Abstract
The Cascade volcanic arc is associated with one of the
warmest subduction zones known. Work is in progress to
evaluate volatile and rare gas budgets across this arc and
to develop these parameters as geochemical indicators of
slab temperature. Also, we have done extensive work on
geochemistry of mafic lavas Leeman et al., 1990; Barker and
Leeman, 1997) from a transect across the southern Washington
Cascades, where rare mantle xenoliths provide additional
insight into petrologic processes in the subarc mantle
(Ertan and Leeman, 1996, 1998, 1999; Leeman and Ertan,
1998).
Selected references:
Barker, S., and Leeman, W.P. (1997) Early High Cascade
magmatism related to intra-arc extension in the Cascadia
subduction zone. Abst. Geol. Soc. Amer. Cordilleran Sec.
Mtg., Hilo, Hawaii.
Ertan, I.E., and Leeman, W.P. (1996) Complex
metasomatism of Cascades subarc mantle: Evidence from a rare
phlogopite orthopyroxenite xenolith. Geology, 24,
451-454.
Ertan, I.E., and Leeman W.P. (1998) The nature of
Cascades subarc lower crust and upper mantle: where were the
subducting slab melts? EOS 79, F924.
Ertan I.E., and Leeman W.P. (1999) Fluid inclusions in
mantle and lower crustal xenoliths from the Simcoe volcanic
field, Washington. Chem. Geol., 154, 83-95.
Leeman, W.P., Smith, D.R., Hildreth, W., Palacz, Z.A.,
and Rogers, N.W. (1990) Compositional diversity of late
Cenozoic basaltic magmas of the southern Washington
Cascades. J. Geophys. Res., 95, 19561-19582.
Leeman, W.P., and Ertan, I.E. (1998) Diverse invasive
melts in Cascadia mantle xenoliths: No subduction
connection. Min. Mag. 62A,
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