TURONIAN TO EARLY CONIACIAN AGE FOR THE CLAYS OF MARTHA’S VINEYARD, MASSACHUSETTS: A REVISION

Flowering plants (angiosperms) first appeared during the Early Cretaceous (≈130 MYA). A small number of structurally preserved flower fossils from the Early and early Late Cretaceous—including several reported from the Magothy Formation of Martha’s Vineyard, Massachusetts—have been instrumental in dating the nodes of the angiosperm phylogeny and polarizing characters within angiosperm clades. However, the Martha’s Vineyard clays were originally dated to the Santonian–Campanian (palynological Zone V-C) based on unpublished data. We re-evaluate the age date of the Martha’s Vineyard clays using palynostratigraphy. Our results show that the majority of the diagnostic angiosperm pollen fall within Complexipollis–Atlantopollis zone IV (Cenomanian to Turonian) of the Atlantic Coastal Plain. The presence of Complexiopollis sp. A Christopher 1979, Complexiopollis sp. M Christopher 1979, Complexiopollis sp. O Christopher 1979, Complexiopollis sp. P Christopher 1979, Complexiopollis funiculus, Tricolporopollenites sp. D Wolf, Doyle and Page 1975, and cf. Ajatipollis tetraedralis (Bolchovitina) Krutzsch (1970) place this sample in Zone IV. However, aff. Porocolpopollenites sp. Doyle and Robbins 1977 and Complexiopollis sp. B Doyle and Robbins 1977 characterize the Complexiopollis exigua–Santalacites minor Zone V-A, which age dates the assemblage to the Turonian or earliest Coniacian. These results, combined with the presence of Complexiopollis sp. E Christopher 1979 and Complexiopollis abditus Tschudy 1973 support a conclusion that these sediments correlate with the South Amboy Fire Clay Member of the Raritan Formation (upper Coniacian to lower Santonian), not the younger Magothy Formation (upper Santonian through Campanian). Therefore, the fossils preserved in the Martha’s Vineyard clays may be somewhat older than originally thought.