DSpace at VNU: The advantages of the new proposals in the improved symmetric induced polarization sounding method

VNU. JOURNAL OF SCIENCE, Mathematics - Physics. T .XVIII, Nq 4 - 2002

TH E ADVANTAGES OF TH E N EW
IN

T H E IM P R O V E D
P O L A R IZ A T IO N

PRO PO SA LS

S Y M M E T R IC
S O U N D IN G

IN D U C E D

M ETHOD

Vu D u e M in h
C o lleg e o f S c ie n c e , V N U

A b s tr a c t. T h e higher resolution, greater investigating depth, increasing reliability of ge­
ology forecasting results and possibility of expanding the application of the improved
symmetric induced polarization sounding method have been illustrated by theoretical and
field medium are th e advantages of the new proposals presented in this article.

I. I n tr o d u c tio n
III th e article [2], th e our n ew p rop osals, e sp ecia lly th e P etro v sk i in d u ced p o la r­
iz a tio n (IP ) p aram eter r/p, h a v e b een in tro d u ced for d a ta p ro cessin g in th e in d u ced p o ­
larization so u n d in g m eth od ; a s a resu lt, th eir a d v a n ta g es in co m p a riso n to th e p reviou s
con ven tion al p a ra m eters have b een illu stra ted by ca lc u la tin g for th e th eo retica l m ed iu m .
H ow ever, th e P etrovsk i tra n sfo rm in g form ula co n ta in s d eriv a tio n w h ich is n ot sta b le, so

d esired resu lts are not. alw ays o b ta in ed . W ith p u rp o se to o v erco m e th e se d isa d v a n ta g es,
w e have p rop osed th e im proved sy m m etric electro d e array and th e co rresp o n d in g m easu re­
m ent procedure, th e sim p le a lgeb raic tra n sfo rm a tio n s (w ith o u t th e d eriv a tio n ) to ap p ly
to th e resistiv ely sou n d in g m e th o d [ l] . T h o se im p roved s y m m e tr ic e le c tr o d e array and
tran sform atio n s are o f scien tific arid p ra ctica l sign ifican ce. B a sin g o n th o se research es, w e
a lso have p rop o sed th e im p roved sy m m etric IP so u n d in g m e th o d (IS IP S ) a n d it h a s b een
te ste d effectiv ely as th e article [3].
In th is a rticle, w e w ill illu str a te th e correctn ess a n d a d v a n ta g es o f th e new p rop osals
in the IS IP S by th eo retica l an d p ra ctica l m edium ; p r o p o sin g p o s sib ility o f ex p a n d in g and
achieve b e tte r geological effectiv e o f th e n ew p rop osals to th e a p p lic a tio n o f th e IS IP S in
fact for d a ta p ro cessin g o b ta in e d b y u sin g th e p rev io u s co n v en tio n a l IP so u n d in g m eth o d .

I I. B a sics o f t h e new p ro p o s a ls in t h e im p ro v e d s y m m e tr ic in d u c e d p o la riz a tio n
s o u n d in g m e th o d
I I . 1 T h e n e w in d u c e d p o la r iz a tio n p a r a m e te r s
A s know n , t he apparent p o la riza tio n is c a lc u la te d by th e fo llo w in g form ula:

Vk = p*k- Pk/Pkt

(!)

w here pị a n d pk are the ap p aren t re sistiv itie s o f th e p o la rized an d n o n - p o la rized m ed iu m ,
resp ectively, corresp on d in g to th e r e sistiv ity p a ra m eters p i a n d Pi w h ich are rela ted by:
p* = P i / ( I — r/i) w here i is th e m ed iu m m o d el in d ex .
T y p e s e t by
13


14

V u D u c IM in h

B a sin g on th e a b o v e d efin itio n s, w e h ave also d efin ite th e n ew I P p a ra m eters [2]
sim ilarly:
- T h e p o la riza tio n o f th e sy m m etric In d u ced P o la riza tio n so u n d in g m ethod: rj9.
- T h e p o la riza tio n o f th e (lip o le-a x is In d u ced P o la riza tio n so u n d in g m ethod: r)r .
- T h e P etr o v sk i p o la riza tio n : Tjp

II.

2 T h e n e w t r a n s fo r m a tio n s

A ccord in g to [3], th e im p ro v ed sy m m etric In d u ced P ola riza tio n so u n d in g ele c tr o d e
array is a llo c a te d a s th e follow ing:

m

2

m

,

a

b

n

,

n,

— ------------ • ------------- • ---------------------- ♦ -------------------♦ --------------------- • ----------------• -------------------w here, w ith o n e cu rre n t-electro d e sep a ra tio n A B , from th e m ea su rem en t w e m ay o b ta in

Psi(r i)> Vsi(r \) a n d Ps 2 (r 2)>Vs2 (r 2 ), co rresp o n d in g to rj and r 2. In such a way 4 curve
Pi \ , Pi2 a n d TỊS\ , ri„ 2 a re o b ta in e d .
T h en :

^ LS (

a M S -frJ'

/ 0\

(2)

where psr - the dipole-axis resistively sounding curve obtained by transform ing from th(!
s y m m e tric re sistiv e ly so u n d in g c u rv e p a.
T h e v a lu es o f P etro v sk i r e sistiv e ly so u n d in g cu rve ppar are ca lcu la ted by the follow ­
ing form ula:

Ppsr = p j ( 2 p sr/ p a - 1).

(3)

T h e n a ll th e n ecessa ry in fo rm a tio n w ill b e ca lcu la ted accordin g to th e sc h e m a show n
o n figure 1 .

Figure 1. S ch em a ca lcu la tin g ..p a ra m eters by u sin g IS IP S array

The

a d v a n ta g e s o f th e n e w p r o p o s a ls i n th e i m p r o v e d s y m m e t r i c

.

15

I I I . C h e c k in g t h e m u tu a l p rin c ip le
W e have m easu red an d c a lcu la ted ex p erim en ta lly th e m u tu a l p rin cip le on th e field
m ed iïiu n . Below w e present o n ly th e ex a m p le resu lt in T an D an - H o a n h B o - Q u an g N in h .
F igure 2 sh o w s the ap p aren t resistiv ely cu rves prstr (rorstr) p r a ctic a lly m easu red by
t h e im p ro v ed sy m m etric so u n d in g array M A B N , Prsng (rorsn g) p r a c tic a lly m ea su red by th e
im p r o v e d sy m m etric sou n d in g array A M N B and th e co rresp o n d in g P etro v sk i resistiv e ly
s o u n d in g curves.
F igu re 3 sh o w s the P etrovsk i resistiv ely cu rves ỌyrstT (rop rstr) for array MA B N and

Pprsng (roprsng) for array A M N B ; th e P etrovsk i resistiv ely cu rv es Pprsxd (rop rsxd ) derived
fro m th e tran sform ation o f th e v a lu es Pr p ra ctica lly m ea su red by th e ID A IP S array and
ơ n e v a lu e Prjxd(r max) m easured by th e eq u atorial d ip o le array a t fin al siz e p max o f the
I D A I P S array.
ị

;

:

;

;
.... ;

i .

.

Î

.i

-i-

.i..

.

—

ro rs*

—

ro rsrç j

—

ro p rs tr

—

f c p re n g

10*1------- — *------ — - *•-------- — -— ----- ~.-iU
10°
to’
1Ơ*

Figure 2. C urves p rstr (rorstr), p rsng (rorsng)
an d corresponding Petrovski curves
W e realize th a t curves are fitted . T h is proves th a t th e m u tu a l p rin cip le is right for
a ll th e arrays, th e electro d e sp acin g, th e m ea su rem en ts as w ell a s th e tra n sfo rm a tio n s th a t
h ave b e e n u sed to confirm th e m eth o d .

IV . C o n firm in g t h e c o rre c tn e s s a n d a d v a n ta g e s o f t h e n e w p ro p o s a ls

I V . 1 Calculating values o f the polarization sound ing curves
★ The threc-laycred g CO-electrical model
B y sim u la tio n m eth o d in P C , w e have b u ilt th e p ro g ra m s o f calfculating th e p o la r­
iza tio n so u n d in g cu rves on layered g e o e le c tr ic a l m o d e ls for d ifferen t ele c tr o d e array by
M atlab lan gu age. W o on ly give a sp ecific ex a m p le o f th e th ree-la y ered g eo -electrica l m o d el
as follow in g: pi = [14.51]; TỊi = [241);

h x = [15]; w ith i = 1 , 2 , 3
F ig u r e 4 sh ow s th e th eo retica l ID A IP S curve Tịr (eta r) a n d th e cu rv e corresp on d in g
to the ID A I P S cu rves 7]sr (eta sr) o b ta in e d by tra n sfo rm a tio n .


16

V u DĩẦc M i r t h

F igu re 5 sh ow s th e th eo retica l P etrovsk i curve T)p (eta p ) an d th e Petrovski cu rv e

vpsr (etap sr) o b ta in ed by tran sform ation .

F igure 4. T h e th e o r e tic a l cu r v e rjr (etar) a n d
cu r v e ĨỊsr (e ta sr ) o b ta in e d by tr a n s fo r m a tio n

Figure 5. T he theoretical curve 7]p (etap)
and

(etapsr) obtained by transformation

★ The field m edium
T h e te stin g ca lcu la tio n s h ave b een p erform ed in Tan D an - H oan h B o - Q uang N in h
and D akson g - G ia Lai. B elow w e o n ly p resen t th e ex a m p le curves m ea su red at point 22

o f th e profile S l l in D aksong - G ia Lai.
F ig u re 6 shows cu rv e 7]r (e ta r) p ra c tic a lly m easu red by th e ID A IP S array; th e
ID A IP S curves 7]sr (etasr) and r]p3r (eta p sr) o b ta in ed by tran sform ation o f carves p8) TỊa
p ractically m easu red by th e IS IP S array an d par.

F igure 6 . T h e p ra ctic a l cu rv e 7]r (eta r) a n d
c u r v e 7/irx(e ta sr ), 7J (eta p sr) o b ta in e d by tr a n s fo r m a tio n
In com p arin g, p ra ctica l m easu red cu rves and corresponding cu rves ob tain ed by
tran sform ation are nearly fitted , o n ly th e v a lu es at som e final sizes is n o t th e sam e. T h is
proves th e correctn ess o f th e algebraic tran sform ation s m en tio n ed a b o v e. B esid es, Petrovski curve also h as reflected clearly resolu tion a b ility - th a t is it s a d van tages.

I V . 2 P ro c e ssin g d a ta o n th e p ro file
T h e new p rop osals h ave b e e n ap p lied in tw o directions:
1. P ro cessin g and a n a ly zin g d a ta o b ta in ed p reviously b y th e n orm al IP sounding


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

17

m eth o d in order t o ex p lo it and add oth er u sefu l in form ation in tw o ways:
4- In terp o la tin g values o f curves TỊk and pk o b ta in ed p reviou sly by the norm al IP
sou n d in g m eth o d to valu es o f th e im p roved IP curves w ith th e correspon d in g sizes o f
electrod e sp acin g an d coefficients.
-f Prom th e sizes o f n orm al electro d e array, ca lcu la tin g corresp on d in g coefficients
o f th e im proved electro d e array.
2. P ro cessin g a n d a n a ly zin g d a ta o b ta in ed by th e IS IP S m eth o d .
B elow w e p resen t o n ly th e resu lts o f a p p ly in g th e new p ro p o sa ls to ex p lo it d a ta
ob tain ed p reviously b y the n orm al S IP S m eth o d on profile 20 in S o n g G iang - Q u an g
N am , w hich were m easu red by U n io n o f P h y sic-G eo lo g y in 1999.
★ The results o f processing and analyzing data obtained previously by the normal

SIP S method on profile 20 (see figures 7, 8 )
• Line 20 w a s form ed in th e N o rth ea st - S o u th w est d irectio n p erp en d icu larly to the
folding stru ctu re w ith N o rth w est - S o u th ea st d irection in th e S o u th e a st o f G iang R iver.

Figure 7. C ontour section Tị on th e profile 20 (%)
(S o u rc e : U n io n o f P h y sic -G e o lo g y )
• A lon g th e profile, th e fo llow in g m a in geological form ation s are identified:
-f B en g ia n g - Q u e son m a g m a com p lex:
GE OL OGI C A L SECTION

IN GIANG RIVEK
0

200

400

600

QUANG NAM
800

1000

Figure 8 : Geological section of th e profile 20
(S o u rc e : U n io n o f P h y sic -G e o lo g y )

1200


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V u D uc M in h

M ain com p on en ts:
blende.

gran od iorite, b io tite hornblende, an d to r a n ite b iot.te h o r n ­

Specific p h ysical fea tu res are resistiv ity w ith p = 2, 000 — 3 ,0 0 0 ohm s.m

po­

larization 7/fc = 3 — 5%

D irections:
1 . G ranod iorite o f B en G ian g - Q u e son com p lex, p h a se 2;
2. S ch ist o f K ham d u e form ation , layer 3;
3. S ch ist o f K h a m D u e form ation, layer 2;
4- A ltered zones;
5. Faults;
6 . V ents o f gold-sulfuric quartz.
+ T h e m etarnorphic sed im en tary rocks o f K ham D u e fo rm a tio n con sist of:
- U p p er layer: b io tite - gran ite quartz shale, m ica quartz, an d p lagioelase - bi-

otite quartz. Specific physical features are resistivity w ith p = 1,000 — 2,000 ohm s.m ,
p olarization w ith T]k = 2 — 4%.
- Lower layer: B im ica gn eis, b im ica quartz, b io tite g n eis, sch ist, a n d b iotite qu artz.
Specific p h ysical featu res are resistiv ity w ith p = 500 - 1 ,0 0 0 o h m s.m , stim u la ted p o la r­
ization w ith 7]k = 2 — 4%.
M etam orp h ic sed im en ta ry form ation s w ere stro n g ly fold ed an d divided by deep
fau lts p erp en d icu larly w ith th e surveyed profile.

A lo n g th e fa u lts, rocks are stro n g ly

d estro y ed a n d in filtra te d by sulfu ric ores. D estroyed zone h a s sm all re s istiv ity p = 2 0 0 —500
o h m s.m and high p o la riza tio n T]k = 3 — 5%.
G old b ea rin g p o ly m eta l surphide - quartz zo n es h ave th e r e sistiv ity relevan t to
altered zon es and high p o la riza tio n rjk = 5 — 10%.
• T h e aim o f the IP so m id in g m eth o d is to solve th e fo llow in g tasks:

+ T o stu d y folded stru ctu res along th e surveyed profile;

4- To define gold b ea rin g su rp hide - quartz zones.
★ The results o f applying the new proposals to exploit data
W ith a p p ly in g th e n ew p rop osals to ex p lo it d a ta o b ta in ed p rev io u sly by th e norm al
S IP S m eth o d on profile 20 in S on g G ian g - Q u a n g N a m th en con tou r sectio n s o f p olar­
ization have b een ca lcu la ted and reported. B elow w e o n ly present, th e ex a m p le co n to iư
sectio n s T)sr and Tjpsr o n figures 9, 10.

F igure 9. C on tou r se c tio n 7]sr (%)


T h e a d v a n ta g e s o f th e n e w p r o p o s a ls i n th e i m p r o v e d s y m m e t r i c .

19

Figure 10. Contour section 77pnxd (%)
The results of applying the new proposals in the ISIPS to exploit d a ta obtained on
profile 20 in S on g G ian g - Q u a n g N a m can b e seen th at:

-f Detail division of geological components in the section;
- M agm a tic gra n o d io rite form ation is ch aracterized by r e sistiv ity 2,000 - 3,000
oh m s.m , p o la riza tio n 4 - 5%;
- M etam o rp h ic sed im en ta ry rocks o f K h am D u e form ation s are characterized by
resistiv ity 1,000 - '2,000 o h m s.m , p o la riza tio n 3 - 5%.
+ T h e b roken zone, d e s tn ic te d alo n g th e fa u lts is d e a r ly d efined.

T h is zon e is

ch aracterized by low resistiv ity ‘200 - 800 o h m s.m , p o la riza tio n 6 - 8%; defining in m ore

d eta il th e gold b ea rin g sur phi d e - quartz zon es w ith th e p o la riza tio n from 8 to 10%.
T h e contour se c tio n TỊpsr, severally, d efined clearly and in d eta il th e v en t b o d ies w ith the

polarization from 8 to 10%.
We see clearly that applying the new proposals in the ISIPS to calculate the ap­
parent resistivity and polarization values perm its defining research objects in more detail
and locating more clearly.
V . C o n c l u s io n s
1.

For th e first tim e, th e P etro v sk i IP p aram eters (esp ecia lly r/p) h ave b een p r o ­

p osed and th eir scien tifica lly th eo retica l b a se b u ilt and a d v a n ta g es th a t th ey ex h ib it higher

reso lu tio n a n d g re a te r in v e stig a tin g d e p th th a n th e co n v en tio n al p a ra m e te rs pki Vk have

been confirmed by us.
2ã. T h e n ew p ro p o sa ls in th e IS IP S h ave h igh scien tific relia n ce, really usefulness,
and scientific and practical significance. T hey elim inated the fundam ental disadvantage
th at the transform ation between curves through the unstable derivation existed for a
long time. One of the advantages of our proposal is only using the simple and reliable
algebraic formulas to transform curves. Creating algorithm s of processing and analyzing
the data using the new proposals in the ISIPS basing on selecting reliable information
with comprehensiveness. T hey also have m ade the geology forecasting results clearer and


20

V u D u c M in h

m ore reliable, reflected th e nearly real IP effect o f stu d y o b jects, in crea sed resolu tion o f
weak an om alies.

A ll o f th o se h ave illu stra ted the d istin gu ish ed a d v a n ta g es o f th e n ew

proposals.
3.

E x p a n d in g and in creasin g p o ssib ility o f th e a p p lication o f IP so u n d in g m e th o d ,

n ot on ly for n ew m easu rem en t p ro ject, b u t also for ex p lo itin g and a d d in g oth er u seful
inform ation to su p p o rt th e p ro cessin g and an a ly zin g o ld o b ta in ed p rev io u s IP d ata. T h is
is q u ite a new problem an d very n ecessary for th e IP so u n d in g m eth o d .
W e con tin u e to d evelop an d co m p lete th is d irectio n o f p ro cessin g an d an a ly zin g th e
IP sou n d in g d a ta b asing o n e x p lo itin g th e ab ove new p rop osals have m a d e by th e au th or,
as w ell as con tin u e to d evelop th is new d irection for 2D - 3D a lg o rith m s.

R eferen c es
1. L ê V iếl Dư K hương, V ũ Đ ức M inh, C ác phương pháp m ới ư o n g đo sâu điỏn ư ở dùng
tổ hợp hê cực đo hợp lý, T ạ p c h í C á c Khoa h ọ c v ề Trái đ ấ t, 23 3 (2 0 0 1 ), tr. 217 -2 2 4 .
2. Vu Duc M inh, Le V iet Du K huong, Som e Induced-Polarization soun d in g m ethods and
th eừ ability in in vestigating g e o lo g ic a l m edium , VNU. Journal o f Science, N atural
S c ie n c e s , t X V II 4 (2 0 0 1 ), pp. 2 8 -3 4 .
3. Vu D uc M inh, Induced-Polarization Sounding m ethods in a n ew manner, Journal o f

G eology , Seri B, N o. 17, 18(2001), pp. 94-101.