The Scandinavian Mountain chain: deep processes

Valérie Maupin and the TopoScandiaDeep

working group

Major tectonic event (480-400 My): formation of the Caledonides by closing of Iapetus Ocean

From Univ. of Lausanne www-sst.unil.ch

Axis of Caledonian

orogeny

Baltic shield

Age 1000+ My

Oslo Graben +basinsAge ~300 My

Opening of the Atlantic Ocean

From Nielsen et al. (2009) after Skogseid et al. (2000)

North Sea subsidence Norway uplift

20My ago: increase of sediments to the North Sea

Compilation of Neogene erosion/deposition

From Japsen and Chalmers (2000)

+ : erosion

O : deposition

Stages in the fluvial cycle of erosionacc. Davis, W.M., 1909:

Geographical essays. Boston.

Present elevation of present and old surfaces

From Rohrman et al. (2002)

E = Hpaleo – Hpresent

Hpresent Hpaleo

From Rohrman et al. (2002)

Hpaleo = Hpaleopast + T + R(E)

Telastic = 20km

From Rohrman et al. (2002)

Hpaleopast=0mT=1500m

Hpaleopast + T

Hpaleopast=1500mT=0m

or

A: 100% uplift 20Ma

B: ICE-hypothesis:Topography can live long. Erosion is modulated strongly by climate.Climate may be the global agent behind coordinated Neogene uplifts seen in Norway, Greenland and globally.

1 km

0~400+

ICE-hypothesis

~50 ~20

Young tectonic uplift

From Rohrman and van der Beek (1996)

Possible mechanismfor tectonic uplift about 20My ago

From Rohrman and van der Beek (1996)

Initial temperature anomaly of 400o:

Residual thermal anomalies or compositional heterogeneities

Density anomaliesSeismic velocity anomalies

Possible model for elevated surface:

A remnant of Caledonides flattened by glacier erosion.

Remnant of Caledonides implies a

root to sustain the topography, whereas recent uplift would imply mantle anomalies below a rootless crust.

TopoScandiaDeep

A TOPOEUROPE project to reveal the deep processes associated with the Scandinavian Mountains

Valérie Maupin, Univ of Oslo (NO)

with J. Ritter (Karlsruhe, DE)

H. Thybo (Copenhagen, DK)

N. Balling (Aarhus, DK)

R. Mjelde (Bergen, NO)

J. Ebbing (Trondheim, NO)

D. Sokoutis (Amsterdam, NL)

R. England (Leicester, UK)

Data collection in seismics and magneto-tellurics

CENMOVE, SCANLIPS, MAGNUS, MAGNUS-rex etc

integrated into TopoScandiaDeep

(see poster)

Data analysis

Quantitative geodynamical modelling

Interaction with projects on other regions

Is the mountain sustained by a crustal root?

Moho depth from receiver function along the Cenmove profile (Univ. Aarhus)

Refraction (Magnus-Rex) in the same area gives 36-38km for Moho depth.

Receiver functions Cenmove

Moho depth to the North

Moho depth to the South

Moho depth to the North

Moho depth to the South

From Ebbing (2007)

Residual gravity anomaly

corrected for Moho depth,

lithospheric thickness,lower crustal body,granitoid body.

Seismic wave velocity fromtomography

from Weidle and Maupin (2007)

Bijwaard et al., 1998

Marquering & Snieder, 1996

Goes et al., 2000

P-residuals corrected for crust

Could part of the lithosphere has delaminated?

Realistic from a time scale point of view?

Can a dynamic process has produced this without a density anomaly visible today?

Relation to Atlantic opening, Icelandic plume?

How long can we keep topography?

First: a new complete seismic model

P-wave tomography

S-wave tomography

SKS-splitting

P-wave receiver function

S-wave receiver function

Surface wave analysis

Noise-based surface waves

Other elements

Magneto-telluric data

Heat-flow and potential field data

Geodynamical modelling

Comparison with other regions

Input from other fields

MAGNUS experiment

Deployment of Univ of Karlsruhe broadband seismological stations from Sept 2006 to Spring 2008.

Additional data from NORSAR and permanent Norwegian stations

Get a 3D model

From Nielsen et al.(2009) after Mosar (2003)