Margins : a research initiative for interdisciplinary studies of processes attending lithospheric extension and convergence : proceedings of a workshop sponsored by the National Research Council, Beckman Center, Irvine, California, November 20-23, 1988 / Continental Margins Committee, Ocean Studies Board, Commission on Physical Sciences, Mathematics, and Resources, National Research Council.

Format:

Book

Contributor:

National Research Council (U.S.). Continental Margins Committee.

Language:

English

Subjects (All):

Plate tectonics--Congresses.

Plate tectonics.

Continental margins--Congresses.

Continental margins.

Earth (Planet)--Crust--Congresses.

Earth (Planet).

Physical Description:

1 online resource (295 pages) : illustrations

Edition:

1st ed.

Place of Publication:

Washington, D.C. : National Academy Press, 1989.

Language Note:

English

Summary:

Approximately 70 percent of the world's population is concentrated in the coastal borderlands, which geologists recognize to be the present continental margins. This new book on these continental margins provides a detailed account of a meeting which brought together specialists in marine and terrestrial geology, geochemistry, and geophysics. The workshop garnered widespread support and enthusiasm for a new direction in margins research focused on interdisciplinary studies of the fundamental processes of continental margin evolution. Scientific problems and solutions were identified for both divergent and convergent margins. Results of the workshop show that many of the fundamental plate interaction processes are common to all margins, whether formed by extension, contraction, or translation. This conclusion suggests a unified approach to margins research. A margins initiative has been proposed to follow up on the workshop results by developing science programs aimed at understanding the processes that control the initiation and evolution of continental margins.

Contents:

Margins: A Research Initiative for Interdisciplinary Studies of Processes Attending Lithospheric Extension and Convergence

Copyright

PREFACE

Contents

PART I REPORT OF THE CONTINENTAL MARGINS WORKSHOP

Executive Summary

OVERVIEW

Mechanics of Faulting

Fluid Flow

Growth and Modification of Continental Crust

Depositional Systems at the Edge of the Continents

DEVELOPMENT OF A SCIENCE PLAN

Formation of a Margins Initiative Committee

Organization of Workshops

1 Introduction

IMPETUS FOR THE WORKSHOP

ORGANIZATION AND SUPPORT OF THE WORKSHOP

Passive Margins

Active Margins

CHARGES TO THE WORKING GROUPS

2 Results of the Workshop

MARGIN PROCESSES: A NEW RATIONALE FOR RESEARCH INTO LITHOSPHERIC CONVERGENCE AND DIVERGENCE

Divergent Margins

Convergent And Translational Margins

Deformational Processes

Magmatic Processes

Sedimentation Processes

Mantle Dynamics

FUTURE DIRECTIONS FOR RESEARCH ON MARGIN PROCESSES: REQUIREMENTS FOR SUCCESS

Communication and Collaboration Among Scientists

Databases

Computational Facilities

Scientific Drilling

Seismic Facilities

Chemical Analytical Facilities

Theoretical and Computational Studies

3 Components of A Margins Initiative

A NEW APPROACH FOR MARGINS RESEARCH

A MARGINS INITIATIVE COMMITTEE

PLANNING WORKSHOPS

DRAFTING A SCIENTIFIC PLAN

PART II REPORTS OF THE WORKING GROUPS

4 Passive Margins: Group 1 Mechanics of Rifting and Associated Magmatism

PREAMBLE

Surface Geological Mapping in the Basin and Range Province

Deep Seismic Reflection Profiling On Extended Continental Lithosphere and Laboratory Measurements of Lithospheric Materials

Shallow Marine Reflection Profiling and Surface Geologic Studies of the East African Rift System.

Marine Geophysical Studies of the Deep Structure of Passive Margins in the Central and North Atlantic Oceans

Theoretical Modeling of Subsidence and Thermal History In Sedimentary Basins and the Lithosphere a Continuum

Isotope And Trace Element Analysis of Rift Volcanics and Xenoliths

THE SINGLE MOST IMPORTANT SCIENTIFIC OBJECTIVE

NEEDED STUDIES

Determine the Distribution of Three-Dimensional Strain in the Lithosphere

Low-Angle Normal Faulting in the Crust

The Interplay Between Extension and the Rheological Stratification of the Lithosphere

Structural and Magmatic Segmentation of Rifts in the Context of the Mechanics of Rifting and Heterogeneities of the Lithosphe

Determine the Causes of Compositional, Temporal, and Spatial Variations in Magmatism and Degassing

Vertical and Lateral Magmatic Transport

The Transition From Rift to Ridge Magmatism

Mobility of the Crust-Mantle Boundary During Rifting

Determine the Cause for Spatial and Temporal Variability of Uplift and Subsidence in Rift Systems

The Timing and Rate of Vertical Motion

Isostasy During and After Rifting

Uplift and Subsidence as an Independent Constraint on the Overall Structure of the Rift

The Interplay Between Rift Structure, Topography, Erosion, and Deposition

5 Passive Margins: Group 2 Rift and Passive Margin Basins- The Sedimentary Record

BACKGROUND

Scientific

Economic

Biospheric

The Specific Processes Involved

Origin of Stratification

Origin of Stratigraphic Sequences

Stratigraphic Documentation of Global Synergisms

Improved Temporal Resolution

Critical Problems

Stratigraphic Problems

Processes

Events

Kinds of Information

Data Collection Methods and Tools

Laboratory, Theoretical, and Numerical Developments.

Dynamical Sediment Flux and Accumulation Models

Backstripping Models

Seismic Expression of Stratal Geometries

Measurement Capabilities Needed

STRATEGIES REQUIRED TO ACHIEVE THE GOALS

6 Passive Margins Group 3 Divergent Continental Margins-Post-Rifting Internal Processes

SUMMARY

Processes Involved

Obtaining Snapshots of Fluid and Chemical Fluxes in Divergent Margin Basins

Fluid Seeps on Flanks and Toes of Divergent Margins

Geopressured Fluid Flow

Heat Flow

Determining the Cumulative Effects of Fluid and Chemical Fluxes in Divergent Margin Basins

Diagenetic Cements

Gas Hydrates

Hydrocarbon Maturation

Developing Integrated Models to Simulate Fluid-Chemical Processes in Divergent Margins

Local Models

The Integrated Process Model

STRATEGY REQUIRED TO ACHIEVE GOALS

BROADER IMPLICATIONS

Selected Bibliography

7 Active Margins: Group 1 Dynamics of Short-Term Deformation At Active Margins

THREE MAJOR AREAS FOR INVESTIGATION

What Controls Aseismic Deformation and the Recurrence Characteristics and Locations of Catastrophic Earthquakes?

What Controls Accretion, Nonaccretion, and Erosion of the Upper Plate at Convergent Margins?

What Determines the Partitioning of Deformation In Plate-Boundary Zones?

Geometry of the Downgoing Plate

Structures, Geodetics, and Seismicity of Subduction Margins

Numerical Modeling

Enhanced Geophysical Instrumentation

Submarine and Rapidly Deployed Geodetics

Ocean-Bottom Seismometers

Measurements of Stress and Deep Structures

Rheological Studies

8 Active Margins: Group 2 Geologic Evolution of Active Continental Margins.

THE SINGLE MOST IMPORTANT SCIENTIFIC OBJECTIVE

How are Terranes Formed, Moved, and Accreted?

What are the Consequences of Changes in Plate Motion for Active Plate Boundaries?

What Controls Vertical Motions in the Forearc Region of Convergent Margins?

Specific Problems

What Controls Arc Rifting and the Development of Backarc Basins?

What Causes the Initiation of Subduction?

Mapping, Paleomagnetics, Petrology, and Geochemistry of Terranes

Cross-Disciplinary Studies of Rifting and Backarc Basins

Geodetic and Geomorphic Studies of Propagating Subduction

9 Active Margins: Group 3 Mass and Chemical Transfer

INTRODUCTION

Melting Pot of the Earth: Crustal Formation and Modification at Active Margins

CRITICAL PROBLEMS

Chemical Variability of Input from the Subducting Plate

Mass Transfer Across Plate Boundaries

Mantle Wedge Processes

Crustal Processes

Chemical Variability of the Output: Geochemistry of Magmas and Fluids at Active Margins

Episodicity of Volcanism: Reflection of a Nonlinear System

10 Supplementary Note on Rock Mechanics Problems at Active Margins

LABORATORY EXPERIMENTS

CONDITIONS IN CONTINENTAL MARGINS

PARADOX OF STRESS MAGNITUDES ON FAULTS

PART III BACKGROUND PAPERS

ACTIVE CONTINENTAL MARGINS MECHANICS OF PLATE MOTION

MECHANICS, KINEMATICS, AND DEFORMATION MODES AT CONVERGENT MARGINS

Introduction

Selected Problems

Future Research Directions

References

Figure Captions

DRIVING FORCES: SLAB SUBDUCTION AND MANTLE CONVECTION

State of Current Knowledge

Empirical

Observations

Models

Key Questions

New Observations, Experiments, and Models

Seismology

Geodesy

Mineral Physics

Bibliography

FIGURE CAPTIONS.

ACTIVE CONTINENTAL MARGINS EGEOLOGIC EVOLUTION OF ACTIVE CONTINENTAL MARGINS

INITIATION OF SUBDUCTION

State of Knowledge

Outstanding Questions

Targets for Future Research

1. Conventional Oceanographic Studies

2. On-land studies of ophiolites and other emergent forearcs

3. Special Projects

INTRAOCEANIC CONVERGENT MARGINS

Magmatism

Structure and Stratigraphy

Fluids and Thermal Regime

Methods for Studying These Margins

Selected References

COLLISION OF SEAMOUNTS, RIDGES, AND CONTINENTAL FRAGMENTS: THEIR EFFECTS ON CONVERGENT MARGINS

Some Tectonic Processes Accompanying Collision

Questions

Figure Caption

ACTIVE CONTINENTAL MARGINS MASS AND CHEMICAL TRANSFER

MASS FLUX AND CRUSTAL EVOLUTION AT CONVERGENT MARGINS

I. Introduction: the Present Crust-Mantle System

II. Mass Flux at Convergent Margins

a) Global Overview

b) Input-Output Analysis Of Subduction Process (S-Process) Crustal Recycling

c) Regional Variability

III. Crustal Evolution

a) Coupling of Mantle-Crust Evolution

b) Crustal Additions, Crustal Composition, and Lower Crustal Delamination

a) Processes of Mass Transfer

b) Mass Flux and the Geological Record

c) Relation of Mantle Heterogeneity to Plate Convergence

PASSIVE CONTINENTAL MARGINS MECHANICS OF RIFTING OF THE LITHOSPHERE

COMMENTS ON RIFTING AND PASSIVE MARGIN EVOLUTION IN LIGHT OF SOME RECENT STUDIES

IGNEOUS PROCESSES AND THE EVOLUTION OF RIFTED CONTINENTAL MARGINS

Some Suggestions for Future Research

PASSIVE CONTINENTAL MARGINS RIFT AND PASSIVE MARGIN BASINS - THE SEDIMENTARY RECORD

INVESTIGATING THE SEDIMENTARY RECORD: SEQUENCE STRATIGRAPHY-THE RECORD OF TECTONISM AND THE GLOBAL OCEAN ENVIRONMENT.

Introduction.

Notes:

Bibliographic Level Mode of Issuance: Monograph

Includes bibliographical references.

ISBN:

9786610212774

9781280212772

1280212772

9780309543279

0309543274

9780585144009

0585144001

OCLC:

427404659