Tomas,
Yes, all one needs is higher water pressure and the stability of
garnet amphibolite is greatly extended. Many of the amphibolites
associated with eclogites are formed as a decompressive overprint on the
eclogites however. Many eclogites have primary hornblende (often but not
always barroisite), and adjacent layers in eclogitic gneisses can be rich
in barroisite with some albite and garnet. Many of thesehornblende rich
rocks in the eclogite facies are garnet hornblendites rather than
amphibolites. How often amphibolites form in the eclogite facies would
depend on how low the P-T field is drawn for the eclogite facies boundary.
If drawn down to 10-12 kbar at 600-700°C, amphibolites should be common. I
think that the boundary should be raised by 4-5 kbar. Garnet-hornblendites
and garnet-amphibolites with sodic plagioclase would still occur but be
less common.
eric
>
>Eric,
>
> Amphibolites in the eclogite facies??
>
> Tomas Feininger
> Geologist & Prof
Eric Essene
Professor of Geology
Department of Geological Sciences
2534 C.C. Little Bldg.
425 E. University Ave.
University of Michigan
Ann Arbor MI 48109-1063 USA
fx: 734-763-4690
ph: 734-764-8243
