Abstract There are a variety of pore types in unconventional resource mudstones and shales. The currently preferred method by geologists and petrophysicists is to examine and analyze these mudstones and shales by argonion and focused ion-beam milling to produce an ultrasmooth surface, coupled with observation under the field emission scanning electron microscope (FESEM). Potential issues with Ar-ion milled/FESEM preparation and imaging include (1) the small size of sample cubes for upscaling, (2) loss of structural fabric during the milling–imaging process, (3) fewer non-inorganic pore types observed than when observed with an unpolished surface, (4) analog use of pores from one shale to another, although the pore types and composition might differ, and (5) the creation of potential artifacts related to desiccation and rock expansion because of core retrieval and sample preparation. Conventional FESEM images obtained from freshly broken surfaces reveal much more textural detail than those obtained from ion-milled (polished) surfaces. Although conventional FESEM methodology may share some of the same limitations as Ar-ion beam-milled/FESEM technology, FESEM methodology should not be overlooked because it provides a more cost-effective and potentially more accurate analysis for estimating porosity and determining pore types and their distribution in shales. Comparison of FESEM images from ion-milled and fresh, non-ion-milled surfaces reveals that organic matter and internal organoporosity are best viewed on ion-milled surfaces, but shale microfabric and non-organoporosity is best viewed under non-milled surfaces. Complete FESEM imagery for shale characterization should include both types of analyses.

Abstract Organo-clay fabric and physico-chemistry of marine mud play important roles in early sediment diagenesis including the development of mass physical properties, consolidation behavior, and sequestration of organic matter (OM) in sediments over geologic time. Transmission electron microscopy (TEM) images of nano- and microfabric reveal that organic matter is sequestered following enzymatic digestion despite the pervasive openness of pore-fluid pathways observed in 3D rotated images. The locations of sequestered organic matter correspond to those predicted by modeling of the potential energy of interaction. Initial flume experiments on high porosity clay-mineral-rich mud deposited under dynamic flow and static (vertical settlement) conditions demonstrate differences in clay fabric and the distribution of organic matter (we define the term organo-clay fabric as the contiguous association and arrangement of organic matter and clay domains). These differences in organo-clay fabric impact the preservation-degradation mechanisms and dynamics during depositional and burial processes. Organo-clay fabric and physico-chemical modeling of potential energy fields coupled with direct observations of organo-clay fabric, three-dimensional (3-D) clay fabric reconstructions, sediment static and dynamic properties, and controlled flume experiments are providing new insight into the developmental history of sedimentary sequences, nano- to macroscale environmental processes, and diagenesis from unconsolidated mud to shale.

Abstract Ichnology is a fascinating field of endeavor. As with science in general, it is a process of solving mysteries–in this case, mysteries of fossil behavior. In a very real sense the ichnologist is Sam Spade or Sherlock Holmes–following footprints, searching for traces of dastardly deeds, studying artifacts, attempting to reconstruct a sequence of events from subtle clues, pursuing the identity of someone (or something) long dead. Who was the culprit? What was he/she doing? Where was he/she living, working or going? Not only intellectually intriguing, ichnology also has practical application and economic importance. In today’s frenzied quest for energy and mineral resources, exploration geologists value every tool that aids their search. Ichnologic observations and analyses can help the sedimentologist reconstruct ancient depositional environments, help the stratigrapher correlate sedimentary strata, help the paleontologist determine the nature of fossil communities, and help the geochemist determine the effect of organisms on sediment composition. This publication was written to serve as a comprehensive and intelligible introduction to ichnology for anyone with even rudimentary geologic training, whether or not that person enrolls in a formal course on the subject. The book emphasizes sedimentologic, stratigraphic and paleoecologic al aspects of ichnology.