University of Oklahoma
School of Geology and Geophysics 

Sarkeys Energy Center
100 East Boyd St.
Room A107

(405) 325-1032 lab phone

Dr. Megan Elwood Madden

(405) 325-1534 phone
(405) 325-3140 fax

Dr.Andy Elwood Madden
(405) 325-5327 phone

(405) 325-3140 fax


Transmission electron micrograph of aggregated uraninite crystals from iron-reducing bacterial cultures (image by Andrew Swindle).

HRTEM image of nanodiamond from the Bull Creek, OK site.

Aggregated hematite nanoparticles extending into the microscope vacuum observed with Scanning Electron Microscopy.

jarosite photo

Photograph of jarosite powder synthesized in the laboratory

goethite on jarosite

Atomic force microscope image image of jarosite and decomposition products demonstrating the sensitivity of jarosite to the presence of water.  When observed freshly after depositing on a glass slide, only the large jarosite crystal was observed.  The reaction products developed over a period of weeks as the sample was exposed to the humidity of the ambient laboratory atmosphere. The laths of various sizes are likely goethite laths based upon morphology.

Atomic Force Microscopy image of jarosite reacted at pH 8 (image by Jesse Blumenthal).

High-resolution TEM image of shwertmannite forming from jarosite dissolution at low temperatures. The 'needle' in the foreground is wiggling in the beam.


AFM image of a sulfate reducing bacteria with flagella evident

biogenic Mn-oxide

Transmission electron microscope image of biogenic manganese oxide



Archived News




OU logo School of Geology and Geophysics, University of Oklahoma




MEEM in the labDR. MEGAN ELWOOD MADDEN                     

Physical and planetary geochemistry

Stubbeman-Drace Presidential Professor
School of Geology and Geophysics, University of Oklahoma

Wigner Fellow, 2005-2007, Oak Ridge National Laboratory
Ph.D. (geochemistry), 2005, Virginia Tech
B.S. (geology), 2000, University of Illinois


Nanoscale geosience and low-temperature geochemistry

Associate Professor
School of Geology and Geophysics, University of Oklahoma

Postdoctoral Research Associate, 2005-2007, Oak Ridge National Laboratory
Ph.D. (geochemistry), 2005, Virginia Tech
B.S. (geology), 2000, Michigan State University

Postdoctoral research associates

Dr. Young Ji Joo                   

Deep time signatures of rock weathering

Ph.D. (geology), 2013, Northwestern
M.S. (geology), 2005, Seoul National University
B.S. (geology), 2003, Seoul National University

Dr. Charity Lander

Dissolution in brines

Ph.D. (geology), 2014, University of Kansas
M.S. (geology),
B.S. (geology),

Graduate students

KRISTEN MARRA, Ph.D. student (co-advised with Lynn Soreghan)

Physical and Chemical Weathering in Alluvial Systems of the McMurdo Dry Valleys, Antarctica

MOLLY SEXTON, M.S. student

Stratigraphic and Textural Analysis of Nanodiamonds Across the Younger Dryas Boundary in Sediments of Western Oklahoma

JEFF WESTROP, M.S. student

The geochemistry of chromum in the Central Oklahoma Aquifer- Norman, OK

Undergraduate students


Deep time signatures of rock weathering.


Thermodynamic modeling of barite hashemite solid solutions in the Central Oklahoma Aquifer.

Raman microscopy.

Dissolution of minerals in sulfate brines.

Powder XRD lab, clays of the Central Oklahoma Aquifer

Group graduate student alumni

  Where they are now
Dan Ambuehl (M.S.) EOG Resources, Oklahoma City
Debajyoti Basu Sarkar (M.S.) just finished
Xiaofeng Chen (Ph.D.) postdoctoral researcher, UT-Austin BEG
Emily Dixon (M.S.) Scientist, National Energy and Technology Laboratory
Seth Gainey (M.S.) Ph.D. program, UNLV
Matt Kendall (M.S.) Associate Geologist, DeGolyer and MacNaughton
Matt Miller (M.S.) Geologist, J.M. Waller and Associates, Inc.
Sumudu Munasinghe (M.S.) Geochemist, Chesepeake Energy, Oklahoma City OK
Brittany Pritchett (M.S.) Scientist, Oklahoma Geological Survey
Margaret Root (M.S.) Awesome Mom
Allison Stumpf (M.S.) Apache (Midland, TX)
Andrew Swindle (Ph.D.) Assistant Professor, Wichita State University



ATOMIC ABSORPTION SPECTROSCOPY: Our PerkinElmer AAnalyst 800 combines flame and furnace atomization capability in a single instrument to provide elemental analysis of liquid samples.  The absorbance of unknown samples at an appropriate wavelength is compared with the absorbance of known standard solutions.  We have lamps for most elements of interest in the Earth and environmntal sciences. The furnace is transversely heated and utilizes Zeeman background correction.   Contact one of the Elwood Maddens to inquire about the appropriateness of flame or furnace for your samples.

ATOMIC FORCE MICROSCOPY: The Pacific Nanotechnology NanoR2 is designed to probe the nanometer-scale topographic, physical, electronic, and magnetic properties of surfaces. 

GAS ADSORPTION ANALYSIS (BET surface area and pore size distribution): Gas adsorption analysis for surface area and pore size distribution (Quantachrome Nova 2000e) of powdered samples.

POWDER X-RAY DIFFRACTION (XRD): Dr. A. Elwood Madden oversees the powder X-ray diffractometer (Rigaku Ultima IV) in the Devon Energy NanoLab. We have updated reference databases and software such as MDI Jade2010, PDXL, and ClaySim.

RAMAN MICROSCOPY: Our new Renishaw InVia scanning Raman microscope was installed in Jan. 2015! Featuring 532nm and 785nm lasers, this is a great method for spot and mapping analyses of a range of materials. A linkham heating/cooling stage allows the collection of temperature-dependent spectra.



Other equipment includes:
- anaerobic chamber
- analytical balances
- furnaces
- geochemical thermodynamic and reaction path modeling software (Geochemist’s Workbench)
- geochemical reactors of various types
- pH meters and electrodes
- ultracentrifugation

Additionally, we have expertise in techniques such as the following which are readily available at OU or elsewhere:

Kinetic Phosphorescence Analysis (KPA), Scanning Electron Microscopy (SEM), Surface (zeta) potential measurement, synchrotron x-ray spectroscopy, Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Fluid Inclusion Analysis.

We also have access to many other types of geochemistry facilities, as found on the GEOCHEMISTRY at OU website