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Map of magnetic anomaly numbers
Deep Sea Drilling sites
magnetic anomaly number
Age (Ma) from geomagnetic reversal chronology extrapolated in South Atlantic assuming constant rate of spreading
pale
onto
logi
cal a
ge,
Ma
Seafloor ages from deep sea drilling versus geomagnetic reversal chronology
Deep sea drilling in the South Atlantic Ocean
Chronology of geomagnetic field reversals
magnetic anomaly “number”
Ocean floor age, millions of years (Ma), determined largely from deep sea drilling
Geologic time scale
http://www.geo.ucalgary.ca/~macrae/timescale/timescale.html
4600 My 600 My
Age range of modern ocean floor
Transform faults
7000
3500
1500
-250
0
-150
0
-500
0 500
-550
0
-450
0
-350
0
-650
0
South Atlantic Ocean
7000
3500
1500
-250
0
-150
0
-500
0 500
-550
0
-450
0
-350
0
-650
0
South Atlantic Ocean
inactive fracture zone
active transform faultactive ridge crest
inactive fracture zone
active transform fault
active ridge crest
inactive fracture zone
Transform faults and fracture zones
Map pattern of magnetic anomaly number
Deep sea drilling calibration of chronology of geomagnetic field reversals back to 180 Ma.
Map pattern of ocean floor age
5 6
10.9 120.4
anomaly no. 1813 25 31 3421 M16M10N
M4M0 M21 M25
154.3 180
Age of ocean floor
From Muller, et al., 1997
