Author/Authors :
Esteban Gazel، نويسنده , , Richard N. Abbott Jr.، نويسنده , , Grenville Draper، نويسنده ,
Abstract :
Two competing hypotheses have been proposed for garnet-bearing ultramafic rocks in the Dominican Republic: (1) The ultrahigh pressure (UHP) – ultrahigh temperature (UHT) hypothesis involves a magmatic protolith of mantle origin, which was then delivered to, and incorporated into deep-subducted oceanic crust (eclogite) at UHP conditions (Abbott et al., 2005, 2006, 2007; Abbott and Draper, 2010; Gazel et al., 2011). (2) The low-pressure (LP) hypothesis involves a plagioclase-bearing, arc-related protolith of crustal origin, which was then subducted to UHP conditions (De Hoog, 2011; Hattori et al., 2010a,b). In both hypotheses, the rocks were uplifted to the surface by an as yet poorly understood mechanism. Here we respond to concerns regarding the integrity of REE analyses, Cpx-Grt REE partitioning, other matters related to the interpretation of the trace element data, and Grt-Spl major-element thermometry. We show that none of the concerns precludes a UHP magmatic origin.
Keywords :
REE partitioning , Garnet-spinel thermometry , Garnet peridotite , Corundum , Ultrahigh-pressure metamorphism , Dominican Republic