Wilson Cycles and the Opening of the North Atlantic &
Norwegian – Greenland Sea
Chris Parry (DEA Norge AS)
78th EAGE Conference & Exhibition 2016
Vienna, Austria, 30 May – 2 June 2016
78th EAGE Conference & Exhibition 2016
Vienna, Austria, 30 May – 2 June 2016
Introduction
The North Atlantic & Norwegian – Greenland Sea has opened and closed at least twice
during geological time (Wilson Cycles). Along the entire length of the Mid Ocean Ridge
spreading center is offset by regularly spaced transform boundaries, which are deep seated
crustal fracture zones that are linked to the continental crust by fracture zones. These have
been reactivated during all subsequent tectonic episodes, creating positive and negative
flower structures, which influence both reservoir distribution and hydrocarbon migration.
Fracture Zones
The Eastern Seaboard of the North American Continent has experienced at least two
complete Wilson cycles. The Proterozoic Grenville Orogeny closure of an ocean formed the
Rodinia supercontinent, which was subsequently broken up with the opening of the Iapetus
Ocean in the Cambro-Ordovician. Basement related zones of weakness (failed rift arms) in
the Appalachian Range form the location of the fractures zones for the opening of the Iapetus
Ocean and also influence the Siluro- Devonian Caledonian Orogeny deformation (recesses
and salients) during the subsequent ocean closure, forming the Pangaea supercontinent. These
same zones of crustal weakness are reactivated once again during the breakup of Pangaea,
and influenced the location of the fracture zones in the Mesozoic opening of the Atlantic
Ocean (Thomas, 2006).
Figure 1. The Wilson Cycle (modified after Dewey and Burke, 1974).
Lister et al., 1986, described upper plate and lower plate passive margins, separated by a
detachment fault, which give rise to asymmetric conjugate margins after final continental
78th EAGE Conference & Exhibition 2016
Vienna, Austria, 30 May – 2 June 2016
break up. The upper plate is characterized by a narrow continental shelf, with relatively little
sedimentary accommodation space and is relatively unstructured and has experienced uplift
related to underplating. While on the opposite side of the mid ocean ridge, the conjugate
lower plate is characterized by a wide continental shelf, which has abundant sedimentary
accommodation space and is complexly structured and exhibits bowed up detachment faults
(Torske and Presvik, 1991).
Figure 2. Continental Rifting: Upper and Lower Plate Asymmetric Conjugate Margins (simplified
after Lister et al., 1986).
Transfer faults offset marginal features and can cause the upper/lower plate polarity to
change along the strike of the margin. The Fram Strait is a transform margin, which was
initiated in the Eocene as a result of the onset of spreading in the North Atlantic and
Norwegian - Greenland Sea. This is a result of the North American Plate sliding past the
Eurasian Plate during the opening of the North Atlantic and Norwegian - Greenland Sea
(Lowell, 1972).
Figure 3. Convergent Strike Slip or Transform Motion Upthrust Zone (block diagram
modified after Lowell, 1972, map symplified from Torsvik et al., 2010 - from Parry, 2011).
The easiest direction for space relief for the squeezed sediments is vertical and a zone of
downward tapering wedges and up-thrust margins is created: This structure is not necessarily
symmetrical and the faults coalesce and anastomose with depth, creating a positive flower
structure of transpressional origin. These zones of long-lived crustal weakness can be
78th EAGE Conference & Exhibition 2016
Vienna, Austria, 30 May – 2 June 2016
subsequently reactivated during later tectonic episodes, the concept of “tectonic inheritance”
associated with Wilson cycles, the opening and subsequent closure of an ocean.
Figure 4. Basement Terranes and Tectonic Lineamants of Norway (Parry, 2015).
Conclusions
Wilson Cycles and Tectonic Inheritance: continental collision suture zones become
detachment zones during subsequent rifting events, with basement fractures controlling the
assembly and breakup of continents throughout geologic time (Bergh et al, 2012, Faleide et
al, 2008, Henriksen and Higgins, 2008). These have been reactivated most recently during
post-glacial isostatic readjustment. The fracture zones have been sites of intensely weathered
since their formation: especially during the Triassic-Jurassic, when Baltica drifted northwards
though the sub-tropical climates (Olesen et al, 2013). They have been re-used most recently
78th EAGE Conference & Exhibition 2016
Vienna, Austria, 30 May – 2 June 2016
during the Plio-Pleistocene - Recent glaciations, which have removed most of the pre-existing
sediments. Fracture zones control sediment distribution, coarse clastic entry points, provide
hydrocarbon migration routes, create trapping geometries (strike-slip faulting geometries) and
allow development of new models for exploration.
References
Bergh, S.G., Corfu, F., Myhre, P.I., Kullerud, K., Armitage, P.E.B., Zwaan, K.B., Ravna, E.R.,
Holdsworth, R.E. and Chattopadhya, A. [2012] Was the Precambrian Basement of Western Troms
and Lofoten-Vesterålen in Northern Norway Linked to the Lewisian of Scotland? A Comparison of
Crustal Components, Tectonic Evolution and Amalgamation History. Intech. Tectonics – Recent
Advances, Chapter 11, 283 – 330.
Dewey, J.F. and Burke, K. [1974] Hot Spots and Continental Break-up: Implications for Collisional
Orogeny. Geology, 57 – 60.
Dinkelman, M.G., Granath, J.W. and Whittaker, R. [2010] The NE Greenland Continental Margin.
Geo Expro, December, 36 – 40.
Faleide, J.I., Tsikalas, F., Breivik, A.J., Mjelde, R., Ritzmann, O., Engen, Ø., Wilson, J. and Eldholm,
O. [2008] Structure and evolution of the continental margin off Norway and the Barents Sea.
Episodes, 31, 82 - 91.
Gabrielsen, R.H., Braathen, A., Dehls, J. and Roberts, D. [2002] Tectonic lineaments of Norway,
Norsk Geologisk Tidsskrift, v. 82, 153 - 174.
Henriksen, N. and Higgins, A.K. [2008] Geological research and mapping in the Caledonian orogen
of East Greenland, 700N - 820N. In: Higgins, A.K, Gilotti, J.A and Smith, M.P., eds., The Greenland
Caledonides: Evolution of the Northeast Margin of Laurentia. Geol. Soc. Am., Mem. 202, 1 - 27.
Lister, G.S., Etheridge, M.A. and Symonds, P.A. [1986] Detachment Faulting and the Evolution of
Passive Continental Margins. Geology, 246 - 250.
Lowell, D.L. [1972] Spitzbergen Tertiary Orogenic Belt and Fracture Zone. Geol. Soc. Am. Bull.,
3091 - 3102.
Olesen, O.O., Keirulf, H.P., Brönner, M., Dalsegg, E., Fredin, O. and Solbakk, T. [2013] Deep
weathering, neotectonics and strandflat formation in Nordland, northern Norway. Norwegian Journal
of Geology, Vol 93, 189–213. Trondheim 2013, ISSN 029-196X.
Parry, C.C. [2011] Opening of the North Atlantic & Norwegian – Greenland Sea Basin: Lessons from
the South Atlantic. 3P Arctic Polar Petroleum Potential Conference, Halifax.
Parry, C.C. [2015] Wilson Cycles and the Opening of the North Atlantic & Norwegian – Greenland
Sea. oral presentation: 3P Arctic Polar Petroleum Potential Conference, Stavanger, 2015.
Thomas, W.A. [2006] Tectonic inheritance at a continental margin. GSA Today, 4 – 11.
Torske, T. and Prestvik, T. [1991] Mesozoic detachment faulting between Greenland and Norway:
Inferences from Jan Mayen Fracture Zone system and associated alkalic volcanic rocks. Geology, 481
– 484.
Torsvik, T.H., Steinberger, B., Gurnis, M. and Gaina, C. [2010] Plate tectonics and net lithosphere
rotation over the past 150 My. Earth and Planetary Science Letters, 106–112.
78th EAGE Conference & Exhibition 2016
Vienna, Austria, 30 May – 2 June 2016