K/Ar Ages of the Volcanic Region of Ali Sabieh (French Territory of the Afar, East Africa)

Article

Reference

K/Ar Ages of the Volcanic Region of Ali Sabieh (French Territory of the Afar, East Africa)

CHESSEX, Ronald, et al.

Abstract

La région d'Ali Sabieh, située entre la dépression de l'Afar et le horst d'Aisha, a été le témoin d'une intense activité volcanique, de caractère essentiellement fissural, entre le Miocène inférieur et le Pleistocène. Les roches datées sont des basaltes, émis tout au long de la période d'activité, et des roches acides (rhyolites et ignimbrites) bien représentées dans la partie inférieure de la série.

CHESSEX, Ronald, et al. K/Ar Ages of the Volcanic Region of Ali Sabieh (French Territory of the Afar, East Africa). Eclogae Geologicae Helvetiae, 1974, vol. 67, no. 1, p. 235-238

Available at:

http://archive-ouverte.unige.ch/unige:151467

Disclaimer: layout of this document may differ from the published version.

1 / 1

'LH )HOGEHIXQGH ZHUGHQ ]XVDPPHQ PLW GHQ HUVWHQ 0HVVUHVXOWDWHQ HV LQ HLQLJHQ -DKUHQ HUODXEHQ HLQ JH]LHOWHV DXVVDJHVLFKHUHV 3URJUDPP IU GLH (UIDVVXQJ DOOIlOOLJHU

UH]HQWHU %HZHJXQJHQ DXV]XDUEHLWHQ

/,7(5$7859(5=(,&+1,6

-lFNOL ⁺ 9HUZHUIXQJHQ MXQJTXDUWlUHQ $OWHUV LP VGOLFKHQ $DUPDVVLY EHL 6RPYL[5DELXV (FORJDH JHRO +HOY

(FNDUGW ³ =XU 7DOJHVFKLFKWH ^GHV 7DYHWVFK VHLQH %UXFKV\VWHPH XQGMXQJTXDUWlUHQ ^9HUZHU¤

IXQJHQ 'LVV 8QLY =ULFK

5RQDOG

&KHVVH[

0LFKHO

'HODOR\H -DFTXHV

0XOOHU

^DQG

^0DUF

:HLGPDQQ

.$U

^{$JHV RI WKH 9ROFDQLF 5HJLRQ}

RI $OL

6DELHK )UHQFK 7HUULWRU\ RI ^WKH

$IDU (DVW $IULFD

5(680(

/D UpJLRQ G$OL 6DELHK VLWXpH HQWUH OD GpSUHVVLRQ GH O$IDU HW ^OH KRUVW G$LVKD D pWp OH WpPRLQ GXQH LQWHQVHDFWLYLWp YROFDQLTXH ^GH FDUDFWqUH HVVHQWLHOOHPHQW ILVVXUDL HQWUH OH 0LRFqQH LQIpULHXU HW OH 3OHLVWRFqQH /HVURFKHV GDWpHV VRQW ^GHV EDVDOWHV pPLV WRXW DX ORQJ^GH OD SpULRGH GDFWLYLWp^{HW GHV} URFKHV DFLGHV UK\ROLWHV HW LJQLPEULWHV ELHQUHSUpVHQWpHV GDQV OD SDUWLH LQIpULHXUH ^GH OD VpULH

,QWURGXFWLRQ

7KH UHJLRQ VWXGLHG ^LV VLWXDWHG QHDU WKH (WKLRSLDQ IURQWLHU ^{LQ WKH} )UHQFK 7HUULWRU\

RI

^{WKH $IDUV DQG WKH ,VVDV}

7)$, ,W

FRYHUV WKH OLPLWV VHSDUDWLQJ WKH

$IDU

GHSUHVVLRQ WR WKH ZHVW IURP ^WKH $LVKD KRUVW WR ^WKH HDVW

$IWHU

WKH SLRQHHU ZRUN

RI

'UH\IXVV JHRORJLF PDSV

RI

^WKH

7)$,

^KDYH

EHHQ SXEOLVKHG E\ %HVDLULH DQG _E\

&OLQ

^{DQG 3RXFKDQ} 7KH UHFHQW V\QWKHVHV

RI

%DNHU HW DO

%DUEHUL

HW DO D DQG E

%ODFN

^{HW DO}

0F&RQQHO

DQG

0RKU

LOOXVWUDWH YDULRXV VWUXFWXUDO LQWHUSUHWDWLRQV

,Q DQG WKH &HQWHU IRU _*HRORJLF 6WXGLHV DQG 'HYHORSPHQW &(*'

RI

WKH

7)$,

^{XQGHUWRRN WKH} JHRORJLFDO PDS

RI

^WKH

$OL

^6DELHK TXDGUDQJOH DW ^{D VFDOH}

RI

7KH SUHVHQW SDSHU ^{LV D} VXPPDU\

RI

^{WKLV ZRUN $} PRUH FRPSOHWH DFFRXQW

ZLOO

^EH SUHVHQWHG LQ

$SULO

^{DW WKH}

$IDU

6\PSRVLXP LQ .DUOVUXKH *HUPDQ\

:H VLQFHUHO\ ZLVK WR WKDQN RXU FROOHDJXHV

RI

^WKH &(*' IRU WKHLU FRQWULEXWLRQ

DV ZHOO DV LWV GLUHFWRU SURIHVVRU 0LFKHO &OLQ 8QLYHUVLW\

RI

^%RUGHDX[

,,,

$QDO\WLFDO ^{GDWD DQG}DJH UHVXOWV

7KH

.

FRQWHQW GHWHUPLQDWLRQV ZHUH FDUULHG RXW RQ ^D (HO IODPHSKRWRPHWHU ^IROORZLQJ WKH QRZ FRQYHQWLRQDO PHWKRG 7KH SUHFLVLRQ ^LV “

'HSDUWPHQW RI0LQHUDORJ\ 8QLYHUVLW\ RI*HQHYD

/DERUDWRU\ RI6WUXFWXUDO *HRORJ\ 8QLYHUVLW\RI%RUGHDX[,,,

&DQWRQDO 0XVHXP RI*HRORJ\ /DXVDQQH

5 &KHVVH[ HW DO .$UDJHV RI $OL ^6DELHK 5HJLRQ $IDU ^(DVW $IULFD

-?

A -- ^?? ?

^$5$%,$

?ƒ ^{? ?? ? ??} _? ^???

^Yw

^??

^&222

_ƒ ? ?? ? _{? ?? ? ??}

_,

^Q

\WH?? AaAA

q ^{WH?? WH?} ?8G ^a

w q

q A ?8 ?8

^{*X I}

G G _BA

X ^{V O A OO}

^620$/,$

-

P PDSSHG DUHD

-

)LJXUH /RFDWLRQ _PDS RI^WKH VWXGLHG DUHD

7KH

$U

^LV DQDO\VHG RQ D $(,06 PDVV VSHFWURPHWHU RQ OLQH ZLWK D S\UH[

H[WUDFWLRQDQG SXULILFDWLRQ ^{OLQH 7KH} VSLNH ^{XVHG LV}IURP .OXVLXV =ULFK 7KH_DFFXUDF\

LV “ RQ GXSOLFDWH UXQV 7KH FRQVWDQWV XVHG DUH

;H [ O2L2\U

A

^[

^O2A\U

7KH RYHUDOO SUHFLVLRQ RQ WKH DJH GHWHUPLQDWLRQ LV “

LI

DWPRVSKHULF DUJRQ ^LV

OHVV WKDQ 7KH GHWHUPLQDWLRQV ZHUH FDUULHG RXW RQ ZKROH URFN VDPSOHV 7DEOH .$U ^{GDWD DQG} DJH UHVXOWV RQ YROFDQLF URFNV IURP WKH $OL ^6DELHK UHJLRQ 6DPSOH 5RFN _W\SH )RUPDWLRQ R. ^0ROHV$U UDGJ ^$U DWP $JH

1R O2LR P\

-0 %DVDOW *DOLOH

“

*( %DVDOW *DOLOH

“

-0 ,JQLPEULWH *DOLOH “

-0 ,JQLPEULWH *DOLOH

“

*( 5K\ROLWH *DOLOH “

*( ,JQLPEULWH *DOLOH

“

-0 'ROHULWH 'LNH VZDUPV “

*( 'ROHULWH 'LNHVZDUPV

“

*( 0LFURV\HQLWH 'LNHVZDUPV

“

*( 0LFURJUDQLWH 'LNH VZDUPV “

*( 0LFURJUDQLWH 'LNHVZDUPV

“

-0 5K\ROLWH ^'DPHUNDGGD “

-0 5K\ROLWH ^'DPHUNDGGD “

*( %DVDOW *DOHPL

“

'- %DVDOW /RXJDJ $OH

“

'- %DVDOW /RXJDJ $OH

“

'- %DVDOW /RXJDJ $OH

“

0& %DVDOW /RXJDJ $OH “

0DILF IUDFWLRQ

6WUDWLJUDSK\ ^DQGVWUXFWXUDOHYROXWLRQ LQ WKH OLJKW

RI

WKH DJH GDWD

:H

ZLOO

ILUVW VXPPDUL]H WKH VWUDWLJUDSKLH ^VHULHV FRPSULVLQJ ^WKH VXEVWUDWXP RIWKH GDWHG YROFDQLF URFNV 7KH OLWKRVWUDWLJUDSKLF GHVLJQDWLRQV DUH SUHOLPLQDU\ IRU ^WKH UHJLRQ

RI $OL

6DELHK WKH\ ZHUH ^FKRVHQ E\ FRPSDULVRQ ZLWK KRPRORJRXV ^VHULHV LQ WKH 6RPDOL 5HSXEOLF (WKLRSLD RU ^<HPHQ %H\GRXQ

%ULQFNPDQQ

^DQG

.UVWHQ

%ODQW

%H\WK HWF

D 3UHFDPEULDQ JQHLVVLF EDVHPHQW GLVFRUGDQWO\ RYHUODLQ E\ FU\VWDOOLQH ^VFKLVWV DWWULEXWHG WR ^WKH 8SSHU3UHFDPEULDQ/RZHU 3DOHR]RLF,QGD $G 6HULHV ,QWKH VWXGLHG DUHD ^WKHVH URFNV _DUH NQRZQRQO\ ^DV [HQROLWLF LQFOXVLRQV LQ D PLFURV\HQLWH GLNH *(

E 7KH GLVFRUGDQW VHGLPHQWDU\ ^VHULHV RYHUO\LQJ ^WKHVH XQLWV LV

RI

^-XUDVVLF DJH DQG LQFOXGHV WKH IROORZLQJ IRUPDWLRQV

^{$GLJUDW 6DQGVWRQH} SUREDEO\ /LDV'RJJHU

^{$QWDOR /LPHVWRQH} &DOORYLDQ3RUWODQGLDQ

^{$JXOD 6KDOH WRSPRVW -XUDVVLF}

F 3KDVH

RI

JHQWOH IROGLQJ SUREDEO\ ^EHWZHHQ WKH -XUDVVLF DQG WKH &UHWDFHRXV G 7KLFN ^VHULHV

RI

^{VDQGVWRQHV DQG} VLOLFHRXV FRQJORPHUDWHV XQGDWHG EXW JHQHUDOO\

DWWULEXWHG WR ^WKH &UHWDFHRXV NQRZQ DV

8SSHU

^{6DQGVWRQH $PED $UDGDP )RUPDWLRQ}

H $UFKLQJ ^DQG IDXOWLQJ

RI

^WKHVH VHGLPHQWDU\ URFNV ^EHWZHHQ WKH &UHWDFHRXV DQG WKH 8SSHU ^2OLJRFHQH SUREDEO\ LQ UHODWLRQ

ZLOK

WKH ILUVW

ULIW

PRYHPHQWV

:H HQWHU QRZ WKH YROFDQLF IRUPDWLRQV

RI

^WKH

$OL

6DELHK UHJLRQ ZKLFK PDUN WKH

OLPLW

EHWZHHQ WKH

$IDU

GHSUHVVLRQ DQG WKH $LVKD KRUVW

I

^7KH $PED $UDGDP )RUPDWLRQ ZDV FRYHUHG E\ ^EDVLF DV ZHOO DV E\ DFLG YROFDQLF SURGXFWV WKH ^*DOLOH )RUPDWLRQ ZKLFK ^LV PRUH WKDQ P WKLFN 7KH ORZHVW SDUW

RI

WKLV IRUPDWLRQ ^LV FRPSRVHG PDLQO\

RI

VXEDHULDO ^DQG VXEDTXDWLF ^EDVDOWV ZLWK WKLQ DOOXYLDO LQWHUFDODWLRQV 1R UHOLDEOH GDOHV ZHUH REWDLQHG RQ ^WKHVH KLJKO\ DOWHUHG URFNV 7KH XSSHU SDUW

RI

^WKH *DOLOH IRUPDWLRQ FRQWDLQV GRPLQDQW DFLG YROFDQLF URFNV UK\ROLWHV LJQLPEULWHV S\URFODVWLFV HPLWWHG IURP ^VHYHUDO FHQWHUV DQG ILVVXUH _V\VWHPV

.$U

DJHV IURP WR P\ ,QWHUFDODWLRQV

RI

^EDVDOW IORZV DUH FRPPRQ

.$U

DJHV IURP WR P\ ^7KHVH

.$U

^YDOXHV SRLQW WR ^D /RZHU 0LRFHQH _DJH

$JHV FRUUHVSRQGLQJ WR ^WKH /RZHU 0LRFHQH P\ DUH WKH ROGHVW IRXQG XQWLO _QRZ LQ WKH YROFDQLF SURGXFWV ZLWKLQ

$IDU

GHSUHVVLRQ

%DQQHUW

^{HW DO} FRPSLODWLRQ

RI

^{WKH DYDLODEOH} DJH GDWD E\

%DUEHUL

^{HW DO} E

2XU GDWD DV WKRVH FLWHG DERYH VWURQJO\ VXJJHVW WKDWWKH VLQNLQJ

RI

^{WKH 6(} SDUW

RI

WKH

$IDU

GHSUHVVLRQ EHJDQ LQ WKH /RZHU _{0LRFHQH RU} SHUKDSV LQ WKH XSSHUPRVW 2OLJRFHQH

J )DXOWLQJ ^{DQG EORFN}

WLOWLQJ

SHULRG ZLWK LQWUXVLRQ

RI

QXPHURXV ^{DFLG DQG EDVLF} GLNHV DQG VLOOV

.$U

DJHV WR P\ ,Q IDFW WKHUH DUH ^VHYHUDO GLNH _V\VWHPV ZKLFK DUH QRW V\QFKURQRXV ^DQG FRUUHVSRQG FHUWDLQO\ WR GLIIHUHQW IDXOWLQJ SHULRGV 6RPH

RI

^WKHVH GLNHV UHSUHVHQW SUREDEO\ ^{WKH IHHGHUV}

RI

^WKH *DOLOH YROFDQLF URFNV K 6HFRQG F\FOH

RI

^{DFLG YROFDQLF} DFWLYLW\ ^WKH SURGXFWV

RI

ZKLFK FRQVWLWXWH WKH 'DPHUNDGGD )RUPDWLRQ 7KH WKLFNQHVV

RI

WKLV IRUPDWLRQ FRPSOHWHO\ GHYRLG

RI

EDVDOW UHDFKHV _D PD[LPXP YDOXH

RI

P 1:

RI $OL

^6DELHK

7ZR _VDPSOHV

RI

_UK\ROLWH FROOHFWHG LQ WKH XSSHU SDUW

RI

^WKH IRUPDWLRQ JDYH

.$U

DJHV

RI

^DQG _P\ FRUUHVSRQGLQJ WR WKH 8SSHU ^0LRFHQH

5 &KHVVH[ HW DO .$U DJHV $OL 6DELHK 5HJLRQ $IDU (DVW $IULFD

L

$W

ODVW DIWHU D QHZ SHULRG EXW QRW ODVW

RI

IDXOWLQJ ^{DQG HURVLRQ EDVDOWLF IORZV} RXWSRXUHG GXULQJ ^D YHU\ ORQJ SHULRG ,Q WKH

$OL

^6DELHK UHJLRQ WKH WKLFNQHVV

RI

^WKHVH

IORRG EDVDOWV *DOHPL )RUPDWLRQ ^UHDFKHV P )DUWKHU QRUWK

LW

H[FHHGV P

$OOXYLDO

LQWHUFDODWLRQV DUH QXPHURXV ZKHUHDV DFLG YROFDQLFV DUH UDWKHU VFDUFH

2QH VDPSOH FROOHFWHG LQ WKH ORZHU SDUW

RI

^{WKH *DOHPL} )RUPDWLRQ JLYHV DQ DJH

RI

P\ 8SSHU 0LRFHQH ZKLFK ^LV FHUWDLQO\ WRR KLJK

7KHVH EDVDOWV DUH UHSUHVHQWDWLYH

RI

^WKH VWUDWRLG YROFDQLVP ZKLFK SURGXFHG D KXJH SLOH

RI

IORRG EDVDOWV LQ FHQWUDO DQG VRXWKHUQ

$IDU

FKLHIO\

%DUEHUL

^{HW DO D $V} LW ^{KDV EHHQ} UHFRPPHQGHG E\ ^WKHVH DXWKRUV ZH SUHIHU WR ^{DYRLG WKH} XVDJH

RI

^VXFK

WHUPV DV

WUDS

^VHULHV

$IDU

^{VHULHV DQG}

$GHQ

^{VHULHV EHFDXVH} ORQJ UDQJH FRUUHODWLRQV

DUH VWLOO KD]DUGRXV

7KH KLJKHU SDUW

RI

^WKH EDVDOWLF SLOH /RXJDJ $OH )RUPDWLRQ ^{LV PDGH} XS

RI

^EDVDOWLF

IORZV ZKLFK IRUP D WKLQ FUXVW P RQ WKH RWKHU IRUPDWLRQV 6DPSOHV IURP IRXU IORZV FROOHFWHG LQ WKH 1( _SDUW

RI

^WKH

$OL

^6DELHKTXDGUDQJOH JLYH DJHV

RI

_P\ IRU WKH ROGHU DQG P\ IRU WKH \RXQJHVW

7KXV LQ WKH

$OL

^6DELHK UHJLRQ ^{WKH EDVDOWLF} VWUDWRLG VHULHV H[WHQGV SUREDEO\ IURP WKH 8SSHU 0LRFHQH WR ^WKH 8SSHU ^3OLRFHQH

,W

^LV ZRUWK QRWLQJ WKDW D PRUH UHFHQW EDVDOWLF DFWLYLW\

RI

3OHLVWRFHQH _DJH RFFXUUHG ORFDO\ RYHU ^WKH SLHGPRQW ^GHSRVLWV 'DWDWLRQV RQ ^WKHVH \RXQJHVW YROFDQLF URFNV DUH LQ _SURJUHVV DV ZHOO DV WKRVH RQ URFNV IURP RWKHU UHJLRQV LQ FHQWUDO DQG VRXWKHUQ $IDU

5()(5(1&(6

%DNHU %+ 0RKU3$ ^DQG :LOOLDPV /$- ^*HRORJ\ RI^WKH(DVWHUQ 5LIW^{6\VWHP *HRO} 6RF $P VSHF SDS

%DUEHUL ) 7D]LHII +^DQG 9DUHW^{- D 9ROFDQLVP LQ WKH$IDU}'HSUHVVLRQ ,WV 7HFWRQLF DQG 0DJPDWLF6LJQLILFDQFH 7HFWRQRSK\VLFV

%DUEHUL ) %RUVL 6 )HUUDUD ^* 0DULQHOOL ^{* 6DQWDFURFH 5 7D]LHII + DQG 9DUHW -}

E (YROXWLRQ RI ^{WKH 'DQDNLO 'HSUHVVLRQ $IDU} (WKLRSLD LQ /LJKW RI 5DGLRPHWULF $JH 'HWHUPLQDWLRQ ^- *HRO

%DQQHUW ' %ULQFNPDQQ - .DGLQJ .& .QHWVFK * .UVWHQ 0 ^DQG 0D\KRIHU ⁺ =XU *HRORJLH GHU'DQDNLO6HQNH *HRO 5XQGVFKDX A

%HVDLULH + &DUWHJpRORJLTXHGHOD&{WHIUDQoDLVH^GHV6RPDOLVDYHFQRWLFH H[SOLFDWLYH 2IILFH 5HFK 6FL FRORQLDOH ^3DULV

%H\GRXQ =5 6RXWKHUQ $UDELD DQG 1RUWKHUQ 6RPDOLD &RPSDUDWLYH *HRORJ\ 3KLO 7UDQV 5R\ ^6RF /RQGRQ $

%H\WK 0 ^7KH 3DOHR]RLF0HVR]RLF 6HGLPHQWDU\ %DVLQ RI ^WKH 0HNHOH 2XWOLHU 1RUWKHUQ (WKLRSLD ,Q 6HGLPHQWDU\ %DVLQVRI^{WKH $IULFDQ &RDVWVSDUW,, $VVRF$IULFDQ}*HRO 6XUY 3DULV

%ODFN 5 0RUWRQ ^{: + DQG} 9DUHW ^{- 1HZ GDWD RQ} $IDU ^WHFWRQLFV 1DWXUH 3K\V 6FL

%ODQW * 6WUXFWXUH HW SDOpRJpRJUDSKLH GX OLWWRUDO PpULGLRQDO HW RULHQWDO GH O$IULTXH ,Q

6HGLPHQWDU\^%DVLQV RI^WKH $IULFDQ ^&RDVW SDUW ,, ^$VVRF $IULFDQ *HRO 6XUY 3DULV

%ULQFNPDQQ - DQG .UVWHQ ⁰ 6WUDWLJUDSKLH GHU 'DQDNLO6HQNH 1(bWKLRSLHQ %HLK

*HRO -E

&OLQ 0 DQG 3RXFKDQ ³ &DUWH JpRORJLTXH GX 7)$, &(*' 'MLERXWL ^HW 8QLY GH%RUGHDX[ ,,,

'UH\IXVV 0 ^{(WXGHV GH}JpRORJLH HW ^GHJpRJUDSKLHSK\VLTXHVXU OD ^&{WHIUDQoDLVH ^GH6RPDOLV 5HY JpRJU SK\V JpRO G\QDP

0F&RQQHO ^5% *HRORJLFDO 'HYHORSPHQW RI^WKH 5LIW ^6\VWHP RI^(DVWHUQ $IULFD ^{*HRO 6RF}

$P %XOO 6L

0RKU 3$ 6XUIDFH 6WUXFWXUH DQG3ODWH 7HFWRQLFV RI^$IDU7HFWRQRSK\VLFV