“VOID SPACE” MADE REAL: IMAGING PORES IN SEDIMENTARY ROCKS

Pores compose an important class of components in sedimentary rocks, being those parts of the rock not made of solid matter but, rather, hosting liquids and gases. Much of the considerable value of sedimentary rocks to society resides in the capacity of porous rocks to contain fresh or briny water, petroleum liquids, or natural gas that can be extracted. Alternatively, porous rocks can serve as deep storage for liquid wastes or CO₂ that we seek to remove from the realm of human habitation. Fluid-filled spaces within rocks are also potential habitats for organisms, and the exploration for life on other planets is, in part, a search for pores. Deciphering the causes of pore evolution across burial history yields insights that can be integrated with measurements of porosity and other bulk-rock properties to yield effective models for prediction of porosity in the subsurface. Petrographic methods have been central to development of this kind of interdisciplinary understanding. This talk will review the techniques of transmitted-light microscopy and electron microbeam imaging that have supplied much of our knowledge about pore history and distribution in sedimentary rocks.