Summary: 233
International Geology Review, Vol. 47, 2005, p. 233­247.
Copyright © 2005 by V. H. Winston & Son, Inc. All rights reserved.
0020-6814/05/788/233-15 $25.00
UHP Magma Paragenesis, Garnet Peridotite, and Garnet
Clinopyroxenite: An Example from the Dominican Republic
RICHARD N. ABBOTT, JR.,1
Department of Geology, Appalachian State University, Boone, North Carolina 28608
GRENVILLE DRAPER, AND SHANTANU KESHAV2
Department of Earth Sciences, Florida International University, Miami, FL 33199
Abstract
Spinel-bearing garnet peridotite and corundum-bearing variants in the Cuaba Gneiss of the Cre-
taceous Rio San Juan Complex show evidence for ultrahigh pressure (UHP) partial melting and
magmatic fractionation (orthocumulate textures). The paragenesis involves the following sequence
of assemblages (plus inferred melt) with declining T: (1) Grt + Ol + Spl + Cpx + Liq (partial melt
assemblage); (2) Grt + Spl + Cpx + Liq (cumulate Cpx with interstitial Grt); (3) Grt + Spl + Crn +
Cpx + Liq (pegmatite, Cpx with interstitial Grt and late Crn). Comparison with 3 GPa liquidus rela-
tionships in CMAS (Milholland and Presnall, 1998) and extrapolation to pressures above which
sapphirine is not possible (> 3.4 GPa at ~1570°C) show that assemblage (1) is consistent with the
equilibrium Spl + Cpx = Ol + Grt + Liq. Liquid fractionated from this assemblage crystallized in

Source: Abbott Jr., Richard N. - Department of Geology, Appalachian State University

Collections: Geosciences