byWilly Fjeldskaar

Rogalandsforskning

• It is generally accepted that the present-day elevated topography of Scandinavia is partly due to significant Late Tertiary surface uplift

• The driving mechanism

of this uplift is not resolved

Late Tertiary uplift

Post-glacial uplift

• It is generally accepted that the present uplift of Fennoscandia is connected to the melting of the last ice sheets in the area

• The driving mechanism of this uplift is glacial isostasy

From Dehls et al., 2000

1) present rate of uplift

0

0,5

1

1,5

2

-12 -10 -8 -6 -4 -2 0Time (thousand years BP)

Trøndelag2) palaeo shoreline tilt

Ice extent and thickness during the last

20 000 years

The Earth's response to the deglaciation in Fennoscandia is modelled using a layered viscous model with elastic lithosphere.

“The most likely ice model gives a flexural rigidity of

1023 Nm (te = 20 km) at the Norwegian coast,

increasing to more than

1024 Nm (te = 50km) in central parts of Fennoscandia”

(Fjeldskaar, 1997)(Fjeldskaar & Cathles, 1991)

0 1 2 3 4 5 6 7

40

60

80

100

120

140

Viscosity (1019 Pa s)

Viscosity vs. thickness

Observed uplift

Best-fit model

Anomalies=

observed uplift-

glacial isostasy

Mid Norway centre

South Norway centre

From Riis, 1996

The areas are characterized byrelatively high seismic activity

Contour interval 200m

1500m

Accumulation Pattern

Ice melting model

Global View

SC R IPT C O M PU TIN G IC E-W ATER LO AD R ED ISTR IBU TIO N :

14000

N ow

Example

Uplift from 20 000 BP

- 2 0 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0

5 0

6 0

7 0

8 0

Ice thickness model – late phase

BMTTM is an advanced 2D basin

modeling system with ability to

create area balanced cross

sections in environments with

normal or reversed faults, and to

analyze the interplay between

tectonic processes, heat flow

and timing of generation. BMT

also has the power to analyze

complex tectonic processes

including salt diapirism and

igneous intrusions, and to model

the related heat flow response.

Dependency in geological modelingDependency in geological modeling

ErosionPorosity/Depth trendsFault modelAge Model

Representation ofPresent-Day

Geology

Reconstruction ofGeologic section

Tectonic modelling

Input parameters UncertaintyModeling task

Interpreted seismic lineStructural FrameworkFault Geometries

Porosity / Depth trends

Palaeo water depths

Lithospheric propertiesRifting Event Characteristics

Depth Conversion

Interpretation

Magnitude/Timing of RiftingLithospheric propertiesPalaeo water depths

Tectonic modelingTectonic modeling

Tectonic modeling in BMT

• Reconstruction of the basin geometry evolution• Fault restoration• Isostatic deflections (w/ flexure)• Lithospheric thinning (w/ necking)• Magmatic intrusions/underplating • Salt movements• Intra plate stress• (Phase boundary migration)

- and their temperature effects –

integrated in one system

1) One by one layer is removed

2) The layers underneath are decompacted (by porosity-depth relation)

3) The fault blocks are translated up the fault system (by vertical shear) until the top

timeline is continuous across the fault surface.

year deliverables amount

2005 New and high resolution ice models of last glaciation

Global high resolution modelling 400 kNOK

2006 Modelling results of last glaciation with high resolution

Ice thickness for previous glaciations/modelling 1226 kNOK

2007 Modelling of previous glaciations

Modelling of first 2D section (prel.) 1326 kNOK

2008 Modelling of erosion/deposition

Modelling of second 2D section 1326 kNOK

2009 Finalizing modelling – 2D and 3D

Reporting 1026 kNOK

Activity schedule