Summary: International Geology Review, Vol. 49, 2007, p. 572­586.
Copyright © 2007 by V. H. Winston & Son, Inc. All rights reserved.
0020-6814/07/939/572-15 $25.00 572
UHP Magma Paragenesis Revisited, Olivine Clinopyroxenite
and Garnet-Bearing Ultramafic Rocks from the Cuaba Gneiss,
Rio San Juan Complex, Dominican Republic
RICHARD N. ABBOTT, JR.,1 BONNIE N. BROMAN,
Department of Geology, Appalachian State University, Boone, North Carolina 28608
AND GRENVILLE DRAPER
Department of Earth Sciences, Florida International University, Miami, Florida 33199
Abstract
Narrow (1­4 cm) dikes of spinel-bearing clinopyroxene garnetite intruded olivine clinopyroxen-
ite. The latter represents the earliest magmatic rocks yet discovered on a previously described liquid
line of descent for a suite of magmatic rocks from the UHP terrane of northern Hispaniola. The
extended liquid line of descent produced the following mineral assemblages, from high to low tem-
perature: (I) Ol + Cpx + Opx + Mag; (II) Oli + Cpx + Grt (inferred); (III) Oli + Cpx + Grt + Spl; (IV)
Cpx + Grt + Spl; (V) Cpx + Grt + Spl + Crn. Phase relationships in the CMAS system constrain the
magmatic conditions to P > 3.4 GPa and T >1540°C, but thermobarometry shows that the mineral
assemblages generally re-equilibrated at subsolidus conditions (~850°C, ~4.2 GPa). The subsolidus
temperatures reflect Mg-Fe adjustments affecting to a greater extent olivine, clinopyroxene, and

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

Collections: Geosciences