View
221
Download
0
Tags:
Embed Size (px)
Citation preview
Bernard BrunhesDiscovered rocks in France in 1906 with reversed magnetic polarity
Cretaceous ‘superchron’
Pacific Antarctic ridge
Schematic model
Drummond Matthews (left) and Fred VineCambridge University
Magnetic anomaliesover the ReykjanesRidge (S. of Iceland) from Vine & Matthews(1963).
Positive anomalies arecolored, negative onesare white.
Magnetic anomalypatterns acquired by the oceanic crust, while it formed during the Gilbert Reversed Chron (top) and afterwards (fromVine & Matthews,1963)
Gauss
Matuyama
Brunhes (today)
Gilbert
Juan de Fuca East Pacific Rise
observed
mirror image
model
Relative spreading rates
Blanco fracture zone
Alfred Wegener
Wegener’s map(1910). Note the distortion of India.
Map made witha computer(1965).
The meaning of an “apparent” polarwander path (APWP).
S. Keith Runcorn(1922 – 1995)
Computer-generatedfit of the Atlantic-bordering continents(Bullard et al., 1965),minimizing gaps and overlaps.
Ages of the Ocean floor determined from magnetic anomalies (~ 1990)
Late Cretaceous (~85 Ma) map of the world (Scotese, 1981)
www.scotese.com
Magnetic field during reversals
Geodynamo simulations (Glatzmaier and Roberts, 1996)
Inner core
Outer core
High fluid velocity intangent cylinder
Magnetic field lines
Close up of inner core