Wadati benioff zone zone of seismicity created by slip between upper surface of slab and lithosphere of the uppe
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (439.96 KB, 16 trang )
Wadati-Benioff zone: zone
of seismicity created by
slip between upper surface
of slab and lithosphere of
the upper plate
Reminder / change in schedule
Friday is a discussion of the paper “How
Erosion Builds Mountains” by Pinter and
Brandon. Paper is on electronic reserve
On Wednesday, we will talk about
tectonic basins
Rift to drift: a story of extension
Four main stages related to
Wilson cycle
RIFT VALLEY
!
"Example: East African Rift
YOUTHFUL#$
!%&!
!'Example: Red Sea
MATURE#
Example: most of the present
Atlantic continental margins
FRACTURE#
Fates of continental rift
elements
()!
)
!
!
!
)
Currently active
continental rifts
*+!!,
-.!
/0-
12!
(!
Some former continental
rifts
-.*
*1
3 !4
3 !4
1
1
!)
Elements of extensional
system
54 4
!
04
(
/
Thermal and uplift
history
+)#!
5'
!
!
!
ISOSTASY
ISOSTASY
Isostasy: the state of
gravitational equilibrium
between the Earth's
lithosphere (analogous to
iceberg) and
asthenosphere (analogous
to seawater). Tectonic
plates ‘float’ at an elevation
which depends on their
thickness and relative
density; thus high areas will
have large lithospheric
‘roots’. Where a balance is
achieved between
topography and size of
roots, lithosphere is said to
be in
6.
Igneous activity
Extension typically
involves ‘bimodal’
volcanism,
characterized by
rhyolite and basalt
Contrasts with
andesitic volcanism
of arcs
Rift basin sedimentation
#
7&!
!!
!
!
4!#
)!'
+48!
Pure Shear
Simple Shear
Depocenter symmetry will
reflect structural symmetry
Conceptual models of rift
evolution
)))!
9)4!4:
+)4 !
!#.!!2!
'!)#
!!+;
<
Rift to drift: a story of extension
Establishing a passive margin
/>
