A Fresh Look at Marine Magnetic Anomalies, One of the Key Datasets in the Development of Plate Tectonics by Ian Norton - 2014 PaleoGIS & PaleoClimate Users Conference
A Fresh Look at Marine Magnetic Anomalies, One of the Key Datasets in the Development of Plate Tectonics by Ian Norton - 2014 PaleoGIS & PaleoClimate Users Conference
Ähnlich wie A Fresh Look at Marine Magnetic Anomalies, One of the Key Datasets in the Development of Plate Tectonics by Ian Norton - 2014 PaleoGIS & PaleoClimate Users Conference
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Architecture decision records - How not to get lost in the past
A Fresh Look at Marine Magnetic Anomalies, One of the Key Datasets in the Development of Plate Tectonics by Ian Norton - 2014 PaleoGIS & PaleoClimate Users Conference
1. A fresh look at marine magnetic anomalies, one of
the key datasets in the development of plate tectonics.
Ian Norton, Larry Lawver, Lisa Gahagan
Institute for Geophysics
University of Texas at Austin
From Vine and Matthews, 1963:
Calculated with reversals Observed
Calculated with constant
magnetization
Sandwell gravity
2. The EDSAC-2 computer used by Vine & Matthews
http://en.wikipedia.org/wiki/EDSAC_2
EDSAC = Electronic Delay Storage Automatic Calculator
3. PLATES Database
• Plate model
• Database: oceanic magnetic and tectonic (plate boundaries, paleomagnetic, hot
spots, geological and geophysical data to extend the span and accuracy of global
plate reconstructions)
• This talk: a look at magnetic anomalies.
Crust Code
4. Data from Global Magnetics Database http://www.soest.hawaii.edu/PT/GSFML/ML/index.html
Green – Cande & Stock, 2004
Black – Granot et al., 2013
Australia
Database run by Paul Wessel (Hawaii) &
Dietmar Müller (Sydney)
Antarctica
-40
-50
-60
100 140
5. Data from Global Magnetics Database http://www.soest.hawaii.edu/PT/GSFML/ML/index.html
115˚E 120˚E
60˚S
Mismatches 5-6 km to as much as 35 km
• Great dataset, needs work to use
Green – Cande & Stock, 2004
Black – Granot et al., 2013
7. Example magnetic profile from Mascarene Basin
• VGG emphasizes fracture zones and extinct ridges
Base: Sandwell vertical gravity gradient 23.1
8. ModMag model of Mascarene Basin profile
• Really good match between synthetic and observed
• Easy to map details of age interpretation
Young end at max +ve, old end at max -ve
ModMag: Matlab program by Mendel, Munschy & Sauter, 2005. This profile is
from example data files that are included with download.
Computers & Geosciences, Volume 31, Issue 5, June 2005, Pages 589–597
13. Line SO183-11 from Mozambique Basin
• Good match over parts of profile
• Need multiple lines for regional identifications
• Mapping of young-old edges of anomalies not quite so accurate
Data from König and Jokat, 2010
Young end close to max –ve, old end close to max +ve
19. The Svalbard Margin – Paleocene-Eocene foldbelt followed by some rifting (age?)
Leever et al. 2011 after Faleide et al. 2008
Leever et al. 2011 after FG = Forlandsundet Graben Bergh et al., 1997 and Braathen et al. 1999
20. Stylized present-day
G
E
Reconstructions should show (in
sequence) transpression to
transtension to oblique divergence
with spreading
Stylized 33 Ma
(e.g. Engen et al. 2008)
G
E
Stylized Oligocene
(overlap to account for
transtension)
G
E
Stylized Paleocene
(gap to account for
transpression)
G
E
Present-day
47 Ma
Should show a gap at 47 Ma,
not overlap
21. 120-130 km overlap
47 Ma reconstruction
Europe fixed, Gaina et al. 2009 poles
22. 47 Ma reconstruction – can Greenland be shifted to avoid overlap with Svalbard?
• Check magnetic lineation identifications in Labrador Sea
23. Labrador Sea magnetic data
Data from http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=8127
24. Labrador Sea magnetic data – modeled profile
Data from http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=8127
30. This is the currently accepted interpretation
• These essentially sinusoidal anomalies are hard to identify with certainty, need
regional context to settle on interpretation
This area not modeled
32. 120-130 km overlap
47 Ma reconstruction
Europe fixed, Gaina et al. 2009 poles
33. 47 Ma reconstruction – can Greenland be shifted to avoid overlap with Svalbard?
• Labrador Sea identifications not definitive
• Triple junction provides strong constraint – can’t move Greenland
• How to fix the overlap? Hopefully PhD student Bereke Karainov at UiS can figure it out!
Triple junction
König and Jokat, 2011
Advanced insights into magmatism and volcanism of the
Mozambique Ridge and Mozambique Basin in the view of new
potential field data.
Geophys. J. Int. (2010) 180, 158–180 doi: 10.1111/j.1365-246X.2009.04433.x
König and Jokat, 2011
Advanced insights into magmatism and volcanism of the
Mozambique Ridge and Mozambique Basin in the view of new
potential field data.
Geophys. J. Int. (2010) 180, 158–180 doi: 10.1111/j.1365-246X.2009.04433.x