Dr. Derek Sawyer led a field trip of SES students to the Guadalupe Mountains of west Texas and southern New Mexico during Spring Break March 11-16, 2019. The 6-day trip featured visits to classic locations of the Permian Reef Trail, Last Chance, Bone, Shumard, Slaughter, and Walnut Canyons, plus the Carlsbad Caverns and roadside stops at the Castille Evaporites and the Rader Slide.

The Guadalupe Mountains provide outstanding continuous exposures of a wide spectrum of carbonate and siliciclastic environments across a shelf-to-basin transect. Prior to the trip, students paired up to research an outcrop locality of their choosing. In the field, day trips were led by each team and as a group worked together to interpret depositional environments and synthesize observations to infer paleogeographic evolution. The goals of the course were to increase educational field-course opportunities for students and to provide direct experience in mixed carbonate-siliciclastic systems.

Class participants included: SES graduate students Christopher Conwell, Teresa Avila, Ryan Heber, Brent Lary, Datu Adiatma, and Brandi Lenz; SES undergraduate Jonathan Bell; and Ohio Department of Natural Resources geologists Erika Danielsen and Chris Waid.

“This trip provided an excellent opportunity to see both the stratal geometry and lithological patterns of depositional sequences in one region (and even at single outcrops!), helping expand my understanding of sequence stratigraphy in mixed clastic-carbonate environments.”

“The Guadalupe Mts region is a textbook case study of sequence stratigraphy. In locations like Last Chance Canyon, we were able to walk along exposed facies and study the sequence stratigraphy in person, which really helped to illuminate concepts that were harder to grasp in theory.”

“The best part of this trip is simply being able to put my finger on Sequence Boundaries (SBs). It is just spectacular!”

“My favorite part of the trip was in Bone Canyon, where we saw amazing angular unconformities, channel scours, breccias, and deformed sandstones in close proximity.”

“As a professional geologist, continuing to take field courses like this is invaluable to me. The mixed carbonate-siliciclastic deposits exposed in the Guadalupe Mountains provided excellent analogues to rocks that are not as well exposed here in the Midwest.  It’s great to bring new knowledge back with me and apply the concepts I studied on this trip to my research in Ohio.”

The field trip expenses were fully supported by The Ohio State University Center for Energy Research, Training, and Innovation (CERTAIN) Faculty Fellows Program award to Dr. Sawyer.

A new journal article led by Dr. Derek Sawyer published in Scientific Reports describes extremely large-amplitude waves that can be generated in hypersaline seafloor brine pools by the impact forces of submarine landslides.
Subsea hypersaline anoxic brine pools are among the most extreme habitable environments on Earth that offer clues to life on other planets. The hypersaline brine is too salty and anoxic to support all but extremophiles. The anoxic and abiotic conditions are favorable for outstanding preservation of sedimentary layers and organics, which makes them well-suited for paleoceanographic studies.

However, while brine pools are often assumed to be quiescent and stably stratified environments, our work describes how the impact forces of underwater landslides can cause significant disturbances of the brine as well as inject mass gravity flows into the sedimentary basin to disrupt the otherwise simple stratigraphy.
This study uses high-resolution seafloor bathymetry and three-dimensional seismic data to image the subsurface geology in the southern half of the Orca Basin in the deepwater Gulf of Mexico. Orca is one of the largest known brine pools in the world and is up to 220 meters deep, approximately 8,000 years old, and was discovered in the mid-1970s. Since its discovery, the Orca Basin, has been the site of important paleoceanographic studies, microbiological, geochemical, and a deep sea drilling program.

We use geophysical data that reveal large landslide scarps that lie hundreds of meters above the brine pool with debris and blocky deposits lying at the bottom of the brine pool (Figure 1). We describe the large-scale disruption to the brine pool that results from submarine landslides impacting the brine pool. Submarine landslides are capable of generating waves with amplitudes on the order of 200 meters, which rival the largest known ocean waves. A vigorous mixing will occur that will introduce significant amounts of oxygen, sediment, and organic matter to the brine pool system. The wave heights could exceed the confinement of their basins thereby spreading hypersaline brines to surrounding topographic lows. Landslides and their impact waves will greatly affect the physical structure of the biological community that are typically observed living at the edges and above brine pools.