(485802537) catena volume 106 issue 2013 [doi 10.1016%2fj.catena.2012.08.008] kasanin-grubin, milica...
TRANSCRIPT
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Catena 106 (2013) 54–67
Contents lists available at SciVerse ScienceD irect
Catena
j ou rna l home a ! e" # # # $ e l sev i e r $ c o m % l ocate % cate na
Cla& mineralo!& as a crucial 'actor in balan hillsloe rocesses
ilica *asanin+,rubin ⁎
Soil -rosion .aborator&/ ilitar& rail 1265/ niversit& o' oronto at Scarborou!h/ / Canaa 1C 14
a r t i c l e i n ' o
*eors"
alans
eatherin!
.itholo!ical roerties
Cla& mineralo!&Smectite
illsloe rocesses
a b s t r a c t
Comrehensive an imortant #or8 has been one in unerstanin! balan rocesses on both the bi!
scale/ an more recentl& on smaller scale in orer to unerstan the subtle i''erences bet#een sites$
o#ever/ most stuies lac8 imortant in'ormation re!arin! cla& mineralo!& an their imortance 'or
#eatherin! ro+ cesses$ &e an rate o' #eatherin! een on material h&sico+chemical roerties/
climatic re!imes an sloe characteristics$ s #eatherin! ro!resses/ the sur'ace conitions chan!e/
in9uencin! erosion rocesses$ suall& balan litholo!ies are reorte as soium+rich/ hi!hl& isersive
materials but that is not invariabl& true$ he rimar& objective o' this stu& is to sho# that cla& minerals
have an imortant role in e:nin! sur+ 'ace an subsur'ace rocesses on balan hillsloes$
;iel stuies conucte in Dinosaur
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$ *asanin+,rubin % Catena 106 (2013) 54 J 67$ *asanin+,rubin % Catena 106 (2013) 54 J 67
it is o'ten har to etermine the e@act #eatherin! rocess that
resulte in a certain #eatherin! rouct (obinson an illiams/
2000)$
5alans/ as ieal “:el laborator&” are intri!uin!
!eomorholo!ists 'or ecaes$ Comrehensive an imortant #or8
has been one in un+ erstanin! rocesses on the bi! scale (e$!$
r&an an Kair/ 1F2G Cambell/ 1FF7G o#ar/ 1FF7)$ ecentl&
more etail #or8 has been one on smaller scale in orer to
unerstan the subtle i''erences be+ t#een sites (e$!$ ;aul8ner et
al$/ 2000/ 2003/ 2004G *uhn et al$/ 2004)$ o#ever / most stuies
oversimli'& imortant in'ormation re!arin! mineralo!&/ eseciall&
content an t&e o' cla& minerals in balan ma+ terials$ suall&/ cla&
minerals are reorte as a !rain siLes 'actor or !en+ erall& balan
materials are characteriLe as “smectite” shales$
alan sloes have comle@ sloe 'orms mostl& because o'con+
trastin! litholo!& (o#ar / 1FF7)$ e!olith r o erties/ to!ether
#ith the ominant rocess #ill etermine the sloe shae an sloe
an!le$ Savat an De
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$ *asanin+,rubin % Catena 106 (2013) 54 J 67$ *asanin+,rubin % Catena 106 (2013) 54 J 67
rocess$ Chi!ira an &ama (1FFF) escribe the i''erent in9uence o'
&rite in the muroc8 an sanstone #eatherin! rocesses$
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an their imortance has been consiere #ith more attention b&'or
(e$!$ Canton et al$/ 2001G ;aul8 ner et al$/ 2000/2003)$
;aul8ner et al$ (2000) sho#e that chan!es that occur in site !eo+
chemical characteristics over time in lmeria balans/ Sain/ #ere
involve in balan stabilisation$ he authors roose the
'unctional relationshi bet#een -C an S4 as a use'ul tool
characterisin! i+ in! rone sites$ =n the #eatherin! ro:le in this
area cla& content is 'oun to increase #ith eth (.oeL+
ermueL an omero+DiaL/
1FF) #hich coincies #ith the :nin! that the subsur'ace material
is more isersive than the sur'ace (,erits et al$/ 1F7)$
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laborator& conitions$ =t is essential to achieve conitions in the labo+
rator& #hich rerouce :el conitions as closel& as ossible$ So 'ar
onl& a 'e# #eatherin! e@eriments have been conucte usin! ba+
lan materials$ o#ever/ the& have not 'ull& reresente natural con+
itions/ an i not observe chan!es in etail$ =n aition/ cla&
minerals have not been ienti:e in etail/ an lin8 to rocesses
has not been establishe$
;urthermore/ material resonse to seasonal chan!es is reorte to
be an imortant 'actor in erosion rocesses over time$ here'ore it is
essential to stu& in etail ho# materials behave in i''erent climatic
conitions$ atural s&stems have man& variables actin! at the same
time/ mainl& ue to climate (amount an t&e o' reciitation/ re+
vailin! #ins/ etc$) an sloe characteristics$ =n orer to minimiLe
the number o' variables it is essential to stu& ro!ressive
#eatherin! o' 'resh material in controlle laborator& conitions$
here'ore/ the rimar& objective o' this aer is to sho# the
imortant role o' cla& minerals/ both their content an mineralo!ical
comosition/ in e:n+ in! sur'ace an subsur'ace rocesses on
balan hillsloes$
2$ aterials an methos
2$1$ ;iel sites
hree balan sites #ere selecte in orer to assure variet& o' muroc8 #ith i''erent content an t&e o' cla& minerals" Dinosaur
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;i!$ 1$ a) lberta balans/ Canaa/ b) Sestino balans/ =tal&/ c) Chin!uacous& balans/ Canaa$
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Smectite+rich
litholo!ies
uroc8 (&ello#/
bro#n/ !re&)
Varicolour shales
(re/ ar8+!re&/
li!ht+!re&)
Sestino
balans
72 Smectite/ illite/
8aolinite
63 Smectite/ illite/
8aolinite
eveloe on all muroc8 sur'aces$ he “ ocorn” sur'ace #as
aroun
2–3 cm thic8/ an the sur'ace “ ocorn” a!!re!ates containe
a bunant vois (;i!$ 3)$ he subsur'ace la&er #as bet#een 10 an 15
cm thic8 $ 5e+ neath #as a la&er o' smaller shars/ 'ollo#e b& the
un#eathere mate+
Smectite+oor arl& shale 65 =llite/ chlorite rial$ similar #eatherin! ro:le #as escribe b& r&an et al$ (1F4)litholo!ies Dar8 re shale Chin!uacous& 6 =llite/ chlorite an o#&er+o#er an r&an (1F6)$ he “ ocorn” sur'ace can also
.i!ht re shale balans 5 =llite/ chlorite'orm #ith reeate 'reeLin!+tha#in! c&cles an e@ansion that occur s
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;i!$ 3$ (a) Di''erence in the rill net#or8 an sur'ace characteristics on the same site in 2001 (le't) an 2003 (ri!ht)$ (b)
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'rom i''erent litholo!ical units #ere e@ose to same conitions$
he aim o' these e@eriments #as to unerstan ho# the rocesses
active reson to i''erent material characteristics$ Sur'ace crust evo+
lution an leachate characteristics #ere closel& monitore$
3$1$1$ Smectite+rich litholo!ies
he Dinosaur
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;i!$ 5$ =ncremental #eatherin! e@eriment 'or the smectite+rich litholo!ies$ Samles subjecte to c&cles 1/ 5 an 10 o' 60 min lon! rain'all (intensit& 45 mm hT 1
)$
an chemical comositions o' the seiment$ he !re& muroc8s ha
the hi!hest leachate volume rate o' smectite+rich litholo!ies #ith t#o
su+ en ea8s in volume rates once in the 30 min samle an t#ice
in the
60 min samle (c&cles 3 an ) (;i!$ b)$ & contrast/ the leachate
vol+ ume increase rail& 'rom the :rst to the thir c&cle an
then remaine almost constant in other smectite+rich muroc8s
(;i!$ b)$ he ee sur'ace crac8s that eveloe in the earl&
#eatherin! sta!es in !re& muroc8 'acilitate 'aster throu!h9o# an
conseAuentl& a lot less #ater #as available 'or r etention$ =n other
smectite+rich seiments
the h&raulic conuctivit& #as limite b& s#ellin! #hich
occurr e mostl& urin! the :rst three c&cles$
elease o' seiments sho#e more variations bet#een i''erent
smectite+rich t&es$ ,enerall&/ the !re& muroc8 release more sei+
ment than other smectite+rich materials$ he cla& structure in the
!re& muroc8 #as easil& estro&e #hen it receive lon!er rain'alls
(50 an 60 min) an articles #ere iserse an transorte$ his
is evient as the 60 min samle release substantiall& more seiment
than the 10 min samles$
;i!$ 6$ =ncremental #eatherin! e@eriment 'or the smectite+oor litholo!ies$ Samles subjecte to c&cles 1/ 5 an 10 o' 10 min lon! rain'all (intensit& 45 mm hT 1
)$
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;i!$ 7$ =ncremental #eatherin! e@eriment 'or the smectite+oor litholo!ies$ Samles subjecte to c&cles 1/ 5 an 10 o' 60 min lon! rain'all (intensit& 45 mm hT 1
)$
=n smectite+rich materials subjecte to 60 min rain'all the sei+
ment concentration #as hi!hest at the be!innin! o' c&cles in all
samles an slo#l& ecrease to#ars the tenth c&cle (;i!$ F b)$
here #as no si!ni:cant i''erence bet#een the samle intervals
because o' the s#i't chan!e 'rom s#ellin! to isersion an the
clo!!in! o' ores$ i!her smectite content revente rai sei+
ment release$ ,re& muroc8 sho#e suen ecrease in the 30
an the 60 min samles in seiment concentration in same c&cles
urin! #hich a suen increase in the volume occurre (c&cles 3
an ) (;i!s$ b/ F b)$ his con:rms that hi!her volumes o' #ater asse throu!h subsur'ace crac8s/ but that the& #ere :lle #ith se+
iment in the 'ollo#in! c&cle an crac8s close a!ain$ o#ever/ it
must be e@ecte 'or this to haen a!ain/ once the seiment is
#ashe out$
.eachate seci:c conuctance #as hi!her in samles subjecte to
10 min samles than 'or 60 min samles$ Seci:c conuctance also
sho#e istinct trens bet#een 10 an 60 min samles (;i!$ 10a
an b)$ =n all 10 min smectite+rich litholo!ies/ the seci:c conuc+
tance increase urin! :rst three to 'our rain'alls an then remaine
at an almost constant (;i!$ 10a)$ his con:rms that most solutes are
release #hen the 'resh material is e@ose to rain'all$ ith time/
sur'ace an subsur'ace crac8s 'orm an act as imortant #ater an
seiment conuits$ =n 60 min samles initiall& hi!h conuctance e+
crease an remaine almost constant in all smectite+rich samles$=n smectite+oor litholo!ies/ leachate characteristics #ere sub+
stantiall& i''erent 'rom the smectite+rich litholo!ies$ =n the marl&
shale an the ar8 re shale/ volume rates increase 'rom the 10 to
the 60 min samles (;i!$ a an b)$ he li!ht re shale #as istinct
'rom other smectite+oor samles because the 10 an 20 min sam+
les ha hi!her volume rates than the other samles (;i!$ a)$
Seiment concentration an seci:c conuctance #ere
e@tr emel& lo# in all smectite+oor samles (;i!s$ Fa an b/ 10a an
b)$ o#ever / in marl& shale volume an seiment concentration
suenl& ecr ease in certain c&cles (c&cles 5 an )/ then increase
a!ain urin! the ' ol+ lo#in! c&cles (c&cles 7 an F)/ #hile the
seci:c conuctance ha the oosite attern$ his haene
urin! shar brea8o#n an #hen #ater use ne# ath9o#s$
Seiment concentrations #ere also hi!hest
in these t#o c&cles$ hese chan!es are ue to comaction #hich is
least evient in the 10 an 20 min samles$ he sur'ace #as
comacte a'ter the :rst c&cle in samles that #ere uner rain'all
'or lon!er increments$ his #as mar8e #ith hi!hest seiment con+
centr ation$ he sur'ace crac8s serve as the stea& ath#a&s 'or
seiment an #ater movement$
4$ Discussion
=n each litholo!&/ eenin! on its r oer ties/ a certain thr eshol
level o' #eatherin! is necessar& to ma8e the material vulnerable to
erosion r ocesses$ he t&e an rate o' #eatherin! een on mate+
rial h&sico+chemical r oer ties/ climatic re!imes an sloe char ac+
ter istics$ s #eatherin! r o!r esses/ the sur'ace conitions chan!e/
in9uencin! erosional r ocesses$ he amount an t&e o' cla& min+
erals are critical 'or #eatherin! rocesses in balan materials an
#ill etermine #hether chemical or h&sical #eatherin! r ocesses
are ominant$
4$1$ lberta balans sanstone
he lberta “sanstone” is e@tremel& suscetible to rill erosion'or t#o main reasons/ both relate to cla& mineralo!&$ he :rst is
the resence o' both smectites an 8aolinites #hich have ver&
i''erent roerties$ aterials containin! both smectite an
8aolinite have about the same shear stren!th at lo# #ater contents
( b 20P)$ s the #ater content increases smectites lose their stren!th
more rail& than the 8aolinite because o' the hi!h cation
e@chan!e caacit& (a&lor an -!!leton/ 2001)$
he secon reason ma8in! lberta sanstone articularl& susce+
tible to erosion is the critical amount o' cla& 'raction resent in these
materials (> 20P)$ Dalr&mle an im (1F4) inicate that #hen the
cla& content in sanstone is 10–20P/ cla& articles coat silt an san
articles an are lin8e b& the bri!in! cla& articles that can easil&
be bro8en$
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a) Leachate v olu m e - 10 m in rainfall30
25
20 SR-yellowSR-brown
SR-greySR- da rk grey
15 SR-redSR-light grey S- ma rly ! h a le S-dark red
10S-light red
5
0
"1 "2 "3 "# "5 "$ "% "& "' "10
cycle number
b) Leachate v olu m e - $0 m in rainfall30
25SR- y e llow
SR-brownSR-grey
20 SR- da rk greySR-red
SR-light grey
S- ma rly ! h a le15 S- da rk red
S-light red
10
5
01 2 3 # 5 $ % & ' 10
c ycl e m uber
;i!$ $ .eachate volume urin! incremental #eatherin! e@eriment$ a) 10 min samles/ b) 60 min samles (S — smectite+richG S< — smectite+oor)$
4$2$ Smectite+rich materials
Si@ materials are istin!uishe as smectite+rich" &ello#/ bro#n
an !re& muroc8 'rom Dinosaur
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a) Sediment concentration - 10 min rainfall#0
35
30
SR-yellow25 SR-brown
SR-grey
SR-dark grey20 SR-redSR-light grey
S-marly !hale15 S-dark red
S-light red
10
5
01 2 3 # 5 $ % & ' 10
cycle muber
b) Sediment concentration - $0 min rainfall#0
35
30
25SR-yellowSR-brown
SR-grey
20SR-dark greySR-red
SR-light grey
15S-marly !hale
S-dark red
S-light red
10
5
01 2 3 # 5 $ % & ' 10
cycle muber
;i!$ F$ .eachate seiment concentration urin! incremental #eatherin! e@eriment$ a) 10 min samles/ b) 60 min samles (S — smectite+richG S< — smectite+oor)$
liAui rich in a an Ca sulhates (.aronne/ 1F1)$ =' salt leachin!
oes not occur/ shar isinte!ration #ill not occur (o#ar/ 1FF7)$
Smectite+r ich seiments are most common in balan areas/
ho#+ ever/ litholo!ies o' similar comosition to Chin!uacous& shales
can be 'oun in other balans$ =llite/ 8aolinite an illite+smectite
mi@e la&ers comrise 26P o' the cla& 'raction in ancos shale/ tah
(;orsans an Schmitt/ 1FF4)$ ;am an Dusseault (1FF) sho#e
that Oueenston shale an ancos shale are similar materials #ith
hi!h ensit&/ lo# cat+ ion e@chan!e caacities an lo# volumetric
#ater content$ Due to the absence o' s#ellin! cla&s these materials
are not as reactive as the ma+ terials in the revious !rou/ ho#ever /
the resence o' t#o cla& min+ erals #ith i''erent roerties ma8es
these materials suscetible to erosion$ Due to i''erent cla& minerals
r esent/ #ater is nonuni'orml& istribute on the sur'ace o' the
shars in9uencin! the 9o# o' #ater throu!h shales (;am an
Dusseault/ 1FF)$ Di''erential s#ellin!/ hi!her isersion rates o'
illite/ an e@losion o' air trae in micr o or es cause
isinte!ration o' shars urin! #ettin!$ Shar s bra8e o#n 'rom
> 5 cm to > 0$5 cm in iameter a'ter onl& a 'e# rain'alls in the con+
trolle laborator& conitions$ he continuous isinte!ration o' shar s
rouces small amounts o' seiment 'or transort urin! rain'all$
he
:ne material that is release usuall& becomes the cementin! a!ent
' or remainin! shars$
.o# seiment &iel 'rom these materials is in accorance #ith the
etachment+limite moel that o#ar (1FF4b) eveloe 'or the
ancos shale$ Conve@ sloes in Chin!uacous& can be attribute to
the ominance o' cree an shallo# slumin!/ as o#ar (1FF4a)
also escribe 'or the orrison ;ormation in tah an the Charon
;ormation in South Da8ota$
5$ Conclusions
eatherin! oes not have the same e''ect on all balan mate+
rials$ n the lberta sanstone onl& a thin #eatherin! rin evelos$
=t can evelo a'ter one rain'all on the un#eathere sanstone an
oes not chan!e its roerties #ith rain'all intensit& an uration$
eatherin! is an imortant rocess on smectite+rich muroc8s$
he #eatherin! rate eens on intensit& an uration o'
reciitation an len!th o' r&in! erios$ Shar s#ellin! an
sur'ace sealin! occurs a'ter onl& 10–20 min o' rain'all$ Dr&in! o'ten
rouces a characteristic “ ocorn” sur'ace$ Durin! subseAuent
rain'alls an r&in! erios
g m l - 1
g m l - 1
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a) S(ecific conductance - 10 min rainfall2500
2000
1500
1000
SR-yellow
SR-brown
SR-grey
SR-dark grey
SR-redSR-light grey
S-marly !hale
S-dark red S-light red
500
01 2 3 # 5 $ % & ' 10
cycle muber
b) S(ecific conductance - $0 min rainfall2500
2000
1500
1000
SR-yellow
SR-brown
SR-grey
SR-dark grey
SR-red
SR-light grey
S-marly !hale
S-dark red S-light red
500
01 2 3 # 5 $ % & ' 10
cycle muber
;i!$ 10$ .eachate seci:c conuctance urin! incremental #eatherin! e@eriment$ a) 10 min samles/ b) 60 min samles (S — smectite+richG S< — smectite+oor)$
esiccation crac8s 'orm on the sur'ace$ ver time crac8s become
#ier an eeer an crac8 re+aearance can rouce 9o#aths
that can evolve into r ills$
hen un#eathere smectite+rich material is e@ose to
sur 'ace conitions seiments an solutes are mostl& release urin!
the :rst one or t#o rain'alls an usuall& reach a constant value
a'ter thr ee more rain'alls$ he ea8 o' seiment &iel usuall&
sho#s a ela& o' one to t#o c&cles comare to the solute
concentr ation$ his is in accor+ ance #ith the crac8 a ear ance$
ost solutes are #ashe thr ou!h crac8s that 'orme initiall&/ causin!
hi!h seci:c conuctance an se+ iment concentration in the
leachate$ 'ter that/ the sur 'ace/ an es e+ ciall& the subsur'ace crac8s
serve as the re'erential 9o# conuits/ so that seci:c conuctance
an seiment concentration ecrease an the leachate volume
increases urin! subseAuent #eatherin! c&cles$
Cla&+rich materials that contain illite an chlorite as ominant
minerals have i''erent #eatherin! rocesses$ Durin! reeate #et+
tin! an r&in! shars brea8 o#n into smaller shars ue to i''er+
ential s#ellin! o' illite an chlorite$ nce the& are reuce to tin&/
9a8& shars (0$5 cm ? 0$2 cm) the sur'ace becomes comacte$
Durin! #ettin! these shales release a constant small amount o' sei+
ments/ #ith re!ular ecrease in seci:c conuctance an leachate
volume over rain'alls$
his stu& has sho#n that cla& mineralo!& is e@tremel&
imor tant 'or the behaviour o' i''erent materials$ ccorin! to their
resonse to reciitation/ t&e o' #eatherin!/ erosional rocess an
rill net#or 8 characteristics/ balan litholo!ies can be !roue b&
cla& mineralo!&" sanstones an siltstone that t&icall& have > 20P
o' cla& miner als/ smectite+rich muroc8s an shales/ an shales thato not have smec+ tite as the ominant cla& miner al$ =n revious
balan stuies cla& min+ eralo!& #as ver& rarel& teste in etail an
it is crucial in'ormation ' or unerstanin! the rocesses active an
reiction o' sloe evolution$ btaine results inicate that
eterminin! the etail miner alo!ical comosition o' materials is
essential 'or unerstanin! !eomor hic rocesses an shoul not be
ne!lecte in 'uture stuies$
So 'ar h&sicall&+base moels o' soil erosion an rill
evelo ment have not incororate litholo!ical characteristics in
an ar o r iate #a&$ his stu& has rove that litholo!ical
roerties/ ar ticular l& cla& miner alo!&/ are o' !reat imortance 'or
hillsloe rocesses$ =n this
u S
c m - 1
u S c m - 1
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stu& it has been sho#n that smectite+rich an smectite+oor
litholo+ !ies behave istinctivel& an this classi:cation shoul be
use as a basis 'or the moel im r ovement$
c8no#le!ments
= #oul li8e to e@ress ee !ratitue to Dr$ or8e r&an 'or his
suort an !uiance throu!hout the research$ = #oul also li8e to
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base 'rom atural Science an -n!ineerin! esearch Council/
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e'erences
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