The Alaskan Shelf: Hydrographic, Sedimentary, and Geochemical Environment

509 Pages·1979·21.9 MB·English

by  G. D. Sharma (auth.)

G.D. Sharma
The Alaskan Shelf
Hydrographic, Sedimentary, and Geochemical Environment
With 345 Illustrations
Springer-Verlag
New York Heidelberg Berlin
G.D. Sharma
Alaska Sea Grant Program
University of Alaska
Fairbanks, Alaska 99701
USA
Library of Congress Cataloging in Publication Data. Sharma, Ghanshyam Datt, 1931-The Alaskan
shelf. Includes bibliographies and indexes. I. Continental shelf-Alaska. 2.
Oceanography-Alaska. 3.' Marine sediments-Alaska. I. Title. GC85.2.A4S5 557.98
79-10454
All rights reserved.
No part of this book may be translated or reproduced in any form without written permission from
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former are not especially identified, is not to be taken as a sign that such names, as understood by the
Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone.
© 1979 by Springer-Verlag New York Inc.
Softcover reprint of the hardcover 1st edition 1979
9 8 7 6 5 4 3 2 1
ISBN-13: 978-1-4612-6196-4 e-ISBN-13: 978-1-4612-6194-0
001: 10.1007/978-1-4612-6194-0
To the memory of my father
Ram Chandra
Preface
From a general point of view the importance of striving to minimize environ-
mental disturbances on the continental shelf cannot be overemphasized. Coastal
areas are sites of population centers, navigation and recreation activities, and re-
source development, all of which contribute to environmental stress on the
shelf. Proper management of the shelf for optimum use requires a thorough
understanding of shelf processes. Complex problems, such as the influence of
hydrodynamics on sediment dispersal, element differentiation and migration,
physiochemical changes at the sediment water interface, the relationship be-
tween the pollutants and sediments, and the type of substrate with regard to
benthic community and/or man-made structures require a multidisciplinary
approach to their solution. The present study interrelates meteorologic, hydro-
graphic, sedimentologic, and geochemical parameters to derme specific environ-
ments on the Alaskan Shelf. These observations are then related to geologic
principles in an effort to elucidate the sedimentary processes and elemental
migration on the shelf.
Attempts have also been made to relate the sediment texture to the geochemis-
try of the sediments. Obviously the chemistry is complicated as a result of bio-
genic contributions and variable provenance; however, to some extent elemental
differentiation accompanies textural differentiation in sediments.
The distribution of elements in various phases of crustal (source) rocks is gener-
ally interpreted on the basis of crystallographic concepts, especially the concept
of isomorphism. This is the basis of our conception of distribution and abun-
dance of the elements and is a starting point for the hypothesis of the origin
of elements. Studies of geochemical balance in different processes, such as
weathering of crystalline rocks and sedimentation, have provided us with infor-
mation on the mechanism of separation and concentration of the elements. The
understanding of the sedimentary rocks and their elemental distribution, how-
ever, requires the understanding of the processes of their formation as well as of
aquatic chemical processes. This concerns the migration of the chemical ele-
ments, in various specific forms (Le., ions, complexes, atoms), and the develop-
ment of a physiochemical theory related to marine geologic processes. Emphasis
is placed on this theme throughout this treatise. The textural, mineralogic, and
geochemical parameters are extenSively used to identify the sources and path-
ways of sediments on the shelf. The interrelations between the texture and
geochemistry of shelf sediments reveal the effects of marine transport on the
mineral and elemental differentiation.
vi Preface
There are undoubtedly shortcomings in this book, particularly in regard to
station coverage, and perhaps a need for some additional analyses on sediments.
Although it is always highly desirable to have additional data, the logistic prob-
lems and the harsh climatic conditions place formidable limitations on the
collection of comprehensive data.
G. D. Sharma
Professor of Marine Science
Alaska Sea Grant Program
University of Alaska
Fairbanks, Alaska
Acknow ledgment
This volume represents the work achieved over a number of years during which
many students and assistants provided their talents in the laboratory as well as
onboard ship. Special thanks are extended to Miss Shalini Sharma and Mr. David
Burbank who helped generously during collection and analysis of samples, data
processing, and drafting.
I am especially grateful to Dr. Joe S. Creager for providing sediment samples
from some regions of the Chukchi and Bering seas and for his generous cooper-
ation and assistance extended to me during my stay at the University of
Washington.
The computer analysis was performed under the supervision of Mr. Ivan
Frohne, Dr. Dan Hawkins, and Dr. James Kelley, and their expert assistance is
much appreciated.
The book was reviewed by Dr. Tom Mowatt, Prof. AI Belon, Dr. D. M. Hopkins,
and Prof. G. M. Friedman. These reviews deserve many thanks for their cooper-
ation and quality efforts.
Finally, I wish to thank my wife, Norma, for typing the original draft and for
her patience.
Contents
Chapter 1. Regional Setting ................................... 1
Introduction ............................................1
Southeastern Alaska ...................................... .4
Northeastern Gulf of Alaska .................................5
Central Gulf of Alaska .....................................5
Prince William Sound ......................................6
Port Valdez ............................................6
Northwestern Gulf of Alaska .................................6
Cook inlet .............................................7
Bering Sea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., . . .7
Chukchi Sea ............................................8
Beaufort Sea ............................................9
Sediment Parameters ......................................9
Textural ............................................9
Chemical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Chapter 2. Southeastern Alaska ............................... 13
Introduction ........................................... 13
Geology .............................................. 13
Bathymetry ........................................... 16
Hydrology ............................................ 29
Hydrography .......................................... 30
Sediments ............................................ 32
Detrital Sediments ..................................... 34
Biogenic Sediments .................................... 54
Geochemistry .......................................... 59
Sediment Source and Transport .............................. 72
Summary ............................................. 75
References ............................................ 76
Chapter 3. Gulf of Alaska Shelf ............................... 80
Introduction ........................................... 80
Geology .............................................. 80
Hydrology ............................................ 82
x Contents
Hydrography .......................................... 82
References ............................................ 83
Chapter 4. Northeastern Gulf of Alaska Shelf ...................... 85
Introduction ........................................... 85
Geology .............................................. 85
Bathymetry ........................................... 87
Hydrology .............' ............................... 88
Hydrography .......................................... 89
Sediments ............................................ 89
Shelf. ...............•............................. 89
Yakutat Bay ......................................... 90
Geochemistry .......................................... 94
Sediment Source and Transport .............................. 94
References ............................................ 97
Chapter 5. Central Gulf of Alaska Shelf. ......................... 99
Introduction ........................................... 99
Geology ............................................. 100
Bathymetry .......................................... 101
Hydrology and Hydrography ............................... 102
Sediments ........................................... 103
Geochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Sediment Source and Transport ............................. 120
References ........................................... 135
Chapter 6. Prince William Sound ............................. 136
Introduction .......................................... 136
Geology ............................................. 136
Bathymetry .......................................... 141
Hydrology ........................................... 141
Hydrography ......................................... 142
Sediments ........................................... 144
Geochemistry ......................................... 155
Sediment Source and Transport ............................. 171
References ........................................... 184
Chapter 7. Port Valdez .................................... 185
Introduction .......................................... 185
Geology ............................................. 186
Bathymetry .......................................... 187
Hydrology ........................................... 187
Contents xi
Hydrography ......................................... 187
Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
Geochemistry ......................................... 200
Sediment Source and Transport ............................. 208
References ................................ .. ........ . 216
Chapter 8. Northwestern Gulf of Alaska Shelf. .................... 218
Introduction ......................................... . 218
Geology .......................................... ',' .219
Bathymetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
Hydrology . . . . . . . . . . ................................. 222
Hydrography ......................................... 223
Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Geochemistry ......................................... 232
Sediment Source and Transport ............................. 242
References ........................................... 250
Chapter 9. Cook Inlet. .................................... 253
Introduction ............................. . ............ 253
Geology ............................................. 253
Bathymetry .......................................... 256
Hydrology ........................................... 256
Hydrography ......................................... 256
Sediments ........................................... 260
Geochemistry ......................................... 260
Sediment Source and Transport ............................. 260
References ...................................... .... . 270
Chapter 10. Bering Shelf. ................................. . 272
Introduction .......................................... 272
Geology ............................................. 274
Bathymetry ...... . ... . ...... . ........................ 276
Hydrology ........................................... 278
Hydrography ......................................... 279
Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284
Geochemistry ......................... . ............... 303
Sediment Source and Transport ..... . ............ . .... .. .... 321
Sediment Transport in Suspension ......................... 321
Ice-Rafted Sediments .................................. 341
Bottom Sediment Transport ............................. 346
References ........................................... 362
xii Contents
Chapter 11. Chukchi Sea Shelf. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370
Introduction .......................................... 370
Geology ............................................. 370
Bathymetry .......................................... 373
Hydrology and Hydrography ............................... 373
Sediments ........................................... 377
Geochemistry ......................................... 382
Sediment Source and Transport ............................. 395
References ....... . ................................... 415
Sediments. . ............................... 426
Geochemistry ......................................... 427
Sediment Source and Transport ............................. 428
References ........................................... 431
Chapter 12. Beaufort Sea Shelf .............................. 418
Introduction. ......................................... 418
Geology .................... . ........................ 418
Bathymetry .......................................... 419
Hydrology and Hydrography ............................... 424
Chapter 13. Textural and Geochemical Evolution .................. 434
Textural Evolution ..................................... 434
Geochemical Evolution. .................................. 436
Chemical Transformation ................................. 438
Major Elemental Migration ................................ 445
Introduction ........................................ 445
Aluminum ......................................... 448
Iron ............................................. 449
Calcium ........................................... 455
Magnesium ......................................... 455
Sodium ........ . .................................. 459
Potassium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461
Titanium .......................................... 463
Manganese ......................................... 466
Trace Element Migration .................................. 466
Introduction ........................................ 466
Barium ........................................... 467
Cobalt ............................................ 468
Chromium ......................................... 469
Copper . . ......................................... 471
Nickel ............................................ 472
Strontium ......................................... 473
Zinc ............................................. 474
References ........................................... 475