this study showed mid-range hardness values, owing to the increased levels of silica and decreased levels of carbonate paired with increased clay content. However, the RST deposits show the highest overall bulk hardness values, which is attributed to the increased deposition of siliciclastic silts without an increase in clay or carbonate material, resulting in more brittle lithology. The higher brittleness is paired with spikes Ni, Cu, and Zn, supporting the idea that there was an increase in organic matter rain at the time of deposition. These properties, in addition to other petrographic properties such as increased micro-porosity, make these RST deposits good sweet spots for unconventional targets. | en_US |
