Platt reported in 1975 via U.S. Geological Survey Open-File Report 75-269 that 20 thin sections were made from samples dredged from the central Chukchi Sea. The samples were examined petrographically and compared with some onshore rocks in northern Alaska. Of these, 16 are sandstones, three are highly CaCO3-rich silts and carbonate rocks, and one is an olivine-magnetite-rich basalt.
Eight of the sandstones have been point-counted in an effort to determine compositional trends. Sample numbers, lithologies, and locations are
summarized in Table 1, and locations are shown in Figure 1. Dr. Joe S. Creager of the University of Washington kindly provided the dredge samples and thin
sections for study. The hand specimens of the sandstones are nearly all slab-like, indicating parting parallel to probable bedding. Parallel laminations are visible in many of the samples. Ripple cross-laminations were found in one very fine-grained sandstone. Thus, bedding, either internal or external,
is present in all sandstones. These features are summarized in Table 2. Negative results of staining for potassium feldspar are presented in the Appendix.
Not enough samples have been obtained to delineate distinctive assemblages within the sandstones with confidence; however, the degree of compaction of the sandstones is a characteristic which seems to provide an initial framework for their classification. All the sandstones are highly indurated, yet some show more severe presolution than others. On this basis, 10 of the sandstones fall into a "highly compacted" group, 4 into a "less-compacted" group, and 2 cannot be assigned to either group with assurance. The features of the sandstones will be discussed according to these tentative groupings. These groupings, the ranges of grain sizes of the sandstones (fine and very fine grained sizes predominate), and the degrees of sorting are summarized in Table 3.
All of the less compacted sandstones, all of the calcareous rocks and the basalt are from Station 65. For a summary of the most likely onshore correlatives to the less compacted sandstones, see page 11. A discussion of the regional geology and tectonic significance of these samples is presented in Grantz and others (1975).
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