The Tectonics of North America A Discussion to Accompany the Tectonic Map of North America Scale 1:5,000,000 GEOLOGICAL SURVEY PROFESSIONAL PAPER 628 The Tectonics of North America A Discussion to Accompany the Tectonic Map of North America Scale 1:5,000,000 By PHILIP B. KING GEOLOGICAL SURVEY PROFESSIONAL PAPER 628 UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969 UNITED STATES DEPARTMENT OF THE INTERIOR JAMES G. WATT, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director First printing 1969 Second printing 1970 Third printing 1970 Fourth printing 1978 Fifth printing 1981 For sale by the Distribution Branch, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 CONTENTS Page "The Tectonic Map of North America" Continued Pw Abstract..._______________________________________ 1 Phanerozoic foldbelts Continued Introduction __ ___ __ ____ ___________ 1 Sedimentary units______________ ________ 4C Tectonic maps defined ___________________________ 1 Geosynclinal deposits.... __ 46 Historical sketch __ ______ _____________ 2 Eugeosynclinal deposits _ _ 47 Appraisal of existing tectonic maps ________________ 7 Miogeosynclinal deposits. _____________ 47 Representation of platform areas_________________ 8 Metamorphism of geosynclinal deposits..__ 4P Representation of foldbelts_____________________ 8 Deposits of successor basins....__________ 4P "Tectonic Map of United States"_____ ^_ 8 Younger basinal deposits.__ ______ 50 "Tectonic Map of Australia".________________ 9 Thick deposits in structurally negative "Tectonic Map of U.S.S.R. and Adjacent Areas," areas._________________ ____________ 50 and "Tectonic Map of Europe"_________ 9 Volcanic units_______________ _ 50 "Tectonic Map of Canada"___________ 11 Plutonic units____________ ______ 51 "Tectonic Map of Mexico" and "Tectonic Map Granitic rocks.______ _ __ 51 of U.S.S.R."___________________________ 15 Mafic plutonic rocks_____ 5? Representation of subsea areas.______________ 17 Ultramafic rocks______________________ 5? "The Tectonic Map of North America".-_____________ 18 Description of foldbelts____________________ 5f Compilation of the map_________________________ 18 (K) Innuitian foldbelt____________ Specifications of the map____________________ 19 (J) East Greenland foldbelt_________ Platform areas.______________________________ 21 (L) Appalachian foldbelt..______________ 56 (A) Platform areas within the Precambrian. ___ 21 Northern Appalachians.__________ 56 (B) Platform deposits on Precambrian base­ Southern Appalachians.____________ 5f ment _________________________________ 22 (M) Ouachita foldbelt____________ 61 (C) Platform deposits on Paleozoic basement. _ 24 Structural systems related to Ouachita (D) Platform deposits on Mesozoic basement. _ 27 foldbelt-..._____________. 64 (E) Volcanic rocks and associated sediments of (O) Cordilleran foldbelt____________ 64 North Atlantic province.________________ 27 Northern Cordillera___________ 65 (F) Icecaps________________________________ 29 Central Cordillera. __ __________ 6r Foldbelts of Precambrian age_________________ 30 Southern Cordillera_______.___ 7? Stratigrapbic classification._________________ 30 (P) Pacific foldbelt______________ 74 Tectonic classification. ______________________ 32 Alaska. ____________________ 7ft Foldbelts of Canadian Shield_________________ 33 Washington and Oregon. 7ft Foldbelts of Greenland________________ 36 California and Baja California.__... 76 Foldbelts south of Canadian Shield. __________ 37 (Q) Antillean foldbelt_____________ 77 Precambrian of northern South America______ 42 (N) Andean foldbelt______________ 7f Phanerozoic foldbelts ___________________ 43 Subsea areas______________________ 80 The tectonic cycle_______________ 43 Fault zones______________________ 81 Terminology _________________________ 44 Glossary.____________________________ 8f Geosyncline___________.._____________ 44 References cited______________________ 87 Orogeny______________________ 44 Index of units on "Tectonic Map of North America" Names of orogenies..._____________ 45 which are referred to in text_______________ 9f m IV CONTENTS ILLUSTRATIONS Page FIQTJRE 1. Structural map of Bighorn Mountains uplift, Wyoming and Montana, by N. H. Darton___________________ 2 2. Structural maps of the Jura Mountains, Switzerland, after Albert Heim____________________________ 3 3. Tectonic map of the Alps, by Rudolf Staub____--_-____- __ _______________________________________ 4 4. Tectonic sketch map showing the chief belts of folding in the American Cordilleran system, by Hans StillS__ 6 5. Maps of eastern Tennessee and western North Carolina showing three methods of representing the geology.__ 13 6. Tectonic map of north-central Nevada showing "structural stages" in an area of complex superposed rocks and structures.-_____-_--__-_-_-_-------_---------------------_------- _____ __ ___ 14 7. Map of Gulf Coastal Plain in Texas, Louisiana, and Mississippi showing structure contours on two horizons in the strata of the platform cover_________________-________-__-_-_____-_--__-___________ ____________ 26 8. Map of North Atlantic Ocean and adjacent lands showing plateau basalts of North Atlantic province. ______ 28 9. Map of the Canadian Shield showing provinces that contain Precambrian rocks of different ages.______________ 34 10. Map of North America showing inferred extent of exposed and buried provinces of Precambrian rocks__ 39 11. Map of northeastern Greenland showing inferred extent of the late Precambrian Carolinidian foldbelt._______ 55 12. Tectonic maps of the two larger areas of exposure of the Ouachita foldbelt_________________________________ 62 13. Map of northern Nevada showing extent of Antler orogenic belt of middle Paleozoic time___________________ 71 14. Map showing transverse structural features in the southern part of the area of the "Tectonic Map of North America," and in adjacent regions_______________-_-_---_---_--__-_____________________________ 82 TABLES Page TABLE 1. Comparison of various classifications of the Precambrian-__.__________________________ ___________ __ 31 2. Classification of orogenies in Canadian Shield_______-_____--_--_-_-___---_-__-__-_- __ ___ 33 3. Summary of Precambrian rocks and events south of Canadian Shield______________ , ______________._ 40 THE TECTONICS OF NORTH AMERICA A DISCUSSION TO ACCOMPANY THE TECTONIC MAP OF NORTH AMERICA, SCALE 1:5,000,000 By PHILIP B. KING ABSTRACT use and understanding of the map, by providing expla­ The "Tectonic Map of North America," on a scale of nations more lengthy than could be included in th^ 1: 5,000,000, has been compiled by the United States Geologi­ cal Survey in collaboration with other national geological sur­ legend of the map itself. Such a discussion is the mor> veys, and with the assistance of various individuals. The desirable because the map embodies innovations derived- compilers made use of tectonic maps of some of the countries partly from techniques of tectonic mapping that hav maps that have been published or are in process of publication. been developed during the last few decades by geologists In addition, many other basic maps and reports were consulted. in other countries, and that may not as yet be well North America is divided technically into foldbelts of dif­ known, or be well understood in North America. ferent ages and platform areas where flat-lying or gently tilted rocks lie upon basements of earlier foldbelts. The two most TECTONIC MAPS DEFINED extensive platform areas are those with Precambrian basement in the central craton, and those with Paleozoic basement in the A tectonic map portrays the architecture of the up­ Atlantic and Gulf Coastal Plains. Configuration of the upper per part of the earth's crust that is, the features prc - surface of the basement beneath the platforms is shown by contours on a 500-meter interval. duced by deformation and other earth forces and rep­ The foldbelts include three of Precambrian age whose principal resents this architecture by means of symbols, pattern1" exposures are in the Canadian Shield, but which also emerge and colors. Such a map differs from the more familir.r in various outlying areas. The foldbelts of younger ages lie areal geologic map, whose primary aim is to represent nearer the edges of the continent, and include four that are the surface distribution of rocks of various kinds and mainly of Paleozoic age, two that are mainly of Mesozoic age, and two that are mainly of Cenozoic age. Each foldbelt was ages. Nevertheless, most tectonic maps contain some in­ formed during a geotectonic cycle many geologic periods in dication of the ages and kinds of rocks from which th^ length, beginning with a geosynclinal phase, passing through structures were made, and areal geologic maps contain a time of orogeny, and ending with a postorogenic phase. some indication of the structures of the rocks repre­ On the "Tectonic Map of North America" the foldbelts are sented, so that distinctions between the two kinds of distinguished by different colors according to age; where several significant times of deformation occurred within them, these maps are not absolute. Tectonic maps are nearly synony­ are represented by tints of the prevailing colors. The different mous with structural maps, just as the subject of teu­ kinds of rocks which make up the foldbelts are shown by pat­ tonics is nearly synonymous with that of structural terns of these colors. geology. Nevertheless, geologists commonly make a In the foldbelts, the principal sedimentary rock units