4. THE ECLOGITE FACIES GNEISSES
76
$OEHUW HW DO -RXUQDO RI ,EHULDQ *HRORJ\
JQHLVV IRUPDWLRQV FDQ WKHQFH EH FDOFXODWHG LQ WKH UDQJH
RI NEDU
7KH HFORJLWH IDFLHV JQHLVVHV
7KH HFORJLWH JQHLVVHV LV D FD NP ORQJ DQG
P WKLFN XQLW )LJV DQG PDLQO\ FRPSRVHG RI PHWD
VHGLPHQWDU\ URFNV HFORJLWHV IHOVLF URFNV DEXQGDQW PHOWV
DQG WKHLU UHWURJUHVVHG SURGXFWV )LJ 6RPH VFDUFH LQ
FOXVLRQV RI XOWUDPD¿F URFNV DOVR DSSHDU LQ D XQLTXH OR
FDOLW\ $FFRUGLQJ WR WKH FRH[LVWHQFH RI 2PS *UW DE
EUHYLDWLRQV DIWHU .UHW]
LQ WKH PD¿F LQFOXVLRQV
WKLV JQHLVV IRUPDWLRQ LV WKH RQO\ RQH LQ WKH XSSHU XQLWV
RI WKH &DER 2UWHJDO &RPSOH[ WKDW UHDFKHG HFORJLWH IDFLHV
FRQGLWLRQV $V WKH PD¿F LQFOXVLRQV DUH HFORJLWHV DQG UHW
URHFORJLWHV ZH DVVXPH WKDW WKH PHWDVHGLPHQWDU\ URFNV
ZHUH DOVR HFORJL]HG EXW WKH\ GR QRW VKRZ DQ\ FOHDU SHW
URORJLFDO HYLGHQFH RI DQ HFORJLWH IDFLHV PHWDPRUSKLVP
DV WKHLU PLQHUDO DVVHPEODJHV DUH QRW GLDJQRVWLF IURP D
SHWURJUDSKLF SRLQW RI YLHZ 7KLV LV SUREDEO\ GXH WR WKH
UHWURJUDGDWLRQ SURFHVVHV WKDW WRRN SODFH RU EHFDXVH WKH
PLQHUDO DVVHPEODJH LV RQO\ VXVFHSWLEOH WR UHYHDO WKH +3
FRQGLWLRQV E\ WKHUPRG\QDPLF PRGHOLQJ ZKLFK KDV QRW
EHHQ SHUIRUPHG 7KH PHWDVHGLPHQWDU\ URFNV FDQ EH GL
YLGHG LQWR PHWDSHOLWLF DQG PHWDJUH\ZDFNLF W\SHV DQG
WKH\ DOZD\V DSSHDU LQWHQVLYHO\ PLJPDWL]HG DQG VKHDUHG
GLVSOD\LQJ DEXQGDQW TXDUW]R IHOGVSDWKLF OHXFRVRPHV
7KH RULJLQDO VHGLPHQWDU\ VHTXHQFH ZDV LQWUXGHG E\ WZR
PDLQ W\SHV RI PDJPDWLF URFNV 7KH ¿UVW W\SH PXFK PRUH
DEXQGDQW WKDQ WKH VHFRQG ZDV IRUPHG E\ GLDEDVLF GLNHV
DQG JDEEURV QRZ GLVSOD\HG DV HFORJLWHV UHWURJUHVVHG HF
ORJLWHV DQG UDUH FRURQLWLF PHWDJDEEURV ZKLOH WKH VHFRQG
W\SH LV UHSUHVHQWHG E\ WKLQ LQFOXVLRQV RI RUWKRJQHLVVHV
SUREDEO\ GHULYHG IURP JUDQLWLF WR WRQDOLWLF SURWROLWKV
$ XQLTXH H[SRVXUH ORFDWHG LQ WKH 0DVDQWHR SHQLQVXOD
)LJ VKRZV D WKLFN PD¿F ERG\ RI HFORJLWHV VFDUFHO\ DI
IHFWHG E\ SRVW SHDN VKHDULQJ 7KH HFORJLWHV DUH LQWUXGHG
E\ DEXQGDQW PHVRFUDWLF PHOWV ZLWK WRQDOLWLF FRPSRVLWLRQV
)LJ I VKRZLQJ RXWVWDQGLQJ IHDWXUHV VLPLODU WR WKRVH
VHHQ LQ D PLQJOLQJ RI EDVLF DQG IHOVLF URFNV 7KH PD¿F
ERG\ GRHV QRW VKRZ LQ LWV LQWHUQDO ]RQH WKH FRPPRQ WLJKW
IROLDWLRQ WKDW LV JHQHUDOO\ REVHUYHG DORQJ WKH IRUPDWLRQ
,QVWHDG WKLV VHFWRU H[KLELWV EUHFFLDWHG IRUPV DQG URXQGHG
VKDSHV LQ FRQWDFW ZLWK WKH PHOW ,WV PD¿F SDUWV DUH ZHOO
SUHVHUYHG HFORJLWHV EXW WKH PHWDPRUSKLF FRQGLWLRQV RI
WKH PHOWV DUH QRW VR FOHDU EHFDXVH QR GLVWLQFWLYH PLQHUDO
DVVHPEODJHV KDYH EHHQ LGHQWL¿HG \HW +RZHYHU ZH EH
OLHYH WKDW WKH IHOVLF URFNV ZHUH SUREDEO\ GHULYHG IURP
H[WHQVLYH SDUWLDO PHOWLQJ DIIHFWLQJ WKH PHWDVHGLPHQWDU\
JQHLVVHV GXULQJ WKH ¿UVW VWDJHV RI GHFRPSUHVVLRQ 7KHVH
PHOWV LQWUXGHG DQG EUHFFLDWHG SDUWV RI WKH IRUPDWLRQ LQ
FUHDVLQJ KHWHURJHQHLW\ EXW WKHLU UHDO SDUWLFLSDWLRQ LQ WKH
JQHLVV IRUPDWLRQ FDQ RQO\ EH DSSUHFLDWHG LQ WKH UDUH GR
PDLQV ZLWK PRGHUDWH VKHDULQJ $FFRUGLQJ WR WKLV GDWD DQG
LQWHUSUHWDWLRQV WKH SDUWLFLSDWLRQ LQ WKLV IRUPDWLRQ RI IHO
VLF PDWHULDO JHQHUDWHG E\ GHFRPSUHVVLYH SDUWLDO PHOWLQJ
FDQ EH YHU\ LPSRUWDQW PDNLQJ GLI¿FXOW WKH GLVWLQFWLRQ RI
WKH SUH PHWDPRUSKLF OLWKRORJLHV DQG FRPSRVLWLRQV
/LWKRORJLHV DQG PLQHUDO DVVHPEODJHV
7KH PRVW UHSUHVHQWDWLYH OLWKRORJ\ LQ WKLV IRUPDWLRQ LV D
JQHLVV EHDULQJ 4W] *UW 3O %W .\ DV SULPDU\ PLQHUDOV
ZKLFK LV FRQVLGHUHG D PHWDVHGLPHQWDU\ URFN )LJ E
$FFRUGLQJ WR WKHLU GLIIHUHQW FRPSRVLWLRQV WZR GLVWLQFWLYH
JQHLVVLF W\SHV FDQ EH GLVWLQJXLVKHG RQH KDV UHODWLYHO\
KLJK DOXPLQD FRQWHQW DQG LW LV FRQVLGHUHG PHWDSHOLWLF
WKH RWKHU ODFNV .\ DQG WKH RWKHU DOXPLQD ULFK PLQHUDOV
DUH VFDUFH DQG WKHUHIRUH LW LV WKRXJKW WR EH PHWDJUH\ZDF
NLF ,Q WKH ¿HOG WKHVH JQHLVVHV GH¿QH D EDQGHG IRUPDWLRQ
YDULDEO\ PLJPDWL]HG EXW JHQHUDOO\ ULFK LQ FHQWLPHWUH WR
GHFLPHWUH WKLFN OHXFRVRPHV ZKLFK DOZD\V DSSHDU VKHDUHG
E\ WKH UHJLRQDO SHUYDVLYH IROLDWLRQ :LWKLQ WKHVH JQHLVVHV
WKHUH DUH WZR W\SHV RI EDVLF URFNV YDULDEO\ UHWURJUHVVHG
HFORJLWHV ZLWK *UW &S[ +EO 3O &]R 5W ,OP 6SQ
)LJ I DQG J DQG ZKDW LW LV WKRXJKW WR EH D SURJUDGH
SUH HFORJLWLF W\SH FRURQLWLF PHWDJDEEURV FRPSRVHG RI
2O *UW 3O &]R 5W ,OP 6SQ )LJ K DQG L 7KH HFORJ
LWLF LQFOXVLRQV DUH FRPPRQ LQ PRVW VHFWLRQV RI WKH JQHLVV
IRUPDWLRQ EXW WKH FRURQLWLF PHWDJDEEURV DUH YHU\ UDUH
7KH HFORJLWHV DQG UHWURJUHVVHG HFORJLWHV DUH GLVSOD\HG DV
YDULDEO\ VL]HG ERXGLQV IURP GHFDPHWUHV WR FHQWLPHWUHV
DQG LQ WKH FDVH RI WKH WKLFNHU LQFOXVLRQV WKH\ FDQ FRQWDLQ
DQ LQWHUQDO IROLDWLRQ GLIIHUHQW WR WKH UHJLRQDO IROLDWLRQ WKDW
VXUURXQGV WKH ERXGLQV ,Q WKH EHVW SUHVHUYHG HFORJLWHV LW LV
SRVVLEOH WR REVHUYH WKDW WKLV LQWHUQDO IROLDWLRQ ZDV GHYHO
RSHG LQ HFORJLWH IDFLHV FRQGLWLRQV EHFDXVH LW LV GH¿QHG
E\ WKH GLPHQVLRQDO RULHQWDWLRQ RI RPSKDFLWH 7ZR W\SHV
RI RUWKRJQHLVVHV FDQ EH GLVWLQJXLVKHG D JUDQLWLF RQH ZLWK
4W] *UW 3O 0F %W )LJ G DQG D WRQDOLWLF RQH ZLWK
4W] *UW 3O +EO &]R )LJ F 7KHVH RUWKRJQHLVVHV GR
QRW GH¿QH OHQWLFXODU ERXGLQV DV LQ WKH FDVH RI WKH PD¿F
LQFOXVLRQV E\ WKH FRQWUDU\ WKH\ DSSHDU DV FHQWLPHWUH WR
PHWUH WKLFN OHXFRFUDWLF EDQGV ZLWKLQ WKH PHWDVHGLPHQ
WDU\ URFNV LQWHQVLYHO\ VKHDUHG E\ WKH UHJLRQDO IROLDWLRQ
*HQHUDO VWUXFWXUH
'HWDLOHG JHRORJLFDO FURVV VHFWLRQV
)LYH FRQVHFXWLYH HYHQWV ZHUH GHYHORSHG GXULQJ WKH WHF
WRQRWKHUPDO HYROXWLRQ RI WKH HFORJLWH IDFLHV JQHLVVHV $OO
RI WKHP JHQHUDWHG UHSUHVHQWDWLYH VWUXFWXUHV WKDW FDQ EH
GLVFXVVHG XVLQJ WKH JRRG H[SRVXUHV RI WKH FRDVWDO VHFWLRQ




