Whole-rock geochemistry in the ultramafic and lower banded series of the Stillwater Complex, Montana, USA

Texte intégral

(1)0123456278ÿ 42714

(2) 6ÿ

(3) ÿ14ÿ36

(4) 7ÿÿ32046ÿ 4ÿ 46

(5) 4 ÿ2ÿ14ÿ

(6) 33046ÿ72 34ÿ 2ÿ ÿ. ÿ. -ÿ5ÿ!ÿ"#"$$ÿ%&!ÿ'ÿ "(#ÿ)"*+,ÿ /01230G24ÿ52ÿ67ÿ82992:ÿ;31<2941=>ÿ5?ÿ@?>A20ÿBÿCD10E?=1F1ÿ ;31=25ÿ/=7=24ÿH2E6EI1076ÿ/?9<2J:ÿ/KEL732ÿ. ÿ MNOPQMRPÿ ÿSÿTÿÿ#%ÿUVTÿWXÿ$$ÿWÿ*ÿ *"##Y*ÿ**"%$Zÿ$*W#W%Zÿ'ÿV"#ÿ (V"*Z[ÿWYSÿ*ÿÿÿ#"V"*'ÿUVTÿWXÿVW'ÿYW#5W(+ÿ#ZÿXWÿ*ÿXU##ÿU"*ÿWXÿ V\Wÿ'ÿ*(ÿ#V*]ÿ"ÿYW+ÿ$*ÿU#*ÿXWVÿ#"*W$"#5#V*ÿ#Zÿ$XWV'ÿWÿ V$#ÿ*+ÿ#W%ÿÿ**"%$"(ÿ(*"WÿWXÿ*ÿ#*VX"(ÿ'ÿ3WYÿ''ÿ"ÿ"ÿ*ÿ WU*"ÿ^"YÿÿWXÿ*ÿ *"##Y*ÿ7WV$#_ÿ W*]ÿ

(7) ÿ*ÿ3WYÿ''ÿ"ÿ$#%"W(#ÿ"ÿ*ÿVW*ÿ(WVVWÿV"#ÿ$*ÿ'ÿ$#W*ÿWXÿ#,2`ÿ Sÿ#V*ÿ(WV$*"T#ÿY"*ÿ$#%"W(#ÿa]%]ÿ,2ÿ ÿ ÿ'ÿ4UbÿWYÿ*W%ÿ$W"*"Sÿ(W#*"W]ÿ ÿ'ÿ8,2ÿ#WÿWYÿ$#%"W(#ÿ(W*W#ÿ#*WU%ÿ#*'ÿV$#ÿWYÿ8,2ÿ"(V*]ÿÿW(+ÿ XWVÿ*ÿ 5Xÿ'ÿ*ÿ2

(8) ÿU"*ÿ'WÿW*ÿWYÿÿ'"XX*ÿ*']ÿ#W*ÿWXÿ#V*ÿ(WV$*"T#ÿY"*ÿ $ZW_ÿa"2,ÿ 2ÿ7ÿ (ÿ^ÿÿ1644ÿ'ÿ)bÿ#WÿWYÿ$W"*"Sÿ(W#*"WÿY"*ÿ %2ÿaU$ÿ*Wÿ ,cÿY*ÿdÿ %2b]ÿ

(9) ÿW(+ÿY"*ÿVWÿ*ÿ,cÿY*ÿdÿ %2ÿ*ÿVX"(ÿV"#ÿ$*ÿ"ÿW#"S"ÿ*ÿ*ÿ $ZW_ÿ'ÿVW*ÿWXÿ*ÿ#V*ÿÿ"(WV$*"T#ÿWÿW#Zÿ#"%*#Zÿ(WV$*"T#ÿY"*ÿW#"S"ÿ'ÿ *Uÿ*ÿ(W(**"WÿWXÿ*ÿ#V*ÿX##ÿWÿV"ÿX#*ÿÿ %2ÿ(W**ÿ"(ÿTWSÿ,cÿY*ÿd]ÿ ÿ"(WV$*"T#ÿ#V*ÿÿÿTÿ)ÿ'ÿ1Xÿÿ$*ÿ*ÿSZÿ#WYÿ#S#ÿc]!ÿ*Wÿ!ÿ*"VÿV*#ÿ S#U]ÿÿ$W$W'ÿ#"eU"'ÿXWÿ*ÿ3WYÿ''ÿ"ÿ"ÿT'ÿWÿ*ÿ%WU$ÿ,ÿ'Z+ÿaSZÿX"5 %"'ÿ%TTWW"*bÿY"(ÿ(W*"ÿ$$W_"V*#Zÿ!cÿ*"VÿV*#ÿ"(WV$*"T#ÿ#"*W$"#ÿ #V*]ÿUÿ*ÿ#"eU"'ÿX(*"Wÿ"ÿ*ÿ3WYÿ''ÿ"ÿ$*ÿf!cdÿWXÿ*ÿW(+]ÿ$"*ÿ *ÿ'"U$*"WÿWXÿ#Z"%ÿ*ÿ*ÿ#S#ÿWXÿ2

(10) ÿ'ÿ*ÿ$$(ÿWXÿW#"S"ÿ*ÿ#"*W$"#5#V*ÿ (WV$W"*"WÿWXÿ*ÿW(+ÿ"ÿ2

(11) ÿÿ"V"#ÿ*WÿW(+ÿXWVÿW*ÿU"*]ÿ

(12) ÿ$*"(U#ÿ*ÿXÿ"ÿW*ÿ "('ÿ"ÿ"(WV$*"T#ÿ#V*ÿ'ÿU#"+ÿ*ÿ +ZÿXÿWXÿ*ÿUS#'ÿ7WV$#_ÿTU*ÿ"V"#ÿ *Wÿ*ÿ *ÿZ+ÿ*ÿ'WÿW*ÿVÿ*WÿTÿÿ(%ÿ"ÿV%Vÿ#"%ÿ(W ÿ*ÿX]ÿ

(13) ÿ*ÿ#*VX"(ÿ"ÿ"ÿ''"*"Wÿ*WÿW#"S"ÿ'ÿ$ZW_ÿ(WV"*ÿ"ÿÿ"V$W**ÿV"#]ÿ #W*ÿWXÿ7,2`ÿSÿ#,2`ÿ2ÿ7Wÿ ÿ^ÿ'ÿ)ÿWYÿ**ÿ(WV"*ÿ"ÿ*ÿV"ÿV"#ÿ(W*W##"%ÿ *ÿ#V*]ÿ7WV$*"T#ÿ#V*ÿU(ÿÿ 2ÿ'ÿ"ÿWYÿ(WV"*ÿW*W$ZW_ÿ'ÿW#"S"ÿ (W*W#]ÿ

(14) (WV$*"T#ÿ#V*ÿ(W(**"WÿÿSZÿ#WYÿ*ÿc]!ÿ*Wÿ!ÿ*"VÿV*#ÿS#Uÿ"'"(*"%ÿ ÿSZÿ#WYÿ#"eU"'ÿX(*"W]ÿÿ *#5WV#"g'5*(5#V*ÿ$#W*ÿWYÿ#%ÿ%*"SÿTÿWV#"ÿahTbÿ'ÿ a3hTbÿijÿ"ÿTW*ÿ"]ÿ "'ÿXWVÿ*ÿTÿWV#"ÿ*ÿ$**ÿÿ#*"S#ZÿX#*ÿ"ÿ*ÿ #*VX"(ÿ"]ÿ

(15) ÿ*ÿ3WYÿ''ÿ"ÿ*ÿ$**ÿÿ#Wÿ#*"S#ZÿX#*ÿ$*ÿXWVÿ*"ÿ $W"*"Sÿÿ ÿ'ÿ4UÿWV#"ÿX#(*"%ÿ*ÿ$(ÿWXÿ$#%"W(#]ÿ ÿ3WYÿ''ÿ"ÿW(+ÿ(ÿTÿVW'##'ÿTZÿ(Z*##"g*"WÿXWVÿ*ÿ%WU$ÿ,ÿ'Z+]ÿÿ #*VX"(ÿ"ÿ"ÿVWÿ$WT#V*"(ÿ"ÿ**ÿ*ÿ"2,ÿ'ÿ#,2`ÿ(W**ÿWXÿ*ÿV "Sÿ(WV"*ÿ "'"(*ÿ**ÿ*ÿ#"eU"'ÿ**ÿ*Zÿ(Z*##"g'ÿXWVÿ(W*"'ÿiÿc]kÿdÿ"2,ÿ'ÿ!`ÿY*ÿdÿ#,2`]ÿÿ (W(**"Wÿÿ"%ÿ*ÿ*WÿWXÿ*ÿ$W$W'ÿ$*#ÿV%VÿWXÿ*ÿ#*VX"(ÿ"ÿ*ÿ %WU$ÿ`ÿ'Z+]ÿÿ.

(16) 0123456ÿ8955 4 0ÿ38ÿ4 ÿ845

(17) ÿ 16852. 4254 ÿ2 ÿ 04 0ÿ 9259ÿ ÿ 8ÿÿ. ÿ!"#$%&'ÿ$()*%+$(ÿ,$%-.ÿ/*(-%&'"&ÿ ÿ 01234053ÿ 2ÿ788ÿÿ9:;<ÿ=ÿ>?=ÿ;=@ÿABÿ=ÿC8;CÿD<ÿEÿA7ÿA8F9ÿC8GEÿ;ÿ=;ÿ 7A:=AHIÿJ?KLÿ8Aÿ9:ÿ=ÿM?ÿ;@ÿABÿA=ÿ8E9:ÿHFG8;C;Aÿ;ÿ8@Eÿ;F;Aÿ HA8A<@Iÿ 9HG88NÿOKPQLRÿC;;SFÿABÿC8;C8ÿCF9F8Fÿ=A@Tÿ5=;ÿHHIÿ7=;C=ÿ=Eÿ;ÿ<;ÿ;ÿ 9HG88NÿU=ÿ=;ÿ7A:ÿAÿ=ÿV;9G8ÿ@:ÿ;ÿDÿ2F8;Iÿ;EÿÿF9GÿABÿ8;ÿABÿ ;ECÿAÿ<Fÿ=ÿ9FC=ÿABÿ=ÿC@88;;Aÿ;ÿ8@Eÿ;F;Aÿ=HHÿÿÿF8ÿABÿ;W;Fÿ FC8;AÿEÿ<A7=ÿ;ÿGAFE@ÿ8@ÿÿ=ÿ9<;ÿABÿ=ÿCAC;<ÿ9<9Iÿ=ÿ=ÿG@ÿ CCF9F8;AÿABÿC@8ÿ=ÿFC8Eÿ87=ÿEÿ:ÿAÿ=ÿB8AAÿABÿ=ÿC=9GTÿ5=;ÿ CA;GF;AÿCA;EÿA9ÿABÿ=ÿ9XAÿHA;ÿ;EÿG@ÿ 9HG88ÿOKPQLRIÿA9ÿABÿ7=;C=ÿ7ÿ CF88@ÿB;ÿ;Eÿ;ÿ=ÿ9ÿ@ÿÿ=ÿD<ÿEÿA7ÿA8F9ÿO 9HG88IÿKPYLRTÿ4ÿCA;EÿAÿ 7=ÿZÿ=;ÿ7A:ÿ=ÿ=8EÿFHIÿEÿ=A7ÿBÿFGSFÿC=ÿ=ÿ=8HEÿA8ÿ=ÿ CAA@Tÿ[ÿ7ÿ9Eÿ;<;B;CÿHA<ÿ;ÿE9;;<ÿ7=ÿEÿ=A7ÿC@8ÿ<A7ÿ;ÿ 9<9ÿC=9G\ÿ 5=ÿ<F9ÿ;EÿG@ÿ 9HG88ÿOKPQLRÿEÿ;ÿFGSFÿHHÿOT<Tÿ 9HG88ÿKPLQRÿ<;ÿ C@8ÿ8;<ÿB88ÿ;Aÿ=ÿC<A;ÿ KTÿ[@EF8;CÿABÿ<;@ÿ8;<ÿ]ÿ;ECÿBA9ÿ;8@ÿ<EEÿ8@ÿ7;=ÿH8<;AC8ÿÿ =ÿGAA9^ÿGFA@C@ÿABÿH8<;AC8ÿ;ÿ_W;C=ÿ9<9^ÿÿ JTÿ8AH9ÿABÿCF9F8FÿZFÿ;ÿAC:ÿE8AHEÿAÿHÿ;Eÿ788ÿEÿA=<;<ÿ FHHÿ9<;ÿABÿV;9G8ÿEÿA=ÿ;F;A^ÿ `Tÿ5=ÿHCÿABÿaC8F;<bÿABÿCF9F8FÿH=ÿ;E;C;ÿABÿ=A<AFÿ8BÿFC8;AIÿ Eÿ;CA;ÿ7;=ÿBÿ8;<ÿAÿ<;@ÿB8A7ÿEHA;;AÿABÿ;E;;EF8ÿAWE=;<ÿC@8Tÿ 5=ÿB;ÿ7AÿAG;AÿÿGEÿAÿ;<=BA7EÿB;8EÿAG;AÿEÿZH;98ÿ;ECÿ Eÿÿ8<8@ÿFC=88<ETÿ_A9;AÿABÿ788ÿEÿAABÿCF9F8ÿC88@ÿSF;ÿ;W;FÿFC8;AIÿ F8ÿA9ÿ9C=;9ÿ;ÿHA;G8ÿ7=G@ÿC@8ÿFHEEÿ7;=;ÿCAC;<ÿ9<9ÿCÿGCA9ÿ H=@;C88@ÿC=EÿAÿ=ÿ788ÿEÿAABTÿ5=ÿ@F;ÿ=@HA=;ÿABÿ8C=7;E;<ÿÿ8TÿOKPPPRÿ =A8Eÿ=ÿFHEEÿC@8ÿ;ÿÿG8;Cÿ9<9ÿCÿ;C:ÿA<=ÿBA88A7;<ÿBAF;AFÿ;9HCIÿEÿ =;ÿHA;EÿÿHA;G8ÿ;Bÿ=ÿ;9H8F;G8ÿ7@ÿAFÿABÿ=ÿHAG89^ÿFHEEÿC@8ÿ;ÿCAC;<ÿ 9<9ÿCAF8EÿGCA9ÿH=@;C88@ÿH8EÿAAÿ=ÿ788ÿEÿAABTÿ[A7IÿAÿ9;CAZF8ÿ ;ECÿFC=ÿÿ=ÿBA9ÿ;EÿH;<A;ÿC8FÿAEÿG@ÿ 9HG88ÿOKPQLRIÿ;ÿ;ÿ9FC=ÿ9Aÿ 8;:8@ÿ=ÿC@8ÿC8Fÿ;ÿ8ÿEÿ;ÿCF9F8ÿBA9ÿG@ÿ=A<AFÿ8BWFC8;AIÿ;TTÿ FC8;AÿABÿ<;ÿAÿÿFGÿABÿA=ÿ<;ÿABÿ=ÿ9ÿ9;8Tÿ5=;ÿHA;Eÿÿ9Aÿ CAA9;C8ÿZH8;AÿBAÿAABÿEÿ;E788ÿCF9F8Tÿ 5=ÿ=;EÿAG;AIÿ;ECÿABÿC8F;<Iÿ;E;C;ÿABÿ=A<AFÿ8BWFC8;AIÿ;ÿGFEÿ ;ÿCF9F8ÿAC:Tÿ2ÿC8@ÿCA<;EÿZ9H8ÿ;ÿ=ÿCA99AÿHCÿABÿ8;ÿ@ÿAÿC=;ÿABÿ C=A9;ÿ<;ÿHEÿ7;=;ÿH8<;AC8ÿEÿH@AZÿA;:AC@ÿ;ÿC=A9;;ÿ9Tÿ5=ÿ BFÿÿHÿ;ÿ=ÿG8ÿC=A9;;ÿABÿ=ÿc:@ÿ1BIÿ7=ÿ=@ÿACCFÿGA=ÿ;ÿaA98bÿ BÿEÿ;ÿC=A9;;ÿE8AHEÿÿHÿ;Eÿ788ÿABÿHA=A8ÿ=ÿCÿA8@ÿ=ÿBA9EÿG@ÿ;ÿ;Fÿ <A7=ÿO @HAÿÿ8TIÿJ?KQ^ÿ @HAÿÿ8TIÿJ?K>RTÿ8FC=ÿZFÿÿ8Aÿ;ECÿ<;ÿ:;;Cÿ ;;<ÿ;ÿ<;@ÿCFIÿÿCF8@ÿHAHF8ÿ=@HA=;ÿBAÿ=ÿE8AH9ÿABÿ=ÿc:@ÿ1Bÿ EÿA=ÿE8;C8@ÿH=W8@EÿF;ÿ;ÿ=ÿF=8Eÿ A9H8ZÿOc;ÿÿ8TIÿJ?K`RIÿ7=;C=ÿSF;ÿ =ÿC@8ÿG=ÿÿ;E;;EF8ÿAW;C;<ÿH;C8ÿO_A;ÿÿ8TIÿJ?K>RTÿÿ.

(18)