UNDERSTANDING THE MAGMATIC ASSOCIATION OF A DIKE FOUND NEAR KILLINGTON, VERMONT

New England has been shaped by several igneous events over the past 200 million years, following the rifting of Pangea and the development of a passive margin. These events, which are separated temporally and distinguished by geochemistry, resulted in the formation of lava flows, dikes, sills, and plutons. The oldest of these events occurred about 201 Ma and is referred to as the Central Atlantic Magmatic Province (CAMP). CAMP is made up of shallow intrusions and large lava flows that erupted on Pangea as rifting was occuring (Marzoli et al., 2018). The formation of the New England-Québec igneous province can be broken up into two different events, plume derived Great Meteor Hotspot (GMH) and edge driven convection (EDC) derived Burlington and Taconic lobes. GMH magmatism occurred ~126-120 Ma as a series of plutons, dikes, and seamounts through Quebec and New Hampshire (Kinney et al., 2021). The Burlington and Taconic lobes produced via EDC occurred at ~140-130 and ~110-100 Ma, respectively, and are made up of dikes and sills predominantly in NY and VT (Bommels et al., 2024).

A sample of a basaltic dike collected along Vermont Route 4 near Killington has an origin in these three possible igneous events. Due to the similar geographic distribution and characteristics of these igneous events, analyzing the geochemistry of the sample can help provide insight to the province and magmatic association of the dike. Thin section analysis using a polarized light microscope was done, revealing an abundance of pyroxene phenocrysts and groundmass made up of plagioclase feldspar and Fe-Ti oxides. In order to determine the igneous origin, whole rock geochemistry was studied via XRF/LAICPMS. Phenocryst and groundmass geochemistry was studied with SEM-EDS. Preliminary results suggest that the dike is of a similar composition to sheet intrusions analyzed in Bommels et al., 2024 thus suggesting petrogenesis via EDC.