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

Abstract

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:
Research Org.:
Univ. of Tennessee, Knoxville
OSTI Identifier:
5376920
Alternate Identifier(s):
OSTI ID: 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
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

Citation Formats

Driese, S.G., Fischer, M.W., Easthouse, K.A., and Schoner, A.E.. Tidal and storm wave deposition in Lower Silurian shelf sequences, east Tennessee. United States: N. p., 1986. Web.
Driese, S.G., Fischer, M.W., Easthouse, K.A., & Schoner, A.E.. Tidal and storm wave deposition in Lower Silurian shelf sequences, east Tennessee. United States.
Driese, S.G., Fischer, M.W., Easthouse, K.A., and Schoner, A.E.. Thu . "Tidal and storm wave deposition in Lower Silurian shelf sequences, east Tennessee". United States. doi:.
@article{osti_5376920,
title = {Tidal and storm wave deposition in Lower Silurian shelf sequences, east Tennessee},
author = {Driese, S.G. and Fischer, M.W. and Easthouse, K.A. and Schoner, A.E.},
abstractNote = {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 but 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.},
doi = {},
journal = {Am. Assoc. Pet. Geol., Bull.; (United States)},
number = ,
volume = 70:5,
place = {United States},
year = {Thu May 01 00:00:00 EDT 1986},
month = {Thu May 01 00:00:00 EDT 1986}
}

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  • Detailed stratigraphic sections through Upper Ordovician-Lower Silurian shelf strata of the Eastern Great Basin were measured in two Utah localities, Barn Hills (Confusion Range) and Lakeside Mountains. Six major subfacies occur in these strata: mud-cracked and crinkly laminated subfacies, Laminated mudstone subfacies, cross-bedded grainstone subfacies, cross-laminated packstone subfacies, grainy bioturbated subfacies, muddy bioturbated subfacies, and thalassinoides burrowed subfacies. These occur in 1--10 m thick cycles in three facies: muddy cyclic laminite facies (tidal flats), cross-bedded facies (subtidal shoals), and bioturbated facies (moderate to low-energy shelf). The vertical facies succession, stacking patterns of meter-scale cycles, and exposure surfaces define correlatable sequences.more » The authors recognize four Upper Ordovician sequences (Mayvillian to Richmondian). An uppermost Ordovician (Hirnantian) sequence is missing in these sections but occurs basinward. Lower Silurian sequences are of early Llandoverian (A), middle Llandoverian (B), early late Llandoverian (C1--C3), late late Llandoverian (C4--C5), latest Llandoverian (C6) to early Wenlock age. In general, Upper Ordovician and latest Llandoverian-Wenlockian facies are muddier than intervening Llandoverian facies. The shift to muddier shelf facies in latest Llandoverian probably corresponds to the development of a rimmed shelf. The sequence framework improves correlation of these strata by combining sedimentologic patterns with the biostratigraphic data. For example, in the Lakesides, the Ordovician-Silurian boundary is shifted 37 m downward from recent suggestions. In addition, the sequence approach highlights intervals for which additional biostratigraphic information is needed.« less
  • The Erwin Formation of northeast Tennessee consists of three facies, which are thought to indicate deposition on a storm-dominated shelf. Facies A consists of interbedded siltstone and hummocky-stratified, fine-grained sandstone. Commonly, in facies A, 1 to 8-m sequences coarsen and thicken upward. These sequences are interpreted to represent storm wave deposition below fair-weather wave base. The thicknesses of sandstone beds reflect the proximity and intensity of storms or the quantity of sediment available, or a combination of both. Facies B is characterized by medium to large-scale, planar-tabular and trough cross-stratified sandstone and rare siltstone interbeds. This facies commonly succeeds faciesmore » A upward in a vertical sequence. Facies B is thought to have been deposited by storm-generated, unidirectional currents on the shoreface. Facies C consists of very thick-bedded, medium to very coarse-grained, supermature sandstone. The sandstone appears to be crudely cross-stratified, and interbedded siltstone or shale is completely absent. Facies C is interpreted to have been deposited on the upper shoreface during storm erosion of the foreshore and nearshore zones. High textural and compositional maturity indicates constant agitation and winnowing of the sediment on the shoreface. The three facies of the Erwin Formation are arranged in two 50-m thick, coarsening-upward sequences, in the order A, B, C. These sequences are thought to represent two depositional pulses in which shoreface sand prograded over shelf sediment.« less
  • Exposures of Silurian to lowermost Devonian strata in the Porcupine River region consist of an unnamed carbonate unit and the Road River Formation. Petrographic studies indicate that these rocks display facies representative of five depositional environments: basin, open sea shelf, deep shelf margin, open platform, and restricted shelf. The unnamed carbonate unit, exposed in the Linear Ridge area, is 390 ft (126 m) thick and records a history of restricted shelf to basinal sedimentation. Stratigraphic relations and paleontological studies suggest a Middle to Late Silurian (Ludlovian) age for this unit. The Road River Formation is Late Silurian (Ludlovian) to Earlymore » Devonian (Lochkovian) in age and is exposed near the confluence of the Porcupine-Salmontrout Rivers and downstream along the Lower Ramparts. It consists of 30-190 ft (10-61 m) of graptolitic shale with interbeds of siliceous limestone. Petrographic studies of the shales are interpreted to reflect deposition in a basinal setting, whereas the siliceous limestones represent deep shelf-margin debris flows derived from nearby, coeval shallow-water shelf environments. Together, the unnamed carbonate unit and the Road River Formation represent a shelf to basin transition on a carbonate ramp that transcends the Silurian-Devonian boundary. Petrographic examination of these rocks reveals that they are susceptible to a wide range of diagenetic processes, including (1) micritition, (2) neomorphism, (3) syntaxial overgrowths, (4) pressure solution (stylolitization), (5) trapping of dried hydrocarbons, (6) tensional stress (calcite veining), and (7) silicification.« less
  • The 130-170-m thick Becscie Formation represents continuous deposition on a shallow, open-marine carbonate ramp across the Ordovician-Silurian boundary. The sequence reflects a generally quiet, shallow marine environment punctuated by episodic, storm-generated, high-energy events. These events deposited individual storm units, or tempestites, which occur as fining-upward sequences ranging from 0.5 to 80 cm thick. A complete ideal storm deposit consists of a sharp erosional base overlain by intraclastic to bioclastic rudstone fining upward into calcarenite and then into finely laminated calcisiltite grading upward into shale. Tempestites exhibit a variety of storm-generated structures which are today exposed on extensive bedding planes. Guttersmore » and gutter casts occur throughout the sequence and show a range of morphologies and fill/substrate combinations. Hummocky cross-stratification is widespread and restricted exclusively to the calcisiltite-rich tempestites. Flat-pebble conglomerates (intraclastic rudstone) occur through most of the sequence and contain clasts of mudstone, packstone, and grainstone, indicating extensive early sea floor lithification. Tempestite sequences display lateral and vertical variations controlled by water depth and distance from shore. Construction of proximality trends permits recognition of lower order sea level changes within the overall regressive sequence. Sea level changes are believed to be eustatic, yet diastrophic-tectonic influences should not be dismissed due to regional tectonic activity. Paleocurrent data suggest sediment transport by predominantly southwest-oriented geostrophic currents. Together with sedimentologic evidence, this supports a combined-flow model for storm sediment transport in the Anticosti basin.« less
  • In Coal Creek Canyon, Utah the Spring Canyon Member of the Blackhawk Formation is divisible into four regressive hemicycles of deposition each representing the downdip part of a nearshore-to-offshore sequence punctuated locally by hummocky cross-stratification. Bedding units span middle shoreface to lower offshore shelf lithofacies, the latter corresponding to a transgressive intertongue of the Mancos Shale. Trace fossil assemblage include 21 ichnospecies distributed among 17 ichnogenera: Ancorichnus, Aulichnites, Chondrites, Cylindrichnus, Ophiomorpha, Palaeophycus, Phoebichnus, Planolites, Rosselia, Schaubcylindrichnus, Scolicia, Skolithos, Taenidium, Teichichnus, Terebellina, Thalassinoides, and Uchirites. Distal deposits are typified by bioturbate textures; Cylindrichnus concentricus, Palaeophycus heberti, and Rosselia socialis otherwise aremore » prevalent throughout the lithofacies suite. Ophiomorpha irregulaire and Schaubcylindrichnus are most common in middle shoreface beds and Chondrites sp. in upper offshore beds; O. nodosa and O. annulata also are common in this part of the sequence. Planolites-type feeding burrows must have been predominant in many depositional settings but now remain inconspicuous and poorly preserved. Despite gradients in environmental distributions of trace fossils, all resident ichnofaunas are referable to the archetypical Cruziana ichnocoenose. Ichnofaunas in hummocky beds mainly represent either an archetypical Skolithos ichnocoenose or mixed Skolithos-Cruziana ichnocoenose. These post-storm ichnocoenoses correspond primarily to a sere of opportunistic pioneers and secondarily to ensuing seres of resilient resident populations. Differences in ichnofacies also are related to differences in post-storm rates of deposition: the slower the rate of sediment accumulation, the greater the degree of overprinting by burrows from subsequent seres or equilibrium communities.« less