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GRACE
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Free air gravity anomalies derived from radar altimetric determinations of geoid height
milligals
Bathymetry determined from satellite radar derived gravity plus shipboard measurements
Major types of isostatic compensation
1. Airy: crustal root compensates elevated topographya. Ocean-continent crustal thicknessesb. Majority of variations in elevations on continental
mountain beltsc. Oceanic plateaus
2. Thermal: elevated topography a result of thermal expansiona. Ocean ridge systemb. Basin and Range
3. Flexural isostasya. Bending of the lithosphere: oceanic trenchesb. Regional isostasy
crust
mantle
Airy isostasy
crustal thickening
crust
mantle
Airy isostasy
topographic “load”
compensating root
Simple Airy isostasy is dealt with in more detail ingrav_anom.ppt
crust
mantle lithosphere
mantle athenosphere
1300 C
Temperature, degrees C
0 1300
50
100
150
200
Thermal isostasy
A
B
Lithospheric
thinning
uplift from thermal expansion
A
B
Thermal thinning and uplift are dealt with in more detail inthermal.pdf
Outstanding continental examples of thermal or Airy isostasy
thermal
AiryAiry