CHEMICAL COMPOSITION OF INTRUSIVE ROCKS FROM THE FAIR HAVEN HEIGHTS AND FOXON REGIONS, HARTFORD BASIN, CONNECTICUT
A new suite of 22 samples from the Fair Haven-Foxon intrusions, collected from an area extending from Black Rock to Peter’s Rock, have been analyzed for major and trace elements using XRF and HR-ICP-MS. Traditionally, Mesozoic igneous rocks from the Hartford Basin have been distinguished by variations in MgO and TiO2 compositions, however this can lead to ambiguities for individual rock samples and localities when alteration is significant. Our new analyses include a number of high-field strength elements (REE, Y, Zr, Hf, Nb, Ta, U, Th) that are more resistant to alteration and preserve the original magmatic elemental ratios that can be used to identify and correlate the flows and intrusive rocks with greater reliability. The new chemical data establish that all the Fair Haven-Foxon samples represent a single magmatic lineage related predominantly by fractional crystallization processes. The new analyses are also compared directly to complementary data for other units in the southern Hartford Basin. The data provide clear genetic links between the Fair Haven-Foxon, East Rock, West Rock, Pine Rock intrusions, the Higganum dikes, and the Talcott lavas.