12.6 Foreland Basins, Molasse
SUBDUCTION
LOAD
SEA L.
RETROARC
FORELAND B.
C ONE CYCLE OF THRUSTING. RELAXATION. AND REBOUND
.
CD LOADING
fr li~!t,~, , ~r!!; ~ i ! ; ~ ' ~ ; ~ ~ ~ : ~ ~ J ; ; ; i ; j i i ; : ' : : i . : ; f r : ; ; : : ~ ~ ~ ~ ; o , : ; : T ~ ~ : z : ~ ~ ~ · ~ ; : ; ' i ~ r L ; g ~ ~
: ~ ~ ~ 1 f : r :
. F ~ / : r ~ { 0 r ; ' ~ o 6 ~ ~ : : , 0.
~ ~ ~ : ~ : t f :
: : :~ . : : : : : \ \
CHANGE IN
f,;\
SOURCE AREAS
\Y RELAXATION
~
___ ~ ........ \ SS DECR.
EROSION
•
NEW SEDIMENT
'
SOURCE ~.. •••• _ •• ".
@ REBOUND
·1!:' f t i ::#~ : ' i i i i i i i ~ i Ä . ; { & ; , g . f l ; ; ~ i y , ,~~~ii~~~~;~l!~tt~:
d MODIFIED FORELAND BASIN MODEL
PIGGYBACK B .
. 1,..- - - - - - -\-- FORELAND BASIN SYSTEM - - - - - - - - - -. -------OROGENIC WEDGE - - - \- -- ~
: »:::::::::-:-:-:-...... }~\-<-- WEDGE TOP - -+ FOREDEEP--*t., FOREBULGE{-- BACK.BULGE1,~,~, . . ; ; ;;~~~iiii~~;;i~ib*r;I!~g~!~it~~;ii~~!~: T~fififg~i
611
Fig. 12.34. a,b Two types of foreland basins, loeated
either in the foreare region (peripheral setting) or in
the baekare area (retroare setting) of a magmatie are
evolving to an oro-genie belt. Note different types of
loads eausing subsidenee. c Foreland basin evolution
during one eycle of (1) aetive over-thrusting, (2)
erustal relaxation, including uplift and migration of
forebulge toward thrust front Via (3) a stage of ± uniform subsidenee to (4) isostatie rebound and "antiperipheral bulge". The sediment sourees and an unconformity in the region of the fore-bulge ehange
with time. d Revised eoneept of a foreland basin system adapted to examples where the front of the orogenie wedge OWF is buried under younger sediments. Note spatial differenee between OWF and
topographie front TF of the thrust belt. (a,b and d
Modified from DeCelles and Giles 1996; c based on
several sourees, e.g. Zweigel1998)
SUBDUCTION
LOAD
SEA L.
RETROARC
FORELAND B.
C ONE CYCLE OF THRUSTING. RELAXATION. AND REBOUND
.
CD LOADING
fr li~!t,~, , ~r!!; ~ i ! ; ~ ' ~ ; ~ ~ ~ : ~ ~ J ; ; ; i ; j i i ; : ' : : i . : ; f r : ; ; : : ~ ~ ~ ~ ; o , : ; : T ~ ~ : z : ~ ~ ~ · ~ ; : ; ' i ~ r L ; g ~ ~
: ~ ~ ~ 1 f : r :
. F ~ / : r ~ { 0 r ; ' ~ o 6 ~ ~ : : , 0.
~ ~ ~ : ~ : t f :
: : :~ . : : : : : \ \
CHANGE IN
f,;\
SOURCE AREAS
\Y RELAXATION
~
___ ~ ........ \ SS DECR.
EROSION
•
NEW SEDIMENT
'
SOURCE ~.. •••• _ •• ".
@ REBOUND
·1!:' f t i ::#~ : ' i i i i i i i ~ i Ä . ; { & ; , g . f l ; ; ~ i y , ,~~~ii~~~~;~l!~tt~:
d MODIFIED FORELAND BASIN MODEL
PIGGYBACK B .
. 1,..- - - - - - -\-- FORELAND BASIN SYSTEM - - - - - - - - - -. -------OROGENIC WEDGE - - - \- -- ~
: »:::::::::-:-:-:-...... }~\-<-- WEDGE TOP - -+ FOREDEEP--*t., FOREBULGE{-- BACK.BULGE1,~,~, . . ; ; ;;~~~iiii~~;;i~ib*r;I!~g~!~it~~;ii~~!~: T~fififg~i
611
Fig. 12.34. a,b Two types of foreland basins, loeated
either in the foreare region (peripheral setting) or in
the baekare area (retroare setting) of a magmatie are
evolving to an oro-genie belt. Note different types of
loads eausing subsidenee. c Foreland basin evolution
during one eycle of (1) aetive over-thrusting, (2)
erustal relaxation, including uplift and migration of
forebulge toward thrust front Via (3) a stage of ± uniform subsidenee to (4) isostatie rebound and "antiperipheral bulge". The sediment sourees and an unconformity in the region of the fore-bulge ehange
with time. d Revised eoneept of a foreland basin system adapted to examples where the front of the orogenie wedge OWF is buried under younger sediments. Note spatial differenee between OWF and
topographie front TF of the thrust belt. (a,b and d
Modified from DeCelles and Giles 1996; c based on
several sourees, e.g. Zweigel1998)