Physics of Sedimentology

Springer-Verlag Berlin Heidelberg GmbH

Kenneth J. Hsu

Physics of Sedimentology Textbook and Reference

2nd edition

With 65 Figures

Springer

Author Dr. Kenneth ]. Hsii. 71 South Lane New Malden Surrey England, KT3 5HL e-mail: Kenjhsu@aol.com

The first edition of this book was published under the title "Physical Principles of Sedimentology. A Readable Textbook for Beginners and Experts". © Springer-Verlag Berlin Heidelberg New York 1989

ISBN 978-3-642-05832-5 ISBN 978-3-662-09296-5 (eBook)

DOI 10.1007/978-3-662-09296-5

Library of Congress Cataloging-in-Publication Data Hsu, Kenneth J. (Kenneth Jinghwa), 1929-Physics of sedimentology : textbook and reference / Kenneth J. Hsu.

QE471.H78 2004

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Preface to the Second Edition

I was asked by the publisher to prepare a revised second edition after the cop­ies of the first edition were sold out. I happily complied, because my slim vol­ume has achieved a purpose. Many readers wrote me during the last decade and half, not only from US and UK, but also from India, Cuba, Brazil, China, and other developing countries. They were geology students, and they complained that their college curriculum did not include a very healthy dose of physics. There has been an over-emphasis on natural-history approach. My readers found my slim volume unique in revealing to them a physicist's logic in ana­lyzing geological problems.

As I wrote in the original preface, common-sense induction from observa­tions is necessary, but not sufficient. There are infinite observations to be made, but, as Karl Popper said, a million white swans cannot prove that all swans are white, while the sighting of one black swan is sufficient to falsify the postulate. Geological deductions from the few fundamental principles of physics are not unlimited. Deductions which are physically impossible can be ruled out as working hypotheses. Geology may seem complex to geology students, only if they have not learned to eliminate the physically impossible.

I often heard the murmurings of my geologist friends that they do not be­lieve in thermal convection of the earth's mantle. I used to feel the same way until my friend Leon Knopoff told me that the "belief" should not be an ex­pression of an opinion or of a faith, but it is an issue of physics. A dimension­less number dictates whether thermal convection is or is not going to take place. It would be physically impossible not to have convection when the Rayleigh Number exceeds a certain critical value. I could understand Knopoff because there are such dimensionless numbers in sedimentology. For example, whether the motion of the basal boundary layer of a density flow is turbulent or lami­nar depends upon the Reynolds number of the fluid motion; there is no room for intuitive speculations.

Reading the text of the first edition again, I found little need for revision. The Newtonian Laws of Motion are as good today as they were 15 years ago, nor have the fundamental physical principles of sedimentology changed. I did find that

VI Preface to the Second Edition

an amendment of Chapt. 5 and 6 desirable. Progress has been made in under­standing the physical motions of rockslides and of subaqueous density flows. I could amend the chapters on the basis of new insight, and I depended greatly on the two excellent review articles by Chris Kilburn and by Thierry Mulder and Jan Alexander.

I also have some new ideas on the subject of teaching and research since my retirement from ETH. I did add a few words on Chapt. 14 Why Creativity in Geology?

I am suggesting to the publisher a change of the subtitle of this book to A Readable Textbook of Physics for Geology Students. Physics is a required course for all geology students in college. Unfortunately, the classes are commonly taught by physics professors with little interests in geology. College physics is just an in-depth repetition of middle-school physics. Most geology students find little relevance of physics which they have learned to the geology which they are studying. Few acquire the skill of analyzing geological problems as one of Newtonian physics. I wrote in the original preface that my purpose in writing the book is less to teach sedimentology, but rather to instill in students the skill to view earth phenomena as physical processes. I am proposing to the curricu­lum committee of the geology or earth science department in all universities that they consider to teach a course Physics for Geology Students as a comple­ment or substitute for the ordinary College Physics course. I do think that the geologists of the 21st century should be able to think as a physicist as well as they can think as a geologist.

London, Summer 2003 Kenneth J. Hsii

Addendum

I was pleasantly surprised that the first edition of the Physical Principles of Sedimentology has become a collector's item; used copies are sold on the internet market at more than twice the original publication price. The fact is a verification of my prediction that the geologists of the 21st century are think­ing as physicists.

Preface to the First Edition

This is a textbook for geology undergraduates taking their first course in sedi­mentology, for graduate students writing a term paper on sedimentology or preparing for their qualifying examinations, and for instructors, who deem it necessary to infuse a more physical-science approach to the teaching of geol­ogy. I also hope that some physics students might find the book readable and comprehensible, and that some of them might be inspired to start a career in the physics of geology.

This textbook is a revision of my lecture notes for my course Principles of Sedimentology at the Swiss Federal Institute of Technology. It is a two unit se­mester course given to second- or third-year undergraduate students, who have acquired a basic knowledge in physics, chemistry, mathematics, and geology. The purpose of teaching this course is to bridge the gap between what has been learned in middle school and in the first year of university to what shall be learned in geology during later years. I intend especially to impart the impres­sion to my students that the study of geologic processes is applied physics, ap­plied chemistry, and applied mathematics. The content of the book is some­what more extensive than what I have taught, and could be used as a textbook for a three-unit semester course, or even for a two-semester course, if a lecturer chooses to do so. We teach a second course in sedimentology, for which the stu­dents are recommended to consult textbooks on depositional environments and facies models. This textbook is not intended to replace, but to supplement those.

James Hutton in the late 18th century and Charles Lyell in the middle of the last century established the natural-history approach to study geology, and the success of the method is witnessed by the progress of the science over the last 2 centuries. The logic is inductive reasoning: Noting that quartz sands are ter­rigenous detritus derived from deeply weathered terranes, quartz sandstones or orthoquartzites are given paleoclimatic significance. Observing that marine organisms lived, died and are buried in marine sediments, fossil ecology be­comes a key to interpreting sedimentary environments. There needs to be no reference to Newtonian mechanics or to Gibbsian thermodynamics, because physical laws cannot be invoked to prove or falsify the interpretation.

VIII Preface to the First Edition

The method is necessary, reliable, but, in some cases, insufficient. Ortho­quartzites may have been altered from radiolarian oozes, not from quartz sands. Shallow marine microfossils are found in some deep-sea sediments. Simple rules of thumb may not give the correct explanation of complex processes. While the natural-history approach is necessary, the method is, in some cases, insufficient, and we need to know the physics of the processes involved. What seems likely may be physically impossible. What seems improbable may be the only physi­cally viable explanation. This is the physical-science approach to geology.

The diverse natural phenomena are infinite, and specialization of the earth sciences seems a necessity. Sedimentologists are specialists of sedimentary rocks; they are able to extract valuable data on earth history from the kaleido­scopic sedimentary record. Physical principles are, however, few in number and they are taught to geology students. Recognizing that earth phenomena are physical processes, a person using the physical-science approach can apply the three laws of motion, three laws of thermodynamics, the principles of the con­servation of energy and of matter, and perhaps a few other fundamental rela­tions in science, to explain a diversity of geologic processes.

M. King Hubbert advocated and exemplifies the efficacy of the physical sci­ence approach in geology. Hubbert was a physics student in college, and may not have taken any undergraduate course in hydrology, petroleum geology, or tectonics. Yet, he made his greatest scientific contributions in these three fields of specialization: in hydrology with this theory of groundwater motion, in pe­troleum geology with his research on the oilproduction technique of hydraulic fracturing, and in tectonics with his analysis of the role of pore pressure in overthrust mechanics. Similarly, the concept of platetectonics, the new para­digm of geology, is innovated by students of geophysics who knew little geol­ogy and still less tectonics; they made a simple assumption that diverse earth phenomena are the physical consequences of moving rigid plates on the sur­face of the earth.

As I have indicated, my purpose in teaching this course is less to teach sedi­mentology, but rather to instill in students the skill to view earth phenomena as physical processes. In fact, my original aim was to write on the Physical Prin­ciples of Geology, and this was the title of the book which I was contracted in 1971 to write. After 2 decades, I see my limitations and elect only to write on those Principles as illustrated by sedimentary processes.

I have tried to avoid the authoritarian attitude in writing this textbook, al­though I realize that we cannot start out from kindergarden. Since my students are mostly freshmen or sophomores in college, I made middleschool physical sciences a prerequisite for my course, and I presumed that they have a rudi­mentary knowledge of differential and integral calculus. I expect the same for my readers.

Preface to the First Edition IX

Textbooks are commonly not readable. After having written three books on geology for general readers, I find no reason why should I not also use the same "trade-book" style to compose a textbook for geology students. Several of my colleagues and students have read a draft of the manuscript and they found the claim of my subtitle - "A Readable Textbook" - justified.

I am indebted to many persons in having produced this volume, but I could single out only a few in this short acknowledgment. M. King Hubbert was the inspiration of my teaching philosophy. Several friends, especially Max Carman, Gerald Middleton, and Harvey Blatt gave me encouragement. Dave Kersey con­sented to be a co-author when I first began to write, but he had to back out because of his other commitments. My former assistants, Helmut Weissert, Guy Lister, David Hollander, Ulrich Henken-Mellies and Jon Dobson, helped in many ways in my teaching of the course, and their numerous corrections of the ear­lier drafts helped improve the manuscript.

lowe a special thanks to Ueli Briegel who not only instructed me in the use of the word-processor, but also consented to make a laser-print copy of the manuscript for photo-offset production. His effort preserves the aesthetics of the volume and at the same time reduces the cost to potential readers. Albert Uhr and Urs Gerber prepared the illustrations. I am indebted to the many col­leagues and publishers who gave me permission for reproducing modified ver­sions of their original illustrations.

The book is dedicated to the memory of my first wife Ruth. She grew up in the land where the word Heimweh originated. I promised her that i would write a textbook, so that I would become known, so that I might be offered a job in Switzerland, so that she could return to her native country. It has not turned out that way. Her ashes went to Basel first, before I was called to Zurich, before I became established, before this book was written. Life is full of its little iro­nies, as my favorite writer Thomas Hardy would say.

Zurich, Summer 1989 Kenneth J. Hsu

Contents

1 Introduction .................................................................. 1 1.1 Why Lecturing? ............................................................... 1 1.2 Why This Textbook? .......................................................... 4 1.3 Why Physical Principles? .................................................... 5 1.4 Why a Readable Textbook? .................................................. 8 1.5 Suggested Reading ............................................................ 9

2 Sorting Out and Mixing .................................................... 11 2.1 Bulk Minerals ................................................................ 11 2.2 Heavy Minerals ............................................................... 15 2.3 Size and Sorting .............................................................. 19 2.4 Exclusion Principle .......................................................... 20 2.5 Suggested Reading ........................................................... 22

3 Grains Settle ................................................................. 25 3.1 Stokes' Law .................................................................... 25 3.2 Why Derivation? ............................................................. 27 3.3 Dimensional Analysis ....................................................... 29 3.4 Fluid Resistance .............................................................. 32 3.5 Reynolds Number ........................................................... 35 3.6 Resistance Coefficient ....................................................... 38 3.7 Lacustrine Varves ............................................................ 41 3.8 Suggested Reading ........................................................... 46

4 Sediments Are Moved ...................................................... 47 4.1 Turbidity Currents ........................................................... 47 4.2 Chezy's Equation ............................................................. 50 4.3 Stream Transport ............................................................ 56 4.4 Shields' Diagram ............................................................. 57 4.5 Hjulstrom's Curve ............................................................ 60 4.6 Suggested Reading ........................................................... 62

XII Contents

5 Rocks Fall ..................................................................... 65 5.1 Sediment-Gravity Flows .................................................... 65 5.2 Elm Landslide ................................................................ 67 5.3 Grand Banks Slide ........................................................... 73 5.4 Speed of Slides ............................................................... 77 5.5 Debris Flows .................................................................. 80 5.6 Sand Avalanches ............................................................. 82 5.7 Mud Slide ..................................................................... 83 5.8 Olistostrome .................................................................. 84 5.9 Volume Dependence of Sturzstrom ....................................... 85 5.10 Suggested Reading ........................................................... 87

6 Suspensions Flow ........................................................... 89 6.1 Suspension Current .......................................................... 89 6.2 Auto-suspension ............................................................. 90 6.3 Bagnold's Criterion .......................................................... 92 6.4 Chezy-Kuenen Equation .................................................... 93 6.5 Keulegan's Law ............................................................... 95 6.6 Energy Line ................................................................... 96 6.7 Hyperconcentrated Density Flows ......................................... 97 6.8 Suggested Reading ......................................................... 100

7 Sand Waves Migrate ...................................................... 103 7.1 Richardson Number ....................................................... 103 7.2 Froude Number ............................................................ 105 7.3 Model Theory .............................................................. 106 7.4 Point-Bar Sequence ........................................................ 111 7.5 Bedform ..................................................................... 113 7.6 Facies Models ............................................................... 118 7.7 Suggested Reading ......................................................... 121

8 Oceans Are Ventilated .................................................... 123 8.1 Ocean Currents ............................................................ 123 8.2 Bernoulli's Theorem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 129 8.3 Darcy-Weisbach Equation ................................................ 131 8.4 Contourites ................................................................. 134 8.5 Suggested Reading ......................................................... 135

9 Groundwater Circulates .................................................. 137 9.1 Darcy Equation ............................................................ 137 9.2 Poiseuille Law .............................................................. 141 9.3 Hydrodynamic Potential .................................................. 142

Contents XIII

9.4 Permeability ................................................................ 143 9.5 Compaction ................................................................. 146 9.6 Diffusion .................................................................... 148 9.7 Suggested Reading ......................................................... 150

10 Components Equilibrate ................................................. 151 10.1 Mass-Action Law ........................................................... 151 10.2 Gibbs Criteria of Chemical Equilibrium ................................ 152 10.3 First and Second Law of Thermodynamics ............................ 154 10.4 Lewis Concept of Chemical Activity ..................................... 156 10.5 Carbonate Equilibria ...................................................... 157 10.6 Metastable Phases ......................................................... 161 10.7 Calcite Dissolution ......................................................... 163 10.8 Suggested Reading ......................................................... 164

11 Evaporation Pumps ....................................................... 167 11.1 Dolomite .................................................................... 167 11.2 Dolomite Solubility ........................................................ 168 11.3 Material Transfer in Open Systems ...................................... 170 11.4 Seepage Refluxing ......................................................... 172 11.5 Evaporative Pumping ...................................................... 173 11.6 Flood Recharge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 175 11.7 Suggested Reading ......................................................... 176

12 Isotopes Fractionate ...................................................... 179 12.1 Isotopes ..................................................................... 179 12.2 Isotope Tracers ............................................................. 180 12.3 Paleotemperature .......................................................... 182 12.4 Paleoproductivity .......................................................... 185 12.5 Strangelove Ocean ......................................................... 187 12.6 Suggested Reading ......................................................... 190

13 Basins Subside ............................................................. 191 13.1 Isostasy ...................................................................... 191 13.2 Airy Model .................................................................. 192 13.3 Crustal Thinning ....... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 194 13.4 Mantle Heterogeneity ..................................................... 195 13.5 Lithospheric Stresses ...................................................... 196 13.6 Suggested Reading ......................................................... 199

14 Why Creativity in Geology ............................................... 201 Suggested Reading ......................................................... 206

XIV Contents

Appendix I .................................................................. 209

Appendix II ................................................................. 213

References ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 217

Index ........................................................................ 223