Lunar and Planetary Science XXXVIII (2007)
7+(6($5&+)25+<'52*(13(52;,'(21(1&(/$'866)1HZPDQ%-%XUDWWL5+%URZQ
5-DXPDQQ-%DXHU70RPDU\-HW3URSXOVLRQ/DERUDWRU\&DOLIRUQLD,QVWLWXWHRI7HFKQRORJ\2DN
*URYH'ULYH0DLO6WRS3DVDGHQD&$/XQDUDQG3ODQHWDU\/DERUDWRU\8QLYHUVLW\RI$UL]RQD
7XFVRQ86$*HUPDQ$HURVSDFH&HQWHU'/5%HUOLQ*HUPDQ\>6DUDK)1HZPDQ#MSOQDVDJRY@
+2 WRJHWKHU UHVXOWV LQ DQ XSZDUG VKLIW LQ WKH
,QWURGXFWLRQ7KHGLVFRYHU\RIDG\QDPLFDFWLYH
ZDYHOHQJWK RI DEVRUSWLRQ EDQGV GXHWR LQWHUPROHFXODU
SOXPHHPDQDWLQJIURPWKHVRXWKSROHRI(QFHODGXVKDV
IUHTXHQFLHV>@
OHIW VFLHQWLVWV ZLWK PDQ\ PRUH TXHVWLRQV WKDQ LW KDV
+2SURGXFHGE\LUUDGLDWLRQRI+2GLVSOD\VWKH
DQVZHUHG:KDWLVFDXVLQJWKHKRWVSRWXQGHUQHDWKWKH
FRPELQDWLRQ EDQG DW ȝP RU ȝP ZLWK
VRXWKSROH"+RZDUHWKHZDWHUYDSRUSDUWLFOHVIRUPHG"
):+0UDQJLQJIURPWRȝP>@$GGLWLRQ
+RZ GRHV 6DWXUQ¶VPDJQHWRVSKHUH LQWHUDFW ZLWKWKHVH
RI2WR+2EHIRUHLUUDGLDWLRQUHVXOWVLQDVKLIWRIWKH
SDUWLFOHV" :KDW LV WKH QDWXUH RI WKH VXUIDFH DQG
DEVRUSWLRQ EDQG IURP ȝP WR ȝP DQG D
VXEVXUIDFH HQYLURQPHQWV RI WKH VRXWK SROH" 2QH ZD\
&2+2 PL[WXUH SURGXFHV D EDQG DW ȝP >@
WR H[SORUH WKHVH TXHVWLRQV LV WR VWXG\ WKH VXUIDFH LFH
2WKHUIDFWRUVDIIHFWWKHSRVLWLRQRIWKLVEDQGLQFOXGLQJ
ZLWKSKRWRPHWULFDQGVSHFWUDOGDWD8VLQJREVHUYDWLRQV
WKHFRQFHQWUDWLRQRI+2DODUJHUFRQFHQWUDWLRQVKLIWV
IURP WKH 9LVXDO DQG ,QIUDUHG 0DSSLQJ 6SHFWURPHWHU
WKH EDQG WR KLJKHU ZDYHOHQJWKV JUDLQ VL]H SRURVLW\
9,06 DERDUG WKH VSDFHFUDIW &DVVLQL ZH KDYH
DQGWKHUPDOKLVWRU\RIWKHLFH>@7KHUHLVDOVRD+2
VHDUFKHG IRU WKH SUHVHQFH RI +2 RQ (QFHODGXV 2XU
SUHOLPLQDU\ UHVXOWV LQGLFDWH D WHQWDWLYH GHWHFWLRQ RI
DEVRUSWLRQ IHDWXUH LQ WKH 89 IURP DURXQG QP WR
+2LQDFRQGHQVHGIRUP7KHSUHVHQFHRUDEVHQFHRI
VKRUWHUZDYHOHQJWKV>@
+2 LV LQGLFDWLYH RI WKH UDGLRO\WLF HQYLURQPHQW RI D
+2 RQ (XURSD +2 KDV SUHYLRXVO\ EHHQ
VXUIDFHRUWKHVXUURXQGLQJDWPRVSKHUH,QDGGLWLRQWKH
GHWHFWHGRQWKHVXUIDFHRI(XURSDZLWKDFRQFHQWUDWLRQ
GHSWK DQG SRVLWLRQ RI +2 EDQGV DUH XVHIXO IRU
RI >@ 7KLV GHWHFWLRQ LQFOXGHV DQDO\VLV RI WKH
GHWHUPLQLQJ JUDLQ VL]H SRURVLW\ DQG WKHUPDO KLVWRU\
ȝP EDQG LQ DGGLWLRQ WR DEVRUSWLRQ LQ WKH 89
6FLHQWLVWV EHOLHYH WKDW WKH +2 LV SURGXFHG E\ WKH
>@
ERPEDUGPHQWRIKLJKHQHUJ\SDUWLFOHVIURPWKH-RYLDQ
3URGXFWLRQRI+2+LJKHQHUJ\UDGLDWLRQVXFK
DV89SKRWRQVRU+LRQVKDVEHHQVKRZQWRFRQYHUW
PDJQHWRVSKHUH >@ $ VPDOOHU +2 VLJQDO KDV DOVR
ZDWHU LFH WR +2 >@ (QHUJHWLF SODVPD GLVVRFLDWHV
EHHQ GHWHFWHG RQ *DQ\PHGH DQG &DOOLVWR ZKHUH WKH
+2 LQWR + 2+ DQG +2 HLWKHU IRUPV IURP WKH
VWUHQJWKRIWKHUDGLDWLYHERPEDUGPHQWLVZHDNHU>@
FRPELQDWLRQ RI WZR 2+ UDGLFDOV RU E\ UHDFWLYH
(QFHODGXV 5HVXOWV :H KDYH WHQWDWLYHO\
VFDWWHULQJ RI + DQG 2+ E\ ZDWHU >@ ,Q LUUDGLDWLRQ
LGHQWLILHG +2 RQ (QFHODGXV ZLWK GDWD IURP WKH
9,06 XVLQJ WKH ȝP DEVRUSWLRQ EDQG DV DQ
H[SHULPHQWV OHVV +2 LV GHWHFWHG DIWHU UDGLRO\VLV DW
KLJKHU WHPSHUDWXUHV KRZHYHU WKH DGGLWLRQ RI 2 RU
LQGLFDWRU 7KLV EDQG DSSHDUV LQ VOLJKWO\ GLIIHUHQW
&2WR ZDWHULFHFDQFRXQWHUWKLVHIIHFW>@&2DFWV
SRVLWLRQV LQ WKH VSHFWUD RI GLIIHUHQW UHJLRQV RI
DVDQHOHFWURQVFDYHQJHUUHPRYLQJIUHHHOHFWURQVWKDW
(QFHODGXV)LJ)RUWKHVSHFWUXPRIWKHVRXWKSRODU
FDQ EUHDN XS +2 DQG 2 SURYLGHV DQ DGGLWLRQDO
³WLJHUVWULSHV´WKHEDQGLVORFDWHGDWȝP)RUWKH
SDWKZD\ IRU WKH IRUPDWLRQ RI +2 WKURXJK +DWRP
UHJLRQEHWZHHQWKHVWULSHVWKHEDQGLVDWȝP$
DGGLWLRQ >@ GHWHFWHG +2 DIWHU LUUDGLDWLRQ RI SXUH
JOREDO VSHFWUXP RI (QFHODGXV PLQXV WKH VLJQDO IURP
ZDWHULFHILOPVZLWK0H9+LRQVDW.EXWQRW
WKHVRXWKSROHVKRZVWKHEDQGDWPLFURQV
DW.:KHQ2RU&2ZDVGHSRVLWHGZLWKWKHZDWHU
,QJHQHUDOWKHȝPEDQGLVVWURQJHUDQGVKLIWHG
LFHSULRUWRLUUDGLDWLRQ+2ZDVGHWHFWHGDW.
WR KLJKHU ZDYHOHQJWKV LQ WKH VRXWK SRODU UHJLRQ RI
6SHFWUDO 6LJQDWXUH +2 FDQ EH LGHQWLILHG LQ
(QFHODGXV 7KH ZDYHOHQJWK VKLIW FRXOG EH GXH WR D
QHDU WR PLGLQIUDUHG LFH VSHFWUD 2QO\ WKUHH +2
KLJKHUFRQFHQWUDWLRQRI+2LQWKLVUHJLRQRUDKLJKHU
DEVRUSWLRQ EDQGV LQ WKLV UHJLRQ FDQ EH GLVWLQJXLVKHG
GHJUHH RI DPRUSKRXV DV RSSRVHG WR FU\VWDOOLQH +2
IURP ZDWHULFH EDQGVD FRPELQDWLRQ EDQG DURXQG LFH >@ IRXQG D KLJKHU FRQFHQWUDWLRQ RI DPRUSKRXV
ȝP D V\PPHWULF EHQGLQJ PRGH DW ȝP DQG DQ
ZDWHULFHDWWKHVRXWKSROHRI(QFHODGXVUHODWLYHWRWKH
DV\PPHWULFEHQGLQJPRGHDWȝP>@2IWKHVHWKH
UHVW RI WKH VDWHOOLWH WKXV D KLJKHU FRQFHQWUDWLRQ RI
ȝP EDQG LV WKH VWURQJHVW EXW LWV SRVLWLRQ LV
DPRUSKRXV +2 LFH LQ WKLV UHJLRQ ZRXOG EH LQ
DJUHHPHQWZLWKWKLVUHVXOW
VRPHZKDW YDULDEOH >@ H[DPLQHG WKH VSHFWUD RI WKLQ
$OWKRXJKWKHVRXWKSROHDVDZKROHFRQWDLQVZDWHU
ILOPV RI FU\VWDOOLQH DQG DPRUSKRXV +2 DW DQG . ,Q JHQHUDO WKH FU\VWDOOLQH +2 KDG PRUH GHILQHG
LFHRIDPRUHDPRUSKRXVQDWXUHWKHWLJHUVWULSHVKDYH
SHDNVZKHUHDVWKHDPRUSKRXVEDQGVZHUHEURDGHUDQG
D KLJKHU GHJUHH RI FU\VWDOOLQLW\ WKDQ WKH UHJLRQ LQ
URXQGHU GXH WR K\GURJHQ ERQGLQJ DQG GLVRUGHU )RU
EHWZHHQ WKH VWULSHV >@ ,Q RXU ZRUN ERWK WKH WLJHU
FRQGHQVHG DPRUSKRXV +2 WKH FRPELQDWLRQ EDQG
VWULSHVDQGWKHUHJLRQEHWZHHQWKHPGLVSOD\WKH+2
ZDV IRXQG DW ȝP DQG IRU FU\VWDOOLQH +2 LW
EDQGYHU\FORVHWRWKHDPRUSKRXVSRVLWLRQDWȝP
PRYHGWRȝP,QDGGLWLRQGHSRVLWLRQRI+2DQG
DOWKRXJK WKH SRVLWLRQ IRU WKH WLJHU VWULSH VSHFWUXP LV
1769.pdf
Lunar and Planetary Science XXXVIII (2007)
1769.pdf
VKLIWHG WR D VOLJKWO\ ORZHU ZDYHOHQJWK 7KLV
LQFRQVLVWHQF\ EHWZHHQ WKH IRUPV RI ZDWHU LFH DQG
+2FRXOGEHUHFRQFLOHGE\WKHIDFWWKDWZDWHULFHLV
FU\VWDOOL]HG DW . ZKLOH +2+2 PL[WXUHV
FU\VWDOOL]H EHWZHHQ . >@ 7KXV WKH WLJHU
VWULSHVPD\EHKRWHQRXJKWRFU\VWDOOL]HSXUHZDWHULFH
EXW FRRO HQRXJK VXFK WKDW FRQGHQVHG K\GURJHQ
SHUR[LGHFRXOGUHPDLQDPRUSKRXV
)LJXUH6SHFWUXPRIWKHVRXWKSROHRI(QFHODGXVQHDU
ȝP DQG WKH LQWHUSRODWHG FRQWLQXXP ZLWKRXW WKH
DEVRUSWLRQ EDQG 7KH (QFHODGXV VSHFWUXP LV VKRZQ LQ GRWV
DQGWKHFRQWLQXXPLVVKRZQDVDOLQH
)LJXUH(QFHODGXVVSHFWUDIURPVHYHUDOGLIIHUHQWDUHDV
RIWKHVDWHOOLWHLQWKHUHJLRQRIWKHȝP+2DEVRUSWLRQ
EDQG7KHEOXHOLQHLVIURPWKH³WLJHUVWULSHV´WKHUHGOLQHLV
IURPWKHUHJLRQLQEHWZHHQWKHVWULSHVDQGWKHJUHHQOLQHLVD
JOREDOVSHFWUXP7KHYHUWLFDOGRWWHGOLQHVKLJKOLJKWDQG
PLFURQV WKH SRVLWLRQV RI WKH EDQG IRU FU\VWDOOLQH DQG
DPRUSKRXVFRQGHQVHG+2LFHUHVSHFWLYHO\
7R H[DPLQH WKH ȝP EDQG LQ PRUH GHWDLO ZH
SORW WKH VSHFWUXP RI WKH VRXWK SRODU UHJLRQ RI
(QFHODGXV DQG WKH H[SHFWHG FRQWLQXXP ZLWKRXW WKLV
EDQG )LJ 7KH SRVLWLRQ RI WKLV EDQG LV ȝP
ZLWK D ):+0 RI ȝP 7KH SRVLWLRQ RI WKH +2
FRPELQDWLRQ PRGH EDQG IRU DOO RI WKH (QFHODGXV
VSHFWUD FRUUHVSRQGV EHVW WR WKH ODE VSHFWUD RI
FRQGHQVHG DPRUSKRXV LFH FRQGHQVHG FU\VWDOOLQH LFH
RU D PL[WXUH ,Q DGGLWLRQ LW DOVR PDWFKHV VRPHZKDW
ZHOOZLWKWKHVSHFWUXPRIDQLUUDGLDWHGPL[WXUHRI+2
DQG2>@
&RQFOXVLRQV:HEHOLHYHZHKDYHIRXQGHYLGHQFH
RI +2 RQ(QFHODGXVIURPLQLWLDODQDO\VLV,WLVPRVW
OLNHO\LQDFRQGHQVHGIRUP7KHSRVLWLRQRIWKHEDQGLQ
RXU GDWD VXJJHVWV WKDW WKH VRXWK SRODUUHJLRQ FRQWDLQV
+2LFHRIDPRUHDPRUSKRXVQDWXUHZKHUHDVWKHUHVW
RI WKH VXUIDFH RI (QFHODGXV FRQWDLQV PRUH FU\VWDOOLQH
+2:HSURSRVHWKDWWKH+2KDVEHHQWUDQVIRUPHG
IURP +2 WKURXJK ERPEDUGPHQW E\ KLJK HQHUJ\
SDUWLFOHV FRPLQJ IURP 6DWXUQ¶V PDJQHWRVSKHUH
)XUWKHUPRUH WKH +2 EDQG LV VWURQJHU LQ WKH SRODU
VSHFWUD VXJJHVWLQJ WKDW WKH UDGLDWLRQ DW WKH SROHV LV
VWURQJHUSHUKDSVGXHWRDPDJQHWLFILHOGDW(QFHODGXV
GLYHUWLQJ WKH KLJKHQHUJ\ SDUWLFOHV SROHZDUGV 7KLV
H[SODQDWLRQ FRXOG DOVR DFFRXQW IRU WKH GLVWULEXWLRQ RI
PRUH DPRUSKRXV +2 DW WKH SROHV DQG PRUH
FU\VWDOOLQH +2 HOVHZKHUH DVUDGLDWLYH ERPEDUGPHQW
FRXOG GLVUXSW WKH FU\VWDOOLQH VWUXFWXUH RI +2 DV LW
GRHVZLWK+2>@
:H ZRXOG OLNH WR FRQILUP RXU GHWHFWLRQ RI +2
E\ ORRNLQJ IRU WKH DEVRUSWLRQ IHDWXUH LQ WKH 89 :H
ZRXOG DOVR OLNH WR ORRN IRU +2 RQ WKH RWKHU LF\
VDWHOOLWHVRI6DWXUQ
5HIHUHQFHV>@0RRUH0+DQG+XGVRQ5/
,FDUXV >@ =KHQJ : HW DO $VWURSK\V - >@ &DUOVRQ 5: HW DO
6FLHQFH>@*LJXHUH3$DQG
+DUYH\ .% - 0RO 6SHFWU >@
+HQGUL[ $5 HW DO /36& ;;; >@
1HZPDQ 6) HW DO VXEPLWWHG WR ,FDUXV >@
0RRUH 0+ DQG +XGVRQ 5/ $VWURSK\V -