• 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