Petrographic, X-ray diffraction, and scanning electron microscope investigations of Nanushuk Group and Torok/Topagoruk formation (Brookian) sandstones and siltstones from 9 wells in the National Petroleum Reserve in Alaska resulted in recognition of features of interest regarding the diagenetic development of these rocks. Several kinds of labile materials are present, and secondary dissolution porosity has been developed to various degrees. Mineralogic, geochemical, and textural characteristics indicate the potential for development of appreciable porosity of this type in equivalent horizons and/or similar materials within the northern Alaska Cretaceous basin.

Known regional geologic, geochemical, and geophysical relationships are consistent with this view. Considerations of hydrocarbon resource potential should include concern for these relationships as integral to appreciation of the overall diagenetic evolution of the region.

Heretofore, the potential for the occurrence of significant reservoir rocks in these horizons has been considered to be rather low, based on primary petrologic characteristics. However, this should be reappraised in light of increased knowledge and understanding of the principles and realities regarding diagenetic events, inorganic and organic, including secondary porosity development, clay mineral relationships, and maturation of organic material.

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