Transmission of Flood Basalts through a Shallow Crustal Sill and the Correlation of Sill Layers with Extrusive Flows: The Palisades Intrusive System and the Basalts of the Newark Basin, New Jersey, U.S.A.

Abstract

AbstractThe Palisades Intrusive System consists of a 350-m-thick early Jurassic sill together with thinner comagmatic sills and dikes exposed within the Newark Basin of New Jersey and New York. The Palisades System is overlain by flood basalt that is interbedded with early Jurassic redbed formations. New and recently published data indicate that some of the basalt flows correlate with geochemically defined layers within a central well-exposed sill portion of the Palisades System at Fort Lee, New Jersey. Our interpretation views the sill as a progressively inflated conduit through which huge volumes of flood basalt flowed. The geochemical data are consistent with a Palisades sill fed by three compositionally distinct intrusion events. The first magma flowed through the sill and broke out near the northern end as three Orange Mountain basalt flows. Each of the three extrusive pulses is identified within the lower 150 m of the sill on the basis of distinct geochemical reversals. The end stage of each pulse w...