Metallogenesis and Tectonics of the Russian Far East, Alaska, and ...

occurrence of turbiditic clastic rocks. On the basis of geochemical data, either back-arc rifting or hot-spot activity is int
have formed the widespread basalt fields of the Nikolai Greenstone and Ka~mutsen Formation and coeval rnafic and ultramafic
sills and plutons (Barker and others, 1989; Richards and others. 1991; Lassiter and others, 1994). Herein, back-arc rifting is
inte~preted as the tectonic environment for the Triassic strata and contained massive sulfide deposits. The rifting is tectonically
linked to the coeval Bonzana-Takeetna island arc which occurs along the length of the Wrangellia superterrane for several
thousand km (Nokleberg and others, 3000). %iw -- . -
Host Rocks v M
Metamorphosed argme and cafc-argme
Chlorite-calcite phyllite
IT] Greenstone
Sulfide Assemblages 8 Related Units (Triassic)
[mm White ore carbonate and locally barite ricl.
Massive sulfide, base-metal rich
I_ Massive sulfide. fine-grained cNly pyrite e!P? I
n
/ Contact
mite massive suitides. sfica-rich rr , .'
Siliceous. carbonate breccia
. j.,,
Figure 38. Greens Creek kuroko massive sulfide deposit, Alexander metallogenic belt, Southeastern Alaska, Schematic,
predeformation, cross-section model based on drill core logging and underground and surface mapping. Modified from Newberry
and others (1 997)
?4
=
7.