Late-Glacial rebound and cratonic Te

1
Late-Glacial rebound and cratonic Te
Walcott (1970)
Te 85 km
2
Rifting, extension, and Te
Vening Meinesz wedge model
Rift valley width (East Africa) 65 km Hence, Te
35 km
3
Rifting, Te and a model that combines simple
shear in the (brittle) crust with thinning in the
(ductile) mantle
Ebinger et al (1991)
17 lt Te lt 38 km
Weissel Karner (1989)
4
Gravity anomaly due to rifting and sediment
loading - a process-oriented approach
5
Flexural backstripping, crustal restoration and
the gravity anomaly
Te (average) stretched continental crust is 5 km
6
Subsidence, aggradation, sediment loading, and
the steers head model
Watts et al (1982)
7
Example Gippsland and Michigan basins
8
Subsidence, progradation and the clinoform break
model
Watts (1989)
9
Example Offshore New Jersey
ODP Leg 174 Ewing 9009 Site Survey
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Orogeny, compression, and Te
11
Example Himalaya foreland basin
12
Example Appalachian foreland basin
Stewart Watts (1997)
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Orogenic loading of a rifted margin
Example Taiwan
Lin Watts (2002)
14
Surface loading
15
Sub-surface (buried) loading
Te 13 km ? stretched continental lithosphere
35 Myr after initiation of rifting
16
Inheritance
17
Spatial variations in Te and structural styles
The highest Te values (gt75 km) occur in the bend
region where they correlate with thin-skin
tectonics in the sub- Andean fold and thrust
belt.
18
Continental Te
No simple relationship between Te (continental)
and age
19
Yield Strength Envelope (YSE) for the Continents
Burov Diament (1995)
20
Continental Te
Continental Te studies suggest that rifts are
weak but, that cratons are both weak and strong.
21
The long-term strength of Europe
Note the Te derived from spectral studies (e.g.
Bouguer coherence) does not necessarily
represent Te at the time of loading. Rather, it
represents the combined response to specific
loading events as well as subsequant loads such
as erosion and sedimentation.
22
Pasquale et al (2001)
Te gtgt Ts and Te is high (gt 60 km) The long-term
strength of cratonic lithosphere, like oceanic
lithosphere, resides mainly in the mantle