Glossary of Normal Faults Peacock Et Al 2000

8/21/2019 Glossary of Normal Faults Peacock Et Al 2000

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P E R G A M O N

Journal of S tructural Geology 22 (2000) 291-305

JOURN LOF

STRUCTUR L

GEOLOGY

www.elsevier.nl/locate/jstrugeo

G l o s s a r y o f n o r m a l f a u lt s

D . C . P . P e a c o c k a * , R . J . K n i p e a , D . J . S a n d e r s o n b

aRock Deformation Research Group, School of Earth Sciences, University oJ'Leeds, Leeds, LS 2 9JT, UK

bT.H. Huxley School of Environment, Earth Sciences and Engineering, Imperial College, Royal School of Mines Building, Prince Consort Road,

London SW 7 2BP, UK

Received 27 October 1997; accepted 1 Sep temb er 1999

A b s t r a c t

Inc reased in te rest in norm al fau l ts and ex tended te rranes has led to the deve lo pment o f an inc reasingly complex te rminology .

The m os t imp ortan t te rm s a re de fined in th is pap er , w i th o r ig ina l re ferences be ing g iven wherever poss ib le , a long with examples

of curren t usage. © 2000 Elsevier Science Ltd. All rights reserved.

1 I n t r o d u c t i o n

T h e l a r g e a m o u n t o f w o r k o n n o r m a l f a u l t s o v e r th e

l a s t f e w d ec a d e s h a s l ed t o t h e i n t r o d u c t i o n o f m a n y

n e w t e r m s a n d s o m e c o n f u s i n g t e r m i n o l o g y . F o r

e x a m p l e , t h e t e r m

r e l a y r a m p

( L a r s e n , 1 9 8 8 ) h a s a l s o

b e e n a p p l i e d t o s t r u c t u r e s i n s t r i k e - s l i p f a u l t z o n e s

( e . g . H e r z e r a n d M a s c l e , 1 9 9 6 ) , a n d o t h e r t e r m s h a v e

b e e n a p p l i e d t o r e l a y r a m p s i n n o r m a l f a u l t s y s t e m s

(e .g . a c c o m m o d a t i o n z o n e , f a u l t b r i d g e, t r a n s f e r z o n e ) .

T h e a i m o f t h i s g l o s s a r y i s t o g i v e d e f i n i ti o n s o f t h e

m o s t i m p o r t a n t t e r m s c u r r e n t l y u s e d i n c o n n e c t i o n

w i t h n o r m a l f a u l t s ( F i g . 1 ) . T h e g l o s s a r y i s i n t e n d e d

f o r n o n - s p e c i a l i s t s w h o h a v e n o t r e a d t h e l a r g e n u m b e r

o f r e ce n t p a p e r s a b o u t n o r m a l f a u l ts . O t h e r g e n e r a l

t e r m s f o r f a u l t s a r e a v a i l a b l e i n s t a n d a r d t e x t b o o k s

( e. g. R a m s a y a n d H u b e r , 1 98 7; P r i c e a n d C o s g r o v e ,

1 99 0; T w i s s a n d M o o r e s , 1 9 92 ) , a s a r e g e n e r a l t e r m s

u s e d i n s t r u c t u r a l g e o l o g y ( s u c h a s

s t r a i n

a n d

s t r e s s ) .

S i m i l a r g l o s s a r i e s f o r t h r u s t s a r e g i v e n b y B u t l e r ( 1 9 8 2 )

a n d b y M c C l a y ( 1 9 9 2 ) , a n d f o r s t r i k e -s l i p f a u l t s b y

B i d d l e a n d C h r i s t i e - B l i c k ( 1 9 8 5 ) . W e h a v e a t t e m p t e d

t o f i n d t h e f i r s t u s a g e , o r t h e e a r l i e s t r e a s o n a b l e u s a g e ,

o f t e r m s . A p r o b l e m e n c o u n t e r e d w h e n a t t e m p t i n g t o

* Corresponding author. Present address: Department of G eology,

876 N atural Science Com plex, St ate University of New York at

Buffalo, Buffalo, NY 14260, USA .

E-mail address:

[email protected](D.C.P. P eacock).

f i n d f i r s t u s a g e i s t h a t m a n y t e r m s w e r e f i r s t u s e d i n

t h e m i n i n g o r h y d r o c a r b o n i n d u s t r i e s , g r a d u a l l y c r e e p -

i n g i n t o t h e g e o l o g i c l i t e r a t u r e ( e . g .

i n v e r s i o n

a n d

ac-

c o m m o d a t i o n z o n e ) .

W h e r e u s a g e h a s c h a n g e d t h r o u g h

t ime (e . g .

h o r s e ) ,

w e p r o v i d e e x a m p l e s o f c u r r e n t p o p -

u l a r u s a g e .

G l o s s a r y

A c c o m m o d a t i o n z o n e .

T h e a r e a b e t w e e n t w o s u b -

p a r a l l e l , n o n - c o l l i n e a r , o v e r l a p p i n g f a u l t s ( e . g .

R e y n o l d s a n d R o s e n d a h l , 1 9 84 ) . R o s e n d a h l e t a l .

(1986 , f ig . 8 ) de f ine an

a c c o m m o d a t i o n z o n e

a s

t r a n s f e r r i n g d i s p l a c e m e n t o r s t r a i n f r o m o n e

h a l f -

g r a b e n

t o a n o t h e r w i t h o p p o s i t e s e n s e v i a o b l i q u e

s h e a r a l o n g a n i n t e r - b a s i n a l r i d g e . S e e

t r a n s f e r z o n e .

F o r a d i sc u s s i o n o f t h e F a u l d s a n d V a r g a ( 1 9 9 8 )

r e d e f i n i t i o n o f

a c c o m m o d a t i o n z o n e ,

see

t r a n s f e r

z o n e .

A n t i t h e t i c . f a u l t .

D e f i n e d b y C l o o s ( 1 9 2 8 ) a n d H i l l s

(1 9 4 0 , f ig . 4 1 ) a s a m in o r f a u l t t h a t d ip s in th e

o p p o s i t e d i r e c t i o n t o t h e d i p d i r e c t i o n o f t h e b e d s

t h e y d i s p l a c e .

A n t i t h e ti c f a u l t

i s n o w c o m m o n l y u s e d

f o r a f a u l t t h a t d i p s i n t h e o p p o s i t e d i r e c t i o n t o a

r e l a t e d d o m i n a n t f a u l t o r f a u l t s e t , w h i l e

a n t i t h e t i c

i s t h e r e l a t i o n s h i p w h e r e b y t w o r e l a t e d f a u l t s h a v e

th e o p p o s i t e s h e a r s e n s e ( e . g . G ib b s , 1 9 8 4 ) (F ig . 1 ) .

F o r e x a m p l e , a n o r m a l f a u l t w i t h a d o w n t h r o w t o

0191-8141/00/ - see front m atter © 2000 Elsevie r Science Ltd . All rights reserved.

P I I : S 0 1 9 1 -8 1 4 1 (9 9 )0 0 1 4 6 -7


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3/15

D.C .P. Pea cock et al. / Journal of Structural Geology 22 (2000 ) 291-305

293

t h e n o r t h i s

a n t i t h e t i c

t o a l a r g e r n o r m a l f a u l t w i t h

a d o w n t h r o w t o t h e s o u t h . S e e

syn th e t i c f a u l t .

A r r a y , f a u l t :

A s e t o f o v e r s t e p p i n g a n d e n 6 c h e l o n

f r a c t u r e

s e g m e n t s

or fau l t zones (e . g . S ega l l and

Pollard, 1980).

fi-value:

T h e

s t re t ch in g f a c to r ,

def ined a s the inc rease

i n l e n g t h o f a c r o s s - s e c ti o n d u e t o e x t e n s i o n

(McKenz ie , 1978; Bar ton and Wood, 1984) , i . e .

11/

10, whe re l0 = the o r ig ina l l eng th an d l l =

d e f o r m e d l e n g th .

B a s e m e n t f a u l t .

A f a u l t t h a t c u t s t h e b a s e m e n t a n d

t h a t o r i g i n a t e d b e f o r e d e p o s i t i o n o f t h e c o v e r

s e d i m e n t s a n d t h a t m a y b e r e a c t i v a t e d ( e . g . S t e w a r t

et al. , 1997).

B a s e m e n t

i s u s e d h e r e t o r e f e r t o t h o s e

r o c k s t h a t f o r m e d b e f o r e t h e b a s i n i n w h i c h t h e

c o v e r r o c k s a r e d e p o s i t e d .

Ba s in :

G r e e n o u g h ( 18 19 , p . 6 6) s t a te s t h a t w h e n

m a s s e s o r s t r a t a d e c l i n e u p o n e v e r y s i d e t o w a r d s a

c e r t a i n p o i n t , t h e y a r e s a i d t o b e b a s i n - s h a p e d .

Ba s in

i s n o w u s u a l l y d e f i n e d a s a n a r e a o f

s u b s i d e n c e i n w h i c h s e d i m e n t s a r e d e p o s i t e d , w i t h

s u b s id e n c e c o m m o n l y b e i n g c o n t r o l le d b y n o r m a l

fau l t s (e . g . Gibbs , 1984) (F ig . 1 ) . P u l l -apa r t bas ins

can be con t ro l l ed by s t r ike -s l ip fau l t s (e . g . Rodgers ,

1 9 8 0 ) , w h e r e a s f o r e l a n d b a s i n s a r e c o n t r o l l e d b y

thrus t fau l t s (e . g . DeCe l le s and Gi le s , 1996) .

Basin-margin fau l t .

A f a u l t t h a t m a r k s t h e e d g e o f ,

a n d t y p i c a l l y c o n t r o l s , a b a s i n ( e .g . R o b e r t s a n d

Yielding, 1991) (F ig. 1) . Also see

b o rd er - fa u l t s ys t em

a n d

b o u n d a r y f a u l t .

Ben d , a lo n g - s t r i ke :

A b e n d i n a f a u l t i n m a p v i e w ( F i g .

1 ) . A n a l o n g - s t r i k e b e n d o n a n o r m a l f a u l t i s

n e i t h e r d o m i n a n t l y

ex t en s io n a l

o r

co n t ra c t i o n a l ,

a n d

c o m m o n l y r e s ul ts f r o m t h e l in k a g e o f t w o s e g m e n ts

ac ros s a

r e l a y r a m p

( P e a c o c k a n d S a n d e r s o n , 1 9 9 1 ,

1994).

Bend, contractional.

A s p a t i a l v a r i a t i o n i n t h e

o r i e n t a t i o n o f a f a u l t - p l a n e t h a t c a u s e s l o c a l

c o n t r a c t i o n i n t h e w a l l - r o c k s a s t h e y a r e d i s p l a c e d

a r o u n d t h e b e n d ( e . g . P e a c o c k a n d Z h a n g , 1 9 9 4 ) .

S u c h b e n d s o c c u r d o w n t h e d ip o f n o r m a l f a u l t s

where the re i s a loca l dec rease in fau l t d ip (F ig . 1 ) .

S y n o n y m o u s w i t h

closing bend , convergent bend

(B idd le and Chr i s t i e -Bl ick , 1985) and wi th

res t ra in in g b en d

(Crowell , 1974, f ig. 3) .

Bend, extensional .

A s p a t i a l v a r i a t i o n i n t h e

o r i e n t a t i o n o f a f a u l t - p l a n e t h a t c a u s e s l o c a l

e x t e n s i o n i n t h e w a l l - r o c k s a s t h e y a r e d i s p l a c e d

a r o u n d t h e b e n d ( e . g . P e a c o c k a n d Z h a n g , 1 9 9 4 ) .

S u c h b e n d s o c c u r d o w n t h e d i p o f n o r m a l f a u l t s

where the re i s a loca l inc rease in fau l t d ip (F ig . 1 ) .


divergent -bend , opening-bend

(B idd le and Chr i s t i e -Bl ick , 1985) and wi th

releasing-

b e n d

(Crowell , 1974, f ig. 3) .

B e n d , f a u l t :

A s p a t i a l v a r i a t i o n i n t h e o r i e n t a t i o n o f a

faul t -plane. S ibson (1989, f ig. 6) uses

i so la t ed f a u l t

b e n d

f o r a g e o m e t r y in w h i c h a t i p p o r t i o n h a s a

d i f f e r e n t o r i e n t a t i o n f r o m t h e m a i n p a r t o f t h e f a u l t .

Blo ck, fau l t .

A f a u l t - b o u n d v o l u m e o f r o c k ( e .g . D i ll e r ,

18 86; S toces a nd W hite , 1935, fig. 327).

S y n o n y m o u s w i th

horse.

B o o k s h e l f f a u l t s :

A s y s t e m o f s u b - p a r a l le l f a u l t s t h a t

i n v o l v e th e p r o g r e s s i v e r o t a t i o n o f b e d s a n d f a u l t s

a s d i sp lacem ent occurs (e . g . Mandl , 1987) (F ig . 1 ) .

T h e

b o o k s h e l f m e c h a n i s m

w a s d e f i n e d b y M a n d l

(1984) a s s im ple shea r ing or ex tens ion

a c c o m m o d a t e d b y r o t a t i o n o f p a ra l le l f a u l ts i n a n

a r r a y . B o o k s h e l f n o r m a l f a u l t s t e n d t o c a u s e

s t e e p e n i n g o f b e d s , a n d a d e c r e a s e i n t h e d i p o f t h e

f a u l t s. B o o k s h e l f f a u l t s c a n p a s s i n t o a

d e t a c h m e n t

o r i n t o a z o n e o f d u c t i l e d e f o r m a t i o n ( M a n d l , 1 98 7,

fig. 4). See

d o m i n o f a u l t s .

Bo rd er - fa u l t s ys t em.


b a s in -ma rg in

f a u l t

(Schl ische, 1992).

Bo u n d a ry f a u l t .


b a s in -ma rg in f a u l t

(Mor ley , 1995) .

B o x f a u lt s : A n e t w o r k

o f f a u l t s d e v e l o p e d b e t w e e n t w o

o vers t ep p in g

n o r m a l f a u l t s

( r e l a y r a m p )

(Fig. 1),

d e s c r i b e d i n t h e E a s t A f r i c a n R i f t b y G r i f f i t h s

(1980).

Branch.

O n e o r m o r e f a u l t s t h a t e x t e n d o f f a l a r g e r

fau l t (e .g. Nev in, 1931; Butle r , 1 982) (F ig. 1) .

Branch l ine:

A l i n e a l o n g w h i c h t w o f a u l t p l a n e s

intersect (Butler , 1982).

Bridge, fault .


re la y ra mp

( R a m s a y

and Hu ber , 1987 , fig . 23 . 50) .

Cataclasis:

P r o c e s s i n v o l v i n g b r i t t l e f r a g m e n t a t i o n o f

m i n e r a l s , w i t h r o t a t i o n o f g r a in f r a g m e n t s , g r a in -

s i z e r e d u c t i o n , g r a i n b o u n d a r y s l i d i n g a n d v o l u m e

inc rease (de f in i t ion o f S ibson , 1977) . Ca tac la s i s

t y p i c a l l y o c c u r s a l o n g f a u l t p l a n e s o r i n z o n e s o f

b r i t t l e d e f o r m a t i o n . E a r l i e r u s a g e o f

cataclasis

is

g iven by S ibson (1977).

Coherence, geometric:

T h e e x i s t e n c e o f re g u l a r a n d

s y s t e m a t i c d i s p l a c e m e n t p a t t e r n s i n a f a m i l y o f

fau l t s (Walsh and Wat te rson , 1991 , f ig . 4 ) .

Coherence, kinematic.

T h e e x i s t e n c e o f s y n c h r o n o u s

s l i p r a t e s a n d s l i p d i s t r i b u t i o n s t h a t a r e a r r a n g e d

s u c h t h a t

g eo met r i c co h eren ce

i s m a i n t a i n e d ( W a l s h

a n d W a t t e r s o n , 1 99 1) .

Co n ju g a te .

F o r f a u l t s ,

co n ju g a t e

re fe rs to the

r e l a t i o n s h i p b e t w e e n t w o i n t e r s e c t in g s e ts o f f a u l t s

t h a t e a c h f o r m e d u n d e r t h e s a m e s t r e s s f i e l d

(Daub r6e , 1878, c i t ed by Den nis , 1967). Two

c o n j u g a t e f a u l t s h a v e t h e o p p o s i t e s h e a r s e n s e a n d

t h e s a m e a n g l e ( g e n e r a l l y ~ 3 0 ° ) t o t h e m a x i m u m

pr inc ipa l s t re s s d i rec t ion (Anderson , 1951) .

I n t e r a c t i n g c o n j u g a t e f a u l t s m a y m o v e a l t e r n a t e l y

(F re und , 1974; Hors f i e ld , 1980), o r m ay m ove

s y n c h r o n o u s l y to f o r m a n a r e a o f h i g h s t ra i n n e a r

t h e i n t e r s e c t i o n ( P e a c o c k , 1 9 9 1 ; O d o n n e a n d

Massonna t , 1992) . S ee

a n t i t h e t i c

a n d

syn th e t i c .


4/15

294

D.C.P. Peacock et al./ Journal of Structural Geology 22 (2000) 291-305

Connect ing fau l t .

A f a u l t t h a t c o n n e c t s t w o

o vers t ep p in g

fau l t s ac ros s a

t ra n s f er zo n e

o r

re la y

r a m p

P eacock and S an derson , 1994) F ig . 1) .


co n n ec t i n g sp la y

R a m s a y a n d

Huber, 1987, f ig. 23.50b).

Crestal collapse faults.

F a u l t s t h a t d e v e l o p i n t h e c r e s t

o f a n a n t i c li n e a n d t h a t a c c o m m o d a t e e x t e n s i o n in

t h e h in g e r e g i o n e .g . M c C l a y a n d S c o t t, 1 9 9 1 ) .

C r e s t a l f a u l t s i n f o l d s a r e d e s c r i b e d b y D e S i t t e r

1956 , ch ap te r 14) . Cres ta l co l l apse fau l t s can be

n o r m a l o r r e v e r se , b o t h o f w h i c h c a n d e v e l o p

s y n c h r o n o u s l y N i e u w l a n d a n d W a l t e r s , 1 9 9 3, f ig .

5).

Cut-o f f l ine.

T h e l i n e m a r k i n g t h e b o u n d a r y b e t w e e n a

f a u l t su r f a c e a n d a p l a n a r m a r k e r b e d , d y k e , e tc . )

tha t i s d i sp laced b y the fau l t e . g . S uppe , 1985 , fig.

2-28). See

f o o t w a l l c u t - o f f

a n d

hanging wal l cu t -o f f .


f o o t w a l l t r a c e

a n d

h a n g in g wa l l

t race

of Gil l 1935).

D a m a g e z o n e :

L o c a t i o n a t w h i c h a m a j o r c h a n g e i n

fabr ic e .g . caused by pres sure so lu t ion) i s read i ly

v is ib le C h e s te r a n d L o g a n , 1 9 8 6 ; W u a n d

G r o s h o n g , 1 99 1) , o r t h e a r e a o f f r a c t u r i n g a r o u n d

a n d r e l a t e d t o a f a u l t M c G r a t h a n d D a v i s o n , 1 9 9 5)

F i g . 1 ). D a m a g e z o n e s a r e t y p i c a l l y c a u s e d b y

f a u l t

p ro p a g a t io n , l i n ka g e

o r d i s p l a c e m e n t a l o n g t h e f a u l t

e .g . Cow ie and S cho lz , 1992b) . S yn on ym ou s wi th

d e f o r m a t i o n f r o n t

a n d

t ex tu re zo n e

W u a n d

G r o s h o n g , 1 9 9 1 ) .

D~col lement:

A b e d d i n g - o r l a y e r - p a r a l l e l f a u l t o r

s h e a r z o n e , a b o v e w h i c h t h e r o c k s m a y b e d e f o r m e d

e .g . L e e s, 1 9 5 2 ; R a m s a y a n d H u b e r , 1 98 7 ). T h e

p r o c e s s o f

d d co l l emen t

i s desc r ibed by DeS i t t e r

1 95 6) a s t h e d e t a c h m e n t o f t h e u p p e r c o v e r f r o m

i t s s u b s t r a t u m . E a r l i e r u s a g e o f

a b sch eru n g

is

desc r ibed by Lees 1952) . S ee

d e ta ch men t .

De fo rma t io n b a n d .

A p l a n a r z o n e o f d i s t ri b u t e d

d e f o r m a t i o n i n w h i c h t h e s t r a i n i s a p p r o x i m a t e l y

s i m p l e s h e a r, t y p i c a l l y i n v o l v i n g m i c r o - f r a c t u r i n g

a n d

cataclasis

e.g. Aydin, 1978). See

g ra n u la t i o n

sea m.

De n s i t y , . f a u l t .

A m e a s u r e o f t h e n u m b e r o f f a u l ts in a

rock m ass e .g . Gi l l e sp ie e t al . , 1993). F au l t dens i ty

m a y b e m e a s u r e d i n o n e , t w o o r t h r e e d i m e n s i o n s ,

r e s p e ct i v e ly as : i ) t h e n u m b e r o f f a u l t s p e r u n i t

d i s t a n c e u s u a l l y m e a s u r e d p e r p e n d i c u l a r t o t h e

fau l t s e t) ; i i) the to ta l l eng th o f fau l t t race pe r un i t

a rea ; o r i ii ) the to ta l a rea o f fau l t p lane pe r un i t

v o l u m e . T h e u n i t o f f a u l t d e n s i t y i s m - ~ a n d i s

i n v e r se l y p r o p o r t i o n a l t o

fau l t spacing .

D e t a c h m e n t :

F a u l t a l o n g a b a s a l s u r f a c e , a l o n g w h i c h

over ly in g s t ra ta a re de tache d P ie rce, 1963) .

D e t a c h m e n t

i s n o w c o m m o n l y u s e d f o r a r e g i o n a l ly

ex tens ive , gen t ly d ipp ing norm al fau l t F ig . 1 ); they

a r e c o m m o n l y a s s o c i a t e d w i t h e x t e n s i o n i n

m e t a m o r p h i c c o r e c o m p l e x e s

a n d c a n d i s p l a c e

c r y s t a l l i n e r o c k s . A l t h o u g h t h e t e r m i s o f t e n u s e d

s y n o n y m o u s l y w i th

d~collement,

R a m s a y a n d H u b e r

1 98 7) s u g g e s t t h a t d e t a c h m e n t s a r e l o w - a n g l e f a u l t s

t h a t a r e n e a r l y , b u t n o t e x a c t l y , p a r a l l e l t o a n y o n e

h o r i z o n .

Diapir:

Orig ina l ly used by Mraz ec 1915 , c i t ed by P r ice

and Cosgrove , 1990) fo r s a l t bod ies in the cores o f

d o m e s a n d a n t i c l i n e s .

Dia p i r

i s n o w c o m m o n l y u s e d

f o r a n y b o d y o f r o c k t h a t b e h a v e d a s a fl u i d o v e r

t h e t i m e - s c a l e d u r i n g w h i c h i t w a s e m p l a c e d

u p w a r d s t h r o u g h b r i t t l e r o c k s b y b u o y a n c y - d r i v e n

f l o w . D i a p i r s i n c l u d e c e r t a i n i g n e o u s i n t r u s i o n s a n d

s a lt d o m e s. T h e y a r e c o m m o n l y a c c o m m o d a t e d b y

nor m a l fau l t s e . g. Daviso n e t a l ., 1996, f ig . 7 ) F ig .

1). See

halokinesis .

Di la t ion:

A n i n c r e a s e

(posi t ive

di la t ion) o r a dec rease

(negat ive

di la t ion) in vo lu m e e .g . P r ice and

Cosgrove , 1990) .

Di la t i o n a l j o g :


ex t en s io n a l o vers t ep

o r

p u l l -a p a r t

Sibson, 1989, fig. 6).

Dip sep a ra t i o n .

T h e s e p a r a t i o n o f a m a r k e r p l a n e

m e asur ed pa ra l l e l to the d ip o f a fau l t e . g. Gi l l ,

1935; Hil ls , 1940). For a purely

dip-slip

faul t i . e .

n o r m a l o r t h r u s t f a u l t ) , t h e @

sep a ra t i o n

is

iden t i ca l to the

d i sp la cemen t

o f t h e f a u l t .

Dip-slip.

T h e c o m p o n e n t o f

d i sp la cemen t

para l l e l to

the d ip o f the fau l t p lane c f . s t r ike -s l ip ) Re id e t

a l . , 1 9 1 3 ) . N o r m a l a n d t h r u s t f a u l t s a r e b o t h

@ - s l i p

f a u l t s ,

b e i n g d o m i n a t e d b y d i p - s l i p d i s p l a c e m e n t

e.g. Reid et al. , 1913).

Displacement.

T h e r e l a t i v e m o v e m e n t b e t w e e n t w o

o r i g i n a l l y a d j a c e n t p o i n t s o n t h e s u r f a c e o f a f a u l t ,

i .e . t h e m a g n i t u d e o f t h e

disp lacement vector

e.g.

Le i th , 1923) . The d i sp lacem ent can be curved , so

n e e d n o t b e a d i r e c t l i n e b e t w e e n t w o o r i g i n a l l y

a d j a c e n t p o i n t s .

D i s p l a c e m e n t - d i s t a n c e ( ~ x ) a n a l y s i s :

A m e t h o d u s e d

t o i l l u s t r a t e h o w d i s p l a c e m e n t v a r i e s a l o n g a

g e o l o g i c a l s t r u c t u r e . T h e m e t h o d h a s b e e n u s e d t o

d e s c r i b e t h e d i s p l a c e m e n t g r a d i e n t o f f a u l t s , d y k e s ,

e t c. , a n d t h e r e b y i n f e r t h e i r d e v e l o p m e n t M u r a o k a

a n d K a m a t a , 1 9 8 3 ; W i l l ia m s a n d C h a p m a n , 1 9 83 ;

C h a p m a n a n d W i l l ia m s , 1 9 8 4 ; P o l l a r d a n d S e g a ll ,

1987; W alsh and Wat te rson , 1987) . P roced ure : i )

s t a r t a t a f a u l t t i p d i s ta n c e , x 0 = 0 , d i s p l a c e m e n t ,

d0= 0) ; i i) a t d i s t ance Xl a lon g the fau l t t race ,

m e asure d i sp lacem ent d l ; i ii ) a t d i s t ance x2 a lon g

the fau l t trace , m easu re d i sp lacem ent d2 ; iv) repea t

t h e p r o c e s s a s m a n y t i m e s a s p o s s i b l e a l o n g t h e

t r a c e o f t h e f a u lt ; v ) p l o t a g r a p h o f d i s p l a c e m e n t

y-ax i s ) aga ins t d i s t ance x -ax i s ).

Disp la cemen t -d i s t a n ce a n a l ys i s , cu mu la t i ve :

A m e t h o d

o f a n a l y s i n g h o w d i s p l a c e m e n t v a r i e s i n a f a m i l y o f

f a u l t s C h a p m a n a n d W i l l i a m s , 1 98 4 ). P r o c e d u r e f o r

a n a l y s i n g n o r m a l o r t h r u s t f a u l t s i n c ro s s - se c t io n : i )

s e l e c t a p o i n t o n a m a r k e r b e d a l o n g a c r o s s -


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D.C.P. P eacock et al./ Journal of Structural Geology 22 (2000) 291-305

295

s e c ti o n ; ( ii ) f o l l o w t h e b e d a n d m e a s u r e

d i sp lacem ent (d l ) and d i s tance (Xl ) fo r the f i r s t

f a u l t ; ( ii i) m e a s u r e d i s p l a c e m e n t ( d 2 ) a n d d i s t a n c e

(x2) fo r the s econd fau l t ; add d l to

d2;

( iv ) con t inue

the p roces s fo r a l l o f the fau l t s in the s ec t ion ; (v )

p l o t a g r a p h o f c u m u l a t i v e d i s p l a c e m e n t ( y - a x i s)

aga ins t d i s t ance (x -ax i s ) .

Dis p la c e me n t - l e n g th r a t io . M a x i m u m d i s p l a c e m e n t o n

a f a u l t s u r f a c e o r a f a u l t t r a c e , d i v i d e d b y t h e f a u l t

l e n g th

or the t race l eng th ( s ee Barne t t e t a l . , 1987;

W a l s h a n d W a t t e r s o n , 1 9 8 8 ; C o w i e a n d S c h ol z,

1992a; Gil lespie e t a l . , 1992; Dawers e t a l . , 1993).

T h e

s l ip

t o l e n g t h r a t i o f o r s l i p d u r i n g l a r g e

ea r thquakes i s d i s cus sed by S cholz e t a l . (1986) .

S o m e a u t h o r s u s e

l e n g th - d i s p la c e me n t r a t io .

D is p la c e me n t v e c to r .

T h e m a g n i t u d e a n d o r i e n t a t i o n o f

t h e l i n e c o n n e c t i n g t w o o r i g i n a l l y a d j a c e n t p o i n t s i n

t h e

h a n g in g wa l l

a n d

f o o t w a l l

of a fau l t . S ee

d i s p la c e me n t .

Domino faul ts . S y s t e m o f p l a n a r r o t a t i n g n o r m a l

f a u l t s , i n w h i c h t h e d i p o f a p a r t i c u l a r s t r a t i g r a p h i c

d a t u m i s a p p r o x i m a t e l y c o n s t a n t ( e . g . T w i s s a n d

M o o r e s , 1 99 2) . A n e x a m p l e o f d o m i n o f a u l t s is

show n by R an som e e t a l. (1910 , f ig . 15) , bu t

d o m i n o

f a u l t

w a s n o t u s e d . D o m i n o f a u l ts c a n p as s d o w n

in to a

d e t a c h m e n t .


b o o k s h e l f

. fau l ts (e . g . Ram say and Huber , 1987 , f ig . 23 . 19) and

w i t h

r o t a t io n a l p l a n a r n o r m a l f a u l t s

o f W e r n i c k e a n d

Burchf ie l (1982). G am on d (1983) , howev er , uses

d o m i n o f o r a r h o m b - s h a p e d , m i n e r a l i s e d a r e a a t a n

e x te n s io n a l o v e r s te p

( s y n o n y m o u s w i t h

p u l l - a p a r t ) .

D-value:

T h e p o w e r - l a w e x p o n e n t ( D ) f o r t h e

d i s p l a c e m e n t s o f a f a u l t p o p u l a t i o n , s u c h t h a t

N = c x U - D , w h e r e N = n u m b e r o f f a u l t s w i t h a

d i s p l a c e m e n t g r e a t e r t h a n U , a n d c i s a c o n s t a n t

(e . g . Walsh and Wat te rson , 1992; Gi l l e sp ie e t a l . ,

1 9 9 3 ) . S y n o n y m o u s w i t h

C- v a lu e

o f M a r r e t t a n d

Al lm end inge r (1991 ) .

Ef fe c t i v e t e n s io n :

T h e c o n d i t i o n i n w h i c h f l u i d p r e s s u r e

exceeds the l eas t com pres s ive s t re s s , enab l ing

e x te n s io n . f r a c tu r e s

t o f o r m ( se e H u b b e r t a n d R u b e y ,

1959).

Extension. The inc rease in the l eng th o f a l ine , such

t h a t e x t e n s i o n , e = ( l l - l o )/ lo , whe re lo = o r ig ina l

l eng th o f the line , an d l l = new leng th o f the l ine .

Extens ion can be pos i t ive , so the l ine inc reases in

l e n g t h , o r n e g a t i v e , s o t h a t c o n t r a c t i o n o c c u r s .

R e g i o n a l e x t e n s i o n

r e f e r s t o d e f o r m a t i o n d o m i n a t e d

b y e x t e n s i o n i n o n e h o r i z o n t a l d i r e c t i o n .

E x t e n s i o n ( a l ) f a u l t :

A f a u l t c a u s i n g e x t e n s i o n i n t h e

h o r i z o n t a l p l a n e , i . e . n o r m a l a n d n o r m a l / o b l i q u e -

s l ip fau l t s (e . g . Gogue l , 1952) . Of ten used

s y n o n y m o u s l y w i t h

n o r m a l f a u l t .

Ex te n s io n ( a l ) f r a c tu r e .

A f r a c t u r e p r o d u c e d b y

o p e n i n g a p p r o x i m a t e l y p e r p e n d i c u l a r t o t h e w a l l s ,

a n d t h a t u s u a l ly p r o p a g a t e d a s a m o d e I c r a c k

(P ol la rd and S ega l l , 1987) . Ex tens ion f rac tu res a re

u s u a l l y f o r m e d i n

e f fec t ive tens ion ,

i . e . h igh pore -

f lu id p res sure (e . g . Gr os s a nd Enge lde r , 1995) .

F i l le d e x t e n s i o n f r a c t u r e s i n c l u d e d y k e s a n d v e in s .

F a u l t - b e n d f o l d :

A f o l d d e v e l o p e d i n t h e

wa l l - r o c k s

to

a c c o m m o d a t e d i s p l a c e m e n t a r o u n d a . fau l t bend. A

de ta i l ed desc r ip t ion i s g iven by S uppe (1985) . S ee

f a u l t - r e l a t e d f o l d .

Fa u l t ju x ta p o s i t io n d iag r am.

A d i a g r a m u s e d t o p r e d i c t

t h e j u x t a p o s i t i o n s o f h a n g in g wa l l a n d f o o t w a l l

l i t h o l o g i e s f o r a g i v e n f a u l t g e o m e t r y a n d

disp lacem ent (Knipe , 1997) . I t can be used to

e s t i m a t e t h e s e a l in g p o t e n t i a l o f a f a u l t .

Fault- l ine scarp .

A s t e ep s l o p e o r c l if f f o r m e d b y

d i f f e r e n ti a l e r o s i o n a l o n g a f a u l t , t h e h e i g h t o f

w h i c h m a y n o t r e f l e c t r e l a t i v e m o v e m e n t o n t h e

fau l t (e . g . Ra jendran e t a l . , 1996) . S e e fa u l t s c a r p .

Fault popula t ion .

The fau l t s o f a l l s ca le s tha t ex i s t in

a n a r e a o r r e g i o n , f o r m e d d u r i n g o n e o r m o r e

d e f o r m a t i o n e v e n t s .

Fa u l t p o p u la t io n a n a ly s i s

i n v o l v e s t h e s t u d y o f t h e s c a l i n g r e l a t i o n s h i p s a n d

s t ra in o f the fau l t s (e .g . Cow ie e t a l ., 1996) . S ee

f r a c t a l

a n d

p o w e r - l a w .

Fault- re la ted . fo ld . A f o l d d e v e l o p e d i n o n e o r b o t h o f

t h e

walls

o f a f a u l t o r a t t h e f a u l t t ip , c a u s e d b y

f a u l t

p r o p a g a t io n ,

d r a g o r b y t h e n o n - p l a n a r

g e o m e t r y o f t h e f a u l t ( e. g. R i c h , 1 9 3 4 ; D a h l s t r o m ,

1970; Anastas io e t a l . , 1997). A

b r e a k th r u s t

(a fo ld

cu t by a th rus t ) i s shown by Wi l l i s (1839) , and

v a r i o u s f a u l t - r e l a t e d f o l d s a r e s h o w n b y S t o c e s a n d

Whi te (1935 , f igs . 286 291) . Recen t desc r ip t ions o f

f o l d s t h a t a r e r e l a t e d to t h e p r o p a g a t i o n o f n o r m a l

fau l t s in m ap v iew a re g iven by S ch l i s che (1995) and

b y J a n e c k e e t a l . ( 1 9 9 8 ) , w h i l e H a r d y a n d M c C l a y

(1999) desc r ibe fo lds re la ted to norm a l fau l t

p r o p a g a t i o n i n c r o s s - s e c t i o n .

Fault rock .

R o c k a l o n g a f a u l t p l a n e w i t h t e x t u r e a n d /

o r c h e m i c a l c o m p o s i t i o n c o n t r o l l e d b y d e f o r m a t i o n

a n d a l t e r a t i o n a l o n g t h e f a u l t . A c c o u n t s a n d

c l a s s i f i c a t i o n s o f f a u l t r o c k s i n c l u d e t h o s e b y H o b b s

et a l . (1976) and Sibson (1977).

Fa u l t - r o c k w id th . See t h i c k n e s s , fa u l t .

Faul t scarp .

D e f i n e d b y L e i t h ( 1 9 2 3 ) a s a l a n d f o r m

c a u s ed a t t h e E a r t h s s u r fa c e b y f a u l t m o v e m e n t o r

b y l a t e r e r o s i o n a l o n g t h e f a u l t t h a t l e a v e s o n e s i d e

o f t h e f a u l t p l a n e s t a n d i n g h i g h e r t h a n t h e o t h e r

s i d e . C o m m o n u s a g e i s n o w f o r a t e c t o n i c l a n d f o r m

c o i n c i d e n t , o r r o u g h l y c o i n c i d e n t , w i t h a f a u l t p l a n e

t h a t h a s d i s l o c a t e d t h e g r o u n d s u r f a c e , i . e . i t h a s

n o t b e e n s t r o n g l y m o d i f i e d b y w e a t h e r i n g a n d

e r o s i o n ( S t e w a r t a n d H a n c o c k , 1 9 9 0 ) . S e e f a u l t - l i n e

scalT .

Fault s tra in .

U s e d b y J a m i s o n ( 1 9 8 9 ) t o d e s c r i b e t h e

d e f o r m a t i o n c a u s e d b y a n u m b e r o f f au l ts , b e c au s e

s t r a in

s h o u l d o n l y b e a p p l i e d to c o n t i n u o u s

d e f o r m a t i o n .


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D.C.P. P eacock et a l./ Journal of Structural Geology 22 (2000) 291-305

Flexural uplift or subsidence: B u o y a n c y - i n d u c e d

ver t i ca l ( i sos t a t i c ) defo rmat i on t ha t decreases i n

magn i t ude away f rom a f au l t ( e .g . Egan , 1992) .

F l exu ra l up l i f t and subs i dence a re t yp i ca l l y

model led as an elast ic response to faul t s l ip (e.g .

Ro ber t s and Yi e l d ing , 1991) . F l exu ra l exp l ana t i ons

are commonl y accep t ed fo r cer t a i n cases

o f f o o t w a l l

uplift

a n d

hanging wall subsidence.

Flower structure.

A sys t em o f f au l ts t ha t

splay

u p w a r d

wi t h i n a s t r i ke- s l i p f au l t zone (Hard i ng and Lowel l ,

1979).

Negative

f l ower s t ruc t u res i nvo l ve s t eepen i ng

upwards ex t ens i ona l sp l ay f au l t s , whereas

positive

f l ower s t ruc t u res i nvo l ve sha l l owi ng upwards

con t r ac t i ona l sp l ay f au l ts (Hard i ng , 1983 , 1985) .

Footwall: An o l d mi n i ng t e rm fo r t he rock mass t ha t i s

be l ow a l ode o r f au l t ; ea r l y u sage o f

foo twa l l

is

g iven by Dennis (1967) .

Footwall

h a s b e e n e x t e n d e d

t o i nc l ude t he vo l ume o f rock be l ow a d i pp i ng f au l t ,

i .e . t he up t h row n s i de o f a no rma l f au l t .

Footwall cut-off.

The l i ne i n t he foo t wal l mark i ng t he

b o u n d a r y b e t w e e n a f a u l t s u r f a c e a n d a p l a n a r

marker (bed , dyke , e t c . ) t ha t i s d i sp l aced by t he

faul t (e.g . Gibson et al . , 1989) (Fig . 1) . Synonymous

wi t h

footwall trace

(Gi ll , 193 5) . See

cu t -o f f

a n d

hanging wall cut-off.

Footw all uplift:

Upl i f t that occurs below a faul t , e .g . in

t he foo t wal l o f a no rma l f au l t ( e .g . Jackson and

M c K e n z i e , 1 9 8 3 ) . S y n o n y m o u s w i th

rollunder

(Barnet t et al . , 1987) .

Seeflexural upl i f t

a n d

hanging

wall subsidence.

Fractal:

T h e g e o m e t r y w h e r e b y o b j e c t s a r e s c a l e

i ndependen t , be i ng

seale invariant

at al l scales

be t wee n upper and l ower li mit s; a ny po r t i on o f the

sys t em i s geomet r i ca l l y s i mi l a r t o t he who l e sys t em

(Ma nd l eb ro t , 1982 ; Turco t t e , 1989 ; Gi l l esp i e e t a l .,

1993) . Fo r na t u ra l ob j ec t s ,

f rac ta l

i s general ly used

i f the s tat i s t ical proper t ies are

scale invariant

a n d

exhibi t a power-law distribution. N o r m a l f a u l t s h a v e

been shown t o be f r ac t a l ( e .g . Scho l z and Cowi e ,

1990; M arre t t and Al lmen dinger , 1992).

Fracture:

Geol og i ca l f r ac t u res i nc l ude such

approx i mat e l y p l anar d i scon t i nu i t i es as dykes ,

f au l ts , j o i n t s and ve i ns . App ear s t o be synon ym ous

wi t h

discontinuity

(Pr i est and Hu dson , 1976 , 1981).

Fracture nucleation.

The i n i t i a t ion o f a fr ac t u re t ha t

t hen

propagates

(e.g . Segal l and Pol lard , 1983;

Reches and Lockner , 1994) .

Gouge.

Defined by Reid et al . (1913) as pulver i sed

rock , genera l l y c l ay - l i ke when moi s t , t ha t occu r s

be t ween t he wal l s o f a f au l t . Def i ned by S i bson

(1977, table 1) as an incohesive faul t rock wi th a

r a n d o m f a b r ic i n w h ic h f r a g m e n t s c o m p r i s e < 3 0

o f t h e r o c k m a s s .

Graben:

Lon g-and r e l a t ive l y nar row area o f subs i dence

m o s t l y b o u n d e d b y s u b - p a r a l l e l n o r m a l f a u l t z o n e s

t ha t d i p t owards t he a r ea o f subs i dence (Rei d e t a l . ,

1913 ; Denn i s , 1967) (F i g. 1 ). Graben s a r e co mm onl y

b o u n d e d b y

horsts. Graben

o r i g i n a t e d a s a G e r m a n

mi n i ng t e rm (Denn i s , 1967) . See

rift.

Granulation seam.

A p l a n a r z o n e o f d e f o r m a t i o n i n

w h i c h p o o r l y c o n s o l i d a t e d g r a i n s m o v e p a s t e a c h

o t h e r ( e.g . P i t tm a n , 1 9 8 1 ) . S y n o n y m o u s w i t h

deJormation band

(Knot t , 1994) .

Growth faul t:

A normal g rowt h f au l t i s charac t e r i sed

by : ( a ) an i ncrease i n d i sp l acemen t down t he d i p o f

t he f au l t ; and by (b ) t h i cker sed i men t s i n t he

hanging wall

near t he f au l t t han i n t he

foo twa l l

or in

t he

hanging wall

aw ay f rom t he fau l t (Ocam b, 1961)

(Fig . 1) . This impl ies that , dur ing sedimentat ion, the

fau l t was ac t i ve and cu t t he Ear t h ' s su r f ace .

Synonymous t e rms are g i ven by Denn i s (1967) .

Growth-fault basin:

Bas i n t ha t t h i ckens t owards , and i s

related to , a

growth faul t

( e .g . Harms and Pr i ce ,

1992).

Half-graben:

A s y m m e t r i c a r e a o f s u b s i d e nc e c o n t r o l le d

b y hanging wall subsidence above a s ingle

con t ro l l i ng

(basin-bounding)

fault (e.g. Barr, 1987)

(Fig . 1) . A hal f -graben typical ly contains a

hanging

wall sed i men t ary wedge t ha t t h i ckens t owards t he

fau l t , w i t h o l der beds hav i ng s t eeper d i ps t han

y o u n g e r b e d s .

Rollover

i n a ha l f -g raben can be

con t ro l l ed by a

listric

faul t , whi le recent

i n t e rp re t a t i ons have i nvo l ved app rox i mat e l y p l anar

faul t s (e.g . R ob er t s and Yielding, 1991 , f igs . 1 and

4).

See flexural subsidence.

Halokinesis:

Prop osed b y Trushe i m (1957, c i ted by

Trushe i m, 1960) fo r t he fo rm at i on o f sa l t s truc t u res ,

and t he i r s t ruc t u ra l and s t r a t i g raph i c i mp l i ca t i ons ,

r e su l ti n g f r o m a u t o n o m o u s m o v e m e n t o f s a lt d r iv e n

by g rav i ty (e .g . S t ewar t and C owa rd , 1995) .

H a l o k i n e s i s i s c o m m o n l y a c c o m m o d a t e d b y n o r m a l

fau l t s ( e.g. Koe s t l e r and Eh rman n , 1991) . See

diapir.

Hanging wall: A n o l d m i n i n g t e r m f o r t h e r o c k m a s s

t ha t i s above a l ode o r f au l t ; ea r l y u sage o f

hanging

wall

i s g i ven by Denn i s (1967) . Hang i ng wal l has

b e e n e x t e n d e d t o i n c l u d e t h e v o l u m e o f r o c k a b o v e

a d i pp i ng f au l t , i .e . t he dow nt h ro wn s i de o f a

no rmal f au l t .

Hanging wall cut-off

The l ine in the

hanging wall

t ha t

m a r k s t h e b o u n d a r y b e t w e e n a f a u l t s u r f a c e a n d a

p l anar marker (bed , dyke , e t c . ) t ha t i s d i sp l aced by

the fau l t (e.g . Gi bso n et al ., 19 89 ) (Fig . 1).


hanging wall trace

(Gill, 1935).

See

cu t -o f f

a n d

footwall cut-off.

Hanging wall subsidence:

T h e d o w n w a r d m o v e m e n t o f

t he

hanging wall

of a no rm al f au l t (e .g . Jack son and

M c K e n z i e , 1 9 8 3 ) .

Hanging wall

subsidence i s

i l lust rated by DeSi t ter (1956, f ig . 73) . See

foo twa l l

u p l i f t

Hard-linkage:

T h e g e o m e t r y o r p r o c e s s w h e r e b y t w o

fau l t s a r e connec t ed by one o r more (u sua l l y

smal ler ) faul t s that are v is ib le at the scale of


7/15

D. C . P . P e a c o c k e t a l . / J o u rn a l o f S t ru c tu ra l Ge o lo g y 2 2 2 0 0 0 ) 2 9 1 - 3 0 5 97

o b s e r v a t i o n W a l s h a n d W a t t e r s o n , 1 99 1) . S e e

c o n n e c ti n g f a u l t s

a n d

so f t - l i n ka g e .

H e a v e :

D e f i n e d b y G e i k i e 1 8 82 ) a s a h o r i z o n t a l

d i s p l a c e m e n t o f s t r a t a a t a f a u lt . D e f i n e d m o r e f u l l y

by Hi l l s 1940) an d by Bi l l ings 1942) a s the

h o r i z o n t a l c o m p o n e n t o f t h e

d ip - sep a ra t i o n

o f a

n o r m a l o r r e v e r s e f a u l t m e a s u r e d i n v e r t i c a l c r o s s -

sec t ion pe rp end icu la r to the fau l t s t r ike F ig . 1 ).

H e a v e

i s d e f i n e d i n t e r m s o f t h e

sep a ra t i o n ,

h e n c e i t

a p p l i es t o t h e f a u l t e d g e o m e t r y o f a p l a n e a n d n o t

t o t h e d i s p l a c e m e n t o f th e f a u l t . O n l y f o r a p u r e

dip-slip

f a u l t n o o b l iq u e - s li p c o m p o n e n t ) i s t h e

h e a v e e q u i v a le n t t o t h e h o r i z o n t a l c o m p o n e n t o f t h e

d i sp la cemen t .

See

t h ro w.

E a r l y u s a g e i s g i v e n b y

Dennis 1967) .

Horse.

U s a g e o f t h e o l d m i n i n g te r m

h o rse

h a s

c h a n g e d . F o r e x a m p l e , M i l ls 1 79 0 ) a p p e a r s t o u se

h o rse

t o m e a n

d y k e . H o r s e

i s now de f ined a s a fau l t -

b o u n d b l o c k o f r o c k e .g . B u t l e r , 1 98 2) . I n a n o r m a l

f a u l t s y s t e m , h o r s e s c a n r e p r e s e n t a

b rea ch ed re la y

r a m p

P eaco ck an d S ande rson , 1994 ) F ig . 1 ). S ee

b lo ck , f a u l t .

H o r s t :

E l o n g a t e a r e a o f u p li f t m o s t l y b o u n d e d b y s u b -

p a r a l l e l n o r m a l f a u l t z o n e s t h a t d i p a w a y f r o m t h e

a rea o f up l i f t e . g . Re id e t a l ., 1913; Den nis , 1967)

F i g. 1 ). H o r s t s a r e c o m m o n l y b o u n d e d b y

g ra b en s

o r

hal f -grabens.

In t era c t i o n , f a u l t :

M e c h a n i c a l i n t e r a c t i o n b e t w e e n

f a u l t s i n v o l v e s t h e b e h a v i o u r a n d d e v e l o p m e n t o f

o n e f a u l t b e i n g i n f l u e n c e d b y a n o t h e r f a u l t o r f a u l t s

e .g . S e g a ll a n d P o l l a r d , 1 9 8 0 ; A y d i n a n d S c h u l tz ,

1990; Bf i rgm ann e t a l . , 1994) .

Overs t ep p in g

n o r m a l

f a u l t s i n t e r a c t a c r o s s

t ra n s f er zo n es

Morley e t a l . ,

1990).

R i f t

i n t e r a c t i o n i s d e s c r i b e d b y N e l s o n e t a l .

1992).

Inversion.

O r i g i n a l l y u s e d f o r t h e o v e r t u r n i n g o f s t r a t a ,

so the s equence i s reve rse e .g . Mu rch i son , 1859).

In vers io n

is n o w c o m m o n l y u s e d f o r th e

rea c t i va t i o n

of a d ip -s l ip fa u l t such th a t th e re i s a reve rsa l o f the

s e n se o f t h r o w e .g . S to n e l e y , 1 9 8 2 ; B u c h a n a n a n d

Buchanan , 1995) .

Reverse - rea c t i va t i o n

o f a n o r m a l

f a u l t o r t h e c o n t r a c t i o n o f a r e g i o n t h a t p r e v i o u s l y

u n d e r w e n t e x t e n s i o n i s t e r m e d

posi t ive inversion .

A l t e r n a t i v e l y ,

negat ive inversion

i s t h e n o r m a l -

r e a c t i v a t i o n o f a r e v e r s e f a u l t o r t h e e x t e n s i o n o f a

r e g i o n t h a t p r e v i o u s l y u n d e r w e n t c o n t r a c t i o n e .g .

W i l l i am s e t al . , 1989) . F o r a d i s cus s io n of the usage

o f

inversion

a n d

react iva t ion ,

see N ee dh am 1989) .

I s o l a t e d f a u l t :

A f a u l t t h a t w a s n o t a f f e c t e d b y

in teract ion

w i t h o t h e r f a u l t s d u r i n g i t s

p ro p a g a t io n

e . g . M u r a o k a a n d K a m a t a , 1 9 8 3 ; W a l s h a n d

W a t t e r s o n , 1 9 8 7 ) . A n i s o l a t e d f a u l t i s u s u a l l y

c h a r a c t e r i s e d b y a d i s p l a c e m e n t m a x i m u m n e a r t h e

c e n t r e o f t h e f a u l t t r a c e , w i t h d i s p l a c e m e n t

d e c r e a s i n g a p p r o x i m a t e l y l i n e a r l y t o w a r d s t h e t i p s

B a r n e t t e t a l ., 1 9 8 7 ; W a l s h a n d W a t t e r s o n , 1 98 7) .

H a r d i n g a n d L o w e l l 1 97 9 ) d e s c r ib e

so l i t a ry

s t r u c t u r e s , t h a t a r e i s o l a t e d , s i n g u l a r f e a t u r e s . N i c o l

et a l . 1996) descr ibe

u n res t r i c t ed

fau l t s , tha t a re

b l i n d d o n o t i n t e r s e c t t h e f re e s u r f a ce ) a n d t h a t

h a v e n o t i n t e r a c t e d w i t h o t h e r f a u l t s o r w i t h

s u b s t a n t i a l b o d i e s o f i n c o m p e t e n t r o c k .

Jog.

Us ed by S ibson 1989 , f ig . 6 ) fo r an

overstep

o r

b e n d

t h a t c o n n e c t s t w o s u b - p a r a l l e l b u t n o n -

co l l inea r por t ion s o f a fau l t zone . S ibson 1989)

d i v i d e s j o g s i n t o

di la t ional

a n d

ant i -d i la t ional ,

t h a t

a re

ex t en s io n a l

a n d

co n t ra c t i o n a l ,

re spec t ive ly .

L e n g t h , f a u l t :

T h e d i s t a n c e b e t w e e n t h e t i p s o f a f a u l t ,

u s u a l l y m e a s u r e d a l o n g a f a u l t t r a c e a n d i n t h e

hor izon ta l p lane e . g. S cholz an d Cowie , 1990;

P e a c o c k , 1 99 1) . S y n o n y m o u s w i t h

trace length.

N o t e , h o w e v e r , t h a t

length

i s used by Barne t t e t a l .

1987) and by W alsh and W at te rso n 1988 , fig . 1 )

f o r t h e m a x i m u m d i s t a n c e p a r a l l e l t o t h e s l i p

d i r e c t i o n o f a f a u l t .

Linkage.

T h e p r o c e s s b y w h i c h , o r c o n d i t i o n i n w h i c h ,

t w o o r i g i n a l l y s e p a r a t e f a u l t s b e c o m e c o n n e c t e d

P o l l a r d a n d A y d i n , 1 98 4) .

Li s t r i c :

I n t r o d u c e d b y Su e s s 1 90 9) f o r a n o r i g i n a l ly

c u r v e d f a u l t , s u p p o s e d l y b e c a u s e i t i s a n c i e n t G r e e k

f o r

shovel.

W h e n a p p l i e d t o n o r m a l f a u l t s ,

l istric

u s u a l l y i n d ic a t e s a d e c r e a s e i n d i p d o w n w a r d s e .g .

Davison , 1986; Wi l l i am s and Vann , 1987) . L i s t r i c

n o r m a l f a u l t s m a y p a s s d o w n w a r d s i n t o a

d e t a c h m e n t

or a

d~collement

F i g . 1 ) . A l t h o u g h

rollover

w a s p r e v i o u s l y s e e n a s p r o o f o f a l i s t r i c

g e o m e t r y , n o r m a l f a u l t s w i t h r o l l o v e r s a r e n o w

o f t e n i n t e r p r e t e d a s b e i n g p l a n a r e .g . R o b e r t s a n d

Yie ld ing , 1991 , f igs . 1 and 4). L i s t r i c geo m et r i e s a re

c o m m o n l y o b s e r v e d t o o c c u r w i t h i n l a n d s l i d e s ,

d e l t a ic d e p o s i ts a n d i n m u c h o f th e B a s i n a n d

R a n g e P r o v i n c e , U S A e .g . B e a c h a n d T r a y n e r ,

1991, fig. 2).

Membrane.

A f a u l t p l a n e t h a t i s i m p e r m e a b l e e .g .

Knipe, 1992).

M e t a m o r p h i c c o r e c o m p l e x :

A g e n e r a l l y d o m a l o r

a r c h - l i k e u p l i f t o f d e f o r m e d m e t a m o r p h i c a n d

p l u t o n i c r o c k s o v e r l a i n b y t e c t o n i c a l l y d e t a c h e d a n d

d i s t e n d e d r e l a t i v e l y u n - m e t a m o r p h o s e d c o v e r r o c k s

C o n e y , 1 9 8 0 a ,b ) . O r i g i n a n d e a r l y u s a g e o f

m e t a m o r p h i c c o r e c o m p l e x

i s d i s c u s s e d b y C o n e y

1 9 8 0 a ) , w h i l e t h e d i s t i n c t i o n b e t w e e n

m e t a m o r p h i c

c o m p l e x e s

a n d

m y l o n i t i c d e t a c h m e n t c o m p l e x e s

is

d i s c u s se d b y D e W i t t 1 98 0) . T h e f a u l t s t h a t e x h u m e

m e t a m o r p h i c c o r e c o m p l e x e s t y p i c a l l y h a v e l o w t o

m o d e r a t e d i p s , a n d m a y b e n o r m a l f a u l t s e .g .

Cr i t t end en e t a l . , 1980; Dew ey, 1988) o r th rus t s e . g.

Da l lm e yer e t a l , 1992) .

Net s l i p .

See

slip.

Ne two rk , f a u l t .

A s y s t e m o f l i n k e d a n d i n t e r a c t i n g

f a u l t s , m o r e d i f f u s e t h a n a

f a u l t z o n e

e.g. S toces

and Whi te , 1935 , f ig . 327) . When m ore than two


8/15

298

D.C.P. Peacock et al./Journ alofStructu ral Ge o~g y22 (2000) 291-305

fau l t s e t s a re p resen t , the ne twork represen t s a

t r i ax ia l s t ra in sys tem Reches , 1983; Kr an t z , 1988).

No rma l d ra g .

F o l d i n g a d j a c e n t t o a f a u l t s u c h t h a t a

m a r k e r i s c o n v e x t o w a r d s t h e s l i p d i r e c t i o n , u s u a l l y

caused by re s i s t ance to s lip e . g. Ha m b l in , 1965;

Bidd le and Chr i s t i e -Bl ick , 1985) . S ee

reverse drag.

N o r m a l . f a u l t :

A f a u l t i n w h i c h t h e

h a n g in g wa l l

rocks

a b o v e t h e f a u l t ) i s d i s p l a c e d d o w n w a r d s i n r e l a t i o n

to the

f o o t w a l l .

T h e t e r m o r i g i n a t e d i n E n g l i s h c o a l -

m i n i n g , w h e r e

n o r m a l

f a u l t s w e r e m e t m o s t

co m m on ly e . g . Den nis , 1967).

O f } e t :

T h e a p p a r e n t

d i sp la cemen t

o f a m a r k e r e .g .

Hobbs e t a l . , 1976) . Note , however , tha t

o f f se t

h a s

a ls o b e e n u s e d s y n o n y m o u s l y w i t h

overstep

e.g.

S ega l l and P o l la rd , 1980) . We sugges t tha t th i s

l a t t e r u s a g e s h o u l d b e a v o i d e d b e c a u s e o f t h e m o r e

c o m m o n u se o f

o f f se t

f o r t h e a p p a r e n t d i s p l a c e m e n t

o f a m a r k e r .

Orogenic collapse.

G r a v i t y - i n d u c e d e x t e n s i o n o f a n

o r o g e n i c b e l t , u s u a l l y i n f e r r e d t o o c c u r w h e n

c o m p r e s s i o n a l s t r e s s e s a r e r e l a x e d d u r i n g o r a f t e r a

m o un ta in -bu i ld in g even t e .g . Dew ey, 1988).

Overlapping faults.

T w o s u b - p a r a l l e l , n o n - c o l l i n e a r

f a u l t s w i t h t r a c e s t h a t p a r t l y e x t e n d p a s t e a c h o t h e r .

Overlap

i s t h e d i s t a n c e b e t w e e n t h e e n d s o f t w o

o vers t ep p in g

f a u l t s , m e a s u r e d p a r a l l e l t o t h e f a u l t s

e .g . R o d g e r s , 1 98 0) . S y n o n y m o u s w i t h

jog , overstep

a n d

stepover.

N o t e , h o w e v e r , t h a t

overlap

has a

d i f f e r e n t m e a n i n g i n s e d i m e n t o l o g y e .g . D e n n i s ,

1967).

Overstep:

T h e a r e a b e t w e e n t w o s u b - p a r a l l e l , n o n -

co l l inea r fau l t s e . g . B idd le and Chr i s t i e -Bl ick ,

1 98 5) . S y n o n y m o u s w i t h

j o g

Sibson, 1989),

of fset ,

overlapping fau l ts

a n d

s t ep o ver

A y d i n a n d N u r ,

1982) . Note tha t But le r 1982) de f ines

overstep

p ro p a g a t io n

o f t h r u st s a s t h e p r o p a g a t i o n o f a

f a m i l y o f th r u s t s i n t h e d i r e c t i o n o p p o s e d t o t h e

th rus t t ranspor t d i rec t ion , i . e . a new th rus t deve lops

in the

h a n g in g wa l l

o f a n o l d e r t h r u s t .

Overs t ep

h a s

a d i f f e re n t m e a n i n g i n s e d i m e n t o l o g y e .g . B i d d l e

and Chr i s t i e -Bl ick , 1985) .

Overstep , a long-str ike:

A n

overstep

vis ib le in m ap-v iew.

F o r n o r m a l f a u l t s , a n a l o n g - s t r i k e o v e r s t e p i s

n e i t h e r

co n t ra c t i o n a l

n o r

ex t en s io n a l ,

a n d i s m a r k e d

by a

t ra n s f er zo n e

e.g. Morley e t a l . , 1990).

Overstep, contractional.

A n

o vers t ep

t h a t h a s t o b e

a c c o m m o d a t e d b y

co n t ra c t i o n ,

e.g. a r ight-s tep

be tween s in i s t ra l fau l t s . Th i s type o f ove rs tep occurs

i n c r o s s - s e c t i o n a l o n g n o r m a l f a u l t s , w i t h t h e l o w e r

f a u l t o v e r s t e p p i n g o r p r o j e c t i n g i n t o t h e

h a n g in g

wa l l

o f t h e u p p e r f a u l t P e a c o c k a n d Z h a n g , 1 9 9 4)

F i g . 1 ). S y n o n y m o u s w i t h

a n t i -d i l a t i o n a l j o g

S ibson , 1989) , and wi th

compressional-, convergent-

a n d

restraining-overstep

Biddle and Chr i s t i e -Bl ick ,

1985).

Overstep , extensional:

A n

overstep

t h a t h a s t o b e

a c c o m m o d a t e d b y e x t e n s i o n , e . g . a r i g h t - s t e p

b e t w e e n d e x t r a l f a u l t s . T h i s t y p e o f o v e r s t e p o c c u r s

i n c r o s s - s e c t i o n a l o n g n o r m a l f a u l t s , w i t h t h e l o w e r

f a u l t o v e r s t e p p i n g i n t o t h e

f o o t w a l l

o f t h e u p p e r

f a u l t P e a c o c k a n d Z h a n g , 1 9 9 4 ) F i g . 1).


d i la t io n a l j o g

Sibson, 1989), and

w i t h

divergent-

a n d

releasing-overstep

B i d d l e a n d

Chris t ie-Blick, 1985).

Pa la eo s t ress o r i en ta t i o n a n a l ys i s .

U s e o f f a u l t

o r i e n t a t i o n s a n d d i s p l a c e m e n t d i r e c ti o n s o f a

p o p u l a t i o n o f f a u l t s t o i n f e r t h e o r i e n t a t i o n s o f t h e

for ma tive s t resses e .g. An gel ier , 1984).

Perm ea b i l i t y , . f a u l t.

T h e a b i l i t y o f f l u i d s t o f l o w a l o n g

or ac ros s fau l t s S m i th , 19 66; M or ro w e t a l. , 1984) .

F a u l t p e r m e a b i l i t y c a n b e a n i s o t r o p i c , w i t h

d i f f e r e n c e s i n f l o w p e r p e n d i c u l a r a n d p a r a l l e l t o a

fau l t e . g . Zh an g and Tul l i s , 1998) . S ee

seal.

Polygonal fau l t s .

A n e t w o r k o f f a u lt s w i th n o

r e g i o n a l l y c o n s i s t e n t p r e f e rr e d s t ri k e o r i e n t a t i o n .

P o l y g o n a l n o r m a l f a u l t s h a v e a s i m i l a r a p p e a r a n c e

i n m a p v i e w to m u d - c r a c k s e .g . L o n e r g a n e t a l. ,

1 9 9 8 ) . L a y e r - b o u n d p o l y g o n a l f a u l t s i n t h e N o r t h

S e a a r e d e s c r i b e d b y C a r t w r i g h t a n d L o n e r g a n

1 99 6) a n d a r e a t t r i b u t e d t o v e r t i c a l c o m p a c t i o n .

Power- law.

T h e r e l a t i o n s h i p w h e r e b y

N o e S - D ,

w h e r e

N i s t h e n u m b e r i n a p o p u l a t i o n w i t h a s i z e g r e a t e r

t h a n S , a n d D i s t h e p o w e r - l a w e x p o n e n t e .g .

W a l s h a n d W a t t e r s o n , 1 9 9 2 ) . D i s p l a c e m e n t s f o r a

p o p u l a t i o n o f f a u l t s h a v e b e e n s h o w n t o o b e y a

p o w e r - l a w S c h o l z a n d C o w i e , 1 9 9 0 ; M a r r e t t a n d

A l l m e n d i n g e r , 1 9 9 2 ; W a l s h a n d W a t t e r s o n , 1 9 9 2 ;

Scholz et al. , 1993). See

D - v a l u e a n d f r a c t a l .

Process zone.

U s e d i n m a t e r i a l s c i e n c e f o r a n a r e a o f

m i c r o - c r a c k i n g a t t h e t i p o f a p r o p a g a t i n g f r a c t u r e ,

i n v o l v i n g n o n - l i n e a r b e h a v i o u r . P r o c e s s z o n e s i n

r o c k a r e g e n e r a ll y d i l a t i o n a l a r e a s A t k i n s o n , 1 9 8 7 ,

f ig . 1 . 4 ) . P roces s zones in norm a l fau l t zones a re

d e s c r i b ed b y C o w i e a n d S h i p t o n 1 99 8) .

Pro p a g a t io n , f a u l t :

T h e i n c r e a s e i n l e n g t h , a r e a a n d

d i s p l a c e m e n t o f a f a u l t o r f a u l t z o n e e .g . W a l s h

a n d W a t t e r s o n , 1 9 8 7 ; R e c h e s a n d L o c k n e r , 1 9 9 4 ;

P e a c o c k a n d S a n d e r s o n , 1 9 9 6 ) .

Pul l -a part basin . A basin

d e v e l o p e d a t a n

ex t en s io n a l

b e n d

o r

extensional overstep

be tween two s t r ike -s l ip

fau l t s e . g . Burchf ie l and S tewa r t , 19 66; Crow el l ,

1 9 7 4 ) . T h e y a r e g e n e r a l l y a p p r o x i m a t e l y r h o m b -

s h a p e d , w i t h s u b s i d e n c e i n t h e b a s i n c o m m o n l y

con t ro l l ed by norm al fau l t s e . g. Crow e l l , 1974 , f ig .

3 ). S y n o n y m o u s w i t h

r h o m b o c h a s m , r h o m b o g r a b e n

a n d

sa g p o n d . Pu l l -a p a r t

h a s a l s o b e e n u s e d f o r a

r h o m b - s h a p e d a r e a a t a n

extensional overstep

e.g.

P e a c o c k a n d S a n d e r s o n , 1 9 9 2 ; P e a c o c k a n d Z h a n g ,

1 99 4) s y n o n y m o u s w i t h

d o m i n o

o f G a m o n d , 1 98 3 )

Fig. 1).

Pu l l -a p a r t s

c a n o c c u r w h e r e n o r m a l f a u l t s

a r e r e f r a c t e d t o a s t e e p e r d i p t h r o u g h m o r e b r i t t l e

beds .


9/15

D.C.P. Peacock et al. / Journal of Structural Geology 22 (2000) 291-305 299

Reactivation.

R e n e w e d d i s p l a c e m e n t o n a f a u l t t h a t

h a s u n d e r g o n e a p r o l o n g e d p e r i o d o f i n a c t iv i t y (e .g .

S h e p h a r d - T h o r n e t a l. , 1 9 7 2 ; S i b s o n , 1 9 8 5) ; t h e

f a u l t h a s t h e r e f o r e b e e n a f f e c t e d b y t w o d i s t i n c t

t e c t o n i c e v e n t s . T h e l a t e r d i s p l a c e m e n t m a y o r m a y

n o t b e o f t h e s a m e s e n se a s t h e p r e v i o u s

d i sp lacem ent . S ee

invers ion

a n d

reverse- reac t iva t ion .

Re lay pat tern . A n a r r a n g e m e n t o f o v e r la p p in g o r

u n d e r la p p in g

s u b - p a r a l l e l f a u l t s ( H a r d i n g a n d

Lowel l , 1979; B idd le and Chr i s t i e -Bl ick , 1985 , f ig .

2).

R e l a y f a u l t s

a re desc r ibed by Gogue l (1952) .

R e l a y r a m p :

A n a r e a o f r e o r ie n t e d b e d d i n g b e t w e e n

t w o n o r m a l f a u l t s t h a t o v e r s t e p i n m a p v i e w a n d

t h a t h a v e t h e s a m e d i p d i r e c t i o n ( F i g . 1 ) . T h e f a u l t s

m a y b e

l is tr ic

a n d m e e t a t d e p t h ( L a r s e n , 1 9 8 8 ) ,

a p p r o x i m a t e l y p l a n a r a n d u n c o n n e c t e d a t d e p t h

( P e a c o c k a n d S a n d e r s o n , 1 9 9 1 ) , o r m a y s p l a y o f f

t h e s a m e a p p r o x i m a t e l y p l a n a r f a u l t ( H u g g i n s e t a l . ,

1995). F irs t cal led

r e la is d e s fa i l l e s ( r e la y fa u l t s )

b y

G o g u e l ( 1 95 2, f ig . 7 3) . S y n o n y m o u s w i t h s t r i k e

r a m p

(Mor ley , 1995 , f ig . 16) ,

s y n th e t i c

a c c o m m o d a t i o n z o n e

( F a u l d s a n d V a r g a , 1 9 9 8 ) a n d

w i t h

s y n th e t i c t r a n s fe r z o n e

(Morley e t a l . , 1990).

Re la y r a mp , b r e a c h e d .

A r e l a y r a m p t h a t h a s b e e n

b r o k e n b y o n e o r m o r e

c o n n e c ti n g f a u l t s

(Chi lds e t

a l . , 1993)(Fig. 1) .

Re v e r s e d r a g : F o l d i n g a d j a c e n t t o a f a u l t p l a n e s u c h

t h a t a m a r k e r i s c o n c a v e t o w a r d s t h e s l i p d i r e c t i o n

(Ham bl in , 1965) . An exam ple i s

ro l l -over

a b o v e a

l is tr ic n o r m a l f a u l t . F i r s t d e s c r i b e d b y D u t t o n

( 18 82 ), a n d s y n o n y m o u s w i t h

d o w n b e n d i n g

a n d

t u r n o v e r

(Ham bl in , 1965) .

Re v e r s e - r e a c t i v a t io n : T h e r e a c t i v a t io n o f a n o r m a l f a u l t

by a l a te r ep i sode of reve rse d i sp la cem ent (e . g .

S ton eley , 198 2; D ar t e t a l ., 1995). See

invers ion

a n d

reac t iva t ion .

R h o m b b l o c k .

R h o m b - s h a p e d f a u l t - b o u n d b l o c k o f

r o t a t e d b e d d i n g r e s u l t in g f r o m t h e l i n k a g e o f f a u l t s

wi th z igz ag t races (M or ley , 1995 , fig . 16) . S im i la r to

the

h o r s e

s h o w n b y R a m s e y a n d H u b e r ( 1 9 8 7 , f i g .

23.50).

R f f t :

A r e l a t i v e l y n a r r o w t r o u g h o r b e l t o f s u b s id e n c e

b o u n d e d o n e i t h e r s i d e b y n o r m a l f a u l t s ( e . g .

N e l s o n e t a l ., 1 9 9 2) . R i f t s c o m m o n l y c o n t a i n o r

c o n s i s t o f

g r a b e n s

o r

half-grabens .

V a r i o u s u s a g e s

( e . g . f o r s t r u c t u r e s o n v o l c a n o e s ) a r e d e s c r i b e d b y

Dennis (1967).

Rif t va l ley .

D e f i n e d b y G r e g o r y ( 18 9 4) a s a v a l l e y w i t h

s t ee p p a r a l l e l w a l ls , f o r m e d b y s u b s i d e n c e o f a p a r t

o f t h e E a r t h s c r u s t .

Ro l l - o v e r .

Beds in the

h a n g in g wa l l

t h a t s t e e p e n

t o w a r d s a n o r m a l f a u l t t o f o r m a n a n t i c l i n e ( e . g .

S toneley, 1982; Gibbs , 1984).

Ro l l - o v e r

m a y i n d i ca t e

a l is tr ic

geom et ry (e . g . Wi l l i am s and Vann , 1987) , o r

r e v e r s e d r a g

a r o u n d a p l a n a r f a u l t ( B a r n e t t e t a l . ,

1987).

Ro ta t io n , h o r i z o n ta l - a x i s .

R o t a t i o n o f a f a u l t b l o c k

a b o u t a h o r i z o n t a l a x i s . H o r i z o n t a l - a x i s r o t a t i o n

c o m m o n l y a c c o m p a n i e s n o r m a l f a u lt in g , f o r

e x a m p l e d u r i n g

b o o k s h e l . f fa u I t in g

(e .g. Anders e t a l . ,

1993) and in r e l a y r a m p s ( e . g . P e a c o c k a n d

S and erson , 1994 , f ig . 8 ) . S y no ny m o us wi th

tilting.

Ro ta t io n , v e r t i c a l - a x i s .

R o t a t i o n o f a f a u l t b l o c k a b o u t

a v e r t i c a l a x i s . V e r t i c a l a x i s r o t a t i o n c o m m o n l y

occurs in norm a l fau l t sys tem s (e . g . J anecke e t a l . ,

1991) , fo r exam ple in

r e la y r a mp s

( P e a c o c k a n d

Sanderson, 1994, f ig. 8) .

R o u g h n e s s , f a u l t .

A m e a s u r e o f t h e i r r e g u l a r i t y o f a

fau l t su r face (e .g . P ow er an d Tul l i s , 19 91; Lee and

Bru hn , 1996; S tewar t , 1996) .

Scale invar iance:

T h e p r o p e r t y w h e r e b y a s e t o f o b j e c t s

a t one s ca le a re geom e t r i ca l ly iden t i ca l to the s e t o f

ob jec t s when v iewed a t ano the r s ca le (e . g . Turco t t e ,

1 9 8 9 ; M a i n , 1 9 9 6 ) . T h e c o n c e p t t h a t f a u l t s h a v e

s c a l e i n v a r i a n t g e o m e t r i e s w a s i n t r o d u c e d b y

Tch a len ko (1970) . S ee

f r a c ta l , s e l f - a f f in e

a n d

se l f -

s imilar .

S c a l in g r e la t io n s h ip .

T h e r e l a t i o n s h i p b e t w e e n

di f fe ren t - s i zed s t ruc tures (e .g . S cholz and Cow ie ,

1 9 90 ; M a r r e t t a n d A l l m e n d i n g e r , 1 9 9 2 ; W a l s h a n d

W at te rs on , 19 92 ; S cholz e t a l ., 1993). S ee

d i s p la c e me n t l e n g th r a t io , D- v a lu e

a n d

p o w e r - l a w .

S e a l .

A fau l t i s

s e a l in g

i f f lu id is unab le to f low

t h r o u g h t h e r o c k b e c a u s e t h e

f a u l t r o c k s

a re

i m p e r m e a b l e , o r b e c a u s e o f t h e g e o m e t r y o f th e

f a u l t ( e .g . S m i t h , 1 9 6 6 ; K n o t t , 1 9 9 3 ) . S ee f a u l t

j u x t a p o s i t i o n d i a g r a m

a n d

s me a r .

S e g m e n t , fa ul t.

A n i n d i v i d u a l

s l ip p la n e

t h a t i s p a r t o f

a s e t o f su b - p a r a l l el f a u l t s t h a t t o g e t h e r f o r m a f a u l t

z o n e (e .g . S ega l l and P o l la rd , 1980) . S y no ny m o us

w i t h

s t r a n d

(B idd le and Chr i s t i e -Bl ick , 1985) .

Self-affine.

A s e t o f o b j e c ts o r p r o p e r t i e s t h a t e x h i b i t

f r a c t a l

b e h a v i o u r , b u t t h a t s h o w s y s t e m a t i c c h a n g e s

i n g e o m e t r y w i t h s c a l e a c c o r d i n g t o a l i n e a r

t r a n s f o r m a t i o n ( s ) ( M a n d l e b r o t , 1 9 8 2 ; G i l l es p i e e t

a l . , 1993) . S e l f -a ff ine ob jec t s a re the re fore n o t

pe r fec t ly se l f - s imilar .

S e ( f - s im i la r :

A se t o f ob jec ts o r p rope r t i e s th a t exh ib i t

j i ac ta l

b e h a v i o u r a n d t h a t s h o w

scale invar iant

g e o m e t r y a t a l l sc a le s ( e .g . T u r c o t t e , 1 9 8 9 ; M a i n ,

1996) . S e l f - s im i la r i ty o f fau l t geom et r i e s was f i r s t

i l lus t ra ted by Tcha lenko (1970) . S ee se l f -a f f ine .

S e p a r a t io n :

T h e a p p a r e n t d i s p la c e m e n t o f a p l a n a r

m a r k e r ( e . g . b e d ) a c r o s s a f a u l t , m e a s u r e d i n a n y

ind ica ted d i rec t ion (Re id e t a l . , 1913) . Note ,

h o w e v e r , t h a t

s e p a r a t io n

has a l so been used fo r : (a )

t h e d i s t a n c e b e t w e e n t w o o v e r s te p p in g fau l t s ,

m e a s u r e d p e r p e n d i c u l a r t o t h e f a u l t p l a n e s ( e. g.

R o d g e r s , 1 9 8 0 ) ; a n d ( b) t h e d i s t a n c e b e t w e e n

o v e r s te p p in g

f a u l t s m e a s u r e d p a r a l l e l t o t h e i r s t r i k e s

( S e ga l l a n d P o l l a r d , 1 98 0) ( s y n o n y m o u s w i t h

o v e r la p ) .

W e s u g g e s t t h a t t h e s e t w o l a t t e r u s e s


10/15

3 D. C . P . P e a c o c k e t a l . / J o u r n a l o fS t ru c tu ra l Ge o lo g y 2 2 2 0 0 0 ) 29 1 3 0 5

s h o u l d b e a v o i d e d b e c a u s e

separation

i s m o r e

c o m m o n l y u s e d f o r a p p a r e n t d i s p la c e m e n t, w i t h

overstep a n d overlap b e i n g m o r e s u i t a b le t e r m s .

Slip: T h e d i s t a n c e b e t w e e n t w o f o r m e r l y a d j a c e n t

p o i n t s o n o p p o s i t e w a l l s o f t h e f a u l t , m e a s u r e d i n a

s t ra igh t l ine on the fau l t su r face (Re id e t a l . , 1913) .

S y n o n y m o u s w i th net slip, cf. displacement. C o w i e

and S h ip ton (1998) use

slip

s y n o n y m o u s l y w i th

slip

event.

Slip, cumulative: T h e f i n i t e d i s p l a c e m e n t s p r o d u c e d b y

a n u m b e r o f i n d i v i d u a l sl ip e v e n t s o n a f a u l t ( W a l s h

and Wat te rson , 1987) .

Slip event: A s ing le d i sp lacem ent even t on a fau l t (e . g .

W a l s h a n d W a t t e r s o n , 1 9 8 7 ) , i . e . a s s o c i a t e d w i t h a n

ea r thquake (Cowie and S cholz , 1992b) . The ne t s l ip

a n d f i n a l d i s p l a c e m e n t p r o f i l e o n a f a u l t i s u s u a l l y

t h e r e s u l t o f m a n y s li p e v e n ts ( W a l s h a n d

W a t t e r s o n , 1 9 8 7 ; P e a c o c k a n d S a n d e r s o n , 1 99 6) .

Slip plane:

U s e d i n m a t e r i a l s c i e n c e f o r a p l a n e a l o n g

which d i sp lacem ent m ay occur (e . g . Dennis , 1967) .

U s e d i n g e o l o g y f o r a s u r f a c e a l o n g w h i c h

d i s p l a c e m e n t h a s o c c u r r e d ( e . g . S t e w a r t a n d

H a n c o c k , 1 9 91 ). S y n o n y m o u s w i t h

fau lt p lane.

Slip vector.

T h e o r i e n t a t i o n a n d m a g n i t u d e o f t h e

d i s p l a c e m e n t o f f o r m e r l y a d j a c e n t p o i n t s o n

o p p o s i t e s i d e s o f a f a u l t m e a s u r e d a l o n g t h e f a u l t

surface (Reid e t a l . , 1913), cf .

displacement vector.

S m ea r : W a l l - r o c k m a t e r i a l , u s u a l l y c l a y - r i c h , s p r e a d

a l o n g a f a u l t s u r f a c e ( P e r k i n s, 1 9 6 1 ; K n i p e , 1 9 9 2 ;

K no t t , 1993; L in dsa y e t a l ., 1993). S ee

seal.

So ft domino.

B l o c k r o t a t i o n a c c o m m o d a t e d b y d u c t i l e

s t ra in , inc lud ing fau l t s be low the s ca le o f the

a n a l y s i s ( G i b s o n e t a l. , 1 9 8 9 ; W a l s h a n d W a t t e r s o n ,

1991 , f ig . 1 0) . Th i s b ehav iour im pl ie s g eo m etr ic

coherence.

Soft- linkage. Coherence b e t w e e n f a u l t s a c h i e v e d b y

d u c t i l e s t r a i n o f t h e

wall-rocks,

i . e . there is no

l i n k a g e b y f a u l t s v i s i b l e a t t h e s c a l e o f o b s e r v a t i o n

( W a l s h a n d W a t t e r s o n , 1 9 9 1 ) . A relay ramp i s an

e x a m p l e o f soft- linkage. See hard-linkage a n d so ft

domino.

Spacing , fau lt:

The (ave rage ) d i s t ance be tween fau l t s ,

u s u a l l y m e a s u r e d i n a l i n e p e r p e n d i c u l a r t o t h e f a u l t

p l a n e o r t h e f a u l t s t r i k e . I t o n l y h a s a r i g o r o u s

de f in i t ion , the re fore , fo r s e t s o f sub-pa ra l l e l fau l t s ,

b u t m a y b e a p p l i e d t o t r a v e r s e s p e r p e n d i c u l a r t o t h e

s t r i k e o f c o n j u g a t e n o r m a l f a u l t s e t s . Discontinuity

spacing i s d i s c u s s e d b y P r i e s t a n d H u d s o n ( 1 9 7 6 ,

1981).

See fau lt densi ty .

Sp lay, fau lt:

O n e o r m o r e s m a l l e r fa u l t s t h a t j o i n a

la rge r fau l t , to which i t i s re la ted (e . g . B idd le and

Chris t ie-Blick, 1985, f ig. 2) . The larger faul t

splays

i f

i t i s c o n n e c t e d w i t h o n e o r m o r e s p l a y f a u l t s

(DeSit ter , 1956). See

branch.

S tepover . S y n o n y m o u s w i th overstep ( A y d i n a n d N u r ,

1982).

S yn th e t ic fa u l t : Orig ina l ly de f ined by Cloos (1928) a s a

m i n o r f a u l t t h a t d i p s i n t h e s a m e d i r e c t i o n a s

d i p p i n g b e d s . S yn th e t ic fa u l t is now used (e .g.

G i b b s , 1 9 8 4 ) f o r a m i n o r f a u l t t h a t h a s t h e s a m e

d i s p l a c e m e n t s e n s e a n d a s i m i l a r o r i e n t a t i o n t o a

r e l a t e d m a j o r f a u l t , o r t h e r e l a t i o n s h i p w h e r e b y t w o

r e l a t e d f a u l t s h a v e t h e s a m e s h e a r s e n s e . T w o

n o r m a l f a u l t s w i t h d o w n t h r o w s t o t h e n o r t h a r e

synthet ic to each o the r . S ee antithetic fau l t .

Synthetic transfer zone: S y n o n y m o u s w i t h relay ramp

(Morley e t a l . , 1990).

Tension fracture.


extension fracture

( e . g . M c G r a t h a n d D a v i s o n , 1 9 9 5 ) .

Termination , fau lt: T h e e n d o f a f a u l t o r f a u l t z o n e ,

w h e r e d i s p l a c e m e n t d e c r e a s e s t o z e r o ( e . g . Z h a n g e t

al. , 1991). Termination h a s a l s o b e e n u s e d f o r t h e

l o c a t i o n a t w h i c h a n e a r t h q u a k e r u p t u r e e n d s ( e . g .

Aki , 1989). See damage zone a n d tip.

Thermal subsidence and thermal upli f t .

Ver t i ca l

m o v e m e n t s r e l a t e d t o t h e r m a l c o n t r a c t i o n a n d

ex tens ion of th e Ea r th s c rus t , re spec t ive ly (e .g .

S l ee p , 1 9 7 1 ; M c K e n z i e , 1 9 7 8 ; R o b e r t s a n d Y i e l d i n g ,

1991).

Thickness, fault. T h e e x t e n t o f t he d e f o r m a t i o n a n d

g r a i n s i z e r e d u c t i o n i n a f a u l t z o n e , u s u a l l y

m e a s u r e d p e r p e n d i c u l a r t o t h e f a u l t ( E v a n s , 1 9 9 0 ;

Knot t , 1994) .

Gouge thickness

i s de f ined by Byer lee

a n d S u m m e r s ( 1 97 6) a s t h e t h ic k n e s s o f c r u s h e d

m ate r ia l be tween s l id ing sur faces . S ee width , fau lt .

Throw.

T h e v e r t i ca l c o m p o n e n t o f t h e

dip-separation

o f

a n o r m a l o r r e v e r s e f a u l t , m e a s u r e d i n a v e r t i c a l

c r o s s -s e c t io n p e r p e n d i c u l a r t o t h e s t r ik e o f a f a u l t

(e .g . Ge ik ie , 1882 ; Hi l l s , 1940 ; B i l l ings , 1942 ) (F ig .

1 ). Th ro w i s de f ined in t e rm s o f the

separation,

h e n c e i t a p p l i e s t o t h e f a u l t e d g e o m e t r y o f a p l a n e

a n d n o t t h e d i s p l a c e m e n t ( n e t s l i p ) o f t h e f a u l t . T h e

t h r o w i s e q u i v a l e n t t o t h e v e r t i c a l c o m p o n e n t o f t h e

displacement o n l y f o r a p u r e dip-slip faul t . See

heave.

Tilting.

R o t a t i o n o f a f a u l t b l o c k a b o u t a h o r i z o n t a l

a x is . T i l t i n g c o m m o n l y a c c o m p a n i e s n o r m a l f a u l t i n g

(e . g . Anders e t a l . , 1993) , fo r exam ple in relay ramps

( P e a c o c k a n d S a n d e r s o n , 1 9 9 4 , f i g . 8 ) . S y n o n y m o u s

w i t h

horizontal axis rotation.

Tip: A t ip poin t i s a s i t e where fau l t d i sp lacem ent d ie s

to ze ro , e . g . where a fau l t t race ends on a m ap (e . g .

C o w a r d a n d P o t t s , 1 9 8 3 ) ( F i g . 1 ). A tip line is the

l i n e a r o u n d a f a u l t p l a n e w h e r e d i s p l a c e m e n t

becom es ze ro . Barne t t e t a l . (1987) sugges t tha t

isolated norm al fau l t s have e l l ip t i ca l t ip l ines . A tip

zo n e i s a n a r e a o f damage a t t h e t e r m i n a t i o n o f a

f a u lt . S y n o n y m o u s w i t h fau lt termination .

Transfer fau lt:

A fau l t tha t l inks , i s a t a h igh ang le to ,

a n d t h a t t r a n s f e r s d i s p l a c e m e n t b e t w e e n t w o n o r m a l

faul ts (Gibbs , 1984, f ig. 15) (F ig. 1) . Transfer faul ts

b e t w e e n n o r m a l f a u l t s i n m a p v i e w u s u a l l y h a v e a


11/15

D.C.P. P eacock et al./ Journal of Structural Geology 22 (2000) 291-305 301

s i g n if i c a nt s t r ik e - s l ip c o m p o n e n t S t e w a r t a n d

H a n c o c k , 1 9 9 1 ) .

T rans fe r fau l t

i s a p p r o x i m a t e l y

s y n o n y m o u s w i t h

t r a m f o r m f a u l t

Bal ly , 1981 , f ig . 2 )

a n d w i t h cross - st r ike fau l t Morley , 1995 , f ig . 16 ) .

Transfer zone. D a h l s t r o m 1 9 70 ) u s e s transfer zone f o r

t h e s t r u c t u r e s t h a t c o n s e r v e s h o r t e n i n g , o r a l l o w a

r e g u l a r c h a n g e i n s h o r t e n i n g , b e t w e e n o v e r s t e p p i n g

t h r u s t f a u l t s .

T rans fe r zone

i s a l s o u s e d f o r a n a r e a

o f d e f o r m a t i o n a n d b e d r o t a t i o n b e t w e e n t w o

n o r m a l f a u l t s t h a t o v e r s t e p i n m a p v i e w F i g . 1 ).

M o r l e y 1 9 9 5 ) s u g g e s t s t h a t th e f a u l t s w h i c h d e f i n e

a t r a n s f e r z o n e w e r e a c t i v e a t t h e s a m e t i m e , i n

c o n t r a s t t o accommodat ion zone , i n w h i c h t h e t w o

f a u l t s n e e d n o t h a v e b e e n a c t i v e a t t h e s a m e t i m e

B o sw o r th , 1 9 8 5) . M o r l e y e t a l . 1 9 9 0 , f i g. 1)

d e s c r i b e

syn the t ic t rans fe r zones

a n d

conjugate

transfer zones , i n w h i c h t h e o v e r s t e p p i n g f a u l t s d i p

i n t h e s a m e a n d o p p o s i t e d i r e c t i o n s , r e s p e c t i v e l y .

C o n j u g a t e t r a n s f e r z o n e s c a n b e f u r t h e r s u b - d i v i d e d

i n t o

convergent-

a n d

divergent- transfer

z o n e s

M o r l e y e t a l ,, 1 9 9 0) . S ee

relay ramp.

F a u l d s a n d

V a r g a 1 9 98 ) d i s c us s p r e v i o u s u s a g e o f transfer zone

a n d

accommodat ion zone .

T h e y r e d e f i n e a

transfer

zone

a s a d is c r e t e z o n e o f s t r i k e - s l i p a n d o b l i q u e - s l i p

f a u l t i n g t h a t t y p i c a l l y t ra n s f e r s s t r a i n b e t w e e n e n

6 c h e l o n e x t e n d e d d o m a i n s , a n d d e f i n e a n

accommodat ion zone

a s a b e l t o f o v e r l a p p i n g f a u l t

t e r m i n a t i o n s F a u l d s a n d V a r g a , 1 9 98 , f i gs . 4 , 5 a n d

6 , t a b l e 1 ) . W e s u g g e s t t h a t t h e s e d e f i n i t i o n s a r e

u n h e l p f u l b e c a u s e : a ) t h e y a r e r e d e f i n i t i o n s o f

e x i s t i n g t e r m s ; a n d b ) t h e d i s t i n c t i o n b e t w e e n t h e

t w o t y p e s o f z o n e m a y b e a r b i t r a r y e .g . a n

accommodat ion zone

c a n c o n t a i n e l e m e n t s o f a

transfer zone,

w i t h s t r i k e - s l i p f a u l t s d e v e l o p i n g a s

t h e z o n e b e c o m e s

breached) .

Transtension. A s y s t e m o f s t r es s e s t h a t t e n d s t o c a u s e

o b l i q u e - e x t e n s i o n , i . e . c o m b i n e d e x t e n s i o n a n d

s t r i k e - s l i p e . g. H a r l a n d , 1 9 71 ; S a n d e r s o n a n d

M arch in i , 1 9 8 4 ) .

Underlapping faults. T w o f a u l t s t h a t overs tep s u c h t h a t

t h e y d o n o t p a s s e a c h o t h e r , i . e . a l i n e c a n b e d r a w n

b e t w e e n a n d p e r p e n d i c u l a r t o t h e f a u l t s t h a t d o e s

n o t c r o s s e i t h e r f a u l t e . g. P o l l a r d a n d A y d i n , 1 98 4) .

S ee overlap.

Wal l - rock :

O l d m i n i n g t e r m f o r th e c o u n t r y r o c k

b o u n d i n g a v e i n , n o w c o m m o n l y u s e d f o r t h e r o c k s

s u r r o u n d i n g a n d d i s p l a c e d b y a f a u l t s e e D e n n i s ,

1967).

Width, fault. T h e t e r m h a s t w o u s e s. a ) Faul t w id th is

o f t e n u s e d f o r t h e t h i c k n e s s o f f a u l t r o c k a l o n g a

f au l t p l an e e . g . K n o t t , 1 9 94 ; C a in e e t a l . , 1 9 9 6 ).

S y n o n y m o u s t e r m s i n c l u d i n g f a u l t - r o c k w i d t h a n d

fau l t th icknes s .

b ) B a r n e t t e t a l . 1 9 8 7 ) a n d W a l s h

a n d W a t t e r s o n 1 9 88 ) u s e f a u l t w i d t h f o r t h e m a j o r

a x i s o f a f a u l t p l a n e , t h a t i s u s u a l l y a l o n g t h e s t r i k e

o f a n o r m a l f a u l t . W e s u g g e s t t h a t t h i s l a tt e r u s a g e

s h o u l d b e a v o i d e d b e c a u s e i t i s l e s s i n t u i t i v e t h a n

fau l t l eng th , w h i c h i s u s e d b y s o m e o t h e r a u t h o r s

e . g . S c h o l z a n d C o w i e , 1 9 9 0 ) f o r t h e t r a c e l e n g t h o r

f o r t h e m a j o r a x i s o f t h e f a u l t p l a n e .

Zone, fault.

D e f i n e d b y H i l l s 1 9 4 0 ) a s t h e z o n e o f

d i s t u r b e d r o c k s b e t w e e n f a u l t e d b l o c k s . N o w

c o m m o n l y u s e d f o r a s y s t e m o f r e l a t e d f a u l t

segments

t h a t i n t e r a c t a n d l i n k , a n d a r e r e s t r i c t e d t o

a r e la t i v e ly n a r r o w b a n d o r v o l u m e e .g . N e v i n ,

1 93 1

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