Middle Ordovician Rocks of the Tellico-Sevier Belt Eastern Tennessee GEOLOGICAL SURVEY PROFESSIONAL PAPER 274-F Middle Ordovician• o Rocks of the Tellico-Sevier Belt Eastern Tennessee By ROBERT B. NEUMAN A SHORTER CONTRIBUTION TO GENERAL GEOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 274-F Description of rocks of the outcrop belt containing the type sections of the Tellico and Sevier forma­ tions^ with interpretations of their sedimentary environment UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1955 UNITED STATES DEPARTMENT OF THE INTERIOR Douglas McKay, Secretary GEOLOGICAL SURVEY W. E. Wrather, Director For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 75 cents (paper cover) CONTENTS Page Middle Ordovician section—Continued Abstract- __________________________________________ 141 Chota formation—Continued Page Introduction _______________________________________ 142 Lithic features_____________-----____-----_ 157 Fieldwork and acknowledgments. _____________________ 142 Stratigraphic relations.._______-_--_______--- 158 Analysis of stratigraphic nomenclature ________________ 143 Internal stratigraphy._____________---_-- 158 Historical background- _ _________________________ 143 Contact with the Sevier formation._______ 159 Early work_ _______________________________ 143 Fossils______________________________ 159 Later work _ ______________________________ 144 Soils and topographic expression._____________ 160 Necessity for a revised classification. ______________ 145 Sevier formation______________________-------_ 160 Middle Ordovician section. __________________________ 146 General features._____________-_-__-_-----__ 160 Structure of the Tellico-Sevier belt _ ______-__-__- 146 Name________________________________ 160 Rocks underlying Middle Ordovician__ ____________ 146 Lithic features of main body. ________________ 160 Knox group (Late Cambrian and Early Ordo­ Calcareous shale___________-____-_-----_ 160 vician) — relations with overlying rocks. _____ 146 Calcareous sandstone__________________ 160 Lenoir limestone.. _ _____________________________ 147 Stratigraphic relations---..------------------ 161 General features. _____________--________---- 147 Internal stratigraphy__________________ 161 Douglas Lake member___________-_-____---_- 147 Contact with Bacon Bend member________ 161 Mosheim member __ _______________________ 147 Fossils...__________________________ 162 Argillaceous limestone member. ______________ 147 Soils and topographic expression..____________ 162 Fossils ___ ________________________________ 148 Bacon Bend member___-____--_-______------ 162 Soils and topographic expression. _____________ 148 General features and name_______________ 162 Blockhouse shale. ______________________________ 148 Lithic features________-_-_-_-_-_______-. 163 General features. ___________________________ 148 Stratigraphic relations_________________ 163 148 Contact with Bays formation.__________ 164 Whitesburg limestone member. 149 Fossils_______________________ 164 Name __________________ 149 Soils and topographic expression________ 164 Lithic features ___ _ _____ 149 Bays formation_______________________________ 164 Dark shale member. _________ 150 General features and name___________________ 164 Lithic features ___ ______ 150 Lithic features____________________________ 164 Toqua sandstone member. ____ 150 Stratigraphic relations_____________________ 165 150 Fossils___________________________________ 165 Lithic features ___ ______________ 150 Soils and topographic expression____________ 165 Stratigraphic relations.. _ _____________ 151 Rocks overlying Middle Ordovician-______________ 165 Internal stratigraphy _ _ _________ 151 Chattanooga shale (Late Devonian and Car­ Contact with the Tellico formation 153 boniferous)___________________________ 165 Fossils _ _ _________________________ 153 Correlation of the Tellico-Sevier belt with other belts of Soils and topographic expression. ______ 153 the southern Appalachians_________________________ 166 Tellico formation. _______________________ 154 Correlation with Tazewell County, Va___________ 166 General features and name_ ___________ 154 Correlation with Friendsville-Knoxville belt________ 167 Lithic features __ __________________ 154 Sedimentary environment of the deposits._____________ 167 Calcareous shale__ _______________ 154 Blackford an'd Elway time.______________________ 168 Calcareous sandstone. ____________ 154 Lincolnshire time_______________________________ 168 Stratigraphic relations _ _ ____________ 155 Ward Cove time________---____-________________ 168 Internal stratigraphy _ __ _ _______ 155 Benbolt time_________________________________ 170> Wardell time____________________________ 171 Contact with Chota formation_____ 155 Witten and Moccasin time___.__________________ 171 Fogsils __ __________________________ 155 Blountian orogeny.________„.___.___________________ 171 Soils and topographic expression, ______ 157 Additional collecting localities.----___________________ 171 Chota formation _ _ _____________________ 157 Literature cited_-___________________________________ 174 General features and name____________ 157 Index.-___--„--_-____---_____-._________________ 177 m IV CONTENTS ILLUSTRATIONS Page Plate 25. Representative brachiopods from rocks of Middle Ordovician age in the Tellico-Sevier belt. _____________ Facing 152 26. Contorted bed in the Bacon Bend member of the Sevier formation_________________________________ Facing 153 27. Geologic map showing Middle Ordovician rocks of the Tellico-Sevier belt______________________________ In pocket 28. Stratigraphic diagram of Middle Ordovician rocks in the Tellico-Sevier belt.____________________________ In pocket Figure 22. Map showing distribution of Middle Ordovician rocks in part of eastern Tennessee ________________________ 142 23. Range chart of brachiopods listed from Middle Ordovician rocks in the Tellico-Sevier belt and southwestern Virginia._________________________________________________________________________________________ 156 24. Geologic sketch map of the type section of the Chota formation-_________________________________________ 159 TABLES Page TABLE 1. Thickness, in feet, of constituent units at measured sections of the Lenoir limestone __________________________ 148 2. Thickness and type of bedding at measured sections of the Whitesburg limestone member of the Blockhouse shale__________________________________________________________________________________________ 150 3. Correlation of Middle Ordovician rocks of the Tellico-Sevier belt with the Friendsville-Knoxville belt and south­ western Virginia__________________________________________________________________________________ 166 A SHORTER CONTRIBUTION TO GENERAL GEOLOGY MIDDLE ORDOVICIAN ROCKS OF THE TELLICO-SEVIER BELT, EASTERN TENNESSEE By EGBERT B. NEUMAN ABSTRACT The southernmost outcrop belt that exposes a complete section of rocks of Middle Ordovician age in eastern Tennessee contains the type sections of Tellico sandstone (Keith, 1896a) and Sevier shale (Keith, 1895). Study of a 50-mile segment of this belt reveals the necessity for reclassification of these deposits. The new classification and the probable environments of deposition of these rocks are summarized as follows: Keith, 1895,1896a Classification of present report Description Tectonic environment Bays sandstone. Bays formation. Red calcareous mudrock and silt- Elevated, deeply weathered source stone, with nonred sandstone area; deposition in shallow water and claystone rare; 400-1,000 that was occasionally drained. feet. Sevier shale, upper part___ Sevier formation (revised Bacon Bend member is interbedded Source area generally of low relief; usage), with Bacon Bend gray and red calcareous shale basin of deposition shallow, sedi­ member (new) at top. and siltstone, with some non- ments subject to stirring and sort­ red beds possessing submarine ing by marine currents. Closing slump structures; main body of phase contains transition to Bays formation is gray silty calcareous environment. shale, calcareous sandstone, and calcarenite; total formation thick­ ness, 1,500-2,200 feet. Sandstone lentil in Sevier Chota formation (new). Gray calcarenite, most with quartz- Little new material from source shale. sand grains; 550-900 feet. area; subsidence of area of deposi­ tion uniform, slow; a littoral or offshore bar deposit. Sevier shale, lower part, Tellico formation (revised Gray silty sandy calcareous shale, Maximum relief between source Tellico sandstone, and usage). with lenses of gray feldspathic area and depositional basin: Athens shale, upper part. calcareous sandstone in middle source area of high relief; deposi­ part; 2,700-4,500 feet. tion below wave base. Athens shale, lower part, Blockhouse shale (new), Dark-gray calcareous shale with Lower limestone is unstable shelf and Chickamauga lime­ with Toqua sandstone graptolites, with lateral equiva­ associate; shales accumulated in stone, upper part. member (new) and Whites- lent of gray fine- to coarse­ poorly ventilated basin; terrige­ burg limestone member. grained calcareous sandstone; nous sands carried into basin by basal member is argillaceous streams. limestone; 150-950 feet. Chickamauga limestone, Lenoir limestone with Mos- Gray argillaceous limestone, with Negligible contributions from land lower part. heim member and basal lateral equivalent of light-gray areas; initial deposits on debris- Douglas Lake member. aphanitic limestone; basal mem­