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Title: Tidal and storm wave deposition in Lower Silurian shelf sequences, east Tennessee

Lower Silurian sequences exposed across east Tennessee consist of an easterly quartzarenite (Clinch Sandstone) that grades westward into heterolithic sandstone, siltstone, and shale (Rockwood Formation). Farther west, the sequence intertongues with a cratonic carbonate-shale succession (Brassfield Formation). The Clinch Sandstone represents deposition in shoreface and inner shelf environments. Inferred depositional processes include (1) ebb-dominated tidal currents, (2) wave-induced currents (longshore and shore-oblique), and (3) wave-orbital currents. Strong tidal influence is indicated by abundant medium to large-scale, variably stacked sets of ebb-oriented (west-northwest) cross-strata. These strata exhibit tidal bundling, double clay drapes, reactivation/pause surfaces containing concentrations of shale intraclasts and/or biogenic structures, and shale intraclasts lining deep scours. The cross-strata were produced by migration of large-scale, low-amplitude bed forms (class II, III, and IV sand wave of Allen), and densely bioturbated sequences are interbedded with the cross-strata dominated by Skolithos-assemblage traces. The Rockwood Formation represents deposition in middle to outer shelf environments where storm-induced currents dominated. Possible depositional mechanisms include (1) storm-surge-ebb (relaxation) flows associated with coastal set-up conditions, which may have evolved into geostrophic flows; and (2) turbidity flows initiated by storm-induced liquefaction of shoreface sand. Features suggest deposition above fair-weather wave base (high-angle cross-strata), below fair-weather wave base butmore » within storm wave base (hummocky cross-stratification, microhummocky cross-stratification and wave ripples), and below storm wave base (Bouma bce turbidites). Westerly sand transport was most prevalent, and bioturbation is extensive and dominated by Cruziana-assemblage traces.« less
Authors:
; ; ;
Publication Date:
OSTI Identifier:
5376920
Report Number(s):
CONF-860624-
Journal ID: CODEN: AAPGB
Resource Type:
Conference
Resource Relation:
Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States); Journal Volume: 70:5; Conference: American Association of Petroleum Geologists annual meeting, Atlanta, GA, USA, 15 Jun 1986
Research Org:
Univ. of Tennessee, Knoxville
Country of Publication:
United States
Language:
English
Subject:
02 PETROLEUM; SANDSTONES; DEPOSITION; GEOLOGIC HISTORY; TENNESSEE; GEOLOGIC FORMATIONS; GEOLOGIC STRUCTURES; SILURIAN PERIOD; FEDERAL REGION IV; GEOLOGIC AGES; NORTH AMERICA; PALEOZOIC ERA; ROCKS; SEDIMENTARY ROCKS; USA 020200* -- Petroleum-- Reserves, Geology, & Exploration