ND ISOTOPIC CHARACTERISTICS OF METAMORPHIC AND PLUTONIC ROCKS OF THE COAST MOUNTAINS NEAR PRINCE-RUPERT, BRITISH-COLUMBIA

Nd isotopic data are presented for a suite of metamorphic and plutonic rocks from a traverse across the Coast Mountains between Terrace and Prince Rupert, British Columbia, and for three contrasting batholiths in the Omineca Belt of southern Yukon. A presumed metamorphic equivale nt of Jurassic volcanic rocks of the Stikine terrane gives epsilon(Nd) = +6, and a number of other metaigneous and metasedimentary rocks in the core of the Coast Mountains give epsilon(Nd) values from +3 to +7. A single metasedimentary rock approximately 3 km east of the Work Cha nnel shear zone gives a epsilon(Nd) value of -9. Coast Belt plutons in the traverse yield epsilon(Nd) from -1 to +2. The Omineca Belt pluton s give epsilon(Nd) from -10 to -17. All results are consistent with pu blished data in demonstrating that (i) juvenile origins for both igneo us and metamorphic rocks are common in the Coast Belt; (ii) representa tives of a continental-margin sedimentary sequence with Precambrian cr ustal Nd are tectonically interleaved in the Coast Mountains; (iii) Co ast Mountains plutons can be interpreted as derived from a blend of me tamorphic rocks like those seen at the surface, or as are-type melts c ontaminated with the older crustal component; and (iv) Omineca Belt pl utons are dominated by remelted Precambrian crustal rocks.