Events

Dr. Kitty Milliken, Senior Research Scientist at the Bureau of Economic Geology in the Jackson School of Geosciences, will be presenting on "Quantifying Mechanisms of Porosity Decline in Mud and Mudrocks".

 Abstract:

Mud at the depositional surface typically contains an astonishingly large volume of pores (up to 80 volume percent), yet, even at the earliest stage of burial, the size of the intergranular pores is small (generally <1 µm). Small size presents formidable challenges for imaging of pores and any crystals that might precipitate within them. Field-emission scanning electron microscopy has enabled imaging of mudrock components (grains, pores, and cements) at scales appropriate to unraveling the various contributions of different mechanisms to overall porosity decline. Localized cements such as occur in concretions are typically carbonate minerals and are readily documented, perhaps because they form at the very earliest stages of compaction. Pervasive cement, such as microquartz, that is relevant to modeling the broader mechanical properties of mudrocks is more challenging to image. Recent results using a combination of high-resolution imaging modes (SE, BSE, EDS elemental mapping, and CL) have been used to quantitatively partition the contributions of compaction versus cementation in porosity evolution in muds. Globally, compaction is by far the dominant cause of porosity decline in muds, and compaction may operate to far greater depths in mud and mudrocks than in sand and sandstones. Pervasive cementation in mudrocks is a relatively rare phenomenon, but where it occurs it has profound impacts on the evolution of porosity, permeability, and mechanical rock properties.

 About Dr. Milliken:

Kitty L. Milliken is a Senior Research Scientist at the Bureau of Economic Geology in the Jackson School of Geosciences, University of Texas at Austin. Her research focuses on the diagenesis of siliciclastic sediments and the evolution of rock properties in the subsurface. She has authored and co-authored over 100 peer-reviewed papers and also digital resources for teaching petrography. She served as Associate Editor of the Journal of Sedimentary Research (1993-2000) and as Co-Editor (2004-2008). She was elected a Fellow of the Geological Society of America (2008). She has been recognized by the AAPG with the J. Ben Carsey Distinguished Lectureship (2005-2006), the Robert Berg Outstanding Research Award (2015), the Pratt Award (with co-authors) for best paper in the Bulletin (2015), and a second Distinguished Lecture tour (2017-2018).  Her current work is focused on the application of electron microbeam imaging and analysis to interpret chemical and mechanical histories of mudrocks (oil and gas shales).