grace. see movie free air gravity anomalies derived from radar altimetric determinations of geoid...

GRACE

See movie

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