Date of Award


Degree Name

Master of Science


Geological Sciences


Benjamin Brunner


For oil exploration, stratigraphic correlation of formations over distance and across structural complications is essential. I tested if an established method – carbon and oxygen isotope composition of carbonates (δ 18Ocarbonate, δ13Ccarbonate) and a new chemostratigraphic tool – sulfur isotope composition of Carbonate Associated Sulfate (δ34SCAS) can aid in the correlation of rock packages belonging to multiple stacked carbonate horizons from a carbonate platform.

In my study area, located in the Brokeoff Mountains, north of the Guadalupe Mountains National Park, the δ18Ocarbonate, δ 13Ccarbonate and δ34SCAS scatter strongly within single beds of the Leonardian-aged Victorio Peak Formation. In stratigraphic order, the δ18Ocarbonate, δ 13Ccarbonate and δ34SCAS also strongly scatter, making it difficult to identify distinct isotope trends. The scatter in δ18Ocarbonate and δ 13Ccarbonate is predominantly caused by meteoric diagenesis and dolomitization, processes that change the original δ18O carbonate and δ13Ccarbonate to lighter or heavier values. The scatter in δ34SCAS is mainly caused by the addition of isotopically light sulfate from pyrite oxidation. Importantly, the δ34SCAS for the samples from the Victorio Peak Formation are heavier than what is expected for the ?34S of sulfate from Permian seawater, indicating that during the Leonardian, the sulfur cycle within a part of the Permian basin was partly decoupled from the global ocean.

The findings of this pilot study lead to the conclusion that δ 34SCAS is not a suitable chemostratigraphic tool in an industry setting, where rapid assessment/analysis and low costs are essential. However, for the reconstruction of the paleoceanographic evolution of Permian basin, δ34SCAS has the potential to yield unprecedented insight into intrabasinal sulfur cycling, which is tied to basin restriction, water column stratification, and paleoproductivity.




Received from ProQuest

File Size

112 pages

File Format


Rights Holder

Eric Bergersen