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Sedimentological and petrographic analysis of drill core FC77-1 from the flank of the central uplift, Flynn Creek impact structure, Tennessee

May 26, 2017

Drill core FC 77‐1 on the flank of the central uplift, Flynn Creek impact structure, Tennessee, contains 175 m of impact breccia lying upon uplifted Lower Paleozoic carbonate target stratigraphy. Sedimentological analysis of this 175‐m interval carbonate breccia shows that there are three distinct sedimentological units. In stratigraphic order, unit 1 (175–109 m) is an overall coarsening‐upward section, whereas the overlying unit 2 (109–32 m) is overall fining‐upward. Unit 3 (32–0 m) is a coarsening‐upward sequence that is truncated at the top by postimpact erosion. Units 1 and 3 are interpreted as debris or rock avalanches into finer sedimentary deposits within intracrater marine waters, thus producing progressively coarser, coarsening‐upward sequences. Unit 2 is interpreted to have formed by debris or rock avalanches into standing marine waters, thus forming sequential fining‐upward deposits. Line‐logging of clasts ranging from 5 mm to 1.6 m, and thin‐section analysis of selected drill core samples (including clasts < 5 mm), both show that the Flynn Creek impact breccia consists almost entirely of dolostone clasts (90%), with minor components of cryptocrystalline melt clasts, chert and shale fragments, and clastic grains. Cryptocrystalline melt clasts, which appear isotropic in thin section, are in fact made of exceedingly fine quartz crystals that exhibit micro‐Fourier transform infrared (FTIR ) and micro‐Raman spectra consistent with crystalline quartz. These cryptocrystalline melt clasts are the first melt clasts of any kind to be reported from Flynn Creek impact structure.

Citation Information

Publication Year 2017
Title Sedimentological and petrographic analysis of drill core FC77-1 from the flank of the central uplift, Flynn Creek impact structure, Tennessee
DOI 10.1111/maps.12862
Authors D. R. Adrian, D. T. King, S. J. Jaret, J. Ormo, L. W. Petruny, Justin J. Hagerty, Tenielle A. Gaither
Publication Type Article
Publication Subtype Journal Article
Series Title Meteoritics & Planetary Science (MAPS)
Series Number
Index ID 70211701
Record Source USGS Publications Warehouse
USGS Organization Astrogeology Science Center