Dr. Mary Anne Holmes
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My research is on clay minerals as products of hydrothermal and pedogenic weathering, burial diagenesis, and as sedimentary particles bearing information on provenance and paleoclimates. Clays are best as paleoclimatic indicators when found in place, in paleosols, before being eroded and transported. Paleosols now in the deep sea that were formed on subaerially erupted basalt flows provide a near-ideal condition for interpreting paleoclimate and duration of landscape exposure prior to subsidence. I've studied cores from three Ocean Drilling Program (ODP) legs: Leg 120 (southern Indian Ocean), Leg 144 (central Pacific Ocean), and Leg 152 (North Atlantic Ocean), that have now-submerged paleosols in varying states of development and preservation.
Clays might be used for paleoclimate studies, but in our lab we find that when they have been eroded and transported, they are better provenance indicators. Minor changes in clay content and composition helped us unravel what earthly sedimentologic process varied as Milankovich cycles drove variations in Paleocene sediment type on the Blake Nose, east coast of Florida (ODP Leg 171B). Provenenance signals from clay indicated the shift of sediment being shed from Iceland to sediment being shed from Greenland in the North Atlantic (ODP Leg 152).
Clays can reveal key details of weathering and diagenesis. My research on aged ocean basalt from ODP Leg 102 used clays to decipher the weathering of a mid-ocean ridge by seawater as it passed off-axis. Those weathering processes mimic those in a waterlogged soil. In a different vein, clay altered by high heat flow from the Ivory/Ghana coast of Africa (Leg 159) allowed dating of the opening of the South Atlantic Ocean along the Romanche Fracture Zone.
I have an appointment in the Women's and Gender Studies Program at UNL and am currently doing research on strategies to overcome barriers to the advancement of geoscience women in academia. This interest grew out of my serving as President of the Association for Women Geoscientists in 2000-01. I was named a Fellow of the Association for Women in Science (AWIS) in 2008.
I teach senior/graduate-level courses on Clay Mineralogy and on Sedimentary Core Description, and first-year courses on Physical Geology and Oceanography. We have an active outreach program, working with local teachers and youth-serving organizations. Outreach provides our students (graduate and undergraduate) great opportunities to explain science to the public. We co-sponsor Dinosaurs & Disasters Day with the University of Nebraska State Museum in February. In 2008, attendance reached a record 2,080 paying attendees for a day of fun, hands-on activities that engaged and educated.
Joint Oceanographic
Institutes/U.S. Science Advisory Committee (JOI/USSAC) Distinguished Lecturer,
1995-96. Lecture Title: "Paleosols From the Deep Sea: ODP's Dirty Little
Secret".
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