Reports: DNI856988-DNI8: Determining initiation conditions for glass ramps: case study at the leading edge of the great Permian spiculite belt

Kathleen A. Ritterbush, PhD, University of Utah

Importance of the research Sea sponges rarely made rocks at the kilometer scale, but when they did they made rocks of great economic value but unclear paleo-ecological and geological implications. This project explores the largest sponge-rock event from Earth’s history: the Permian Spiculite Belt. Permian rocks from Utah to Svalbard include cherty rocks made primarily of microscopic sponge spicule grains. Around the world, variously aged “spiculites” produce enormous petroleum reserves (i.e. Kansas, USA) and direct the formation of gold, silver, and polymetallic ore development (Central Peruvian Andes). This project aims to map the temporal and spatial distribution of sponges at the southern frontier of the Permian belt, and to determine ecological and environmental conditions of the sponges’ initiation, persistence, and termination. In academia, marine sedimentary rocks are classed as either siliciclastic or carbonate. The methods, questions, jargon, and people that work on these rocks differ tremendously. Chert rocks, including those reaching thousand-meter thickness in NW Utah, are too often disregarded as difficult to work on, opaque to microfacies interpretation, and likely so diagenetic that they couldn’t reveal past paleoecological information. We are showing that some of these cherts are, instead, vital paleoecological phenomenah that represent a state-shift from carbonate ramp conditions to “glass ramp” conditions. We are learning the environmental context (climate, weathering) and ecological feedbacks (biomineralization, metabolic demands and trophic complexity of the system) of shallow coastal sponge deposits. Now we are poised to ask more fundamental questions about stability and hysteresis in marine ecological state shifts over temporal and spatial scales much broader than those accessible to modern biology. Importance to career of MS student Seana Hood Seana Hood is pursuing a master’s degree to become a geological mapper for a state or national survey. Her success with this ambitious project honed her skills and scientific independence, and placed her in field work and mentoring relationships with mappers for different state surveys. Seana arrived with excellent mapping and stratigraphic skills, and in her first year she learned to plan and execute effective expeditions, including navigating hazardous weather and accessibility conditions safely for her and her team. She learned to identify fossils and biofacies in the field and in microscopic samples, and has now repeatedly assisted state survey mappers in detecting and distinguishing local expressions of regional formations. She is now the lead of our microscopy lab, and trained other graduate students and survey geologists to use our advanced computer-imaging systems for microfacies analysis. Seana’s project is coming together well, and she showed posters at annual meetings of Rocky Mountain Geobiology; Geology and Utah Geophyscis Department; Rocky Mountain GSA; 1st International Geobiology Conference; and the annual Geological Society of America. She is now writing her first paper as a thesis, and I am confident she will get a good job with a survey or mapping organization. Importance for career of PI, Kathleen Ritterbush This research is the centerpiece of my career and of my intellectual group here at the University of Utah. It is the venue for my new field and lab research, the context for my graduate students’ theses, and the common cause uniting collaborations within our lab and abroad. I began planning this project before I interviewed for the faculty position. I scouted field sites when I started the job, and had a solid plan by the end of my first semester. The funding from ACS allowed me to recruit a stellar MS student, Seana Hood, to tackle challenging mapping and field aspects full-time while I was teaching. Anticipating Seana’s arrival, I recruited current MS student Zack Wistort to scout locations with me, and then advised his MS project to work on our rocks and outcrops, on a topic more practical for our purposes. He was thus able to orient Seana to our field sites, our GPS tracking methods, and the peculiarities of our particular cherts in the field. Meanwhile, I coached her on microfacies, stratigraphy, and paleoecological interpretation. This arrangement proved invaluable because I became pregnant by the time Seana arrived, so I could not access our remote field sites. Seana, Zack, and their undergraduate assistants became my eyes on the ground, and kept the project moving forward despite my parental leave. I recruited an additional student for computational work, who was able to help the team make 3D models of outcrops and fossils. I recruited Zack to continue into a PhD on the chert project. At group meetings, in graduate seminars, in presentations to the department and in poster sessions, it was now clear to my faculty colleagues that I was off and running with an ambitious project. Success of this project in our first year has established my research group and our work for an international audience. Seana successfully mapped the spatial distribution of sponge rocks across four small mountain ranges in NW Utah, and presented our ecological interpretations at four meetings, including two in Canada. Zack is submitting his first paper, a method to distinguish trace fossils in cherty carbonates, which should have broad applications for field geologists and paleontologists. Over the summer I gave an invited plenary talk at the first annual Geobiology Conference in Banff, Canada, where I showcased our glass ramp findings as vital ecosystem states and I posed questions about their dynamic changes from carbonate ramps. I used this hook to spice up a spiculite Review paper I submitted to Palaeo3, and as the premise of our second-year investigations. Seana and I also toured Permian spiculites in the Canadian rockies, and we have received invitations to work on spiculites in arctic Canada, in Svalbard, and in Armenia. This project and funding from ACS have established my place in the American west and abroad.