Generation of trondhjemite from partial melting of dacite under granulite facies conditions: an example from the New Jersey Highlands, USA

New field and geochemical data place the Losee Metamorphic Suite (a tonalite/trondhjemite complex) of northern New Jersey into the context of a major Proterozoic continental are represented by a discontinuous belt of northern Appalachian metadacite. Samples of Losee rock range from extremely leucocratic trondhjemite locally associated with amphibolite, to banded biotite, hornblende, pyroxene, and garnet-bearing tonalites. The major element and REE composition of the tonalite closely resembles dacite from continental are settings and model melts extracted from an eclogite residue by partial melting at 15 kbar. The REE composition of most Losee trondhjemite is enriched in REE, particularly HREE, compared with Losee tonalite, and is interpreted as the product of local anatectic melting of Losee tonalite (metadacite) that occurred in a granulite facies environment during the Grenville orogeny. ?? 1991.