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Transcript of Parry_2012_30th_Nordic_Geological_Winter_Meetin_Rekjavik_Opening_of_the_ North_ Atlantic_&_Norwegian...
• Chris Parry
OPENING OF THE NORTH ATLANTIC
& NORWEGIAN – GREENLAND SEA
BASIN – LESSONS FROM THE SOUTH
ATLANTIC
Fracture Zones: Origins, Expression and Evidence
Northeast Greenland 12/2011
Oceanic Fracture Zones:
• Archaean basement control,
• Set up initial basin architecture,
• Influence reservoir distribution,
• Provide migration pathways,
• Set up traps.
USA Eastern Seaboard:
Fracture Zones first set up during
opening of Iapetus Ocean, re-used
during Atlantic opening, still active!
Wilson Cycles and Tectonic Inheritance: Eastern Seaboard USA
1, Grenville Orogeny: Pre-Iapetus Ocean closed 2, Iapetus Ocean opens
3, Caledonian Orogeny: Iapetus Ocean closed 4, Iapetus Ocean opens again a.k.a. Atlantic
Modern Fracture Zones
linked to Iapetus
Fracture Zones
Thomas, W.A., 2006, GSA Today, pp. 4 - 11
1889 Charleston Earthquake (magnitude 6.6 - 7.3)
located on Pangaea break up fault.
Similar faults found along entire East Coast, which
are active due to present day plate movements.
1929 Grand Banks
Earthquake (magnitude 7.2)
2011 Virginia Earthquake (magnitude 5.8).
Reverse fault formed during Taconic and
Alleghenian Orogenies, reactivated
during Pangaea breakup in Mesozoic and
further reactivated during Cenozoic
Modified after Lowell, J.D., 1972, Geol. Soc. Am. Bull., pp. 3091 - 3102
Eurasian
Plate
North American
Plate
• Two plates moving at low
convergent angle causes space
problem.
• Easiest direction for relief is
upwards.
• Upthrusts are not necessarily
symmetrical.
• Faults coalese and anastomose
with depth.
Svalbard: Convergent Strike Slip or Transform Motion Upthrust Zone
Tectonic lineaments
of Norway & Sweden
Finnmark
North
MTFC
West
Southwest
East
Norway
NW-SE to WNW-ESE lineament populations: - clearly different from other populations, since almost evenly distributed throughout study area. - represent inherited structural grain, arising from a megafracture pattern imposed on the western Fennoscandian Shield during Proterozoic time. - evidence from northern Scandinavia and Russia shows, in fact, that several of these NW-SE to ENE-WSW lineaments originated during the Archaean.
After: Gabrielsen, R. H. et al., 2002, Norsk Geologisk Tidsskrift,
Vol. 82, pp. 153 - 174.
• Accreted as series of terranes in the
Precambrian
• Accretion occurred before most brittle
deformation
Pless, J. et al, 2010, AAPG, New Orleans – oral & poster presentation &
Williams, G.E. & Foden, J., 2011, Earth-Sci. Rev., pp 34 - 49.
• Prominent NE-SW & NW-SE fault trends
• NW-SE faults produce the longest lineaments
• Originate in Archean (2490-2400 Ma): Steep
NW-SE shear zones formed due to dextral
transpression
• Reactivated during all subsequent tectonic
episodes
Lewisian Gneiss Complex
I – Intra-Palaeocene Unconformity
North Atlantic & Norwegian -
Greenland Sea Deformation History
1
2
3
4
5
7
1
2
3
4 5
6
7
8 9
6
Iapetus Ocean Spreading
Variscan Orogeny
1 2 3 4 5 6 7 8 NE Greenland AFTA Cooling Events
Break-up & early opening of Central Atlantic
Regional extension in North Atlantic region
Limited seafloor spreading southern North Atlantic
Focus of rifting in North Atlantic region
Opening of southern North Atlantic
I - Main rift axis northern North Atlantic
Main rift axis moved to Labrador Sea
Seafloor spreading Labrador Sea
Rifting in Norwegian-Greenland Sea area
Break-up Norwegian-Greenland Sea area - Magmatism
Seafloor spreading Ægir Ridge
Change in spreading direction Norwegian-Greenland Sea area
Uplift of areas surrounding Norwegian-Greenland Sea area
Glaciations – continued uplift & erosion
Seafloor spreading Kolbeinsey Ridge
Seafloor spreading Mohns Ridge
Seafloor spreading Lena Trough - Knipov Ridge (Fram Strait)
Break-up & early opening of Southern Atlantic
Caledonidian Orogeny
Gravitational Collapse
8
9
Principal stress/strain axes
at low angle to foliation
Reactivation of pre-existing
”weak” foliation planes
U Cretaceous Inversion
Early Cimmerian
Mid Cimmerian
Late Cimmerian
Laramide Orogeny
Extension/Seafloor Spreading
Inversion/Compression
Legend
Block Diagrams from Pless, J. et al, 2010.
Grenville Orogeny
I – Base Tertiary Unconformity
I – Mid-Miocene Unconformity
I - Plate reorganization
I – Upper Eocene Unconformity
I – Mid-Oligocene Unconformity
I – Base Neogene Unconformity
SE Greenland
Guarnieri, P., 2011, Bull. Geol. Soc. Den., 23, pp. 65-68.
Simplified after Tegner, C. et al, 2008, Lithos, pp. 480 - 500
Bathymetric data clearly illustrate the
presence of additional Fracture Zones,
(not illustrated for sake of clarity).
UK Norway
Ritchie, J. D. et al., 2008, Geol. Soc. Lond. Spec. Publ., 306, pp. 121 – 136.
Reproduced with permission of the Geol. Soc.
• Two plates moving at low convergent angle causes space
problem (plate reorientation due to opening of Fram Strait?)
• Easiest direction for relief is upwards.
• Wrench fault flower structures are not necessarily symmetrical.
• Faults coalese and anastomose with depth.
.
. + +
? ?
Oceanic Crust Continental Crust
Pelagic sediments inversion
Gaina et al., 2009*
”mild inversion”,
”several compressive events”
Oceanic crust inversion East Jan Mayen
Fracture Zone
Central Jan Mayen
Fracture Zone
* Gaina, C. et al, 2009, J. Geol. Soc., pp. 601 – 616.
Norwegian - Greenland Sea
The Central and Southern Atlantic Ocean simple symmetric spreading model can be used to explain the opening of the Norwegian – Greenland Sea.
Eocene - Oligocene A. Symmetrical opening in Early Eocene
LEGEND
Spreading Ridge
Hot spot
Fracture Zones
Relative Plate Motion:
C13
C24
Present
Age of Oceanic Crust:
Chron 24 – 21 E Eocene
Chron 21 – 13 M/L Eocene
Chron 13 – 6 Oligo/E Mio
C21
C24
C24
C21 Additional FZs
present e.g. Westray
A
0 Kilometers 250
C. 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)
C13 C6
C6 C13
Slower
spreading
rate
C
0 Kilometers 250
B. Symmetrical spreading Middle - Late Eocene
Slower
spreading
rate
C13
C21
C21
C13
B
0 Kilometers 250
C6 Present
Present C6
F
0 Kilometers 250
F. Middle Miocene – Present: Kolbeinsey Ridge
spreading
C13 C6
C6 C13
E
0 Kilometers 250
E. Early Miocene: Kolbeinsey Ridge becoming
active C13 C6
C6 C13
D
0 Kilometers 250
LEGEND
Spreading Ridge
Hot spot
Fracture Zones
Relative Plate Motion:
C13
C24
Present
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
Miocene - Recent
D. Oligocene: change of spreading from Ægir-
Kolbeinsey Ridge.
Westerly migration
of volcanic centre,
lava flows locally
obscure Eocene
magnetic anomalies
Flood basalts cover
future Jan Mayen
Micro-Continent
C24
C13
Present
C13
C24
Present
C13
C24
Present
C24
C13
Present
NW European plate
N American plate
Plate vectors from
Engen et al., 2008*
* Engin, Ø. et al, 2009, Tectonophysics, pp. 51 – 69.
CONCLUSIONS
A simple symmetric spreading model can be used to explain the opening of the Norwegian – Greenland Sea.
NW-SE trending, coast perpendicular fracture zones, are recognized regionally in the deepwater and adjacent shelf, linked to onshore pre-Cambrian basement fabric.
Transtensional, transpressional and inversion structuring associated with reactivation of the Mid - Ocean Ridge transform boundaries/fracture zones is pervasive throughout the North Atlantic and Norwegian – Greenland Sea (as seen throughout the Atlantic Ocean).
FZ Offshore/Onshore linked shear zones control:
Sediment entry points,
Provide hydrocarbon migration routes,
Create trapping geometries,
&
Allow development of new exploration models.
Acknowledgements:
ConocoPhillips management for support for the publication of this article,
Jennifer Pless and Professor Bob Holdsworth, Durham University (Lewisian Outcrop Project),
Clair Field partnership (permission to share the Lewisian Outcrop Project ongoing research).
Takk fyrir athyglina og takk fyrir mig!
Skjaldargrunn
Eo - Oligocene Iceland!
Iceland
SE Greenland
3D Topography/Bathymetry