Mollies Nipple is a butte located in Kane County, Utah and is part of Grand Staircase-Escalante National Monument (GSENM). Mollies Nipple is now of particular interest to the Mars research community because of the presence of unusual diagenetic alunite and jarosite minerals. These minerals are present in sedimentary environments on Mars and have been used to interpret the diagenetic and depositional environments as acidic and/or arid. On Earth, these minerals are present in modern acid saline lakes, fumaroles, or acid mine drainage, but not commonly as diagenetic cements. The butte was mapped as Navajo Sandstone via photogeologic mapping, but the apex is 200 m higher than the surrounding upper extent of that unit in adjacent areas and there are some lithological inconsistencies that suggest the caprock may be a different overlying formation. Correctly understanding the diagenetic and depositional history of Mollies Nipple will inform future studies on Mars and has the potential to change the paradigm of these interpreted jarosite-bearing Martian environments. Stratigraphic sections were measured in the field and samples were collected for laboratory analysis. The dominant lithofacies is a cross-bedded quartz arenite. Structureless quartz arenite to wacke with lenticular green-gray quartz wacke (ash) is also present. Jarosite cement is common in upper sections of Mollies Nipple and is present, but sparse, in lower section of Mollies Nipple. Alunite is present in the upper section of Mollies Nipple. ANOVA conducted on point count data from samples collected from Nipple and representative samples of potential formations at Mollies Nipple do not differentiate between the possible formation candidate and Navajo Sandstone. Based on distribution of lithofacies, comparison with adjacent outcrops of Temple Cap Formation, Page Sandstone, and Carmel Formation, we conclude that the caprock at Mollies Nipple is most likely the Temple Cap Formation.

The placement of an unconformable surface within a stratal succession affects the interpreted thickness of units and sequences in contact with that surface. Unit thickness influences the interpretation of basin subsidence, paleotopography, diagenesis, and depositional style. Accurate placement of an unconformity results in true formational thicknesses for formations associated with that unconformity. True thicknesses aid in producing more precise surface to subsurface correlations, isopach maps, and paleogeographic maps. An unconformity may be difficult to identify in the stratal succession due to similar rocks above and below the unconformity and the presence of multiple candidate surfaces. Using statistical discriminant analysis of XRF data, formations bounding an unconformity can be discriminated by elemental composition which results in delineation of the associated unconformity. This discrimination is possible even for rocks that do not have significant differences in provenance if they have experienced distinct diagenetic histories. Elemental differences can be explained by quantity and type of cement. Three discriminant models were created. These models were tested with samples from three formations of similar facies, appearance, and provenance that are all associated with the same regional unconformity. All data, regardless of location, facies, or tectonic feature were used to create the first model. This model achieved moderate success by correctly classifying 80% of known samples. In a second model, data were grouped by facies trends. Separating the data by facies resulted in 94% of known samples being correctly classified. This model was most useful for delineation of an unconformity and discrimination of formations. A third model based solely on location or local tectonic feature produced the best results statistically. 96% of known samples were classified correctly. This third model does not compare locations to each other, thus making it less robust. This last model contributes by adding detail to interpretations made with the facies trend model.