PBS-SEPM 2022 February Luncheon - Dr. Pamela Hallock Muller

"Strategies for Energy Capture Indicate Environments of Carbonate Production"
 
Presented by Dr. Pamela Hallock Muller at the February Luncheon Meeting of the Permian Basin Section-SEPM
Tuesday, February 15, 2022
 
ABSTRACT:  The distinction between Photozoan and Heterozoan Associations is a primary consideration when interpreting carbonate depositional environments. Because biogenic carbonate production requires energy, recognizing whether sources are primary or secondary production of organic matter is critical. Photozoan carbonates are produced in waters sufficiently shallow and clear to support photosynthesis as the direct energy source, and the morphologies of major producers reflect whether irradiance supported three-dimensional structures, two-dimensional surfaces, or something in between. Hydrodynamics is reflected in associated sediment textures and by robustness of the calcifiers. Evidence for rapid production rates (i.e., hypercalcification) also indicates mechanisms such as evaporation or warming that increased carbonate supersaturation of surrounding waters. Environments of production and deposition of Heterozoan carbonates are more diverse and challenging. Coralline red algae in Heterozoan carbonates indicate production within the photic zone. Larger benthic foraminifers can thrive in cooler waters and at lower carbonate saturation states than aragonite-producing corals and calcareous algae, so their presence, along with coralline algae, can indicate transitional conditions, especially in shelf and ramp settings. In Heterozoan carbonates where benthic photosynthesizers are absent, conditions that can be inferred are that food supply, generally plankton, is sufficient to support thriving populations of the major carbonate producers. In modern shallow coastal systems, bivalves, gastropods and barnacles thrive in phytoplankton-rich waters, though their preservation potential may be limited by dysoxic pore waters or low carbonate saturation. On outer shelf and slope environments, physical processes such as contour currents and internal waves can deliver plankton to azooxanthellate corals, bryozoans, and crinoids, promoting accumulation of aphotic bioherms. Environmental conditions supporting oligophotic Photozoan assemblages can transition to conditions supporting aphotic Heterozoan plankton feeders with relatively small changes in depth or overlying water transparency. Fortunately, functional morphologies of these two energetic strategies are very different.
 
BIO: Pamela Hallock Muller earned her BS in Zoology from the University of Montana in Missoula in 1969. In 1972 she received her Masters of Science degree and PhD. in Oceanography from the University of Hawai’i at Manoa, Honolulu. She went on to do postdoctoral research at the University of Copenhagen, Denmark and Kiel University in Germany. Pamela had her first professional appointment in 1978 at the University of Texas at Permian Basin as an assistant professor. In 1983 she became an Associate Professor at University of South Florida and eventually Professor in 1988. Through Pamela’s career she has done 10 research cruises and has extensive experience using SCUBA in reef areas worldwide! Pamela has received several honors and awards: Elected Fellow of the GSA, The 1999 Outstanding Educator Award from the Paleontological Society Association for Women, Alfred P Sloan Minority Ph.D. Mentor of the year in 2012, Joseph A Cushman Award for Excellence in Foraminiferal Research in 2015, Hallock and Schlager one of ten “Landmark Papers in Carbonate Sedimentology and Stratigraphy” by the AAPG in 1986, and the Moore Medal for Excellence in Paleontological Research, from the Society of Sedimentary Geology in 2019.