Geochemistry of late Middle Jurassic-Early Cretaceous igneous rocks on the eastern North American margin

Offshore samples of late Middle Jurassic to early Cretaceous volcanic rocks on the eastern North America margin from Baltimore Canyon to the Newfoundland Seamounts were taken from dredge hauls, Deep Sea Drilling Project holes and oil wells. All of the rocks analysed are alkali basalts and related mafic rocks. The geochemical data allow the rocks to be divided into two distinct igneous suites. The New England suite closely resembles many ocean island basalts and shows marked enrichment in LREE and many incompatible trace elements. The east Canadian suite shows slightly convex REE spectra and less enrichment in incompatible elements and is interpreted as the product of a low degree of partial melting of a MORB-type mantle source. Variations in element ratios (e.g. La/Ce vs Zr/Hf) suggest that the mantle beneath the two suites may have different compositions.