Nd and Sr isotopic signatures of Mesozoic plutons in northeastern North America

摘要: Nd and Sr initial isotope ratios are reported for 17 Mesozoic plutons of the Monteregian Hills White Mountain series provinces in northeastern North America. Some variation isotopic at most localities is caused by crustal-contamination processes. When crustal assimilation effects taken into account, apparently uncontaminated, mantle-derived parental magmas show only restricted range /sup 87/Sr//sup 86/Sr (0.7032 to 0.7040) epsilon/sub Nd/ (T) (+5.4 +2.3), which inversely correlated. These characterize alkaline subalkaline emplaced over more than 400 km/sup 2/ about 80 m.y. The trace-element characteristics broadly similar those many modern ocean-island basalts, specifically New England Seamounts, suggesting time-integrated, lithophile-element-depleted mantle sources. results consistent with plume-related sources deeper subcontinental mantle.