ASTROCHRONOLOGY AND CORRELATION OF JURASSIC STRATA OF THE DEERFIELD RIFT BASIN (MASSACHUSETTS, USA) IN RELATION TO MAJOR DINOSAUR FOOTPRINT-BEARING LEVELS

In 1835, the Deerfield Rift Basin of northern Massachusetts produced the world’s first scientifically recognized dinosaur footprints, subsequently published as the "tracks of birds" by Edward Hitchcock in 1836. Throughout the rest of the 19^th century, enterprising local residents, most notably Dexter Marsh, Roswell Field, and Timothy Stoughton, amassed large collections of footprints and other ichnofossils. They sold their fossils to Edward Hitchcock, O.C. Marsh, and others; some specimens were distributed globally. Despite the size and notoriety of these collections, the important fossil localities have not been placed into an accurate geographic, stratigraphic, and environmental context. Here we identify the major localities and correlate the Deerfield Basin strata with the well-developed astrochronology, paleomagnetic polarity, and stratigraphy of the Hartford Basin. The Jurassic lacustrine and marginal fluvial strata of the Deerfield Basin are segmented into six large-scale sedimentary sequences, paced by the 405 kyr-long orbital eccentricity cycle. The oldest sequence is represented by the Fall River beds below the Deerfield Basalt, presumably straddling the Triassic-Jurassic boundary and the end-Triassic extinction. The younger sequences are entirely Jurassic, with the cyclical section west of Millers River spanning about 1.7 Myr. The cycles above the Deerfield Basalt can be informally named as mappable lithologic members which, in succession, are the: "Peskeompskut", "Riverside", "Montague", "Barton Cove", and "Horse Race". In the Hartford Basin, these correlate to the East Berlin Formation and succeeding members of the lower half of the Portland Formation, respectively. This correlation predicts that the three reverse polarity zones (H24r, H25r, H26r) that occur in the South Hadley Falls, Mittineague, and Stony Brook members of the Hartford Basin should be present in the "Montague", "Barton Cove", and "Horse Race" members of the Deerfield Basin. The Hettangian-Sinemurian boundary should be located in the upper "Montague member". Thus, the famous quarries of Field and Stoughton in these units are Sinemurian in age, and their track assemblages comprise the youngest well-collected levels in the Newark Supergroup.