Joint Interpretation of Geophysical and Geological Data Applied to Lithospheric Studies

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Series C: Mathematical and Physical Sciences - Vol. 338

Joint Interpretation of Geophysical and Geological Data Applied to Lithospheric Studies edited by

P. Giese Geophysical Department, Freie Universitat Berlin, Berlin, Germany

D. Roeder The Anschutz Corporation, Denver, Colorado, U.S.A.

and

R. Nicolich Istituto di Miniere e Geofisica Applicata, Universita Trieste, Trieste, Italy

~

" Springer Science+Business Media, B.V.

Based on the NATO Advanced Research Workshop on Improvement of Joint Interpretation of Geophysical and Geological Data with particular Reference to the Lithosphere Structure and Evolution of the Adriatic Microplate and Adjacent Regions Gradisca d'isonzo, Italy October 1-9, 1987 and February 22-23, 1988

ISBN 978-94-010-5592-5 ISBN 978-94-011-3590-0 (eBook)

DOI 10.1007/978-94-011-3590-0

Printed on acid-free paper

All Rights Reserved © 1991 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 1991 Softcover reprint of the hardcover 1st edition 1991

No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photo­copying, recording or by any information storage and retrieval system, without written permission from the copyright owner.

This book contains the proceedings of a NATO Advanced Research Workshop held within the programme of activities of the NATO Special Programme on Global Transport Mechanisms in the Geo-Sciences running from 1983 to 1988 as part of the activities of the NATO Science Committee.

Other books previously published as a result of the activities of the Special Programme are:

BUAT-MENARD, P. (Ed.) - The Role of Air-Sea Exchange in Geochemical Cycling (CI85) 1986

CAZENA YE, A. (Ed.) - Earth Rotation: Solved and Unsolved Problems (CI87) 1986

WILLEBRAND, J. and ANDERSON, D.L.T. (Eds.) - Large-Scale Transport Processes in Oceans and Atmosphere (CI90) 1986

NICOLlS, C. and NICOLlS, G. (Eds.) - Irreversible Phenomena and Dynamical Systems Analysis in Geosciences (CI92) 1986

PARSONS, I. (Ed.) - Origins of Igneous Layering (CI96) 1987

LOPER, E. (Ed.) - Structure and Dynamics of Partially Solidified Systems (EI25) 1987

VAUGHAN, R. A. (Ed.) - Remote Sensing Applications in Meteorology and Climatology (C201) 1987

BERGER, W. H. and LABEYRIE, L. D. (Eds.) - Abrupt Climatic Change - Evidence and Implications (C216) 1987

VISCONTI, G. and GARCIA, R. (Eds.) - Transport Processes in the Middle Atmosphere (C213) 1987

HELGESON, H. C. (Ed.) - Chemical Transport in Metasomatic Processes (C218) 1987

SIMMERS, I. (Ed.) - Estimation of Natural Recharge of Groundwater (C222) 1987

CUSTODIO, E., GURGUI, A. and LOBO FERREIRA, J. P. (Eds.) - Groundwater Flow and Quality Modelling (C224) 1987

ISAKSEN, I. S. A. (Ed.) - Tropospheric Ozone (C227) 1988

SCHLESINGER, M.E. (Ed.) - Physically-Based Modelling and Simulation of Climate and Climatic Change 2 vols. (C243) 1988

UNSWORTH, M. H. and FOWLER, D. (Eds.) -Acid Deposition at High Elevation Sites (C252) 1988

KISSEL, C. and LAY, C. (Eds.) - Paleomagnetic Rotations and Continental Deformation (C254) 1988

HART, S. R. and GULEN, L. (Eds.) - Crust/Mantle Recycling at Subduction Zones (C258) 1989

GREGERSEN, S. and BASHAM, P. (Eds.) - Earthquakes at North-Atlantic Passive Margins: Neotectonics and Postglacial Rebound (C266) 1989

MOREL-SEYTOUX, H. J. (Ed.) - Unsaturated Flow in Hydrologic Modeling (C275) 1989

BRIDGWATER, D. (Ed.) - Fluid Movements - Element Transport and the Composition of the Crust (C281) 1989

LEINEN, M. and SARNTHEIN, M. (Eds.) - Paleoclimatology and Paleometeorology: Modern and Past Patterns of Global Atmospheric Transport (C282) 1989

ANDERSON, D.L.T. and WILLEBRAND, J. (Eds.) - Ocean Circulation Models: Combining Data and Dynamics (C284) 1989

BERGER, A., SCHNEIDER, S. and DUPLESSY, J. Cl. (Eds.) - Climate and Geo-Sciences (C285) 1989

KNAP, A.H. (Ed.) - The Long-Range Atmospheric Transport of Natural and Contaminant Substances from Continent to Ocean and Continent to Continent (C297) 1990.

BLEIL, U. and THIEDE, J. (Eds.) - Geological History of the Polar Oceans - Arctic Versus Antarctic (C308) 1990.

SHEN, H.W. (Ed.) - Movable Bed Physical Models (C312) 1990.

TABLE OF CONTENTS

Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IX

List of Participants................................. XI

List of contributors................................. XV

Introduction P. Giese and M.E. Huch .......................... XVII

computers and Personal Computers in Geophysics P. Neurieder and I.Marson........................ 1

Interpretation of Gravimetric and Magnetic Data: a short Review

E. Klingele...................................... 31

An Introduction to Geophysical Databases and two Examples of the Use for Crustal Studies

T. Buttgenbach and J. Richter .................... 39

Geophysical and Geological Parameters being important for Modelling

H . Kern.......................................... 57

seismic Standard Software in Refraction and Wide-angle Applications

P. Neurieder..................................... 71

Fine Modeling of the Elastic and Anelastic Parameters of the Earth's Crust by means of Complete Synthetic Seismograms

G. Latini, I. Marson, G.F. Panza and P. Suhadolc. 93

A seismic Tomography Program for Geological Investigations

G. Nolet ......................................... 109

compressional Tectonics and the Balancing of Crustal Cross sections

D. Roeder........................................ 127

Enhanced Interpretation of Crustal sections with the Thrustbelt program

H. Linsser....................................... 165

Isostatic Compensation of Balanced Cross sections H. Buness ........................................ 181

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CROP-ECORS Activity in the Western Alps R. Nicolich ...................................... 189

A seismic Refraction Line between the Ligurian Sea and the southern Alps - Evidences for crustal doubling

H. Buness ........................................ 193

The Fragmented Lithosphere of the Northwestern Adriatic Microplate as Revealed by Deep Seismic Sounding

P. Giese, H. Buness and D. Roeder ................ 217

PREFACE

The contributions published in this volume are the re­sults of the NATO Advanced Research Workshop "Improvement of Joint Interpretation of Geophysical and Geological Data", which took place in Gradisca d'Isonzo in October 1987 and February 1988.

Modern computer techniques were applied for geoscien­tific studies in a new dimension. 45 scientists from 7 Euro­pean countries, Canada and the united states of America par­ticipated in the workshop. Interactive discussions and modeling improved the understanding of the very complex structure of the investigated area.

We thank all contributors, but especially those pub­lishing in this volume, for their active participation to ensure the success of the meetings. Not to forget to mention the groups of assistants from the Istituto di Minere e Geo­fisica Applicata of the University of Trieste and from the Institute of Geophysics of the Freie Universitat Berlin. Many thanks for their help around the clock.

However, a major prerequisite for this success was given by the hospitality of the international Centre for Applied Sciences (ICAS) in the wonderful restored ancient pallazzi Torriani and Pretuna of the town of Gradisca d'Isonzo. Thus, we are thankful to the president of ICAS, Dr. H.R. Dahlafi, and to the town of Gradisca d'Isonzo, especially to the mayor, Signore Travan.

The studies carried out in Gradisca d'Isonzo had been supported by a grant of the NATO Scientific Affairs Division and we express our thanks to Dr. L. da Cunha as a steady partner in the background.

We apologize the delayed publication of the papers, which was partly caused by a continuously updating of the last results of the lithospheric structure of the Adriatic microplate a main object of the workshop.

Some papers have been updated and so we think that this pUblication will help to improve the joint interpretation of geological and geophysical data. We thank Mrs. E. Borner, Mrs. I. Rutkowsky and Mr. C. Haberland for their assistance in preparing this final manuscript

Berlin, February 1991 Peter Giese Monika Huch

LIST OF PARTICIPANTS

J. Ansorge ETH Hoenggersberg Institut fur Geophysik CH-8093 Zurich

G. Battici Istituto di Miniere e Geofisica Applicata 1, piazzale Europa I-34127 Trieste

Th. Buettgenbach Institut fur Geophysik und Meteorologie Universitat K6ln Zulpicherstr. 47 D-5000 K6ln 41

H. Buness Institut fur Geologie, Geophysik und Geoinformatik Abteilung Geophysik Rheinbabenallee 49 D-I000 Berlin 33

M. Cattaneo Istituto Geofisico Universita Genova Corso Europa 345 I-16132 Genova

I. Cernobori Istituto di Miniere e Geofisica Applicata 1, piazzale Europa I-34127 Trieste

C. Eva Istituto Geofisico Universita Genova Corso Europa 345 I-16132 Genova

R. Freeman ETH Hoenggersberg Institut fur Geophysik CH-8093 Zurich

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J. Gallart Institut de Geologia Jaume Almero Marti i Franques s/4 E-08028 Barcelona

H. Gebrande Institut fur Allgemeine und Angewandte Geophysik Theresienstr. 41 0-8000 Munchen

P. Giese Institut fur Geologie, Geophysik und Geoinformatik Abteilung Geophysik Rheinbabenallee 49 0-1000 Berlin 33

A. Hirn Institut du Physique du Globe 4, Place Jussieu F-75230 Paris Cedex 05

M.E. Huch Institut fur Geologie, Geophysik und Geoinformatik Abteilung Geophysik Rheinbabenallee 49 0-1000 Berlin 33

H. Kern Mineralogisch-Petrographisches Institut Olsenhausenstr. 40 0-2300 Kiel

E. Klingele ETH Hoenggersberg Institut fur Geophysik CH-8093 Zurich

B. Lahmeyer Institut fur Geophysik Universitat Clausthal Arnold-Sommerfeld-Str. 1 0-3392 Clausthal-Zellerfeld

R. Linari Istituto di Miniere e Geofisica Applicata I, piazzale Europa I-34127 Trieste

H. Linsser 505 4th Av.SW.No.2104 Calgary, Alberta T2P OJ8 Canada

M. Maistrello 1stituto per la Geofisica della Litosfera/C.N.R. Via Bassini 15 1-20133 Milano

I. Marson 1stituto di Miniere e Geofisica Applicata 1, Piazzale Europa 1-34127 Trieste

J. Mechie 1nstitut fur Geophysik Hertzstr. 16 0-7500 Karlsruhe 21

C. Morelli 1stituto di Miniere e Geofisica Applicata 1, piazzale Europa 1-34127 Trieste

st. Mueller ETH Hoenggersberg 1nstizut fur Geophysik CH-8093 Zurich

s. Nadir 1nstitut du Physique du Globe 4, Place Jussieu F-75230 Paris Cedex 05

P. Neurieder 1nstitut fur Allgemeine und Angewandte Geophysik Theresienstr. 41 0-8000 Munchen

R. Nicolich 1stituto di Miniere e Geofisica Applicata 1, piazzale Europa 1-34127 Trieste

G. Nolet Oep. of Theoretical Geophysics P.O. Box 80.021 NL-3508 TA Utrecht

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D. Polizzi Istituto di Miniere e Geofisica Applicata 1, piazzale Europa I-34127 Trieste

D. Roeder The Anschutz Corp. 2400 Anaconda Tower 555 Seventeenth st. Denver, Colorado 80202 USA

M. Roemer Institut fUr Geophysik Universitat Clausthal Arnold-Sommerfeld-Str. 1 D-3392 Clausthal-Zellerfeld

A. Ruthardt Institut fUr Geophysik Hertzstr. 16 D-7500 Karlsruhe 21

S. Scarascia Istituto per la Geofisica della LitosferajC.N.R. Via Bassini 15 I-20133 Milano

M. Schmitz Institut fUr Geologie, Geophysik und Geoinformatik Abteilung Geophysik Rheinbabenallee 49 D-1000 Berlin 33

LIST OF CONTRIBUTORS

Th. Buettgenbach Institut fur Geophysik und Meteorologie Universitat K6ln Zulpicherstr. 47 0-5000 K6ln 41

H. Buness Institut fur Geologie, Geophysik und Geoinformatik Abteilung Geophysik Rheinbabenallee 49 0-1000 Berlin 33

P. Giese Institut fur Geologie, Geophysik und Geoinformatik Abteilung Geophysik Rheinbabenallee 49 0-1000 Berlin 33

M.E. Huch Institut fur Geologie, Geophysik und Geoinformatik Abteilung Geophysik Rheinbabenallee 49 0-1000 Berlin 33

H. Kern Mineralogisch-Petrographisches Institut Olsenhausenstr. 40 0-2300 Kiel

E. Klingele ETH Hoenggersberg Institut fur Geophysik CH-8093 Zurich

G. Latini Istituto Geodesia e Geofisica Via dell'Universita 7 1-34127 Trieste

H. Linsser 505 4th Av.SW.No.2104 Calgary, Alberta T2P OJ8 Canada

I. Marson Istituto di Miniere e Geofisica Applicata I, piazzale Europa 1-34127 Trieste

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P. Neurieder 1nstitut fur Allgemeine und Angewandte Geophysik Theresienstr. 41 D-8000 Munchen

R. Nicolich 1stituto di Miniere e Geofisica Applicata 1, piazzale Europa 1-34127 Trieste

G. Nolet Dep. of Theoretical Geophysics P.O. Box 80.021 NL-3508 TA Utrecht

G.F. Panza 1stituto Geodesia e Geofisica Via dell'Universita 7 1-34127 Trieste

J. Richter 1nstitut fur Geophysik und Meteorologie Universitat K6ln Zulpicherstr. 47 D-5000 K6ln 41

D. Roeder The Anschutz Corp. 2400 Anaconda Tower 555 Seventeenth st. Denver, Colorado 80202 USA

P. Suhadolc 1stituto Geodesia e Geofisica Via dell'Universita 7 1-34127 Trieste

INTRODUCTION

P. Giese

Freie Universitat Berlin Institute of Geology, Geophysics and Geoinformatics, Department of Geophysics Rheinbabenallee 49 1000 Berlin 33

M.E. Huch

Springer Verlag Tiergartenstr. 17 6900 Heidelberg

Northern Italy between the Alps and the Ligurian Sea offers something special to the most different interests. From geographical point of view the fruitful Po plain is surrounded by the mountains of the southern and western Alps, the Ligurian Sea and the more smooth mountains of the northern Apennines. From touristical view the visitor enjoys not only the different landscapes but also the culinary spe­cialities and vines of the various regions. On the geoscien­tific side this region combines the most interesting fea­tures for geological and geophysical studies in Europe. This collisional zone between the Eurasian and the African plate, including the Adriatic microplate, is the result of a very complicated tectonic settlement, quite well investigated since decades by all methods of geosciences. A joint inter­pretation of the available (but wide-spread) data, informa­tion, and experiences was overdue and it was expected to solve some of the still existing question marks during the NATO Advanced Research Workshop "Improvement of Joint Inter­pretation of Geophysical and Geological Data".

The experiences and results obtained within this work­shop were an important input to the workshops and study

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centers of the European Geotraverse Project (EGT) held in 1988, 1989, and 1990, which were confronted with similar problems.

The development in computer techniques arose during the last decade from mainframes with great capacities over me­dium-sized workstations to personal computers (PC) available for almost everybody. In the jungle of available hardware and software each user has to find the collection for his special purpose. NEURIEDER & MARSON outline some aspects for the decision to work with more powerful computers or with personal computers. with the use of expanded PC's with soft­ware packages, suitable for lithospheric modeling, a new level was reached in interpretation techniques for problems related to the lithospheric structure and evolution. Thus, the workshop succeeded in a joint application of data sets of different geophysical and geological methods.

Although the seismic refraction method is one of the most important and most frequently used tool for structural studies of the crust, gravity and magnetic data as well as geological and mineralogical parameters reveal great impor­tance. KLINGELE summarized in his review the most common gravimetric and magnetic interpretation methods. The trans­formation of geophysical sections into petrological and geo­logical models needs relationships between physical parame­ters, e.g. seismic velocity and density variations, and the petrological composition of rock types. Experimental studies of several physical properties of rock samples under simula­ted crustal pressure and temperature conditions are an im­portant link between geophysics and petrology. BUETTGENBACH & RICHTER give an introduction to the concepts of databases and two representative examples for the application. Based on the correlation of rock parameters to the depth interval, the age of a formation and similar geological parameters, the authors first show an application to borehole gravity measurements and second one to a relation of velocity and density data of granites. In addition they discuss the pos­sibility for an integrated interpretation of vertical sect­ions, resulting from refraction seismics. Another example for the correlation of rock parameters, derived from labora­tory measurements, and geophysical data from southern Calabria is presented by KERN.

Nevertheless, most of the contributors of this volume refer to the seismic methods. Data acquisition and evalua­tion of seismic refraction and reflection data had remark­ably been improved in the last years. NEURIEDER gives an overview about seismic standard software and its application in refraction and wide-angle reflection seismics with exam­ples from data along the DEKORP-4 line.

The interpretation of seismic record sections is based on characteristic wave behavior, depending on physical rock conditions. LATINI, MARSON, PANZA & SUHADOLC used the possi-

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bility of complete synthetic seismograms to determine elast­ic and anelastic parameters of the Earth's crust modeling vertical sections, derived from the FENNOLORA profile through Scandinavia.

A very new tool for lithospheric studies is offered by the tomographic method, already used in quite different branches of sciences. NOLET developed a special seismic to­mography, based on S- and P-waves. Up to now only mainframe computers are able to solve the large number of equations necessary for this method.

One tool for reconstructing the evolution of the Earth's crust up to the present stage might be the method of tectonic balancing. In the last years the application of tectonic balancing underwent a revival in tectonic studies. It applies a set of geometric and basic tectonic rules, the most important one of it keeps the volume of masses constant during all stages of deformation, as described e.g. by ROEDER for the southern Alps. Whereas computer programs were widely used by oil companies for exploration studies, this technique was not familiar to most geoscientists for crustal or lithospheric investigations.

The tectonic balancing programme by LINSSER uses the availability of a PC application and enables therefore a very fast test of the viability of a cross section. This original version had been supplemented by BUNESS in a very important point: isostatic compensation is taken into ac­count. Now it is possible to generate very realistic crustal sections in compressional zones with thrusts, duplex struc­tures, roots etc., as well as in tensional ones.

The problem of a tectonically doubled crustal structure has been studied along the EGT section between the central Apls and Ligurian Sea by BUNESS. In the past there were weak indications for the existence of deeply seated roots beneath the southern Alps and the northern Apennins. Now the studies carried out within the EGT project have confirmed these sup­positions.

In this context the great importance of the results of the CROP-ECORS activities in the Western Alps between France and Italy had to be pointed out. The reflection profile, presented by NICOLICH, reveals details of crustal structure never seen before. with clear evidence the forming of the thick Alpine crust by thrusting and stacking can be seen.

The main result of this workshop is a three-dimensional picture of the western part of northern Italy, between the Alpine arc - formed by the southern Alps along the Insubric Line to the Western Alps -, the Ligurian Sea, and the units of the northern Apennines, surrounding the central and western Po plain, presented in the contribution of GIESE, BUNESS, & ROEDER: The crust of the Adriatic plate is clearly set off against that of the European plate by a sudden de­crease of crustal thickness. In respect to the Alps the

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Adriatic lithosphere acts as an upper plate, whereas refer­ring to the northern Apennines it takes the position as lower plate. In the border region of the northern Apennines against the Western Alps these different behavior is inter­ferring, reflecting a complex crustal structure. The Adriatic plate itself is split into a number of separated units.