Similar to Parry_2010_Arctic_Days_iMAGINE_Tromso_Opening_of_the_ North_ Atlantic_&_Norwegian – Greenland_Sea_Basin_Lessons_from_the_South_Atlantic (20)
1. ChrisChris ParryParry
WithWith acknowledgementsacknowledgements toto KhalidKhalid SoofiSoofi andand GuyGuy FlanaganFlanagan
FRACTURES ZONES AND THEIRFRACTURES ZONES AND THEIR
ROLE IN THE OPENING OF THEROLE IN THE OPENING OF THE
ATLANTICATLANTIC –– LESSONS FROM THELESSONS FROM THE
SOUTH ATLANTICSOUTH ATLANTIC
2. Talk Outline
• South Atlantic Fracture Zones,
• North Atlantic Remote Sensing Observations:
Gravity,
Magnetics,
Sparse 2D seismic (where available)
and
Bathymetric data
• Integrated to derive a model for the opening of the
North Atlantic, based on the South Atlantic.
3. West Africa Conjugate Margin
Romanche FZ
Charcot FZ
Boda Verde FZ
Rio de Janeiro FZ
Benguela FZ
Ascension FZ
Martin Vaz FZ
Lower
Plate
Upper
Plate
Upper
Plate
4. 5 KM
West African Offshore Fracture Zone
OCEANIC
CRUST
Basement structural highs related
to volcanic activity along “leaky”
fracture zones in the oceanic crust
set up the initial basin structural
framework.
5. 5 KM
West African Offshore Fracture Zone
OCEANIC
CRUST
Basement structural highs related
to volcanic activity along “leaky”
fracture zones in the oceanic crust
set up the initial basin structural
framework.
Deepwater sedimentation on-
lapped these basement highs
which continued to propagate
into younger strata by
differential compaction.
6. 5 KM
Fracture Zones divide the deep
water into discrete depo-centres
with different fill histories.
West African Offshore Fracture Zone
OCEANIC
CRUST
Basement structural highs related
to volcanic activity along “leaky”
fracture zones in the oceanic crust
set up the initial basin structural
framework.
Deepwater sedimentation on-
lapped these basement highs
which continued to propagate
into younger strata by
differential compaction.
7. Rio Muni & Gabon Basins: Cretaceous Pre Rift Configuration
Lower
Plate
Romanche FZ
Charcot FZ
Boda Verde FZ
Rio de Janeiro FZ
Benguela FZ
Upper
Plate
Ascension FZ
Martin Vaz FZ
Upper
Plate
8. Rio Muni & Gabon Basins: Cretaceous Pre Rift Configuration
Lower
Plate
Romanche FZ
Charcot FZ
Boda Verde FZ
Rio de Janeiro FZ
Benguela FZ
Upper
Plate
Ascension FZ
Martin Vaz FZ
200 Km
Bata FZ
Kribi FZ
Cameroon FZ
Fang
FZ
N’Komi FZ
Mayumba FZ
PanAfricanMobileBelt
Congo
CratonAscension FZ
Simplified after Meyers et al 1996
Pre-Cambrian basement
Cretaceous rift basins
Transfer fault zone
Modern coastline
Mid Atlantic Ridge
Upper
Plate
9. Rio Muni & Gabon Basins: Cretaceous Pre Rift Configuration
Lower
Plate
Romanche FZ
Charcot FZ
Boda Verde FZ
Rio de Janeiro FZ
Benguela FZ
Upper
Plate
Ascension FZ
Martin Vaz FZ
200 Km
Bata FZ
Kribi FZ
Cameroon FZ
Fang
FZ
N’Komi FZ
Mayumba FZ
PanAfricanMobileBelt
Congo
CratonAscension FZ
Simplified after Meyers et al 1996
Some major fracture zones
originate along pre-Cambrian
structural grain
Pre-Cambrian basement
Cretaceous rift basins
Transfer fault zone
Modern coastline
Mid Atlantic Ridge
Upper
Plate
13. Magnetic Expression of the Jan Mayen Fracture Zones
Jan Mayen Island
ÆgirRidge
ÆgirRidge
W
estJan
M
ayen
FZ
ÆgirRidge
ÆgirRidge
EastJan
M
ayen
FZ
CentralJan
M
ayen
FZ
Norway
Basin
FZ
14. Magnetic expression of the Mohn Ridge Spreading Centre
Jan Mayen Island
W
estJan
M
ayen
FZ
KolbeinseyRidge
15. Magnetic expression of the Mohn Ridge Spreading Centre
Jan Mayen Island
W
estJan
M
ayen
FZ
KolbeinseyRidge
Mohn
Ridge
Gleipna
FZ
Surt FZ
Bivost FZ
26. Color variations due to
rock and soil
composition
differences; temperature
differences are
expressed as brightness
variations.
Red hues on the left and
right sides are probably
underlain by rocks with
high silicon-dioxide
content,
White and lavender in
the central part are
dominantly basaltic lava
flows and cinder cone
deposits.
Dark areas within the
complex of basaltic
rocks are mainly domes,
which are highly
fractured.
http://www.nasa.gov/multimedia/imagegallery/image_feature_491.html
Afar Triangle
Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)
28. Symmetrical opening of North Atlantic in Early Eocene
Æ
girRidge
M
ohns
Ridge
R
eykjanes
R
idge
Anton
Dohrn
W
yville
Thom
pson
Judd
Clair
Victory
M
agnus
Erland
Faroe
West Jan Mayen
East Jan Mayen
Central Jan Mayen
Norway Basin
Spar
M
arflo
Additional fracture zones
present e.g. Westray
Gleipna
Surt
Bivost
Lofoten
LEGEND
Spreading Ridge
Hot spot
Fracture Zones
Relative Plate Motion:
Age of Oceanic Crust:
Chron 24 – 21 E Eocene
0 Kilometers 250
C13
C24
Present
C21
C24
C24
C21
29. Symmetrical spreading of North Atlantic throughout Middle - Late Eocene
LEGEND
Spreading Ridge
Hot spot
Fracture Zones
Relative Plate Motion:
Age of Oceanic Crust:
Chron 24 – 21 E Eocene
Chron 21 – 13 M/L Eocene
0 Kilometers 250
C13
C24
Present
Jennega
SenjaVesterålen
Slower
spreading
rate
C13
C21
C21
C13
30. Oligocene plate re-organisation, change of spreading direction
Fram Strait opening - relative plate motion
changes from right-lateral shear to oblique
divergence (left-lateral shear on Victory FZ)
LEGEND
Spreading Ridge
Hot spot
Fracture Zones
Relative Plate Motion:
Age of Oceanic Crust:
Chron 24 – 21 E Eocene
Chron 21 – 13 M/L Eocene
Chron 13 – 6 Oligo/E Mio
0 Kilometers 250
C13
C24
Present
C13C6
C6C13
Slower
spreading
rate
31. Oligocene: change of spreading from Ægir-Kolbeinsey Ridge
LEGEND
Spreading Ridge
Hot spot
Fracture Zones
Relative Plate Motion:
Age of Oceanic Crust:
Chron 24 – 21 E Eocene
Chron 21 – 13 M/L Eocene
Chron 13 – 6 Oligo/E Mio
Oligocene volcanics
0 Kilometers 250
C13
C24
Present
C13C6
C6C13
Westerly migration of volcanic centre,
flows locally obscure Eocene oceanic
crust magnetic anomalies
Location of future
Kolbeinsey Ridge
32. Early Miocene: Kolbeinsey Ridge becoming active
LEGEND
Spreading Ridge
Hot spot
Fracture Zones
Relative Plate Motion:
Age of Oceanic Crust:
Chron 24 – 21 E Eocene
Chron 21 – 13 M/L Eocene
Chron 13 – 6 Oligo/E Mio
Oligocene volcanics
Miocene volcanics
0 Kilometers 250
C13
C24
Present
C13C6
C6C13
Flood basalts cover future
Jan Mayen Micro-Continent
Location of future
Kolbeinsey Ridge
33. Middle Miocene – Present: Kolbeinsey Ridge active
LEGEND
Spreading Ridge
Hot spot
Fracture Zones
Relative Plate Motion:
Age of Oceanic Crust:
Chron 24 – 21 E Eocene
Chron 21 – 13 M/L Eocene
Chron 13 – 6 Oligo/E Mio
Chron 6 – 0 M Mio/Recent
Oligocene volcanics
Miocene volcanics
0 Kilometers 250
C13
C24
Present
C6Present
PresentC6
Segmentation of Jan Mayen Micro
Continent described by Scott et al., 2005
KolbeinseyRidge
35. Conclusions
Oligocene and Miocene lava flows locally obscure Eocene magnetic anomalies in
the Iceland/Jan Mayen Micro-Continent area
36. Conclusions
Oligocene and Miocene lava flows locally obscure Eocene magnetic anomalies in
the Iceland/Jan Mayen Micro-Continent area
A simple symmetric spreading model can be used to explain the opening of the
North Atlantic
37. Assuming the position of Iceland’s hot spot/mantle plume has remained stationary,
the NW European plate has migrated eastwards ~300 Km since ocean
spreading ceased on the Ægir Ridge near the end of the Eocene.
Conclusions
Oligocene and Miocene lava flows locally obscure Eocene magnetic anomalies in
the Iceland/Jan Mayen Micro-Continent area
A simple symmetric spreading model can be used to explain the opening of the
North Atlantic
38. Assuming the position of Iceland’s hot spot/mantle plume has remained stationary,
the NW European plate has migrated eastwards ~300 Km since ocean
spreading ceased on the Ægir Ridge near the end of the Eocene.
A similar magnitude of coeval eastwards movement of Svalbard, relative to
Greenland, is associated with the opening of Fram Strait.
Conclusions
Oligocene and Miocene lava flows locally obscure Eocene magnetic anomalies in
the Iceland/Jan Mayen Micro-Continent area
A simple symmetric spreading model can be used to explain the opening of the
North Atlantic
39. Assuming the position of Iceland’s hot spot/mantle plume has remained stationary,
the NW European plate has migrated eastwards ~300 Km since ocean
spreading ceased on the Ægir Ridge near the end of the Eocene.
NW-SE trending, coast perpendicular transfer zones, are recognized regionally in
the deepwater and adjacent shelf, probably linked to onshore pre-Cambrian
basement fabric.
A similar magnitude of co-eval eastwards movement of Svalbard, relative to
Greenland, is associated with the opening of Fram Strait.
Conclusions
Oligocene and Miocene lava flows locally obscure Eocene magnetic anomalies in
the Iceland/Jan Mayen Micro-Continent area
A simple symmetric spreading model can be used to explain the opening of the
North Atlantic
40. Assuming the position of Iceland’s hot spot/mantle plume has remained stationary,
the NW European plate has migrated eastwards ~300 Km since ocean
spreading ceased on the Ægir Ridge near the end of the Eocene.
NW-SE trending, coast perpendicular transfer zones, are recognized regionally in
the deepwater and adjacent shelf, probably linked to onshore pre-Cambrian
basement fabric.
Transtensional, transpressional and inversion structuring associated with mid
ocean fracture zones has already been recognized in the seismic data on the
Jan Mayen Micro Continent.
A similar magnitude of co-eval eastwards movement of Svalbard, relative to
Greenland, is associated with the opening of Fram Strait.
Conclusions
Oligocene and Miocene lava flows locally obscure Eocene magnetic anomalies in
the Iceland/Jan Mayen Micro-Continent area
A simple symmetric spreading model can be used to explain the opening of the
North Atlantic
