Devonian Shale Succession

Dr. Gary Lash is the resident structural geologist and stratigrapher / sedimentologist professor at SUNY-Fredonia. His research centers on rock fracturing in Western New York and the stratigraphy and tectonics of the Appalachian orogen. Dr. Lash teaches courses in structural geology, stratigraphy, oceanography, physical geology, and astronomy.

As detailed in the January 2015 edition of Marine and Petroleum Geology, the Phenom SEM was used to image geological samples collected from the base of the Upper Devonian Hanover Shale. In addition to providing important insight into the microfabric of shale samples, elemental analysis (EDS) provided a measure of the geochemistry of the barite (BaSO4) nodules contained within the shale. The morphologic and compositional data of the barite gained by use of the Phenom SEM has provided strong evidence that the Devonian shale succession contained abundant methane very early in its depositional and burial history.

Optical and SEM images of barite in shale with barite rhombsA. Optical image of barite crystals in shale matrix. B and C. Backscattered SEM images of barite (white) in shale at locations indicated by optical image. D. Backscattered SEM image of barite rhombs (white) in shale matrix (dark); porous texture of barite suggests effects of dissolution.

 

Full details in:

Lash, G. G. “Authigenic Barite Nodules and Carbonate Concretions in the Upper Devonian Shale Succession of Western New York - A Record of Variable Methane Flux During Burial.” Marine and Petroleum Geology 59 (2015): 305-319.