The Western North Atlantic Region

THE WESTERN NORTH ATLANTIC REGION

The Geology of North America

Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/4149319/9780813754642_frontmatter.pdf by guest on 02 October 2021 Frontispiece 1. Examples of principal lithofacies in the western North Atlantic Ocean basin. All are core samples from the Deep Sea Drilling Project. Each is identified in parentheses below according to cruise leg, site number (with hole number, A., B., etc., if applicable), core number, core-section number, and depth interval in core section (in centimeters). 1. Un-named formation, Blake-Bahama Basin. Upper Callovian to lower Oxfordian dark claystone with coarser radiolarian siltstone lenses, capped at top by lighter pelmicritic limestone that is graded and laminated (76, 534A, 120,1,48-65 cm). These and 63 m of underlying Callovian sedimentary rocks at Site 534A represent the oldest strata cored to date in the western North Atlantic basin. 2. Cat Gap Formation, lower continental rise off New Jersey. Upper Oxfordian to lower Kim- meridgian clayey limestone, well laminated to burrowed (11, 105, 37, 5, 82-113 cm). Colors which reflect the oxidation state of iron in the sediment (reddish = oxidized, grayish = reduced) are separated by diffuse boundaries. 3. Blake-Bahama Formation, lower continental rise off New Jersey. Upper Berriasian to lower Valanginian limestone and chalky limestone (11,105,28,1,92-141 cm). Limestone is well laminated to burrowed and locally contains flow structures. Darker layers contain clay and nannofossils, and light layers are principally recrystallized nannofossil calcite. 4. Hatteras Formation, western Bermuda Rise. Upper Hauterivian-Barremian greenish gray, laminated to burrowed claystone and laminated, black radiolarian mudstone with pyrite crystals and nodules (43,387,37,4,2-48 cm). Deposition was under low-oxygen (green-gray) to anoxic conditions (black). 5. Plantagenet Formation, central Bermuda Rise. Upper Cretaceous dusky yellow brown and moderate brown zeolitic claystone (43, 386, 38, 4, 37-70 cm). Darker brown bands are zeolite-rich (-60%) compared to lighter brown bands (-30%). Plantagenet clays accumulated at extremely low rates (~ 1-3 m/m.y.) beneath well oxygenated waters in the late Cretaceous basin. 6. Plantagenet Formation, lower continental rise off New Jersey. Upper Cretaceous multicolored silty clay with rare sphalerite and zeolites (11, 105, 9, 2, 108-123 cm). 7. Volcaniclastic breccia, flank of Nashville Seamount (43,382, 25, 2, 110-133 cm). Basalt clasts show variable degrees of alteration and are contained within a matrix of gray-white calcite. Nashville Seamount was the easternmost volcanic edifice formed in the New England Seamount Chain as the North American plate migrated across the New England hotspot in the Late Cretaceous. 8. Volcaniclastic breccia, flank of Vogel Seamount, New England Seamount Chain (43, 385, 23, 2,99-123 cm). Variably altered, rounded to angular basalt clasts in this Upper Cretaceous breccia are set in a matrix of calcite cement. 9. Volcaniclastic turbidites, flank of Nashville Seamount, New England Seamount Chain (43,382, 17, 1, 67-114 cm). These lower Campanian beds are laminated to cross-laminated and consist of volcanogenic clay and silty clay with interbeds of marly nannofossil ooze and zeolitic feldspathic silt. They form the uppermost part of the volcaniclastic apron of Nashville Seamount, above the breccias shown in panel 7. 10. Plantagenet Formation, lower continental rise off New Jersey. Upper Cretaceous or Paleogene silty clay with thin clayey quartz-sand stringers, heavy minerals, and palagonite grains (11, 105, 6, 2, 36-61 cm). Sharp color break in lower part of panel is a photographic artifact. 11. Bermuda Rise Formation, western Bermuda Rise. Lower Eocene radiolarian mudstone, more carbonate rich (<25%) in lower part (43, 387, 22, 3, 116-138 cm). Fine-grained, distal turbidites were episodically deposited in the central western North Atlantic basin at this time; the panel shows the upper part of one turbidite: a thick, homogeneous unit capped by burrow-mottled low-carbonate mud at the top of the turbidite sequence. The mudstones commonly are silicified and contain porcelanitic chert, particularly at the tops and bases of turbidites. 12. Blake Ridge Formation, lower continental rise terrace off New Jersey. The middle Miocene, burrow-mottled, gray-brown hemipelagic mudstone is characteristic of the Blake Ridge Formation (11, 106B, 5, 3,76-88 cm). 13. Blake Ridge Formation, central Bermuda Rise. Middle Eocene burrowed-mottled, marly biosiliceous ooze (top of a turbidite) capped by laminated biosiliceous ooze and biosiliceous mud (base of a turbidite) (43, 386, 17, 3, 76-98 cm). Biosiliceous component is primarily sponge spicules and radiolarians. 14. Great Abaco Member, Blake Ridge Formation, Blake-Bahama Basin. Lower Miocene silty, calcareous, biosiliceous claystone capped by laminated marly chalk forming the base of a turbidite (76, 534A, 14,5,50-65 cm). The Great Abaco Member is characterized by intraclastic chalks and calcareous turbidites deposited within the Blake-Bahama Basin.

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Cover photo. Portion of computer-generated image, "Relief of the Surface of the Earth," edited by J. R. Heirtzler, Report MGG-2, National Geophysical Data Center. Submarine topography based on DBDB- 5 (Digital Bathymétrie Data Base) of U.S. Naval Oceanographic Office.

Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/4149319/9780813754642_frontmatter.pdf by guest on 02 October 2021 The Geology of North America Volume M

The Western North Atlantic Region

Edited by

Peter R. Vogt Naval Research Laboratory Washington, D.C. 20375-5000

and

Brian E. Tucholke Woods Hole Oceanographic Institution Woods Hole, Massachusetts 02543

Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/4149319/9780813754642_frontmatter.pdf by guest on 02 October 2021 Acknowledgment

Publication of this volume, one of the synthesis volumes of The Decade of North American Geology Project series, has been made possible by members and friends of the Geological Society of America, corporations, and government agencies through contributions to the Decade of North American Geology fund of the Geological Society of America Foundation. Following is a list of individuals, corporations, and government agencies giving and/or pledging more than $50,000 in support of the DNAG Project:

ARCO Exploration Company Phillips Petroleum Company Chevron Corporation Shell Oil Company Cities Service Company Caswell Silver Conoco, Inc. Sohio Petroleum Corporation Diamond Shamrock Exploration Standard Oil Company of Indiana Corporation Sun Exploration and Production Company Exxon Production Research Company Superior Oil Company Getty Oil Company Tenneco Oil Company Gulf Oil Exploration and Production Texaco, Inc. Company Union Oil Company of California Paul V. Hoovler Union Pacific Corporation and Kennecott Minerals Company its operating companies: Kerr McGee Corporation Champlin Petroleum Company Marathon Oil Company Missouri Pacific Railroad Companies Rocky Mountain Energy Company McMoRan Oil and Gas Company Union Pacific Railroad Companies Mobil Oil Corporation Upland Industries Corporation Pennzoil Exploration and Production U.S. Department of Energy Company

© 1986 by The Geological Society of America, Inc. Library of Congress Cataloging-in-Publication Data All rights reserved. The Western North Atlantic region. All materials subject to this copyright and included in this volume may be photocopied for the noncommercial (The Geology of North America; v. M) purpose of scientific or educational advancement. Bibliography: p. Includes index. Copyright is not claimed on any material prepared "One of the synthesis volumes of the Decade of North by government employees within the scope of their American Geology Project series"—P. employment. 1. Geology—North Atlantic Ocean. 2. Geophysics— North Atlantic Ocean. 3. Paleoceanography—North Published by the Geological Society of America, Inc. Atlantic Ocean. 4. Mines and mineral Resources— 3300 Penrose Place, P.O. Box 9140, Boulder, Colorado 80301 North Atlantic Ocean. I. Vogt, Peter R. (Peter Richard), 1939- . II. Tucholke, Brian E. Printed in U.S.A. III. Geological Society of America. IV. Decade of North American Geology Project. V. Series. QE71.G48 1986 vol. M 557 s 86-19550 [QE350.2] [551.46'08'0931] ISBN 0-8137-5202-7

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Preface xi

Foreword xiii

INTRODUCTION

1. Perspectives on the geology of the North Atlantic Ocean 1 Brian E. Tucholke and Peter R. Vogt

2. Imaging the ocean floor: History and state of the art 19 Peter R. Vogt and Brian E. Tucholke

3. A Jurassic to recent chronology 45

Dennis V. Kent and Felix M. Gradstein

PRESENT ACCRETION AXIS

4. The crest of the Mid-Atlantic Ridge: Models for crustal generation processes and tectonics 51 Ken C. Macdonald 5. Subaerial volcanism in the western North Atlantic 69 Kristjan Saemundsson

6. Model of crustal formation in Iceland, and application to submarine mid-ocean ridges 87 Gudmundur Palmason

7. Seismicity along the eastern margin of the North Atlantic Plate 99 Pall Einarsson

8. "Zero-age" variations in the composition of abyssal volcanic rocks along the axial zone of the Mid-Atlantic Ridge 117 William G. Melson and Tim O'Heam

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9. Geochemical and isotopic variation along the Mid-Atlantic Ridge axis from 79>N to OPN 137 Jean-Guy Schilling

10. The geology of North Atlantic transform plate boundaries and their aseismic extensions 157 Paul J. Fox and David G. Gallo

11. Hydrothermal activity in the North Atlantic 173 J. M. Edmond

12. The present plate boundary configuration 189

Peter R. Vogt

REGIONAL GEOLOGY AND GEOPHYSICS

13. Gravity anomalies in the western North Atlantic Ocean 205 Philip D. Rabinowitz and Woo-Yeol Jung 14. Geoid undulations mapped by spaceborne radar altimetry 215 Peter R. Vogt

15. Magnetic anomalies and crustal magnetization 229 Peter R. Vogt

16. The relationship between depth and age and heat flow and age in the western North Atlantic 257 John G. Sclater and Lewellyn Wixon

17. Petrologic and geochemical evolution of pre-1 Ma western North Atlantic lithosphere 271 W. B. Bryan and F. A. Frey

18. Mid-plate stress, deformation, and seismiciiy 297 Mary Lou Zoback, Stuart P. Nishenko, Randall M. Richardson, Henry S. Hasegawa, and Mark D. Zoback

19. Seismic structure of the ocean crust 313 G. M. Purdy and John Ewing

20. Structure of basement and distribution of sediments in the western North Atlantic Ocean 331 Brian E. Tucholke

21. Subduction of Atlantic lithosphere beneath the Caribbean 341

G. K. Westbrook and W. R. McCann

PLATE TECTONIC EVOLUTION

22. Plate kinematics of the central Atlantic 351 Kim D. Klitgord and Hans Schouten 23. Plate kinematics of the North Atlantic 379 S. P. Srivastava and C. R. Tapscott

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24. Plate kinematics during the last 20 m.y. and the problem of "present" motions 405 Peter R. Vogt

SURFICIAL SEDIMENTATION

25. Surficial sedimentary processes revealed by echo-character mapping in the western North Atlantic Ocean 427 E. P. Laine, J. E. Damuth, and Robert Jacobi

26. Turbidite sedimentation in the northwestern Atlantic Ocean basin 437 Orrin H. Pilkey and William J. Cleary

27. Deep current-controlled sedimentation in the western North Atlantic 451 I. N. McCave and Brian E. Tucholke

28. Oceanic particles and pelagic sedimentation in the western North Atlantic Ocean 469 Susumu Honjo

29. Mass wasting in the western North Atlantic 479 Robert M. Embley and Robert Jacobi

30. Seabed geotechnical properties and seafloor utilization 491

Armand J. Silva and James S. Booth

BIOFACIES

31. Northwestern Atlantic Mesozoic biostratigraphy 507 Felix M. Gradstein 32. Paleogene biofacies of the western North Atlantic Ocean 527 Isabella Premoli-Silva and Anne Boersma

33. Neogene marine microfossil biofacies of the western North Atlantic 547 C. Wylie Poag and Kenneth G. Miller

34. North Atlantic Mesozoic and Cenozoic paleobiogeography 565

W. A. Berggren and R. K. Olsson

PALEOCEANOGRAPHY

35. Paleogeographic and paleobathymetric evolution of the North Atlantic Ocean 589 Brian E. Tucholke and Floyd W. McCoy

36. Paleoceanography and evolution of the North Atlantic Ocean basin during the Jurassic 603 Lubomir F. Jansa

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37. Cretaceous paleoceanography of the western North Atlantic Ocean 617 Michael A. Arthur and Walter E. Dean

38. Tertiary paleoceanography of the western North Atlantic Ocean 631

Brian E. Tucholke and Gregory S. Mountain

RESOURCES AND LAW OF THE SEA

39. Space systems as marine geologic sensors 651 R. J. Anderle 40. Resource potential of the western North Atlantic Basin 661 William P. Dillon, Frank T. Manheim, Lubomir F. Jansa, Gudmundur Pàlmason, Brian E. Tucholke, and Richard S. Landrum

41. The juridical ocean basin 677 John A. Knauss

Index 689

Plates (in accompanying slipcase)

Plate 1. Decade of North American Geology time scale with biostratigraphic correlations and correlative geologic events in the North Atlantic basin. A. Cenozoic. B. Mesozoic. Plate 2. Bathymetry of the North Atlantic Ocean. Plate 3. Magnetic anomalies of the North Atlantic Ocean. Plate 4. Free-air gravity anomalies of the western North Atlantic Ocean. Plate 5. Depth to basement in the western North Atlantic Ocean. Plate 6. Sediment thickness in the western North Atlantic Ocean. Plate 7. Echo character in the western North Atlantic Ocean. Plate 8A. Portrait of a plate boundary: the mid-Atlantic Ridge from the equator to Siberia. Plate 8B. Compositional variation of basaltic layer 2A along the MAR axis. Plate 9. Reconstructions of the North Atlantic Ocean basin from Late Triassic to Late Cretaceous time. Plate 10. Reconstructions of the North Atlantic Ocean basin from Late Cretaceous to Holocene time. Plate 11. Seismicity and state of stress of the North Atlantic Ocean basin and adjacent regions.

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The Geology of North America series has been prepared to mark the Centennial of The Geological Society of America. It represents the cooperative efforts of more than 1,000 individuals from academia, state and federal agencies of many countries, and industry to prepare syntheses that are as current and authoritative as possible about the geology of the North American continent and adjacent oceanic regions. This 29-volume series is part of the Decade of North American Geology (DNAG) Project which also includes eight wall maps at a scale of 1:5,000,000 that summarize the geology, tectonics, magnetic and gravity anomaly patterns, regional stress fields, thermal aspects, seismicity, and neotectonics of North America and its surroundings. Together, the synthesis volumes and maps are the first coordinated effort to integrate all available knowledge about the geology and geophysics of a crustal plate on a regional scale. The products of the DNAG Project present the state of knowledge of the geology and geophysics of North America in the 1980s, and they point the way toward work to be done in the decades ahead. In addition to the contributions from organizations and individuals acknowledged at the front of this book, major support for this volume has been provided by Woods Hole Océano- graphie Institution and the U.S. Naval Research Laboratory. A. R. Palmer General Editor for the volumes published by the Geological Society of America

J. O. Wheeler General Editor for the volumes published by the Geological Survey of Canada

This volume is the first to be published in the DNAG series on The Geology of North America. As volume editors, we consequently have had the opportunity to break new ground in formulating how best to synthesize and present the broad spectrum of geoscience studies applicable to the North Atlantic. By the same token, we have not benefited from prior experience to guide us in avoiding the pitfalls inherent in such a large undertaking. This circumstance slowed completion but in many ways stimulated production of a better volume. Our guiding philosophy, articulated in the 1982 "Perspectives" volume, has been to produce a synthesis of the geology and geophysics of the western North Atlantic that is useful to the widest possible spectrum of earth scientists. It should be comprehensible to earth- science graduate students and yet sophisticated enough to give a meaningful overview to the professional. It should integrate data and concepts into the kind of framework that will be useful to both Atlantic and non-Atlantic geologists. In fact, it is our hope that portions of this book will reach beyond geologists to physical oceanographers, ocean engineers, science historians, and lawyers dealing with the sea. We intended this volume to offer a set of perspectives on the status of knowledge during this Centennial decade. Individual chapters convey much of this information, and we summarize in the first chapter some of our own, broader perspectives on the past and future of geologic research in the western North Atlantic Ocean. We can look forward, in our dotage, to endless hours of evaluating the quality of our prescience and whether our efforts have been of lasting value. Unlike many books compiled around geologic themes or subject areas from collections of contributed papers, we designed this volume carefully from its inception to give complete coverage of the geology and geophysics of the western North Atlantic Ocean basin. We realized early that most of the volume could be effectively organized under the paradigm of plate tectonics, but only if the scope was broadened beyond the physiographic "western North Atlantic" as was initially conceptualized. It made little sense to synthesize only half of a rifted ocean basin and to overlook the present Mid-Atlantic Ridge axis as the factory where crustal generation could be studied in "geological real time." Therefore, a series of chapters was organized around the "present plate boundary." Similarly, an eastward extension of the U.S.-Canadian border was a poor basis for delimiting the geographic scope of a synthesis volume. Iceland has often been used as a boundary, but from the point of view of mantle dynamics, geochemistry, depths, and gravity anomalies, Iceland is the center of a vast regional anomaly, not the edge. Some of our chapters, therefore, synthesize the North Atlantic sensu lato from near the equator north through the Eurasia Basin in the Arctic. Thus the entire accreting plate boundary forming the eastern edge of the North American Plate could be treated in space and time as a single system, and the entire ocean basin could be dealt with as a single paleoceanographic system. Nonetheless, discussions emphasize the western North

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Atlantic, and coordination with other volumes—particularly the Arctic—has ensured com- plementary rather than repetitive treatments in areas of geographic overlap. Once we established the volume outline, we identified potential authors whom we con- sidered among the world-class authorities. Of those invited to contribute chapters, only one turned us down. Another withdrew midway through the process, allowing one of us time to write the chapter (Present Plate Motions). A third chapter on hotspots and absolute plate motion was promised but never submitted, leaving the only gap in our original outline. The authors gave generously of their time to produce chapters through a multi-stage process of formulating chapter outlines, participating in workshops, and responding to editorial direction and peer review of manuscripts. Because of length limits on the volume, we restricted authors to pre-agreed page limits and to citing only the most relevant literature. We also attempted to see that the philosophy outlined earlier was followed, that chapters neither repeated nor missed important subject material, and that chapters effectively utilized the set of plates in the slipcase accompanying this volume. For us, this has been an extremely time-consuming but rewarding, once-in-a-lifetime task, and we trust the quality of the final product will justify the effort. Neither of us could justify claiming the lion's share of the editorial duties, so we settled the order of editorship on the volume in a logical, scientific manner—by the flip of a coin.

Brian E. Tucholke Woods Hole, Massachusetts

Peter R. Vogt Washington, D.C.

July, 1986

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