Cretaceous Tertiary Contraction, Shear and Inversion in the Western Barents Sea

Transcription

1 Cretaceous Tertiary Contraction, Shear and Inversion in the Western Barents Sea Roy H. Gabrielsen,* Jan Inge Faleide*, Karen A. Leever*,** * Department of Geosciences, University of Oslo GeoForschungZentrum Potsdam Exploration Manager Seminar, Polarlys September 2010

2 Deep structure Gabrielsen et al. (1990) Breivik et al. (2005)

3

4 Rønnevik et al. (1981)

5 Inversion of basins

6 Reactivated and rotated extensional fault Snakehead structure Reverse fault geometry Inverted basin Reactivated extensional fault Reverse drag Incipient footwall cut-off Footwall folding Gabrielsen, Grunnaleite & Ottesen (1992)

7 Configurations of inverted basins; I

8 Configurations of inverted basins; II

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10 Configurations of inverted basins; III

11 Configurations of inverted basins; IV

12 Lokna (1994) Unpubl. cand.sci. thesis

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14 Inversion Structures, Western Barents

15 West Spitsbergen Fold- and Thrust Belt

16 Bergh and Grogan (2003) Comparison with WSFTB

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18 Strain partitioning

19 Figure 3 - Model setup a. Model setup, top view of basal plates. A thin plate is fixed at an angle of 15 degrees above an other plate that can be moved at a controlled rate. A, O: along strike and orthogonal components of total displacment. b. Model dimensions and materials, cross section. c. Stratigraphy of the WSFTB (Braathen and Bergh, 1995). Bold arrows indicate weak decoupling layers in Permian evaporites and Triassic and Jurassic shales; d. Mechanical stratigraphy of the model. Solid lines, brittle failure envelopes for quartz sand for different cohesion values according to eq. [4]; dashed line: brittle failure envelope according to Byerlee (1978) scaled down by a factor of 8 x 10 5 (see appendix for explanation). Viscous strength of PDMS for displacement rate of 5 cm/h. A ductile lower crust (cf. Burov, 2007) is not included in the model.

20 Building the model WSFTB-11: 30 o convergence angle Bars to constrain model thickness Basal plastic sheets White and colored sand Guiding bar Strap for pulling the lower plate 250 μm sieves WSFTB-9: 15 o convergence angle

21 km CS A1 A2 A3 A4 45 cm Figure 8 CS CS A1 A1 A2 A2 A3 A4 A3 35 cm 25 cm A4 Interpretation of selected cross sections (at 25, 35 and 45 cm, see Figure 7 for location) showing general characteristics and along strike variations. - Show also pictures - Show more details and deformation stages on model XS - Adapt numbering of A1- A5 - More modelling results cm

22 Bergh and Grogan (2003) Comparison with WSFTB

23 Provinces 1. West Spitsbergen fold & thrust belt 2. Asterias Fault Complex 3. Bjørnøyrenna Fault Complex 4. Vestbakken Volcanic Province 5. Sørvestsnaget Basin Timing 1. L.Palaeocene Eocene Faleide et al. (2008) Rift phases in W Barents Sea. Tertiary Cretaceous Jurassic Paleozoic

24 Asterias Fault Complex

25 Inversion Structures, Western Barents Sea The Asterias Fault Complex

26 Asterias Fault Complex

27 Provinces 1. West Spitsbergen fold & thrust belt 2. Asterias Fault Complex 3. Bjørnøyrenna Fault Complex 4. Vestbakken Volcanic Province 5. Sørvestsnaget Basin Timing 1. Hauterivian-Aptian 2. post Palaeocene Faleide et al. (2008) Rift phases in W Barents Sea. Tertiary Cretaceous Jurassic Paleozoic

28 Bjørnøyrenna Fault Complex

29 Inversion Structures, Western Barents The Bjørnøyrenna Fault Complex

30 Bjørnøyrenna Fault Complex

31 Provinces 1. West Spitsbergen fold & thrust belt 2. Asterias Fault Complex 3. Bjørnøyrenna Fault Complex 4. Vestbakken Volcanic Province 5. Sørvestsnaget Basin Timing 1.?Early - Late Cretaceous 2. post Palaeocene Faleide et al. (2008) Rift phases in W Barents Sea. Tertiary Cretaceous Jurassic Paleozoic

32 Sørvestsnaget Basin

33 Inversion Structures, Western Barents Sea The Sørvestsnaget Basin

34 Harsum (2009)

35 Mid Cretaceous Top early Eocene

36 Provinces 1. West Spitsbergen fold & thrust belt 2. Asterias Fault Complex 3. Bjørnøyrenna Fault Complex 4. Sørvestsnaget Basin 5. Vestbakken Volcanic Province Style and Timing Faleide et al. (2008) Rift phases in W Barents Sea. Tertiary Cretaceous 1.?L.Palaeocene E.Eocene; NW-SEstriking fold axes and inverted faults; Parallel high- and low-frequency folds 2. Eocene: NE-SW-striking folds and inverted faults Jurassic Paleozoic

37 Vestbakken Volcanic Province

38 Inversion Structures, Western Barents Sea (Grunnaleite 2002, 2008) Vestbakken Volcanic Province

39 RE05

40 Mid Miocene BV Wide, open collapsed anticlines and domes

41 Folds with moderately inclined axial surfaces focused along deep-seated faults

42 Flower and half-flower structures in footwall of some larger faults (undated) A

43 Provinces 1. West Spitsbergen fold & thrust belt 2. Asterias Fault Complex 3. Bjørnøyrenna Fault Complex 4. Sørvestsnaget Basin 5. Vestbakken Volcanic Province Style and Timing Faleide et al. (2008) Rift phases in W Barents Sea. Tertiary Cretaceous 1. Eocene Oligocene: open folding & doming 2.?Eocene Miocene: hangingwall folds and inverted faults 3. Flower structures of unknown age Jurassic Paleozoic

44 Margin segmentation A complex sheared and rifted margin along NW Svalbard and SW Yermak Plateau associated with volcanism (79-81 N). An initially sheared and later rifted margin west of Svalbard between Sørkapp and Kongsfjorden (76-79 N) A sheared margin along the southern Hornsund Fault Zone, from Bjørnøya to Sørkapp ( N), A rifted margin SW of Bjørnøya associated with volcanism ( N) A sheared margin along the Senja Fracture Zone ( N)

45 Time West Spitsbergen F&T Belt Asterias Fault Compl. Bjørnøyrenna Fault Complex Sørvestsnaget Basin Vestbakken Volc. Prov. Miocene Oligocene Eocene Palaeocene Late Cretaceous E.Cret.; Aptian - Hauterivian

46 Doré et al. (2008)

47 Cretaceous inversion? Inversion Structures, Western Barents Sea (Grunnaleite 2002, 2008)

48 Palaeocene - Miocene inversion; Contractional component? Inversion Structures, Western Barents Sea (Grunnaleite 2002, 2008)

49 Faleide et al. (2008) continent-continent passive Plate tectonic model

50 Lundin & Dore (2002) PETROBAR Tectonic inversion in the western Barents Sea Leever, Faleide, Gabrielsen, Grunnaleite

51 Conclusions Two distinct stages of inversion; Cretaceous (Hauterivian Albian?) and Palaeocene Miocene Cretaceous inversion most distinct along old basementinvolved fault complexes The Palaeogene event in the Sørvestsnaget Basin and the Vestbakken Volcanic Province oriented c.120 o to the transform > (right-lateral?) strike-slip The northernmost basin (VVP) has indications that inversion was active later (into Miocene times) there than farther south (SSB). Related to other plate tectonic stresses, like e.g. ridge push or domal uplift and spreading