THE COASTAL NEW ENGLAND AND WHITE MOUNTAIN IGNEOUS PROVINCES: TRIASSIC-JURASSIC INTRAPLATE MAGMATISM IN NORTHEASTERN US AND SOUTHEASTERN CANADA (Invited Presentation)
Based on trace element and limited isotopic data, the CNE and OWM provinces are geochemically distinct from the ENA. Petrogenetic modeling suggests that the mafic CNE magmas are derived from the subcontinental lithosphere at depths ranging from 60 to 150 km. Nepheline-bearing rocks are found in the OWM at Red Hill, Rattlesnake Mtn, and Litchfield. It is possible to derive magmas of appropriate composition to form these plutons by fractional crystallization of silica-undersaturated CNE magmas. The volumetrically much more abundant silica-saturated magmas were produced by interaction between CNE magmas and the deep continental crust. Further evolution of the magmas occurred through low-pressure fractional crystallization with limited interaction with the upper continental crust. This model is well-illustrated by the White Mountain batholith where individual plutonic units evolved by closed system fractional crystallization, but with decreasing age each unit shows increasing interaction with the continental crust (a MASH model). CAMP magmatism plays an important role in this process in that the CAMP magmas provide the heat for the partial melting of the continental lithosphere. However, elemental and isotopic data indicate that there was no transfer of material between these reservoirs, only heat energy was transferred.