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USIGP-FY76 T\ JUNE 1976

FIRST ANNUAL REPORT OF Ad Hoc Committee on Geodynamics to TheFederal Council for Science and Technology

PREFACE

The ad hoc Committee on Geodynamics was established upon recognition of the need for an interagency mechanism for the coordination of U.S. Federal activities in the International Geodynamics Project (IGP). At the fall 1973, plenary meeting of the Federal Council for Science and Technology (FCST), the establishment of an ad hoc Committee on the IGP was approved in principle. The Committee was formally established by the chairman of the FCST in a memorandum dated May 21, 1974. The purpose of the ad hoc Committee is to ensure the planning and coordination of Federal activities in the IGP and related matters. The Committee fosters studies and investigations considered appropriate to the IGP and annually reviews the Federal geodynamics programs and budget. It also serves as the focal point for liaison with the U.S. Geodynamics Committee of the National Academy of Sciences, and with other outside bodies concerned with the IGP. Since its inception, the ad hoc Committee has met a total of fourteen times. The first meeting was on August 29,1974 and the most recent meeting on June 17, 1976. The present membership of the Committee is as follows: Member Alternate Organization A.P. Crary, chairman National Science Foundation Dallas Peck, vice-chairman Richard S. Fiske Department of the Interior Gordon Lill George Younger Department of Commerce Carl Romney William J. Best Department of Defense Fernand P. dePercin John G. Heacock Robert G. Morris Department of State George A. Kolstad Jerry Harbour Energy Re search and Development Administration Francis L. Williams Edward A. Flinn National Aeronautics and Joseph W. Siry and Space Administration

Observers Robert D. Lanza Department of Health, Education and Welfare Arthur J. Zeizel Department of Housing and Urban Development Jack W. Keely Environmental Protection Agency David Katcher National Advisory Committee on Oceans and Atmosphere

Executive Secretary: Hugh W. Albers, National Science Foundation

First Annual Report on Federal Activities in Geodynamics

CONTENTS

Page

Background of Geodynamics 1 Societal Benefits from Geodynamics Studies 3 History of the International Geodynamics Project 8 Why the International Geodynamics Project is Timely 10 Questions for Geodynamics to Answer 11 Resume of Federal Activities in IGP, FY 74" FY 75, and FY 76 16 International Participation 23 Appendix I 25 Appendix II 27 Department of Commerce " 27 Air Force 29 ARPA 30 Navy , 31 ERDA 33 NASA 35 NSF 36 USGS 40

iii

BACKGROUND OF GEODYNAMICS

The Earth Sciences are undergoing a period of plate tectonics theory differs from continental rapid advance, the result of a simplifying theory drift theory in that the plate boundaries seldom that has unified geologic thinking and provided a coincide with continental boundaries. new framework for interpretation of obser­ Stated very briefly, the plate tectonics concept vational and experimental data. The major initial holds that new crust is constantly being contributions to the new concept came from generated along mid-ocean ridges; hot molten marine geology and geophysics, and seismology. material rises from the underlying mantle, cools, These observations led to the theory that has and is forced aside by new molten material become known as plate tectonics, centering on coming from the depths. The plates are in the concept that the earth's outer shell, consisting constant movement, the principal direction being of the crust and upper part of the mantle, is made at right angles to and away from the center of the up of a small number of very large semi-rigid mid-ocean ridges. On the opposite sides, the pIates that move relative to one another. The plates collide to form mountains, or one plate

Map showing the plate structure of the Earth. At subduction zones (heavy dark curves) such as the deep trenches ringing the Pacific, the leading edges of the plates plunge downward to be consumed in the mantle. The mid ocean ridges are shown by the dark segmented lines. Along them the mantle wells up and solidifies as the ocean floor spreads. Plates rub edge to edge along transform faults (thin curved lines). The dots mark the location of earthquakes that have been recorded during the last 20 years. edge may be drawn below another at the deep sea national Geodynamics Project (IGP). trenches in what is called a subduction zone. The IGP is an international program of Thus, along their boundaries, the plates either research on the dynamic processes that affect move parallel to one another, move apart (as at and have affected the earth. A major goal of the spreading centers) or converge (as at subduction IGP is to delineate the internal forces that cause zones). According to today's model, the present the horizontal motion of the plates, as well as the spreading cycle started about 200 million years vertical movements of large parts of the plates, ago, at which time the continents were essential­ and ultimately to understand the mechanisms ly one land mass that split apart along what is that give rise to these forces. now the mid-Atlantic ridge. Since then the The IGP is coordinated by the Interunion continents have been moving apart at about two Commission on Geodynamics (ICG) established centimeters a year. by the International Council of Scientific Unions The plate tectonic concept has enormous (ICSU) at the request of the International Union promise in explaining the origin of earthquakes, of Geodesy and Geophysics (IUGG) and the volcanoes, faulting, and mountain building with International Union of Geological Sciences resulting implications for natural disasters, (IUGS), with the provision for active participa­ energy resources, and the emplacement of tion of all interested ICSU unions and com­ economically valuable concentrations of mittees. There are now 52 countries participating minerals and hydrocarbons. The general recogni­ in the IGP with the realization that the plate tion of the potential impact of this "revolution in tectonic model is a global one, and that a earth sciences" led to the concept of an intensive coordinated effort among all parties involved international program to study the basic will achieve greater and more rapid progress mechanism of earth deformation-the Inter- than isolated individual efforts.

2 SOCIETAL BENEFITS FROM GEODYNAMICS STUDIES

Man's safety from natural hazards and man's The possibility of predicting and, to some prosperity are closely linked to his understan­ extent, controlling earthquakes, has been greatly ding of large-scale geodynamic processes oc­ enhanced by the plate tectonics concept. But, in curring at or beneath the earth's surface. Earth­ order to achieve such capabilities, a better quakes; volcanoes; concentrations of understanding is needed of the mechanics of hydrocarbons, minerals, and geothermal heat; earthquakes and of the forces responsible for the and mountain ranges are all manifestations of stress accumulations. The dynamics of the plate such geodynamic or tectonic processes. It has motions is a crucial factor. been known for some time that tectonic activity Certainly, a better understanding of the on a global scale is concentrated in very narrow mechanisms behind crustal movement and the zones but no rationale for the concentration of a state of stress in the interiors of plates is number of seemingly unrelated phenomena was essential before we can venture any effort at available until the advent of plate tectonics. Now earthquake control. Results of several recent the majority of the narrow zones of tectonic experiments at the Rocky Mountain Arsenal and activity are regarded simply as the network of at Rangely, Colorado have indicated that minor pIate boundaries covering the surface of the earthquake activity can be initiated by pumping earth. nuid under pressure down a borehole so that it relieves the stress at depth on a pre-existing Earthquakes fault. The activity can be stopped by withdraw­ Almost 90 percent of the world's earthquakes ing the fluid. This limited experience suggests the occur along these boundaries. Two such zones possibility of control on a large active fault zone cross the United States. One extends from the such as the San Andreas. Once the details of the Culf of California to Cape Mendocino (north of s tress distribution at depth and the mechanism of San Francisco) and includes the sites of the 1906 movement along the fault are reasonably well San Francisco and the 1971 San Fernando earth­ understood, a program of control by fluid quakes. injection might be achieved whereby the stored The second zone extends from southeastern strain energy on the fault is released by inducing Alaska through the Aleutian island chain and a number of small and relatively harmless includes the Aleutian trench, which is the site of earthquakes. many deep focus earthquakes. On land this zone A better understanding of the detailed includes the site of the large earthquake near mechanisms of crustal movements in fault zones Anchorage in 1964. Many of the narrow earth­ would also be of great value in predicting ground quake zones cross densely populated regions, motion from anticipated earthquakes at potential e.g., the Pacific Coast of the United States, Japan, construction sites near or remote from the fault and areas bordering on the Mediterranean Sea. zones. Decisions of great societal and economic Some 500 million people are exposed to personal importance should be based on such predictions, danger and damage to personal property in these e.g. the siting of nuclear reactors, oil pipelines, seismic risk areas. Perhaps more than any other aqueducts, dams and reservoirs, hospitals, and geophysical hazard, major earthquakes are likely public transit systems. to produce almost complete social disruption in Although most major earthquakes are along modern urban areas. The vital technologies of a plate boundaries, the interiors of plates are not city both above and below ground may be immune. In the North American Plate there have shattered. To compound the problem, earth­ been major earthquakes in the vicinity ofBoston, quakes may trigger secondary events such as Massachusetts (1755); at New Madrid, Missouri fires, tsunamis, landslides, or floods, which in the central Mississippi Valley (1811 and 1812); commonly cause more damage and loss of life at Charleston, South Carolina (1886); and at than the earthquakes themselves. Hebgen Lake, Montana (1959). Indeed, most of

3 Seismic Risk Map of the United States Areas of earthquake damage in historic times. Note that of the several areas of major damage only coastal California is associated with one of the plate boundaries. the U.S. has some risk of seismic disturbance. deep seated geodynamic processes. Its impact on The so-called intraplate earthquakes pose man involves not only potential hazard but also special problems to be addressed by potential benefit. The hazard of volcanic erup­ geodynamics research because their relationship tions is of real concern; some 200,000 people have to the horizontal movements of the plates is not been killed by volcanoes in the past 500 years. obvious. Although intraplate earthquakes are Specific hazards include lava flows, pyroclastic rarer than earthquakes on plate boundaries, the flows, ash falls, volcanic mudflows, and floods, long term risk, in terms of property damage and as well as a number of volcanically generated loss of life, is comparable. This is because the events such as tsunamis, forest fires, and debris crust in the interiors of most plates is much more avalanches and landslides. Volcanic hazard is uniform and homogeneous than at the boun­ significant in three major areas of the United daries. Thus it is a more efficient propagator of States: Hawaii, the Cascade Range of the Pacific earthquake disturbances and a given magnitude Northwest, and Alaska. The potential for loss in intraplate earthquake will usually have a much terms of property damage, injury and loss of life, larger area of high intensity and damage than one and social disruption appears to be increasing of equal strength along a plate boundary. because of significant population growth and urbanization in all three major hazard areas. The Volcanoes development of energy resources in Alaska and the Pacific Northwest is magnifying the loss Volcanic activity is a surface manifestation of potential.

4 o 50km. I I CONTINENT

OCEAN BASIN

SEA lEVEL CRUST AND SEDIM

6000

COLD MANtlE

Volcanoes and Plate Boundaries A schematic cross section of a convergent plate boundary. As the oceanic plate moves from left to right, it is forced under the continental plate. When the upper part of the oceanic plate reaches to about the 1500° isotherm partial melting occurs and the magma rises to form volcanic mountains at the surface. Volcanoes are also characteristic of the spreading centers or divergent plate boundaries.

As withearthquakes, volcanic activity is most Natural Resources common in the tectonic zones that characterize the plate boundaries. A better understanding of Recent shortages and embargoes have the geodynamic processes involved at plate highlighted the need to understand the natural boundaries is a necessary precursor to a better processes that have produced petroleum, coal, understanding of a volcanic system, and any metals, and other earth resources, such as hoped for eruption prediction. geothermal heat, that are essential to the Nation's Volcanoes contribute to man's well being in technology. Plate tectonics is clearly related to several ways. Soils derived from volcanic the formation of oil and mineral deposits. The material are extremely fertile. Volcanic formation of oil and gas reservoirs appears to emissions of rock and gas are sources of pumice, have been determined to a large extent by the ammonia, boric acid, and carbon dioxide. The history of plate movements over the past 200 thermal energy of volcanoes is being put to more million years. For example, long-term vertical and more use. Many homes in Iceland are heated movements, which are related to geodynamic by hot water tapped from volcanic springs. processes at depth, have resulted in sediment­ Geothermal steam associated with sites of recent filled basin troughs that are important sources of volcanism is being exploited as a source of hydrocarbons. Almost nothing is known about electricity in New Zealand, Italy, the United the forces that cause these vertical movements, States, Mexico, Japan, and the U.S.S.R. despite their great economic significance. A

5 The Offshore Petroleum Potential of South America Along the east coast of South America are elongated basins filled with sediments that may range back to the time when South America and Africa split apart. These basins are a prime target in the search for oil and natural gas.

6 better understanding of such forces could im­ been found. Future success in mineral explora­ prove our techniques for petroleum exploration. tion will require a sophisticated approach that The total amount expended by U.S. companies includes an understanding of the relationship for petroleum exploration is about $4 billion per between mineral deposits and the underlying year. A modest increase of 1 percent in the geodynamic phenomena responsible for their efficiency of this effort, through better un­ origin. derstanding of basic geodynamic processes, Geothermal heat as a natural resource has been would amount to some $40 million per year. exploited for centuries in areas of easily iden­ It is equally true that mineral deposits are not tified surface manifestations such as steam randomly distributed, but are related to past and vents, hot springs, and geysers. However, the present tectonic zones. The type of are present broader picture of the flow of matter and energy and where it is located depends principally on within the earth is one of the principal goals of tectonic history of the zone. A particularly clear the International Geodynamics Proj ect. An example is the copper sulfide deposits on the understanding of deeper patterns of heat dis­ island of Cyprus. The copper sulfide are occurs in tribution, with little or no surface expression, a distinctive sequence of rocks, called an will also be essential to the exploration and ophiolite sequence, which is now thought to be a development of geothermal resources in the next largely unaltered piece of oceanic crust thrust up two decades. The plate tectonics concept and when Cyprus was formed. The minerals it knowledge of the physics of flow of fluids contains are thus characteristic of those formed through permeable rocks will be valuable guides at mid-ocean ridges. Most of the mineral deposits to these exploration and development efforts. with easily recognizable surface features have

OCEANIC SEDIMENTS (LAYER) WITH MErAL RICH HORIZON AT THEIR BASE COPPER CONCENTRATIONS PORPHYRY COPPER DEPOSITS IN OCEAN IC CRUST OCEAN RISE VOLCANIC CHAIN (S ITE OF M ETAL-R ICH EXHALATIONS) OCEAN

50 KM

700 KM

A Possible Model for Porphyry Copper Ores Magmas rising at the ocean spreading center (divergent plate boundaries) give off hydrothermal solutions rich in copper, iron, and other transition metals. These precipitate and are incorporated into the basalt sediments just above the lavas. When these metal-rich sediments are later forced down in a subduction zone at a convergent plate boundary, and are partially melted (as shown in the previous illustration also) the copper is again reconverted and migrates upward in hydrothermal solution to form large ore deposits like those of the Andes Mountains.

7 HISTORY OF THE INTERNATIONAL GEODYNAMICS PROJECT

Rapid developments that resulted in new London (May 1969), and produced a document concepts of global tectonics were taking place in entitled Report of the Ad Hoc Committee on the the earth sciences in the early and middle 1960's. Long-Range Program of Solid Earth Studies. These advances took place during the period of This report, calling for a program entitled, "The the International Upper Mantle Project-a dis­ Geodynamics Project" was the subject of an cipline oriented program directed primarily at informal meeting convened in Madrid in understanding the structure of the earth's in­ September 1969 during the General Assembly of terior. The exciting new concepts that emerged­ the International Association of Seismology and sea floor spreading and plate tectonics-caught Physics of the Earth's Interior (IASPEI)­ the fancy of scientists all over the world. It was International Association of Geomagnetism and inevitable that means to exploit these fruitful Aeronomy (IAGA), which was held to give the theories would be actively explored. officers of the unions a chance to discuss the The beginnings of the International proposed program with a representative group of Geodynamics Project (IGP) can be traced to an interested scientists. The report, which authoriz­ informal meeting of the Geophysics Research ed the creation of an interunion Commission on Board (GRB) of the National Academy of the Geodynamics Project (ICG), was accepted by Sciences in March 1968. The Chairman, Merle the Executive Committee of ICSU in October Tuve, advocated an international effort, with the 1969. ICG was to consist initially of a bureau of hypothesis of sea floor spreading as the focus, seven, a president agreed to by the two unions which would have a revolutionary impact on and three nominees each from the two unions. almost all earth science disciplines.! These ideas Membership of the bureau was approved by the were approved by the Council of the AGU in officers of ICSU in February 1970. It held its first April 1968 who directed that they be transmitted meeting in Flagstaff, Arizona, July 1970. to the International Union of Geodesy and The recommendations and constitution of the Geophysics (IUGG). Later in the same month, the ICG were approved by the General Assembly of GRB adopted a similar resolution urging that ICSU in September 1970, following which ICSU IUGG and the International Union of Geological called upon the countries to develop programs of Sciences (lUGS) take prompt action to organize a participation in the Geodynamics Project. Ten program under ICSU sponsorship. working groups of the ICG were established by The GRB initiated correspondence with the the bureau at its meeting in London in 1971 and two relevant international unions, IUGG & implemented at the IUGG General Assembly in lUGS. Both reacted favorably to the proposal and Moscow in August 1971. These working groups initiated discussions of it at their executive are problem-oriented; some deal with regional committee meetings in the summer of 1968. The problems, some with global problems. Most of two committees reached agreement on final these working groups have been very active in wording and transmitted the proposal to the developing plans and symposia. They have General Assembly of ICSU in the latter part of prepared a series of frontier reports that are September 1968. ICSU accepted the proposal in intended to assess progress to date in their principle but requested the unions to prepare a respective problem areas and to indicate the most more detailed statement of the nature of the fruitful direction for future research during the proposed program. The unions then appointed an remainder of the Geodynamics Project. ad hoc committee to be chaired by Prof. Charles L. The ICG has met annually since its initial Drake, composed of three members nominated by meeting in July 1970 as follows: Leiden each of the unions. The committee held two Netherlands, March 1971; Moscow, August 1971; meetings-in Paris (February 1969) and in Montreal, August 1972; Lima, Peru, August 1973, Zurich, August 1974; Grenoble, France, August 1975. At each of the meetings, beginning in 1972, 1 Transactions of the American Geophysical Union, Vol. 49, No.6, June 1968. there have been several symposia co-sponsored

8 by the Geodynamics Commission. The largest most likely to be interested in participating in the number of such symposia took place at the program; and received strong endorsement for meeting in Grenoble in August 1975. In keeping the direction of its planning from 9 major with the constitution of the Commission, there geoscience societies. The result of these has been a regular rotation of membership of the deliberations was the issuance in 1973 of a major officers of the Commission. The President in 1970 report, U.S. Program for the Geodynamics through 1975 was Prof. Charles L. Drake who Project: Scope and Objectives. was also the Chairman of the U.S. Geodynamics The geodynamics of the Americas plate is Committee. The new President is Professor naturally a principal focal point of the U.S. Anton Hales of Australian National University, program. Thus. a significant step was the Canberra. There have been three General organization of a meeting of Chairmen of Secretaries: Xavier Le Pichon, 1970-1972, Geodynamics Committees of the countries of the Frances Delany, 1972-1975, R.D. Russell, 1976 western hemisphere in Brazil, March 1973. Other onwards. meetings sponsored or co-sponsored by the The U.S. Geodynamics Committee of the geodynamics commission closely related to the National Academy of Sciences began its work Americas plate were: Buenos Aires, Argentina, early in 1970. The results of the Committee's October 1970; Flagstaff, Arizona, July 1970; initial thinking were published in the Transac­ Montreal, Canada, August 1972; Lima, Peru, tions of the American Geophysical Union, May August 1973; Mexico City, June 1973; Santiago, 1971. After preparation of its initial document, Chile, September 1974; Reykjavik, Iceland, July the U.S. Geodynamics Committee called upon 14 1974; Vancouver, Canada, August 1975; Sao working groups involving some 170 scientists Paulo, Brazil, October 1975. drawn from the academic community, govern­ The following time period for the lGP was ment, and industry to assist in developing recommended at the meeting of the Chairmen of recommendations for the program; sent drafts for Geodynamics Committees of the Americas in comment to correspondents (designated by the March 1973 and was approved by the lCG and by department chairmen) in more than 100 ICSU in September of 1973: 1971-1973 as the geoscience departments throughout the United period of planning and initiation; 1974-1979 as States; consulted with those Federal agencies the period of active research programs.

9 WHY IGP IS TIMELY

International programs such as IGP, that are problems dependent on an equitable inter­ sponsored by one or more of the 17 discipline­ national solution within the United Nations and oriented Unions of the International Council of the Law-of-the-Sea conferences. Scientific Unions (ICSU) and approved by the The plate tectonics theory provided the first governing council of ICSU, usually have several major breakthrough as a working hypothesis for common characteristics. These include: (1) the the horizontal movements of the earth's crust and global character of the science (for example the the sources and sinks of the crust and upper magnetosphere) that usually requires real-time mantle material. It offers some rationale for the observations and coordination of many nations specific locations ofpetroleum fields, the concen­ with similar data-gathering techniques, (2) tration of ore bodies, and of geothermal heat recent major discoveries in the sciences ( as the sources. The study of geodynamics provides a plate tectonics theory) or in the observing major source of the basic information needed for techniques (for example satellite monitoring) the optimum exploration of these earth that represent new opportunities for par­ resources. ticipants, and (3) major societal needs that would The plate tectonics theory would undoubtedly benefit from new scientific or technical have been delayed for a number of years were it knowledge (for example water resources not for the pioneering work of a relatively few research). dedicated scientists who studied the An international program provides, at the cost characteristics of the oceanic crust: the detailed of many man-years of scientific planning and the ocean floor bathymetry, the character of the organization of many symposia and workshops, ocean sediments, and the geophysical parameters cooperation between larger and smaller nations, of the oceanic crust. A decade or two ago, the the timely sharing of significant results, the oceans had few political boundaries outside the elimination of costly duplication of major field 3-mile zone, but today, with the growing realiza­ efforts, and the establishment of data centers tion of the importance of the oceans as a source where specifics of the results of field proj ects are for many of man's future requirements, the widely distributed. International programs are "ownership" of ocean areas has become a major also a means of increasing the scientific man­ political problem for the United Nations. power that is marshalled to a scientific discipline Regardless of the outcome of the Law-of-the-Sea and providing for the identification of major conferences, scientific exploration of a major obstacles to the progress of the subdisciplines. part of the world's oceans will depend largely on Two specific reasons for the timeliness of the international cooperation and goodwill between IGP are (1) international concerns of the future nations. This cooperation can be best initiated depletion of many of the earth's nonrenewable and extended by participation in international material resources: the hydrocarbons and programs, such as the International minerals, and the concomitant need for better Geodynamics Program, whose objectives have information on geothermal heat as an indepen­ long-term mutual benefits. dent source of energy; and (2) the political

10 QUESTIONS FOR GEODYN1AMICS TO ANSWER

Plate tectonics is a very attractive and per­ Nature of processes suasive hypothesis as a base for geodynamics studies because it apparently explains many of Of the different plate boundaries, the diverging the earth's major features and molds them into a type, i.e. the mid ocean ridges where new crust is single picture. Yet it is still barely a dozen years formed, are probably the best understood. Yet old, and many gaps and discrepancies need to be even these have knowledge gaps. Much of what explored before we either give it full credence or we are learning about these zones continues to replace it with a more-encompassing hypothesis. come from standard oceanographic cruises, but Among the important problems now needing much new information is being obtained from the attention and answers are (aJ the nature of use of more sophisticated and expensive tools processes that act on the plates, both the plate such as deeply towed instrument packages, margins and the interiors, (b J the history of ocean-bottom seismometers, and research sub­ spreading and plate movement, and (c J the nature mersibles. The recently completed field ex­ of the driving forces. periments of Project FAMOUS (French-

Topographic Model of the FAMOUS Area A model of the area of the Mid-Atlantic Ridge where the French-American Mid-Ocean Undersea Study (FAMOUS) project took place. Many surveying techniques, including observations from deep manned submersibles, were used to produce this model and label its features.

11 American Mid-Ocean Undersea Study) are good Converging plate boundaries are much more examples. In this project, volcanic and tectonic complex. When the colliding plates both carry processes associated with an active spreading continents near their leading margins, complex center have been directly observed from manned structures such as the Himalayas, subparallel submersibles. Despite these recent advances, mountain ranges, and elevated plateaus are there are still significant unexplained geological, formed. When the convergence is between geochemical, and geophysical variations that oceanic crust and continental crust, the oceanic exist along the axes of the mid-ocean ridges. crust is usually subducted with the formation of These variations must be accounted for in any a deep trench and an island arc system. These are comprehensive model of plate tectonics. complicated geological structures and the

Divergent boundary

Plate Boundaries A&B-Divergent Boundary Magma rises along a rift or spreading center, cools, and is forced aside by new magma coming from below. The rift may split continental crust (A), or oceanic crust (B). CaD-Convergent Boundary C. At the zone of convergence one plate is of oceanic crust, the other (on the left) is continental. A subduction zone, trench, and volcanic and folded mountain chain are developed. D. Both plates carry continental blocks. As these collide, the structu res, both in the subduction zone and in the mountains become exceedingly complex. Great nappe folds such as those of the Alps are common.

12 primary process taking place, underthrusting, evidence for prior plate movement will have to be occurs at such great depth that it is difficult to sought on the continents; the criteria for measure. A better understanding of converging recognizing old plate boundaries on land are not plate boundaries is very important, for these are yet fully developed. Perhaps one of the best the zones of volcanic and earthquake activity indicators is the location of the mineral rich with their far-reaching effects on the population. greenstone belts, volcanic rocks resembling As noted elsewhere, not all deformation takes those of modern island arcs. Such greenstone place at the plate boundaries. Important defor­ belts are found in Canada, Australia, South mations, either large scale faulting or warping, Africa, and other areas of very old crust. If these can and do occur in the interiors of plates. One old greenstone belts are indeed relics of ancient record of large vertical movements is the thick island arc subduction systems they constitute sedimentary sequences of subsided basins where evidence of plate tectonic activity prior to the most oil and gas deposits are found. Other breakup of Pangaea. This is not a universally vertical deformations, often accompanied by accepted hypothesis however, and much more volcanism, are found in such areas as the work needs to be done. Colorado and Himalayan plateaus and in many of the continental shields. Nor are large vertical Driving force movements restricted to continental crust; deep The most fundamental problem to be ad­ ocean areas within plates have also undergone dressed by the IGP is the question of the driving such deformation (e.g., the sediment-filled mechanism that keeps the plates in motion. This depressions beneath the continental rises of driving mechanism is the source of the forces eastern North America and the deep sea floor east involved in all the horizontal and vertical of Florida). motions we observe in the lithosphere and until Vertical movements, both in the interior of we establish its nature a complete description of plates and at their boundaries, control the the geodynamic processes within a planet is occurrence and distribution ofmany economical­ beyond our capabilities. There are several ly valuable mineral deposits. These deposits of promising lines of research to be pursued. igneous and metamorphic origin require a history It is generally agreed that the interior of the of subsidence and subsequent vertical uplift to earth has unstable zones. Three kinds of in­ make them accessible for exploitation. stability important for a general theory of The plate tectonics model in its present form geodynamics are: density inversions, fusion, and more readily explains horizontal than vertical solid-solid phase transformations. The movement. Perhaps vertical movement will be theoretical boundary-value problems associated found to be caused by other dynamic processes with these zones of instabilities will be for­ operating independently of those that are now midable and will require quantum mechanics and causing the horizontal movements. Nevertheless, lattice theory to explain the nature of fusion and if the plate tectonics model is to have general the nature of solid-solid phase transformations. validity it must be able to explain all major In the laboratory, tests of representative crustal movements, oceanic and continental, mantle mineral assemblages at very high vertical and horizontal. pressures and temperatures are needed to deter­ History of spreading mine shear velocities in the vicinity of phase transformations and the creep properties of the For a full understanding of how the earth assemblages-a measure of the relative fluidity behaves as a system, it is crucial to establish of the mantle. The volume capacity of present day whether plate tectonics has been an integral part laboratory test facilities must be increased to of the dynamic history of the earth from the determine these properties. beginning or whether it has appeared during 'Nhen phase transformations are incorporated some later stage of the planet's history. The in a geodynamic theory it is important to know current spreading cycle can only be extrapolated the time scale of the transformation and to know back about 200 million years, when the con­ the energy exchange involved. Experimental tinents as we now know them were joined work on the kinetics of phase transition is just together in one large land mass, called Pangaea. beginning. There may be phase transitions in the As no part of the oceanic crust is older than this, earth that are important to geodynamics but

13 The Drift of Continents The disposition of the continental crust on the surface of the world during the present spreading cycle. About 200 million years ago the continents, which were at that time joined together in the supercontinent Pangaea, began to split and drift apart. A principal split was along the rift zone that today forms the Mid-Atlantic Ridge. The spreading continues and today's picture is but one frame in a long motion picture.

proceed so slowly in the laboratory that they are parameter controlling the dynamics of motion in unobservable. the earth's interior. The interior of the earth is Temperature is probably the most important essentially a heat engine, involving heat transfer

14 by large-scale transport of matter, that provides the patterns of volcanic activity, the distribution the power to drive the plates. Heat from phase of trace elements, and distribution of mantle­ transformations of mantle material and heat type rocks on the earth's surface. from radioactive decay may cause thermal In summary, a few of the important questions instabili ties that would influence the driving to be answered during the International forces. Geodynamics Project by increased effort in the Surface heat flow measurements are not a research areas mentioned above are: sensitive indicator of temperature at depth 1. What is the state of stress in the boundary because a major part of the anomalous surface areas of the plates that manifests itself in the heat flow can be explained in terms of heat horizontal movements that we are beginning transported laterally away from the ocean to understand? spreading centers. Seismic shear-wave velocities 2. What is the state of stress in the plate depend on the temperature and so can be used as interiors resulting in vertical movements an indirect indicator of the thermal state of the still not understood? earth's interior. More laboratory work must be done to determine equations of state, including 3. What dynamic system operating in the the shear properties of matter under temperature earth's interior is producing these stresses? and pressure, especially near the melting point. 4. What are the past locations of the earth's A number of explicit suggestions have been rotation axis relative to the main plates of the made for the driving forces, such as convection lithosphere and the location of these plates cells, mantle plumes, gravity sliding from the relative to each other? mid-ocean ridges, and gravity pulling plates down at trenches. Much of the work being done 5. Does plate tectonics represent a new and on these explicit mechanisms is theoretical. More unique episode in the earth's history or has it constraints from geological evidence are needed been an integral part of the dynamic history that can be placed on mantle motions-such as of the earth from the beginning?

15 RESUME OF FEDERAL ACTIVITIES IN IGP

In order to obtain a reasonable estimate of the of plates depends to a large extent on amount of funds presently being allocated for paleomagnetic measurements and extension of geodynamics-related activities within the U.S. the history of magnetic reversal, and geological Federal Government, it was first necessary to inferences of fault motions. A final category adopt a set of definitions of geodynamics includes the accretions and composition of the acceptable to the Committee so that figures from plates, such as the characteristics of material the various agencies will fall within comparable added at the margins. guidelines. The definitions adopted by the ad hoc On page 22 is shown a table of agency committee were taken primarily from the NAS expenditures in FY 1974,75 and 76 by the various report U.S. Program for the Geodynamics Proj­ categories of geodynamics defined above. The ect. These are divided into two separate two agencies most responsible for geodynamics categories-those activities concerned generally expenditures are the U.S. Geological Survey and with the interior parts of the earth: the lower the National Science Foundation with $26.7M crust, mantle and core, and those which involve and $21.1M for FY 1976, respectively. At a lower the lithospheric plates. The descriptions are level are the composite figures for the four included as Appendix I. contributing offices of DOD $7.9M, followed by Part I, The Internal Processes and Properties, NASA $6.1M, ERDA $4.0M and Commerce is divided into four parts: Dynamical Models, $3.0M. For the major programs involved with Geophysical Observations of Internal Processes, large logistic components, which are only par­ Physical and Chemical Properties of Minerals tially geodynamics related such as NASA's and Mineral Assemblages, and Geological Con­ satellite studies, NSF's Ocean Sediment Coring. straints. This part includes research on the Program, and NOAA's network for horizontal pattern of mantle motion, energy sources within and vertical control, an estimated fraction of the the earth that are responsible for mantle motion, cost related to geodynamics has been made. temperature fields, geothermal history of the Inasmuch as the figures for FY 74 are actual earth, motions and dimensions of the interior of allocations, while those for FY 75 and FY 76 are the plates, the method of plate coupling to the estimates, the increase shown for the 75 and 76 mantle, the phase and mineralogical changes figures over 74 may be somewhat in error. Most taking place in the interior of the earth, melting of the increases are within the USGS, and relate phase changes, and the generalized equation of to their relatively new responsibilities in earth­ state. Most of these activities are either quake research. Several years of actual figures laboratory studies of selected material, data from would be needed to get a reliable estimate of various geophysical measurements, and increased funding to geodynamics. geological character of mantle material found The brief description of agency activities by near the surface through volcanic activities or the geodynamics categories, outlined below, is surface erosion. supplemented by a more extensive description of Part II, Boundaries, Movements, and Structure the work by agencies, Appendix II. The of Lithospheric Plates, is rather straight forward. geodynamics activities consist largely of the A considerable amount of data on boundaries individual efforts of many scientists. These are comes from marine studies, and many plate in-house activities for some agencies, such as the movements are derived from recent magnetic USGS, and at the universities and other non­ lineations found near the spreading centers, or profit institutions, as in the NSF. Major single from independent observations of motions using programs are relatively few and occur mainly extraterrestrial sources as references, or studies where agency mission work is closely related to of recent fault displacements. This category also geodynamics objectives, such as NASA's involves the remeasurements of major networks satellite studies and NOAA's vertical control of control stations in the U.S. The past movement networks.

16 Federal Agency* Activities in IGP

Figures with Agency titles refer to FY 76 Estimates.

I. Internal Properties and Processes

A. Dynamical Models structure of continental margins, axial AFGL (120K)-Obtain more accurate models processes of the mid-Atlantic Ridge, and for the gravitational field by better theories evolution of oceanic crust. and more precise measurements. Predict the ARPA (220K)-From seismic events, study response of the earth model to dynamic and properties of the crust and upper mantle static loading of the crust. underlying the Aleutian Island region, mid­ ERDA (105K)-Modeling of geologic processes Atlantic Ridge, western U.S., central Asia, directed at understanding the emplacement Iran, and the Arctic Basin. of plutons and the thermal state of their ONR (923K)-Marine gravity studies of short­ environments. and long-term wave anomalies by in­ NSF (271K)-Modeling studies of the earth's vestigating gravitational effects of primary core and convective motions in the earth's tectonic features of the ocean floor-Seismic mantle and at the crust-mantle boundary. and electrical studies of crust and upper USGS (1,090K)-Studies of dynamic modeling mantle characteristics. of precursor phenomena as part of the ERDA (885K)-Investigate physical and Earthquake Hazards Reduction Program­ chemical state of the earth's upper mantle by Computer modeling offault displacements to studying specimens derived from the mantle achieve an understanding of fault or analogous synthetic materials­ mechanisms and related effects-Modeling Determination of geothermal gradients and of selected well-known geothermal systems thermal conductivity from drill holes to to study the mechanism by which water and obtain heat flow-Evaluation of heat are transferred in geothermal systems aeromagnetic data to determine depth to within the crust. Curie point. NASA (2,900K)-From existing knowledge of B. Geophysical Observations of Internal lunar motions, support investigations of Processes earth's rotation and polar motion-More precise description of the earth's gravity DOC (630K)-Trans-Atlantic Geotraverse field from measurements of ocean (TAG), an intensive geophysical investiga­ topography taken by GEOS-3. tion of a corridor about 285 km. wide from NSF (3,495K)-Earthquake seismology for Cape Hatteras to Mauritania to study the study of internal processes-Geothermal studies-Seismic studies of internal *DOC-Dept. of Commerce characteristics by controlled explosives­ AFGL-Air Force Geophysics Laboratory Experiments with the ocean bottom ARPA-Advanced Research Projects Agency (DOD) seismograph for earthquake monitoring­ NAVOCEANO-Navy Oceanographic Office Research on telluric, magnetotelluric, ERDA-Energy Research & Development Administration electro-magnetic induction, and electrical ONR-Office of Naval Research NASA-National Aeronautics & Space Administration resistivity methods for crustal and mantle NSF-National Science Foundation properties-Marine gravity observations USGS-U.S. Geological Survey (001) from oceanographic vessels.

17 USGS (8,550K)-Microearthquake studies microcracks, shear strength and electric with dense arrays of short-period properties of rocks under high P-T by seismographs for three-dimensional map­ ultrasonics, shock and static compression­ ping of active fault zones-Refraction Use of high P-T equipment for geochemical seismic surveys to determine structural studies such as equilibrium and mass elements of the crust and upper mantle­ transfer among minerals and aqueous Information on thermal regime of earth's solutions, the diffusion kinetics of trace crust and upper mantle through heat flow elements, mineral crystal chemistry, and measurements-Analysis of thermal in­ thermodynamics of ionic interactions. frared images over broad areas for surface USGS (1,650K)-Measurement of the physical indications of heat flow-Magnetic and properties of rock-forming minerals to gravity surveys to identify zones of determine how the thermal and stress anomalous magnetization and density in the histories of minerals affect their properties­ crust and upper mantle-Detection of zones Igneous petrology directed toward un­ of anomalous conductivity in the subsurface derstanding magmatic systems-Phase by various electrical and electromagnetic equilibria studies of multicomponent techniques-Investigations of the deep systems-Thermodynamic properties of structure of the continental shelf and slope selected minerals-Research in isotopic by continental geophysical surface merged geochemistry, including light stable isotopes with marine geophysical research­ and radiogenic isotopes-Neutron activation Distribution of magnetization and electrical studies-Mechanical, electric, and thermal conductivity within the earth by orbiting properties of rock samples to 1,000°C and 10 satellite magnetometers which record broad kilobars. wa ve-Iength anomalies-Studies of variations of hydrodynamic processes D. Geological Constraints operating in the earth's core by micropulsa­ ERDA (965K)-Field studies of igneous tion data. terrains at LASL to understand the im­ placements of magmas from depth-The C. Physical and Chemical Properties of Minerals dynamics and thermal problems associated and Mineral Assemblages with pluton emplacement and volcanic DOC (126K)-High pressure studies include eruptions by field studies of the Rio Grand calibration of pressure scales, continued rift, the andesite volcanoes of the Cascades work on an ultra-high pressure cell, and of northern California and field studies of extension of the pressure scale. active volcanoes-Studies of lava, volcanic ONR (95K)-Physical properties of the solid rocks, and xenoliths from kimberlite pipes earth by electric resistivity of minerals at and andesites-Observational and elevated pressures and temperatures­ analytical geochemistry and petrology. Effects ofmicrofractures on physical proper­ NSF (3,S99K)-Geology, geochemistry and ties of rocks. geochronology of volcanic rocks from ERDA (1,301K)-Construction of test facility several geographic areas, and of the mantle at LBL to test rock samples to 400°C. and and deep crustal rocks exposed at the 1,000 bars-Use of explosive shock waves surface-Studies of the basalts obtained and static high pressure devices at LASL to from the OSCP and rocks recovered from the extend high P-T ultrasonic and equation of Mid-Atlantic Ridge in the FAMOUS state studies-High P-T phase equilibria Experiment-Stedies of the geochemistry, studies of individual pure mineral phases­ petrogenesis, and geochronology of Antarc­ Physical and chemical properties of silicate tic rocks from the Dry Valley Drilling Proj­ melts-Static deformation of minerals and ect. rocks to permit accurate prediction of USGS (5,000K)-Petrologic and structural response of the earth's crust to stress-Rock studies of volcanic, sedimentary, and mechanics computer code development. plutonic rocks to determine tectonic history NSF (2,423K)-Investigations of sonic veloci­ of the western margin of the North American ty, flow measurements, development of plate-Studies of volcanic rocks and

18 associated plutons in the San Juan and Volcano Observatory of the generation and Absarka Mountains and in central Idaho to movemen t of magmas-Studies in Alaska of determine the chemistry of the igneous rocks island arc volcanic rocks and of ophiolite erupted through the North American plate­ complexes indicative of subduction along the Detailed studies of ankaramites in Hawaii, margins of the North American plate­ caldera deposits in New Mexico, and basalts Studies in southwest Oregon to determine in the Pacific Northwest to estimate the how podiform chromite-bearing ultramafic depths of phenocryst formation and and mafic bodies were scraped off the crystallization history in large volumes of oceanic plate and juxtaposed on the North silicic melt-Studies at the Hawaiian American plate.

II. Boundaries, Movements and Structure of Lithospheric Plates

A. Present Plate Boundaries measurements with Ocean Bottom Seismometer. ARPA (150K)-Study of seismicity of Mid­ USGS (1,510K)-Operation of the Worldwide Atlantic Ridge-Relation of seismicity and Network of Standard Seismographs, 116 tectonics in the Indus Suture zone­ stations in 69 countries, an essential source Characterization of source properties of for seismological data used in laca ting earthquakes in the case of continent-to­ earthquakes-Studies of topography and continent collision to aid in the mapping of geology of mid-Atlantic Ridge in the region present plate dimensions. southwest of the Azores Islands with deep NAVOCEANO (1,3Z5K)-Detailed submersible craft. geophysical survey of the Galapagos Spreading Ridge-Studies of the Mid­ B. Present Motion of Plates A tlantic Ridge with near-bottom recording magnetometers-Aeromagnetic surveys in DOC (1,Z95K)-Establish, maintain and adjust the Arctic Ocean for details on the horizontal and vertical geodetic control Lomonosov Ridge-Geophysical survey of networks over the U.S., including a special the Indian Ocean-Continued studies of the Great Lakes and Mississippi Valley leveling Cayman Trough Spreading Center of the program in cooperation with the Geodetic Caribbean Plate. Survey of Canada-Establish horizontal and ONR (930K)-Geological and geophysical vertical networks across the San Andreas investigations of the dynamics of the fault between Los Angeles and San northwestern borders of the Pacific Plate­ Francisco-Operation of the zenith tube Structure and tectonics of the Bay of Bengal measurements of polar motion at and western Sundra Arc in the Indian Gaithersburg, Maryland, where such Ocean-Structure and interaction of the motions have been observed over the past 75 Cocos and surrounding plates-Structure years-Maintain a gravity base network and seismicity of the Juan de Fuca Plate. across the U.S. ERDA (470K)-Operation of a seismic network ARPA (1,100K)-Studies of anomalous in the Shumagin Islands near the tip of the characteristics and causes of moderate to Alaskan Peninsula, and a large aperture large earthquakes in the normally aseismic seismic array in the eastern Aleutian arc east area of eastern U.S. by an integration of all of Unalaska Island. available data including sea level changes­ NSF (3,349K)-Geophysical studies of the Earthquake focal mechanisms for thrust boundaries and structures of the Nazca faults. Plate, the eastern and southeastern parts of ERDA (Z50K)-Electrical resistivity the Asian Plate and the western part of the measurements to detect changes due to Pacific Plate-Studies of the tectonic evalua­ tectonism within the San Andreas Fault tion of the South Kenya Rift zone-Detailed zone. study of the Mid-Atlantic Ridge-Seismic NASA (3,ZOOK)-Tectonic Plate Motion proj-

19 ect will provide measurements of precise the various stages of the opening of the South motions between defined points, using both Atlantic. laser tracking and very long baseline USGS (780K)-Refinement of geomagnetic interferometry-The Lunar Ranging Experi­ reversal times from radiometrically dated ment will utilize existing knowledge oflunar volcanic and plutonic rocks-Study of motions and continuing range measurements decrease in amplitude of magnetic anomaly to support investigations on plate motion­ stripes with increasing distance from the The Geodynamic Experimental Ocean spreading axis-Research in geochronology, Satellite (GEOS-3) project will provide, including investigation of the 40 Ar/39 Ar age through measurement of ocean topography, spectrum dating technique-Study of use of an improvement in the description of the thermoluminescence as a dating tool for earth's gravity field, and in the variations of young volcanic rocks. solid earth geometry-The Laser Geodynamic Satellite (LAGEOS) project D. Plate Accretion, Composition and Structure will provide the capability of accurate measurements of earth's crustal motion. DOC (45ZK)-Measure sedimentary processes NSF (17ZK)-Response of the earth to late on the continental margin sediment Quaternary ice melting-Earth tide transport system in the mid-Atlantic Bight studies-Application of atomic clock and measure temporal changes of the sedi­ interferometry-Geophysical applications ment substrate. of long baseline interferometry. ONR (65ZK)-Geological and Geophysical USGS (1,480K)-Geodimeter surveys for investigations of interior features of the horizontal movements and level surveys for Pacific Plate: Hawaiian Ridge, Emperor Sea vertical movements are used to determine Mount, and Hess Rise-Properties of Layer elastic strain accumulation and strike-slip 2, defined seismically as the upper one or two along faults and to detect premonitory kilometers of the crystalline oceanic crust, strains-Study of sea level measurements including thickness, velocity structure, for possible use in determining crustal uplift topography, and magnetic properties. or subsidence-Investigations of NSF (3,Z4ZK)-Geological and geophysical seismomagnetic effects along western Un­ investigations of the East Atlantic continen­ ited States fault zones as an indirect means tal margin-Geophysical study of continen­ of monitoring crustal stress. tal margin of Argentina and Brazil­ Sedimentary history of ocean basins from C. Plate Boundaries and Rates of Movement studies of the cores from the Ocean Sediment During the Past Coring Program-Structural development of ONR (9Z0K)-Study of marine magnetic the Southern Cordilleran orogen­ anomalies of ocean basins, including triple Geological history of continental accretion junction of anomalies in south Atlantic and on Kodiak Island-Tectonics, evaluation and Indian Oceans-Regional magnetic field of crustal composition of the western Indian Arctic Basin-Paleo-magnetic studies of Ocean ridge systems-petrochemical and sediment cores. geochemical evolution of the central North NSF (4,757K)-Studies of cores obtained from Atlantic-science program of mid-Atlantic the OSCP-Paleomagnetic projects dealing Ridge, Project FAMOUS-Marine geology with past plate movements-Geological and and geophysics of the Sunda Arc-Geology geophysical studies in areas of plate of the Lassiter Coast, Antarctica­ boundaries-Studies of sediment cores Geological investigations in the Pensacola taken from the Eltanin and from the Dry Mountains, Antarctica-The structure and Valley Drilling Project in Antarctica­ tectonic history of the northern limb of the Geological studies in the Antarctic Moun­ Scotia Arc. tains and the Antarctic Peninsula-Gravity, USGS (6,600K)-Locate recently-active fault heat flow, and magnetic measurements in the strands within the San Andreas system and continental margin of West Africa and determine tectonic history along the active eastern South America in order to construct plate margin-Analysis of intense folding

20 and faulting in the Salton Trough northward region, the continental shelf and the offshore to the Mendocino Fracture Zone to determine islands of western Alaska to determine the the location, direction and magnitude of rates of past and on-going coastal displacements-Geologic and Geophysical deformation-Synthesis and compilation of studies of the Oregon and Washington geologic information on the Colorado Plateau continental margin-Detailed mapping of to determine why this region escaped the active surface faults along coastal Alaska­ deformations that affected the Basin and Study of the Tertiary and Quaternary Range Province to the west and the Rocky geology and biostratigraphy of the coastal Mountains to the east.

21 Fiscal Summary of Geodynamics-Related Programs in Federal Government FY 74, FY 75, FY 76

(In thousands of dollars)

NAVO- DOC· AFGL ARPA CEANO ONR ERDA NASA NSF USGS TOTAL I. Internal Properties & Processes A. Dynamical Models 74 78 45 43 231 1,069 1,466 75 105 60 95 239 1,079 1,578 76 120 50 105 271 1,090 1,636 B. Geophysical Observations 74 600 25 265 35 1,123 253 2,100 2,939 5,015 12,455 of Internal Processes 75 165 25 170 20 1,078 540 2,200 3,236 8,496 16,030 76 630 50 220 10 923 885 2,900 3,495 8,550 17,763 C. Physical & Chemical Properties 74 130 91 795 2,006 1,349 4,371 of Minerals & Mineral Assemblages 75 126 74 1,131 2,141 1,559 5,031 76 126 95 1,301 2,423 1,650 5,595 D. Geological Constraints 74 10 95 593 5,115 4,588 10,401 75 7 30 765 6,814 4,901 12,517 76 5 -- 965 3,899 5,000 9,869 II. Boundaries, Movements, &' Structure of Lithospheric Plates '" A. Present Plate Boundaries 74 108 145 228 950 300 3,386 1,169 6,286 75 350 145 258 510 365 3,416 1,486 6,530 76 10 150 1,325 930 470 3,349 1,510 7,744 B. Present Motion of Plates 74 1,321 362 36 18 1,800 197 1,110 5,004 75 1,197 715 15 125 3,500 178 1,450 7,370 76 1,295 1,100 -- 250 3,200 172 1,480 7,757 C. Plate Boundaries and Rates of 74 20 1,050 6 3,056 546 5,128 Movement During the Past 75 30 770 25 4,096 750 5,671 76 30 920 25 4,757 780 6,512 D. Plate Accretion, Composition 74 680 40 -- 865 2,644 5,639 9,968 & Structure 75 610 60 -- 800 2,631 6,444 10,654 76 452 60 57 652 3,242 6,600 11,163

TOTAL 74 3,199 143 772 329 4,219 2,008 3,900 20,024 20,485 55,079 75 2,838 190 1,030 330 3,322 3,046 5,700 22,751 26,165 65,372 76 2,973 230 1,470 1,427 3,570 4,001 6,100 21,608 26,660 68,039

• DOC Data Center (FY 74-$360K; FY 75 $390K; FY 76 $460K) not included in the DOC column but are added in the TOTAL column. Future reports will contain data center funding of other agencies. INTERNATIONAL PARTICIPATION

Fifty-two countries have indicated their par­ on the geodynamics of the Western Betic­ ticipation in the International Geodynamics Mediterranean Range, the Canarian Archipelago, Project. The first 46 countries in the following list and the Iberian Plateau. The studies included have established national committees for the deep seismic profiling. Similarly, Sweden project. The last six have nominated national reported a grant of $230,000 per year from the correspondents. Swedish Research Council for two principal projects of an international and interdisciplinary *Argentina Israel character; (1) the Caledonian Research Project, *Australia Italy and (2) study of post-glacial earth movements. *Austria *Japan Although fiscal data is not given, it is apparent Belgium Korea from the reports of such countries as France, Bolivia *Mexico Federal Republic of Germany, Japan, U.S.S.R., Botswana *Netherlands and others that expensive world-wide field *Brazil New Zealand programs have been undertaken under the aegis *Canada Nigeria of the program. The French, in addition to the Central American Norway well-known FAMOUS project, have active Regional Committee Poland programs in the Pacific Ocean, the Andes Chile *South Africa Mountains, the Caribbean Sea, the Mediterra­ *Colombia *Spain nean Sea, and the Alps Mountains. The Federal *Czechoslovakia *Sweden Republic of Germany has put special emphasis Denmark *Switzerland on the Rhinegraben, the European plate, the Alps *D.R.G. *Taiwan Mts., Mediterranean Sea, Red Sea, AfarTriangle, Equador *Turkey Indian Ocean, Iceland, South Africa and Latin *F.R.G. *United Kingdom America. The Japanese have devoted 14 research *Finland *U.S.S.R. cruises to the investigation of the movement and *France *U.S.A. structure of the ocean floor of the Western Pacific Ghana Venezuela and have similarly allocated large-scale and Greece Yugoslavia expensive logistic support to a second program Hungary Cuba emphasizing studies of the movement and *Iceland Indonesia structure of island arcs. The USSR has similar *India Pakistan large scale expeditions, not only in the Soviet Iran Philippines Union, but in Africa, Iceland and elsewhere. Ireland Rhodesia Many countries have not received special Thailand funding for the IGP but have successfully put Participating countries were requested to together meaningful programs by reprogram­ prepare reports on their national activities in ming and redirecting existing resources. The Geodynamics for the IUGG General Assembly in Canadian 3rd report, for example, indicates Grenoble in 1975. Reports were received from 25 significant progress in 5 interdisciplinary areas; countries (marked by asterisks in the above list), (1) global dynamics, (2) short term motions, (3) and others will be available in the near future. crustal evolution, (4) Phanerozoic fold belts and The reports indicated a high degree of activity adj acent oceans, and (5) the Canadian shield. in many participating countries with interesting Current activities are broadly distributed among and relevant scientific results. The reports do various Federal and provincial government not, in general, contain fiscal information. Spain, agencies, universities, and mining and petroleum however, did report a specific allocation for the exploration companies. Geodynamics Project at an annual level of Other countries, having limited resources, $231,000 (plus significant logistic support from have inaugurated good programs by means of the Spanish navy) for a program concentrating international cooperation. Two examples are

23 Mexico and Colombia both of which have (2) the plateau basalt area adjacent to the active emphasized cooperative programs with U.S. volcanic zones, and (3) general studies of Iceland universities and institutions. The Mexican and the shelf regions. Geological, aeromagnetic, program includes work in the Gulf ofMexico and and gravity maps are complete or nearly com­ the Cocos Plate, a network of 8 seismic stations plete. Heat flow, magnetotelluric, and seismic around the Gulf of California, 360 km. long studies are underway. Scientists from several seismic refraction profile, heat flow studies, and other nations have been working in Iceland in geodetic studies. Similarly, the Colombians have cooperation with Icelandic scientists. The concentrated on seismic refraction studies of the Geodynamics Program has provided con­ continental margin, oceanographic studies, and siderable stimulus to geophysical and geological magnetotelluric studies. research in Austria focused on the Austrian area Most countries have tailored their programs to of the Alpine belt. The Finnish program is the study of important geodynamic problems concentrated heavily on repeated geodetic and that can be uniquely studied within their own gravity measurements to study crustal borders or because of relevant experimental and movements in Lapland and the Fennoscandian theoretical research practiced in those countries. land uplift, although work is also underway in The G.D.R. presented a broad program encom­ aeromagnetics, magnetic surveys, paleo­ passed within two complex subjects; (1) develop­ magnetism, and seismology. ment of a geodynamic model of the tectonosphere The Czechoslovakian program concentrates on in Central Europe, and (2) investigation of the eight projects; regional studies in the West driving mechanism of geodynamic processes. Carpathians and the Bohemian Massif, together They presented a bibliography of some 360 titles. with more traditional studies of the physical The Turkish program is mainly focussed on parameters and structure of the crust and mantle geological studies related to pIate tectonics of the in Czechoslovakia by deep seismic soundings eastern Mediterrannean, seismological studies and heat flow, the physical properties of rocks with emphasis on the N. Anatolian Fault, under high pressures and temperatures, together with regional gravity, magnetic and geochemistry of mobile zones, secular variation paleomagnetic work. Iceland's program is con­ of gravity and earth tides, recent crustal cerned with 3 areas; (1) the active volcanic zones, movements, geomagnetism and paleomagnetism.

24 APPENDIX I

Description of Geodynamics Studies

I. Internal Properties and Processes

A. Dynamical Models equations of state, kinetics of phase transfor­ Construction of dynamical models of the mations, process of magma generation, par­ processes in the mantle that can explain plate tilioning of trace elements under controlled tectonics observations, the thermal history and conditions of temperature and pressures, thermal gravity fields, the origin of the earth's magnetic and electrical conductivity of rocks at high field, and their possible relation to planetary pressures and temperatures. motions. D. Geological Constraints B. Geophysical Observations of Internal Processes Geological, petrological and geochemical studies that provide constraints on models of: 1) Seismic, gravimetric, geodetic, geomagnetic magmatic differentiation, 2) physiochemical and heat flow measurements as applied to conditions of deep crustal processes, and 3) studies of the structure and dynamics of downgo­ mechanisms by which mantle-derived rocks ing slabs, spreading centers, transform faults, reach the surface. Includes trace element and and plate interiors. Gravimetric and seismic isotopic studies of upper mantle rocks brought to studies of heterogeneities in the asthenosphere. the surface as xenoliths in lavas, kimberlite Applicable seismic studies of the deep internal pipes, diapiric emplacements, and through ob­ structure of the earth. Calculation of temperature duction of ophiolite suites. Petrological study of distribution by electrical conductivity studies blueschists and related rocks representative of and seismic mapping of phase transitions. subducted material altered at depth but now exposed in melanges and other areas that may be C. Physical and Chemical Properties of Minerals fossil plate sutures. Investigation of modern and Mineral Assemblages volcanoes as a basis for inferring internal Ultrasonic and shock measurements on earth dynamic processes, internal reservoir con­ materials, rheological behavior of earth di tions, and mass flux and energy balance of the materials at high pressures and temperatures, volcanic process.

II. Boundaries, Movements, and Stru.cture of Lithospheric Plates

A. Present Plate Boundaries B. Present Motion of Plates Mapping of the horizontal and vertical dimen­ The direction and velocity of present plate sions of present plates, with special attention to movements by geodetic measurements along the subplates in island arc regions. Detailed active faults, the direct measurement of vertical seismic and geodetic studies of plates presently displacements on land and at sea, the develop­ being broken up. Variations in lithospheric ment of satellite geodesy and radio telescope thickness and the properties of the low velocity interferometry, internal plate deformation, zone, on land and at sea, with particular attention relative direction of plate movement by earth­ to high resolution continuous seismic reflection quake focal mechanisms, orientation of sea floor profiling. fracture zones.

25 C. Plate Boundaries and Rates of Movement D. Plate Accretion, Composition and Structure During the Past Geochemistry and mineralogy of crustal Paleomagnetic investigations of unsampled material added to plate margins and intraplate plates, mapping of sea floor fracture zones by areas; nature of geological structures, especially depth soundings, time scale of geomagnetic at convergent plate boundaries and at reversals, pole positions for the Paleozoic, pole transcurrent sutures within or at plate boun­ positions for the Precambrian, fine structure of daries; vertical movement of plates as deter­ the magnetic field, magnetism of sea basalt. mined by geological means; relation of geological structures to dynamics of plate movement.

26 APPENDIX II

Details of Federal Agency Activities in Geodynamics Related Programs

Department of Commerce

In the Department of Commerce, studies seismology, marine geology and geophysics, and related to geodynamics are carried out principal­ geomagnetism and operates the World Data ly in the National Oceanic and Atmospheric Center A for Solid Earth Geophysics. Geo­ Administration (NOAA) through its National physical information is regularly exchanged Ocean Survey (NOS), National Geodetic Survey between this World Data Center and other (NGS), Environmental Research Laboratories similar centers in the USSR, Europe, and Japan. (ERL) and Environmental Data Services (EDS). Several geodynamics-related projects are also The National Geophysical Data Service of EDS carried out at the Bureau of Standards. provides a wide range of information in

I. Internal Properties and Processes

B. Geophysical Observations of Internal crust from the mid-Atlantic Ridge to the con­ Processes tinental margins, and the establishment of a standard crustal section within the TAG corridor The Trans-Atlantic Geotraverse (TAG) is an across the entire central North Atlantic Ocean. intensive geological, geophysical and geochemical investigation of a corridor about 3° C. Physical and Chemical Properties of Minerals (285 kms.) wide across the Central North and Mineral Assemblages Atlantic Ocean from Cape Hatteras in the United States to Mauritania in northwest Africa. At the National Bureau of Standards, high The TAG project has four main objectives: the pressure studies include the calibration of structure and development of the continental pressure scales using the ruby fluorescent margins of eastern North America and method, continued work on an ultra high­ northwestern Africa, axial processes of the mid­ pressure cell, extension of the pressure scale, and Atlantic Ridge between 25° and 28° North some experimental studies involving behavior of latitude, the structural evolution of the oceanic materials at high pressure.

II. Boundaries, Movements, and Structures of Lithospheric Plates

A. Present Plate Boundaries for the establishment, maintenance, and adjust­ Mineralization processes in the rift valley of ment of the horizontal and vertical geodetic the mid-Atlantic Ridge and adjacent fracture control networks over the United States. These zones are studied using samples obtained from basic networks are currently being adjusted, the the French-American Mid-Ocean Undersea work scheduled for completion in the 1980's. A Study (FAMOUS). special Great Lakes leveling program is currently nearing completion, with its objectives the B. Present Motion in Plates determination of the relationship of the National Great Lakes Datum to Mean Sea Level, in The National Geodetic Survey is responsible cooperation with the Geodetic Survey of Canada.

27 This survey also passes through the Adirondack The National Geodetic Survey also maintains a Mountains where evidence of continued up­ gravity base network across the U.S. and heaval has been detected. Similarly, a loop to be planned reobservations will provide information completed soon in the Mississippi Valley will on secular gravity changes that are closely provide data for recent crustal movement in the related to elevation changes. Great Lakes area. Horizontal and vertical networks have been established across the San Andreas Fault at D. Plate Accretion, Composition and Structure intervals between Los Angeles and San Fran­ cisco. These are re-measured as time and funds A long term program is underway to measure permit, though re-measurement would im­ sedimentary processes on the continental margin mediately follow any major earthquakes in the sediment transport system in the mid-Atlantic area. Bight, and to develop a conceptual model of this A potentially valuable source of information system. In FY 76 the temporal variability of the for plate tectonics is obtained by zenith tube sediment substrate will be determined by measurements of polar motion at Gaithersburg, measuring changes in the distribution of its Maryland and Ukiah, California where these physical and chemical characteristics with time. motions have been observed over the past 75 The velocity profile of the boundary layer will be years. Although newer methods of polar motion determined immediately above the substrate observations have shown a potential of higher surface to provide a basis for quantifying the accuracy, the question of continuity with past transfer of storm-driven energy from the water information requires a review of these methods. column to the sediments.

28 Air Force

The Air Force supports, through its Air Force tion of large amounts of heteorogeneous data Geophysics Laboratory, a wide range of geodetic from multiple sources. Basic studies are un­ and geophysical studies for precise position derway of propagating earth motions and location, earth size and shape determination, theoretical investigations to explain the nature of measurements and modeling of the gravity field, long-period and aperiodic crustal motions. and geophysical earth motions. Many of these Theoretical investigations are directed toward mission-oriented research programs are closely predicting the response of the earth model to related to the objectives of the IGP. dynamic and static loading of the crust. In FY 76 Improved knowledge of the earth's properties the North American and European continental and more accurate models for the gravitational geoids will be calculated from combinations of field will be obtained by the development of gravimetric and satellite data and the geoid over better basic theories, improved instrumentation the North Atlantic will be obtained from satellite for more precise measurements, and the formula­ altimetry data. tion of mathematical techniques for the combina-

29 Advanced Research Project Agency

The Advanced Research Projects Agency heterogeneous portions of the crust and mantle, (ARPA) conducts two research programs that or inability to detect seismic waves at high contribute to the objectives of the IGP. The enough signal-to-noise ratio to obtain informa­ Seismic Verification Research Program is con­ tion diagnostic of the source. The Geodesy and cerned primarily with the problem of uniden­ Gravity Research Program is concerned with tified seismic events that may arise from improved methods for the rapid acquisition of peculiarities in the generation of seismic waves precise geodetic and gravity data capable of by certain earthquakes, distortion of seismic providing improvements in regional gravity waveforms caused by propagation through models.

I. Internal Properties and Processes

B. Geophysical Observations of Internal as lateral inhomogeneities in the mantle under­ Processes lying the Aleutian Island region, mid-Atlantic Special attention is being given to structural Ridge, western U.S., Kamchatka and Kurile Islands, Tibet, and the Arctic Basin. properties of the crust and upper mantle as well

II. Boundaries, Movements, and Structure of Lithospheric Plates

A. Present Plate Boundaries quakes) occurring in a normally aseismic area (Eastern U.S.) are being investigated by in­ Studies involving the determination of seismic tegrating all available seismological, geodetic, sources, the regionalization of source geomorphological and geologic evidence, and parameters, and the characterization of source measurements of sea level changes. In addition, properties of earthquakes at the plate boun­ an integrated field measurement program using a daries, in particular for the case of continent-to­ variety of broadband instruments is being continent collision, are being conducted to aid in conducted in the seismically active Bear Valley the mapping of the horizontal and vertical region of California (strike-slip fault region) in dimensions of present plates. an effort to more clearly define the spatial and temporal nature of the source displacement B. Present Motion of Plates function and resultant spectra of signals from The anomalous characteristics and cause of earthquakes in the body wave magnitude range moderate to large earthquakes (intraplate earth- 3.5 to 4.5.

30 Navy

In order to understand its operating environ­ of these mission-oriented programs have a close ment more effectively, the Navy supports connection with the objectives of the Inter­ geological and geophysical research on the national Geodynamics Project. This research is characteristics of the seafloor sediments and supported through two programs of the Office of underlying rock layers. Laboratory and field Naval Research: Marine Geology and research on the physical properties of minerals Geophysics (MGG-ONR), and Earth Physics and rocks are also supported to improve surface­ (EP-ONR) and through activities of the U.S. based geophysical techniques for inferring the Naval Oceanographic Office (NAVOCEANO). physical properties of deep crustal layers. Many

I. Internal Properties and Processes

Marine gravity studies are focused upon the stress distributions; electrical resistivity of problem of determining the geologic source of the minerals at elevated pressures and temperatures; short (kilometers) and medium (hundreds of effect of microfractures on physical properties of kilometers) wavelength gravity anomalies. rocks; and measurements of thermal gradients These studies include the investigation of the and electrical resistivity of crustal rocks to infer gravitational effects of primary tectonic features internal crustal heat distribution (EP-ONR). of the ocean floor, such as ocean ridges, trenches, In part of the Canary Basin, all available island chains, seamount chains, fracture zones, seismic reflection data have been compiled and and marginal basins (MGG-ONR). reduced, and are being analyzed in order to Research on the physical properties ofthe solid determine the physiography of the acoustic earth are supported on an interdisciplinary basis. basement surface. Studies of basaltic rocks These include electrical measurements of dredged along the spreading axis north and south crustal/upper mantle resistivity-depth dis­ of Iceland are focused on the anomalous tributions; seismic studies of crustal/upper geochemical changes that occur in these basalts mantle seismic velocity distributions, Q, along the Reykjanes Ridge (NAVOCEANO). Poisson's Ratio, seismic velocity transitions and

II. Boundaries, Movements, and Strucl:ure of Lithospheric Plates

A number of discreet geological and tasks are examining the thickness and velocity geophysical investigations are supported in the structure, topography, and magnetic properties northwest Pacific. An objective of the program is (MGG-ONR). to examine the dynamics of an old part of the Two aspects of marine magnetics are being Pacific plate. Included in the plate interior are the examined. The first is the delineation of the Hawaiian Ridge, Emperor Seamounts, Hess Rise, amplitude and configuration of the residual and the Hokkaido Rise with the Kuril Island Arc, magnetic anomalies of the world's ocean basins Bonin Island Arc, and Okhotsk Basin at the and their relations to ocean floor structure. margins (MGG-ONR). Particular emphasis is directed towards the Better knowledge of the physical, magnetic, triple junction anomalies in the South Atlantic and chemical properties of the upper one or two and Indian Ocean, the Mesozoic anomaly kms. of the crystalline oceanic crust (layer 2) patterns in the western Pacific, and the regional should lead to improved understanding of the field of the Arctic Basin. The second aspect is an dynamics of ocean basin formation. Specific improved definition of the magnetic time scale

31 through improved analysis and stacking techni­ cooperative geophysical investigation of the mid­ ques, as well as paleomagnetic studies of Atlantic Ridge south of Iceland with Germany sediment cores (MGG-ONR). and Iceland is presently underway. Similar Specific regional studies include examination studies of magnetic data in the vicinity of of the geologic history, structure, and tectonics of Cayman Trough will provide data for further the Bay of Bengal and Western Sunda Arc in the refinement of past rates of movements between Indian Ocean; the structure and interaction of the the Americas. Caribbean geological and Cocos and surrounding lithospheric plates; and geophysical atlas is presently in progress the structure and seismicity of parts of the Juan (NAVOCEANO). de Fuca plate (MGG-ONR). Recent aeromagnetic surveys in the Arctic Near-shore magnetic data collected in the Ocean have now covered about one-third of the northwest Pacific Philippines region are under Eurasia Basin, confirming a separation of the analysis. A geophysical/acoustic study will be Lomonosov Ridge from Eurasia about 60 million made on seamounts in the western Pacific, to years ago. Continuation of this aeromagnetic include seismic reflection data, cores and rock survey is planned for the next several years dredges, and wide-angle reflection/refraction (NAVOCEANO). measurements at selected sites. A geophysical An extensive acoustic/geophysical/ocean­ survey has been carried out along the Galapagos ographic survey of the Indian Ocean is planned in Spreading Ridge both east and west of the FY 76 to include seismic reflection profiles, 3.5 Galapagos Islands (NAVOCEANO). kHz high resolution profiles, 12 kHz bathymetry, Recent studies of the mid-Atlantic Ridge using magnetic and gravity data. Sediment cores and a near-bottom recording magnometer has wide angle reflection/refraction measurements revealed the fine structure of the earth's magnetic will be taken at selected locations polarity for the first 3.5 million years and similar (NAVOCEANO). studies on other sections are planned. A

32 Energy Research and Development Administration

The Energy Research and Development Ad­ ERDA's laboratories: The Los Alamos Scientific ministration (ERDA) consolidates activities Laboratory (LASL], the Lawrence Berkeley related to research and development on the Laboratory (LBL], and the Lawrence Livermore various sources of energy from fossil, nuclear, Laboratory (LLL). In addition, ERDA supports solar, geothermal, and other energy sources. A geodynamics-related research projects through a considerable amount of this research is few university grants or contracts. geodynamics-related, carried out primarily in

I. Internal Properties and Processes

A. Dynamic Modeling young plutons, is likely to be associated with At LASL, modeling of geologic processes shallow Curie-point isotherms. include theoretical, numerical and simulation studies directed at understanding the emplace­ C. Physical and Chemical Properties and Mineral ment of plutons and the thermal state of their Assemblages environments, the eruption mechanism of The construction of a physical properties test volcanoes, computer simulation of the chemistry facility is planned at LBL in FY 76 to test rock of hydrothermal alteration, heat flow, and heat samples at varying temperatures and pressures and mass transfer in the earth's interior. to 400°C and 1,000 bars, respectively. Thermal, electric, and sonic properties of rock-fluid, B. Geophysical Observations of Internal systems would be measured. Processes At LASL experimental programs are carried In a major program focused on magmatic out in geophysics and rock mechanics using both processes at LASL, data are obtained through explosive shock waves and static high pressure field and laboratory studies of the chemical and devices. These programs are directed at the high physical state of the earth's upper mantle by p-T properties of silicates, oxides, and metals studying rock specimens (xenoliths and host with the principal objective the determination of basalts) derived from the mantIe and analogous the composition of the earth's mantle and core. synthetic material. This program includes high Research on melting phenomena and solution pressure-temperature experimental geophysics, geochemistry currently underway will be ex­ thermal and electrical conductivities, thermal panded to include more rock systems and high P­ evolution and convection in the earth's interior T studies of phase equilibria of individual pure by numerical-theoretical methods, fracture mineral phases, mineral assemblages, including propagation, laboratory and in situ rock volatile bearing systems, and the physical and mechanics. thermochemical properties of silicate melts. In a planned field experiment by LBL in Investigations of mineral assemblages in mantle­ northern Nevada, a pattern of drill holes 100-200 derived xenoliths with electronprobe are in meters deep will encompass the Battle Moun­ progress. tains regions of high heat flow. Geothermal The LLL is also involved in a wide range of gradients and thermal conductivity will be experiments on the static deformation and shock determined to obtain heat flow. In another LBL properties of minerals and rocks to permit proj ect, an attempt will be made to evaluate accurate predictions of the response of the earth's aeromagnetic data to determine depth to the crust to various types of stress and loading. A Curie point. Geothermal activity due to large research program is in progress to improve thermally anomalous masses in the crust, such as understanding of the response of geological

33 media to mechanical stimuli such as explosions volcanoes of the Cascades of northern California, or in situ stress. Rock behavior on a microscopic and field studies of active volcanoes. Methods (grain size) scale will be modeled, and results include movies, high-speed and time-lapse verified by experimental work on well­ photography, spectroscopy and interferometry characterized ceramic synthetic rocks. With the for gas and light isotope analysis, geodesy by help of statistical theory, modeling will then be optical and laser methods, seismology, aerial extended to the larger scale of joints, faults, and photography and remote sensing, air, gas and other inhomogeneities that exist in the field. Also particulate sampling at low and very high at LLL numerical modeling of both small scale altitude by aircraft, shallow borehole and field experiments will be conducted for pre­ geophysics, and petrological studies of lava, experiment design and post-experiment volcanic rocks and xenoliths from kimberlite analysis. In an iterative manner, these should pipes and andesites. provide a basis for advancing understanding and Laboratory studies at LASL on rock and improving predictive capability. mineral samples provide major, trace elements, and isotopic data obtained with the goal of D. Geological Constraints establishing the temperature, pressure, and time Field studies at LASL related to volcanism or of formation of the material. From this informa­ plutonic processes provide data in the form of tion, combined with careful field mapping, a structural relationships, detailed studies of sample can be placed in its historical context and petrochemistry of lavas and xenoliths, and also its physical or chemical history established. from physical observations such as spectroscopy At LBL the distribution of trace, major, and of volcanic gases. These activities include field radiogenic-heat-producing elements in Mesozoic studies of igneous terranes directed at the instrusive rocks, and Tertiary and Quaternary understanding of such igneous processes as the igneous rocks, on east-west traverses across the emplacement of magmas from depth, the Great Basin will be examined. Radiogenic heat dynamics of thermal problems associated with production will be determined, and interelement pluton emplacement and volcanic eruptions, and ratios compared which may indicate the presence their relationship to tectonic features such as of, and depth to, plates of oceanic crust that plate interactions. Included are field studies of foundered beneath over-riding continental the Rio Grande rift and its associated volcanics­ plates. both basalt and caldera complexes, andesite

II. Boundaries, Movements, and Structure of Lithospheric Plates

Under a cooperative arrangement between two processes. The Rio Grande rift is relatively young universities, seismic data are analyzed from a and may be a maj or rift zone inan incipient stage network of short period telemetered seismic of formation. stations in the Shumagin Islands near the tip of Possible topical studies would include: bore­ the Alaskan Peninsula, and from a large aperture hole geophysics and core studies along the Rio seismic array in the eastern Aleutian arc east of Grande rift using LASL's 300-m drill rig, the core Unalaska Island. This is part of a seismic tectonic studies to include petrological, geochemical, and study of the active Pacific-North American plate physical properties; regional seismicity using boundary in the eastern Aleutian arc. LASL's seismic net; regional geodesy using three­ At LASL the present state of activity of both color laser geodimeters, tilt and long baseline the Rio Grande rift zone and the Jemez caldera are precision leveling; and deep seismic reflection monitored by geophysical observations and a profiling (University consortium). regional seismic network to provide data on a At LBL a study is underway to detect changes major continental rift feature and the unusual in electrical resistivity that might be caused by volcanism associated with maj or rift zone tectonics within the San Andreas Fault system.

34 National Aeronautics and Space Administration

The NASA Earth and Ocean Physics rotation, polar motion and plate motions. The Applications Program, through satellite and range measurements will be acquired at fixed lunar observation techniques, contributes to the stations located at the University of Texas major rGP elements concerned with geophysical McDonald Observatory and the University of observations of internal processes, and present Hawaii Maui Laser Ranging Observatory. motions of lithospheric plates and the earth's The Geodynamic Experimental Ocean Satellite pole. The NASA projects involved are the (GEOS-3) presently orbiting project has the Tectonic Plate Motion, Measurements Systems objective of demonstrating a much improved and Forecasting Techniques, Experimental Data altimeter that cannot only measure the Analysis, the Lunar Ranging Experiment (LURE) topography of the earth's oceans to an accuracy and the Three Satellite Systems, the Geodynamic of approximately 30 cm, but that can also Experimental Ocean Satellite (GEOS-C), the measure the wave height (or sea state). The Laser Geodynamic Satellite (LAGEOS) and the measurements of the ocean topography will Ocean Dynamics Satellite (SEASAT-A). provide the capability to make a more precise The objective of the Tectonic Plate Motion mathematical description of the earth's gravity project is to utilize existing capabilities to field and improve the measurements of the measure precise motions between defined points, variations in solid earth geometry and other using both laser tracking and very long baseline geophysical areas. interferometry. The Laser Geodynamic Satellite (LAGEOS) Measurements Systems and Forecasting project, launched in 1976, with its very dense Techniques activities involve the planning and spherical satellite covered with laser reflectors, implementation of scientific and technical has the objective of providing the capability to research and other supporting activities in make very accurate measurements of the earth's universities, nonprofit and industrial organiza­ crustal motions (tectonic plate movement, fault tions, NASA centers, and other Government motions, polar wobble and rotation rate). agencies. The first Ocean Dynamics Satellite (SEASAT­ Experiment Data Analysis provides for the A) due for launching in 1977 has as its objective analysis and synthesis of data obtained in the demonstration on a global scale of an EOPAP investigations, e.g. the processing, integrated monitoring and data gathering evaluation, and analysis of data taken during capability for a wide range of physical ocean GEOS-3, Skylab, Apollo-Soyuz Test Project, etc. characteristics, including wave height, shape, The Lunar Ranging Experiment will utilize and direction, the location and motion of existing knowledge of lunar motions and con­ currents, global circulation patterns, ocean tinuing range measurements to the lunar surface, wind speed and direction and the ocean retroreflectors to support investigations on earth geoid (topography of the oceans).

35 National Science Foundation

The National Science Foundation (NSF), FY 75 Cornell University received a large award forbidden by its charter to conduct research or for their deep seismic sounding efforts, while operate research laboratories, supports scientific work by Battelle for geodynamics information at research and programs to strengthen scientific Maryville, Montana decreased. On the whole, it research potential through grants and contracts. is the universities with major facilities that Most of the thousands of awards made annually figure most prominently in geodynamic in­ are to nonprofit organizations-principally U.S. vestigations. Since there is a constant change in universities and colleges. Traditionally, NSF has proposals received, it is impossible to predict an supported basic research through unsolicited exact future categorization, even though total proposals by individuals, although in recent budget figures are available. Information years-there have been an increasing number of supplied in this report indicates what is expected requests for major projects involving a great in FY 76, although FY 74 figures are the latest many scientists, often from consortia of univer­ that have been documented. sities. The NSF supports geodynamics-related pro­ The grants or contracts made that are jects in several offices, as follows: the Earth geodynamics-related fall in both the large and Science Project Support in the Division of Earth small categories. The Ocean Sediment Coring Sciences: Geophysics, Geochemistry, and Program is an example of a project involving a Geology; the Ocean Sediment Coring Program in maj or facility, the Glomar Challenger drilling the Division of Earth Sciences; the Submarine vessel. However, most of NSF funds, and nearly Geology and Geophysics Program (SG&G) in the all of the awards, are for small projects of one or Oceanography Section of the Division of two scientists. Oceanography; the Seabed Assessment Program In FY 74, NSF awarded 243 grants or contracts in the International Decade of Ocean Exploration that were geodynamics-related to 78 universities of the Division of Oceanography; the Polar Earth and other nonprofit organizations. The ten major Sciences Program in the Office of Polar organizations that contributed most to Programs; and the Advanced Geothermal Energy geodynamics through NSF support were Colum­ Research and Technology Program (AGERT) in bia University, the University of California at the Division of Advanced Energy Research and San Diego (including Scripps Institution of Technology. Other offices that also provide some Oceanography), Battelle N.W., Woods Hole of the facilities and logistics for the research Oceanographic Institution, University of projects are the Office of Oceanographic Hawaii, MIT, University of Washington, Har­ Facilities and Support of the Division of vard University, California Institute of Oceanography, for oceanographic research ship Technology, and Stanford University. Although support, and the Earthquake Engineering this list may change each year since grants are for Program of the Division of Advanced Environ­ only 1 or 2 years, most of the universities noted mental Research and Technology for the national above will be among the leading contenders. In s trang-motion seismic network.

I. Internal Properties and Processes

A. Dynamic Models B. Geophysical Observations of Internal Processes Within the Geophysics Program, about half a dozen grants are normally made per year for A major effort by about 50 individual grants is modeling studies of the dynamics of the earth's being made by university scientists to study core, geodynamo, and on convective motion in the internal processes by geophysical methods. earth's mantle and at the crust-mantle boundary. These efforts come from various offices

36 throughout the National Science Foundation that shear strength and electric properties of rocks, deal with geodynamics-related programs, but are particularly the ultrabasic rocks most likely to most heavily concentrated in Geophysics, SG&G, have originated in the lower crust and upper and in AGERT. The principal tool for the mantle under high pressure and high geophysics studies is earthquake seismology, temperature. Considerable development work in and in most of these studies, heavy reliance is put the pas t few years has gone into methods of on the records of the World Wide Standardized obtaining high temperatures and high pressures. Seismograph Network, with about 20 grants and These include ultrasonics and shock compres­ nearly $.90M total. Geothermal studies are sion, as well as s taUc compression, and the carried out mostly in AGERT in the search for advancement has been made at relatively few of methods of locating sources of energy within the the major universities. In the Geochemistry earth. Seismic studies of internal characteristics Program, in many cases using high-temperature, by the use of controlled explosives or mechanical high-pressure equipment, 15 to 20 studies sources account for nearly $.50M in about 10 involving about $.90M are concerned with a large separate university grants. A few universities variety of geochemical problems such as are experimenting with the Ocean Bottom equilibrium and mass transfer among minerals Seismograph (OBS) in an effort to obtain more and aqueous solutions, the diffusion kinetics of detailed information on the ocean sediments, as trace elements, mineral crystal chemistry, ther­ well as a new input to earthquake monitoring. A modynamics of ionic interactions, rate and major award in this category, which is now mechanism of exsolution in minerals, and the developing, is concerned with the fine structure measurements of ion-pair formation constants. of the crust and upper mantle in which con­ The mOE office funded a few projects in which tinuous seismic reflection techniques used in samples recovered from the mid-Atlantic Ridge petroleum exploration seismology can be extend­ were analyzed. ed to deeper structures in the earth. If seismic discontinuities can be mapped in the lower crust D. Geological Constraints and upper mantle, a great deal of information can This area of geodynamics-related programs is be obtained on the evolution of the continental well represented in NSF with nearly 60 awards crust from the primitive mantle and on very deep­ totalling between 2.5 and 3.0 million dollars seated control of surface features. Research on annually. Most of these awards are made in telluric, magnetotelluric, electromagnetic induc­ Geochemistry, Geology, Submarine Geology and tion, and electrical resistivity methods are Geophysics Programs. The Geochemistry increasing and in FY 1974 about $200,000 was Program supports nearly 40 awards varying spent on such projects. A few gravity studies are widely in the topics studied with 6 to 10 on the sponsored through the Geophysics Program on geology, geochemistry and geochronology of continental work and gravity measurements at volcanic rocks from several geographic areas, sea were carried out routinely on a few of the though principally the United States and Mexico. oceanographic vessels. Most of the studies above Several mantle or deep crustal rocks that are are concerned with the continental U.S. and exposed at the surface in various areas of the Hawaii, but several studies were carried out in world are also studied in these programs. The Mexico, Iceland, and in Southeast Asia. SG&G Program supports many studies of the basalts obtained from the Ocean Sediment C. Physical and Chemical Properties of Minerals Coring Program, and mOE supports studies of and Mineral Assemblages rocks recovered from submersibles in the These studies by the NSF can be divided into FAMOUS Experiment on the Mid-Atlantic two or three general groups adding up to about 40 Ridge. A few studies of the geochemistry and awards totalling almost $2 million. The support petrogenesis and geochronology of rocks ob­ by the Geophysics Program is heavily oriented tained from the Dry Valley Drilling Proj ect are towards the investigation of sonic velocity, flow made under the Office of Polar Programs. measurements, development of microcracks,

37 II. Boundaries, Movement, and Structure of the Lithospheric Plates

A. Present Plate Boundaries scientists from many universities and requests are expected to continue to grow. The NSF The NSF effort in this category, which is about support of research on these cores, mainly in $2 million per year, is largely in the oceanic areas Submarine Geology and Geophysics, is actually in the SG&G and mOE Programs. A number of a fairly small percent, about 10-20, of the work on geophysical studies have been made of the the cores for this program. Other investigators boundaries and structure of the Nazca Plate, the also obtain samples for studies and, although a eastern and southeastern parts of the Asian few of these may be reported to this Committee Plate, and the western part of the Pacific Plate. by other agencies, many samples go to in­ The Sunda Arc and the Mid-Atlantic Ridge are vestigators from industry and from universities, also under investigation. Use is made in some of both domestic and foreign, where support is not these studies of the relatively new multi-channel required from the Federal Government. The marine seismic units, often with high energy air Ocean Sediment Coring Program is changing guns, as well as sonabuoys and ocean bottom somewhat in objectives, as it begins its IPOD seismographs. In addition to the seismic work, phase in late 1975, with concentration on deep support has also been provided for major crustal drilling and reduced emphasis on programs involving gravity, heat flow, and paleoenvironmental and ocean margin drilling. magnetic measurements in the continental Thus, this program will be contributing agreater margin of west Africa and eastern South part of its effort to geodynamics-related projects. American in order to construct the various stages Other investigations in this category are of the opening of the South Atlantic.. The supported through Geophysics, SG&G, and the Geochemistry Program includes isotopic studies Office of Polar Programs, and these are about of the older geologic history of the southwestern equally divided between paleomagnetic proj ects margin of North America and the tectonic dealing with past plate movements and evolution of the South Kenya rift zone. geological and geophysical studies in areas of plate boundaries. The Antarctic Program in­ B. Present Motion of Plates volves sediments taken from the Eltanin and A program with about one-half dozen awards from the Dry Valley Drilling Project, as well as in the Geophysics Program involves the model­ geological studies in the Antarctic Mountains ing of the response of the earth to late quarter­ and the Antarctic Peninsula. The Eltanin, now nary ice melting, earth tide studies, and operated by the Argentine Government and applications of atomic clock interferometry. A renamed the Islas Orcadas, works in the South maj or program has been initiated on the Atlantic Ocean in a cooperative study by geophysical application of very long baseline Argentine and U.S. scientists. interferometry. This technique has the potential to clarify our concepts of the current nature of D. Plate Accretion, Composition, and Structure plate motion and deformation. The NSF support in this category is about $1.5 million in 20 or more grants and contracts, with C. Plate Boundaries and Rates of Movements efforts of the Ocean Sediment Coring Program During the Past estimated at about $.30M. A large contribution In this category the NSF supports about 40 comes from the International Decade of Ocean investigations with an estimated total of $2.3 Exploration in their proj ects to provide maj or million which includes a sizable portion ($.90M) support to Woods Hole Oceanographic Institu­ for the Ocean Sediment Coring Program of tion for the studies of the East Atlantic Continen­ Scripps Institution of Oceanography, plus tal Margin and to the Lamont-Doherty Geological several research studies of cores of OSCP Observatory of Columbia University for the proj ects that are not part of initial cruise reports. study of the continental margins of Argentina This research on core material is carried out by and Brazil.

38 U.S. Geological Survey

I. Internal Properties and Processes

A. Dynamical Models [micropulsations) by instruments at land-based geomagnetic observatories. Studies of dynamical models are carried out as part of the Geological Survey's Earthquake B. Geophysical Observations of Internal Hazards Reduction Program, Geothermal Processes Program, and Geophysical Surveys Program. Recent studies by Survey scientists suggest the Numerous geophysical methods are beingused reliable prediction of damaging earthquakes may by scientists of the U.S. Geological Survey to be feasible within a few years for some detect subsurface structures and to describe the earthquake-prone areas. Field measurements dynamics associated with the margins and coupled with laboratory experiments and interior of the North American plate. These theoretical studies of precursor phenomena are methods include microearthquake, refraction being carried out by Survey scientists in order to and reflection seismic, heat flow, magnetic, establish a firm physical basis for predicting the gravity, electrical resistivity, electromagnetic, time, place and magnitude of earthquakes. This and thermal radiometric studies of the continent, research effort includes the collection and the continental shelf, and continental slope. analysis of data on strain accumulation and Microearthquake studies based on dense release, and the study of the behavior of rocks arrays of short-period seismographs (micro­ under physical conditions similar to those seismic nets) permit three-dimensional mapping encountered in the crust and upper mantle. of active fault zones as well as identification of Computer modeling of fault displacements is "locked" sections of known active faults. Record­ underway to achieve an understanding of fault ed microearthquakes are correlated with mechanisms and related effects. These numerical measured strain patterns in studies of the models are used by Survey scientists to develop propagation of strain or slip events throughout simulations of vertical and horizontal deforma­ the network. Microseismic networks are current­ tion arising from possible dilatant changes in a ly operating in California, Washington, Nevada, fault zone. Both plane-strain and three­ Wyoming, Utah, New Mexico, Missouri, Alaska, dimensional analyses have been applied to and Hawaii. problems of source mechanics, earthquake In support of the microseismic studies, refrac­ prediction, and earthquake modification. tion seismic surveys are made over broad regions Survey scientists also study the mechanisms to determine the physical properties, elastic by which water and heat are transferred in regime, and principal structure elements of the geothermal systems within the crust. Conceptual crust and upper mantle. models of selected well-known geothermal Heat flow measurements also contribute to an systems-based on their known geologic, understanding of processes occurring within the hydrologic, geochemical and geophysical earth. Measurements of geothermal gradients in settings-are being improved by means of deep wells and mines together with laboratory shallow drilling to obtain corroborative ther­ measurements of thermal conductivity of rocks mohydrologic data. and radioactive heat production provide infor­ Information about the distribution of mation about the thermal regime of the earth's magnetization and electrical conductivity within crust and upper mantle. the earth is gained by orbiting satellite Surface manifestations of heat flow are magnetometers which record broad-wavelength detected by analysis of thermal infrared images magnetic anomalies plus the small-amplitude obtained over broad regions. After deleting solar fluctuations in the earth's magnetic field heating effects from crustal heating effects, the

39 image information is analyzed using thermal Because the physical properties and chemical inertia and spectral reflectance data obtained in compositions of most rocks and rock-forming the field. The thermal and reflectance data may magmatic materials cannot be directly measured be used as indirect measurements of high surface in their crustal and mantle environments, these heat flows associated with hydrothermal activi­ properties must be analyzed in the laboratory ty in the crust. where physical and chemical conditions can be In addition to seismic and heat flow studies, simulated. Information about the composition, magnetic and gravity surveys are made to state, temperature, and stress conditions in the identify zones of anomalous magnetization and earth's interior is obtained in an integrated density in the crust and upper mantle. Magnetic program of laboratory and field studies in surveys made by air, land vehicle, or on foot are mineralogy, igenous petrology, metamorphic extremely useful in delineating accumulations of phase petrology, phase equilibria, ther­ serpentine within strands of the San Andreas modynamics, isotopic geochemistry, radioele­ and related faults; ophiolitic rocks representing ment analysis, neutron activation, and rock ancient oceanic crust, which occur in the Califor­ mechanics. This program is supported by com­ nia Coast Ranges and Sierra Nevada foothills; prehensive compilations of geochemical and and subsurface shapes of plutonic rock massifs thermodynamic data accessed by digital com­ such as the Sierra Nevada and Boulder batholiths puter. of western United States; Mineralogic research is concerned mainly with Magnetic surveying over broad areas is accom­ precise measurements of the physical properties panied wherever feasible by regional gravity of rock-forming minerals aimed at determining surveying. The gravity data have proven to be how the thermal and stress histories of minerals especially useful in major sedimentary basins, affect their compositions and properties. low-density plutonic rocks that have been Research in igneous petrology is directed intruded into metamorphic rock complexes, high­ toward understanding magmatic systems, with density mafic and ultramafic rocks representing special emphasis on studying the relation of crustal and upper mantle sources, and high chemical variations to physical properties and to density relatively nonmagnetic terranes of such rate-dependent properties as viscosity, metamorphic rocks. diffusion, and kinetics. Various electrical and electromagnetic techni­ Phase equilibria studies of multicomponent ques such as nc. resistivity, transient elec­ systems, which are fundamental to current tromagnetic, audio-magnetotelluric, induced research in igneous and metamorphic petrology, polarization, electromagnetic, self-potential, and are applied to crystal chemistry and physical telluric-current methods are used for detecting chemistry data of rock-forming minerals. zones of anomalous electrical conductivity in the Contributing to information obtained by phase subsurface. These anomalous zones may reflect petrology and thermodynamic studies is a broad stratigraphic or structural barriers controlling area of research in isotopic geochemistry. This the distribution of saline ground water or regions research includes investigations of light stable of elevated temperature associated with high isotopes, such as carbon, hydrogen, oxygen, and geothermal potential. sulfur, and radiogenic isotopes, such as stron­ Continental geophysical investigations merge tium, lead, and intermediate daughter products with marine geophysical research at the Atlantic in the uranium and thorium decay series. continental margin where marine seismic reflec­ An essential companion to the various studies tion, seismic refraction, magnetic, and gravity of the chemical composition of rocks and surveys are made to investigate the deep struc­ minerals are investigations of the physical ture of the continental shelf and slope. Current properties of these materials in laboratory investigations involve structural interpretations experiments that duplicate conditions in the and evaluations of the thickness and distribution earth's crust and upper mantle. This research in of sedimentary rocks in the Baltimore Canyon rock mechanics is largely conducted with ex­ Trough and Georges Bank basins. perimental equipment that simulates conditions at depths of up to 30 kilometers. Mechanical, C. Physical and Chemical Properties of Minerals elastic, and thermal properties of rock samples and Mineral Assemblages are currently measured at pressures of up to 10

40 kilobars (approximately 10,000 atmospheres) supplemented by field and laboratory studies of and temperatures of up to 1,000ae. metamorphic rocks that are providing informa­ tion on load, strain, and fluid pressures during D. Geological Constraints metamorphism as well as means of inferring depths of partial melting. Geologic constrains on models of plate tectonic Consideration of the theory of plate tectonics is evolution and processes are being investigated in an important element of Geological Survey a wide variety of geologic settings. research on mineral resources, because models of In Washington, Oregon, and California, ore genesis that explain the relationship of ore­ petrologic and structural studies of volcanic, forming processes to other geologic events sedimentary, and plutonic rocks supported by should improve the capability to predict the detailed geologic mapping and regional synthesis presence of useful deposits. The emphasis of of large areas of the Cascade, Olympic, and present studies in geodynamics as applied to ore Klamath Mountains are helping unravel the deposits is aimed at understanding the origin of tectonic history of the western margin of the important regional structural features and the North American Plate and to clarify its interac­ correlation of the geologic environments of tion with the Nazca and Pacific plates during deposits with identifiable parts of the plate Mesozoic and Tertiary time. tectonic cycle. Both detailed and reconnaissance studies of volcanic rocks and associated plutons of Tertiary Mapping and petrologic studies are showing the existence of island arc volcanic rocks and of age in the San Juan and Absaroka Mountains and ophiolite complexes indicative of subduction and in central Idaho are underway to help explain the possibly obduction along the margin of the North relation between the chemistry of the igneous American plate in late Paleozoic and early rocks erupted through the North American plate Mesozoic time. and geodynamic processes along the western Reconnaissance studies in southwest Oregon compressional margin of the plate. are aimed at determining how podiform Studies in geochemistry and geophysics are chromite-bearing ultramafic and mafic bodies providing constraints to models of properties and and related melange units of volcanic rocks from processes of plate tectonics through in­ island arcs were scraped off the oceanic plate and vestigations of igneous and metamorphic rocks juxtaposed on the North American plate in and of active and dormant volcanoes. Detailed Mesozoic time. studies of ankaramites in Hawaii, caldera Studies of the base-metal deposits in the deposits in New Mexico, and basalts in the Eastern States are concerned with examining Pacific Northwest are being made to estimate depths of phenocryst formation and develop­ evidence that links mineralizing episodes to plate ment, physio-chemical processes and crystalliza­ deformation before and during opening of the tion history in large volumes of silicic melt, and proto-Atlantic in early Paleozoic time. Some of the mechanics of extrusion and spreading of these deposits provide clues that pulses of prodigious volumes of basalt over vast areas. mineralization occurred in paleoaquifers whose Additional studies of the generation and flow regimes may have been determined by warping during early stages of rifting. movement of magma are being conducted at the In Puerto Rico, geologic mapping, isotopic Hawaiian Volcano Observatory, where dating, and petrologic studies are attempting to measurements of deformation at Kilauea Volcano establish the relations between the emplacement are made and examinations are conducted of old of porphyry copper deposits, volcanic and lava flows and of magma in the process of plutonic rocks, and the subduction events of eruption. Cretaceous to Eocene age. All of these investigations of igneous rocks are

41 II. Boundaries, Movements, and Structure of Lithospheric Plates

A. Present Plate Boundaries annually, are stitched across faults of the San The Worldwide Network of Standard Andreas system, the Nevada seismic zone, the Seismographs (known as WWNSS), composed of Wasatch fault in Utah, and in the Hebgen Lake 31 continuously recording stations in the United area of Montana. States and 85 similarlyinstrumented cooperative Sea level measurements recorded at automatic stations in 68 other countries is the most tide gages also are being studied for their important international seismological effort. possible utility in determining crustal uplift or This network is the essential source for the subsidence along tectonically active coast lines. seismological data that are used in locating National Ocean Survey tide gage records along earthquakes, determining focal mechanisms, the coast of the western United States and investigating seismic wave propagation, and Alaska are being analyzed to detect possible developing concepts of global and regional tectonically induced trends. tectonics. The Geological Survey operates 7 Seismomagnetic effects along western United seismic observatories in the conterminous Un­ States fault zones are being investigated as an ited States, Alaska, and Guam and provides indirect means of monitoring crustal stress. One equipment maintenance and supplies for the aspect of the program has been to search for other stations of the WWNSS. broad-scale long-period effects with a pair of The Geological Survey's National Earthquake magnetometers that operate synchronously in a Information Service (NElS) in Golden, Colorado, "leap-frog" survey mode. is responsible for receiving data on potentially damaging earthquakes, rapidly locating such C. Plate Boundaries and Rates of Movement earthquakes, and notifying the proper During the Past authorities and the public. NElS locates as many Current paleomagnetic research includes refin­ earthquakes worldwide as can be accurately and ing the geomagnetic reversal time using rapidly determined with data collected from radiometrically dated volcanic and plutonic USGS observatories and seismic stations and rocks as well as stratigraphically dated sedimen­ from the WWNSS. tary rocks from the Western and Southwestern USGS scientists are continuing research into United States. the geologic nature of the mid-ocean plate Other major paleomagnetic problems related to boundaries. A cooperative investigation, the interpretations of sea floor spreading rates and French American Mid-Ocean Underseas Study apparent polar wandering are the decrease in (FAMOUS), provided a unique opportunity for amplitude of magnetic anomaly stripes with direct observation of the topography and geology increasing distance away from a spreading axis ofthe Mid-Atlantic Ridge in the region southwest and fluctuations of the geomagnetic field intensi­ of the Azores Islands. Using deep submersible ty throughout geologic time. Paleomagnetic and craft, Geological Survey geologists were able to petrologic data from samples of sea floor and sea observe, photograph, and sample across the mount basalt from the Hawaiian-Emperor innermost rift valley of the Ridge. volcanic chain indicate that the observed decrease in anomaly amplitude away from a B. Present Motion of Plates spreading center is caused by oxidation of Precise geodetic techniques-geodimeter sur­ titanomagnetite to cation-deficient veys for horizontal movements and level surveys titanomaghemite within the basalt. for vertical movements-are used to determine Recent research in geochronology, important to elastic strain accumulation and strike-slip along improving the time framework for interpreting faults and to detect premonitory strains that rates of plate motion and tectonic processes, might be useful for earthquake prediction. includes investigations of the 4°Ar/39 Ar age Trilateration networks, which are resurveyed spectrum dating technique. This total fusion

42 technique, which can be used on the same the evaluation of geologic evidence for Late materials and nearly the same age range as the Cenozoic faulting is in progress along coastal conventional technique, has the advantage of Alaska. In western Alaska the emphasis is on using smaller and less homogeneous samples deciphering the Tertiary and Quaternary than those used with the conventional technique. geology and biostratigraphy of the coastal Other research in geochronology is concen­ region, the continental shelf, and the offshore trated on the use of thermaluminescence (TL) as a islands. The objective of this study is to deter­ dating tool for very young volcanic rocks. The mine and correlate the nature and rates of past age range over which the TL method is and on-going crustal deformation. The demonstrated to work using samples in­ stratigraphy and tectonic style of the shelf and dependently dated by C14 and K-Ar methods is slope of the Beaufort-Chukchi sea area are being 2,500 to 450,000 years for tholeiitic basalts and studied by relating the onshore geology in the 4,500 to 200,000 years for alkalic basalts. Brooks Range thrust belt to the offshore areas, using seismic reflection, magnetic, and gravity D. Plate Accretion, Composition, profiling. Seabed sampling and heat flow studies and Structure are also contributing to a synthesis of the Much of the Geological Survey's research on regional tectonic picture. the Pacific margin of the Americas Plate is Since the early 1950's the Geological Survey concentrated on the San Andreas Fault zone from and other Federal, State, and private institutions the Salton Trough to the Mendocino Fracture have assembled a prodigious amount of geologic zone. Significant efforts are also underway in the information on the Colorado Plateau. The vicinity of the Gorda rise and Juan de Fuca Rise original work, primarily large-scale geologic and along the Aleutian Trench-Arc system and mapping in support of uranium exploration, is coastal Alaska. A major objective of this research now being synthesized and compiled at 1:250,000 is locating recently active fault strands within scale for the entire Colorado Plateau. This the San Andreas system and the determination of syn thesis of vast amounts of stratigraphic and the tectonic history along this active plate structural information should provide an inte­ margin. grated data base to help answer the perplexing A detailed analysis of the intense folding and questions of why and how this plate fragment faulting in the Salton Trough is underway to rose epeirogenically and escaped the intense determine the tectonic history of the area. These Laramide and Post-Laramide deformations that studies should establish or refute the hypothesis affected the Basin and Range Provipce to the west of transform faulting and sea-floor spreading in and the Rocky Mountains to the east. the Salton Trough. From the Salton Trough The geologic features of the sedimentary northward to the Mendocino Fracture zone, the wedge under the Atlantic margin of the Americas Survey is engaged in detailed mapping of Pre­ Plate are being determined by shallow (300 Tertiary to Recent deposits to determine the meters or less} core drilling. Studies of the location, direction, and magnitude of dis­ paleontology, lithology, mineralogy, and placements and the recurrence interval of geochemistry of the cores provide a regional faulting along the San Andreas, Garlock, picture of the depositional history of the area. Hayward, Concord, Calaveras, Sierra Nevada, This study will provide information about the Elsinore, and San Jacinto faults. relationship between crustal tectonic fluc­ Geologic and geophysical studies of the Oregon tuations and transgressions and regressions of and Washington continental margin are designed the sea, and provides control for marine to unravel the tectonic history of this part of the geophysical investigations. Geophysical inter­ Pacific margin and to relate the deformational pretations of the offshore sedimentary section history to mineral resource accumulation and and basement complex are based on seismic igneous activity. The unique onshore exposures reflection and refraction surveys, plus gravity of oceanic crust provide an excellent opportunity and magnetics data. From these data the geology to infer offshore plate boundary geology. of the shelf, slope, and rise are studied to identify Detailed mapping of active surface faults and the structural and tectonic features.

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