Geology and Geological Engineering

Dr. Sarah W. Keenan
Geobiology in Modern and Ancient Systems
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Dr. Sarah W. Keenan

Ph.D. (2014), University of Tennessee
Assistant Professor
Geology and Geological Engineering
South Dakota School of Mines & Technology
Rapid City, SD 57701
Phone: (605)394-2461
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Research Synopsis

Nutrient hotspots and animal decomposition

  • The first steps in a vertebrate’s taphonomic history start after death. The breakdown of soft tissues by abiotic and biotic processes, including microorganisms and scavenger activity, releases compounds back into the environment. The complex biogeochemical processes that occur after death play an important role in determining the preservation potential of hard parts-bones-over geologic time. However, we have only begun to explore these processes. My research focuses on: (1) evaluating how and when animal-sourced compounds are recycled post-mortem; (2) what biogeochemical conditions bones are exposed to after animal death; and (3) assessing how bones change (physically and geochemically) during decomposition.

    Microbial interactions with bone

  • Microbial communities are known to degrade bone through the breakdown of organics (collagen) and mineral (bioapatite). Through field and experimental approaches, this research aims to unravel: (1) how microbes interact with bone (and when); (2) what microbial communities are involved (using next-generation sequencing approaches); and (3) how soil and water geochemical conditions facilitate (or restrict) microbial activity. This research integrates both field and lab-based experiments to quantify and characterize microbial activity.

    Modern and fossil bone geochemistry

  • Fossil bones provide a physical and chemical archive of past life, including paleoenvironment and the geochemical conditions leading to bone preservation. My research combines observations from modern bone interactions with the environment to guide interpretations about fossil bone preservation. This research focuses on a variety of depositional settings, including karst systems (sinkholes and caves), wetlands, and rivers.

  • Contact: Dept. of Geology and Geological Engineering, 501 E. Saint Joseph St., SDSMT, Rapid City, SD 57701
    Phone: (605)394-2461 / Fax: (605)394-6703 / Email: / Updated: 20 April 2021