REVIEW
Main Types of
Bedding
level bedding
ripple bedding
cros
s-be
dding
graded bedding
laminaeplate
wedge
trough
Main Bedding Types Bedding Shape
Different Stratigraphic
Break(from Roberts,1982)
diastem
paracomformity
disconformity
unconformity
Zhu Zhicheng et al,[China University of Geosciences]
Strike and dip of a plane
Trend & plunge of a line Pitch and pitch direction
Relationship between true dip(?) and
Apparent dip(? or ??)
Equation:
? = atan[tan(?)cos(d)]
?= apparent dip angle,? = true dip angle,d = angle between
true and apparent dip direction.
?
?
d
APPARENT DIP ANGLE CALCULATION
NE
SE
NW
SW
0
90270
180Trend,S30W Trend,210
Bearing Azimuth
Bearing and Azimuth
?Bearing,a horizontal angle measured east or west of true
north or south.
?Azimuth,a horizontal angle measured clockwise from the
true north.
?Trend,the direction of a line in a horizontal plane,
commonly specified by its bearing or azimuth.
Structural Contour
marl
shale
sandstone
limestone
thin
limestone
Re
d
A-B SECTION
Red Water
River
LEGEND
Jianfeng
Jianfeng
conglomerate
mudstone
marl
limestone
shale
sandstone
au
ra
Lecture 6 Fault Basis
FRACTURING:
1) Rupture – loss of cohesion,breaking of
bonds
2) Displacement
a) No sliding – Joint
b) Sliding – Fault
3) Filled by minerals - Vein
Jointing Faulting
Veining
Components of Fault Displacement
ss,strike-slip component; ds,dip-slip component; PP’,
true displacement vector
TERMINOLOGY FOR DISPLACEMENT
Net SlipDip Slip Strike-Slip
?
? is the Rake Angle
（落差） Throw,Vertical component of dip slip
（平错） Heave,Horizontal component of dip slip
Geometry of Dip-Slip Fault Displacement
h,heave; t,throw; ?,angle of dip;
?,angle of hade(=90-dip angle);
ds,dip-slip component of displacement
1983 Borah Peak Earthquake,Idaho
Fault Scarp
Fault Displacement
BB- Dipping bedding (A)
DD- Vertical dyke
PP’- True displacement vector
Map of erosion level E of A shows
horizontal displacement of bedding and
dyke along fault,Note that the amount of
displacement appears to be different,The
true horizontal displacement is shown by
the vertical dyke DD,(B)
View of fault plane looking down from the
right,the true displacement PP’ is given
by the movement of intersection X of BB
and DD to position of X’,The strike slip
component ss is given by the displacement
of DD to DD’.The dip-slip displacement ds
must be measured using both dyke and
bedding displacements,(C)
Normal Reverse Strike-slip
Reverse-oblique Normal-oblique
TYPES OF FAULTS BASED ON DISPLACEMENT
Reverse
Thrust
Angle,< 30
Angle,> 30
STRIKE-SLIP FAULT
Left lateral
Right lateral
Normal fault
Normal
Fault
KEYSTONE THRUST FAULT,NEVADA
KEYSTONE THRUST FAULT,NEVADA
Paleozoic Rocks in hanging wall
Mesozoic Rocks in foot wall
LEWIS TRHUST FAULT,MONTANA
Photo,Martin Miller,U,of Oregon
Precambrian in Upper Plate
Paleozoic in Lower Plate
LEWIS TRHUST FAULT,MONTANA
Photo,Martin Miller,U,of Oregon
Precambrian in Upper
Plate
Paleozoic in Lower Plate
STRIKE-SLIP FAULT,NEVADA
Photo,Martin Miller,U of Oregon
Brittle fault and ductile fault in
different level
Brittle fault
Ductile fault
Incohesive
Fault breccia (visible fragment > 30% of rock mass)
Fault gouge (visible fragment < 30% of rock mass)
Cohesive Grain size Proportion of
matrix(%)
Protobreccia （初角砾岩） ﹥ 5mm 0～ 10
Breccia （角砾岩） 2～ 5mm 10～ 50
Protocataclasite （初碎裂岩） 0.1～ 2mm 50～ 90
Cataclasite （碎裂岩） 0.01～ 0.1mm 90～ 100
Ultracataclasite （超碎裂岩） ﹤ 0.01mm 90～ 100
Pseudotachylite （假玄武玻璃） ﹤ 0.005mm 90～ 100
Fault Rocks (Modified after Sibson,1977)
Correction Of Mistakes On
Table 2.1,Page 10
Fault breccia
Slickenslide Striations
On A Fault Surface
Scale bar,6 cm
Calcite Growth Fibre Steps
On A Fault Surface In
Limestone
Diagram Showing How Growth
Fibre Steps Form As A Result
Of Fault Movement
FAULT SCARP 断层崖
Wufoshan,Yanshi County,Henan Province
(Ma Xinyuan et al,1981)
断层三角面 Terminal Facet