the scandinavian mountain chain: deep processes
TRANSCRIPT
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)