Crustal structure modelling and interpretation of the East Greenland continental margin between 72N̊ and 77N̊ [Elektronische Ressource] / von Max Voss

Crustal structure modelling and interpretation
of the East Greenland continental margin
between 72°N and 77°N
DISSERTATION
zur Erlangung des Grades Dr. rer.nat.
vorgelegt dem Fachbereich Geowissenschaften
der Universität Bremen
von
MAX VOSS
Alfred-Wegener-Institut für Polar- und Meeresforschung
Bremerhaven
Hamburg, 19. December 2007 Name: Max Voß Datum: 19.12.2007
Anschrift: Fraenkelstr. 6
22307Hamburg
ERKLÄRUNG
Hiermit versichere ich, dass ich
1. die Arbeit ohne unerlaubte fremde Hilfe angefertigt habe,
2. keine anderen als die von mir angegebenen Quellen und Hilfsmittel benutzt habe und
3. die den benutzten Werken wörtlich oder inhaltlich entnommenen Stellen als solche kenntlich
gemacht habe.
Bremen,den Max VoßDIE TRAGÖDIE DER WISSENSCHAFT –
DAS ERSCHLAGEN EINER SCHÖNEN
HYPOTHESE DURCH EINE HÄßLICHE
TATSACHE.

THERE IS NO SADDER SIGHT IN THE
WORLD THAN TO SEE A BEAUTIFUL
THEORY KILLED BY A BRUTAL FACT.

BERTRAND RUSSELL, 1872-1970CONTENTS
KURZFASSUNG ................................................................................................................................................IV
ABSTRACT.........................................................................................................................................................VI
1 INTRODUCTION ...................................................................................................................................- 1 -
1.1 GREENLAND – A UNIQUE LANDSCAPE ............................................................................................... - 1 -
1.2 GEOPHYSICAL INVESTIGATIONS OFF EAST GREENLAND ................................................................... - 3 -
1.3 AIM OF THE THESIS ........................................................................................................................... - 5 -
1.4 STRUCTURE OF THE THESIS ............................................................................................................... - 6 -
2 CLASSIFICATION OF CONTINENTAL RIFTED MARGINS .......................................................- 8 -
2.1 NON-VOLCANIC RIFTED MARGINS..................................................................................................... - 8 -
2.2 VOLCANIC RIFTED MARGINS ........................................................................................................... - 10 -
3 DATA ACQUISITION AND PROCESSING METHODS................................................................- 12 -
3.1 SEISMIC REFRACTION...................................................................................................................... - 12 -
3.1.1 Seismic data acquisition............................................................................................................- 12 -
3.1.2 Data processing.............- 14 -
3.1.3 Phase identifications............- 16 -
3.1.4 P-wave velocity models through ray-tracing ............................................................................- 17 -
3.2 GRAVITY DATA...............................................................................................................................-19-
3.2.1 Gravity data acquisition..........- 19 -
3.2.2 Latitude correction....................................................................................................................- 20 -
3.2.3 Eötvös correction .........................................................................................................- 20 -
3.2.4 Free-air (FA) and Bouguer (BA) correction.............................................................................- 20 -
3.2.5 2D gravity modelling.................................................................................................................- 20 -
3.3 MAGNETIC DATA ............................................................................................................................ - 23 -
3.3.1 Magnetic data acquisition.........................................................................................................- 23 -
3.3.2 Magnetic line data editing.........................................................................................................- 23 -
3.3.3 IGRF correction........................................................................................................................- 23 -
3.3.4 Diurnal correction ....................................................................................................................- 25 -
3.3.5 Levelling....................................................................................................................................- 25 -
4 CONTRIBUTION TO SCIENTIFIC JOURNAL PUBLICATIONS ...............................................- 27 -
4.1 CONTINENT-OCEAN TRANSITION AND VOLUMINOUS MAGMATIC UNDERPLATING DERIVED FROM P-
WAVE VELOCITY MODELLING OF THE EAST GREENLAND CONTINENTAL MARGIN ......................................... - 27 -
4.2 VARIATIONS IN MAGMATIC PROCESSES ALONG THE EAST GREENLAND VOLCANIC MARGIN........... - 27 -
4.3 FROM DEVONIAN EXTENSIONAL COLLAPSE TO EARLY EOCENE CONTINENTAL BREAKUP: AN
EXTENDED TRANSECT OF THE KEJSER FRANZ JOSEPH FJORD OF THE EAST GREENLAND MARGIN................. - 28 -
5 CONTINENT – OCEAN TRANSITION AND VOLUMINOUS MAGMATIC UNDERPLATING
DERIVED FROM P-WAVE VELOCITY MODELLING OF THE EAST GREENLAND
CONTINENTAL MARGIN...........................................................................................................................- 29 -
5.1 SUMMARY ...................................................................................................................................... - 29 -
5.2 INTRODUCTION-29-
5.3 DATA ACQUISITION AND PROCESSING............................................................................................. - 32 -
5.4 MODELLING..... - 34 -
5.5 RESULTS.......... - 37 -
5.5.1 The Godthåb Gulf profile (GG) AWI-20030400 .......................................................................- 39 -
5.5.1.1 Continental crust (km 0 – 100)........................................................................................................- 40 -
5.5.1.2 – ocean transition zone (100 – 224 km) ..........................................................................- 41 -
5.5.1.3 Oceanic crust (224 – 320 km)..........................................................................................................- 42 -
5.5.2 The Kejser Franz Joseph Fjord profile (KFJF) AWI-20030500 ...............................................- 43 -
5.5.2.1 Continental crust (0 – 130 km)..............- 43 -
5.5.2.2 – ocean transition zone (130 – 260 km)..- 43 -
5.5.2.3 Oceanic crust (260 – 460 km..............- 45 -
5.5.3 Gravity models ............................................................................................................- 47 -
5.6 INTERPRETATION AND DISCUSSION................................................................................................. - 48 -
5.6.1 Continental crust.......................................................................................................................- 48 -
5.6.2 The continent – ocean transition (COT)....................................................................................- 50 -
i5.6.3 The oceanic crust ......................................................................................................................- 52 -
5.6.4 The lower crustal body (LCB)...................................................................................................- 54 -
5.6.5 Rift propagation ........................................................................................................................- 55 -
5.6.6 Competitive interpretation of the conjugate margins................................................................- 56 -
5.7 CONCLUSION .................................................................................................................................. - 59 -
5.8 ACKNOWLEDGEMENTS ................................................................................................................... - 59 -
5.9 REFERENCES.... - 59 -
6 VARIATIONS IN MAGMATIC PROCESSES ALONG THE EAST GREENLAND VOLCANIC
MARGIN .........................................................................................................................................................- 64 -
6.1 SUMMARY....... - 64 -
6.2 INTRODUCTION-66-
6.3 BRIEF REVIEW OF GEODYNAMIC MODELS FOR VOLCANIC RIFTED MARGIN...................................... - 67 -
6.4 NEW TRANSECTS OF THE NORTHEAST GREENLAND MARGIN........................................................... - 68 -
6.4.1 Processing and modelling .........................................................................................................- 68 -
6.4.2 Profile AWI-20030200 ..............................................................................................................- 71 -
6.4.2.1 Continent – ocean transition............................................................................................................- 71 -
6.4.2.2 Oceanic section ...............................................................................................................................- 72 -
6.4.2.3 Gravity modelling..........................................................................................