TIME CALIBRATION OF TRIASSIC-JURASSIC MICROFLORAL TURNOVER, EASTERN NORTH-AMERICA

Palynological data from the Newark basin of the Newark Supergroup reve al a spike in the spore/pollen ratio at the Triassic/Jurassic boundary . This spore spike is coincident with a 60% regional extinction of the palynoflora and approximately synchronous with terrestrial vertebrate extinctions. Orbitally controlled sedimentary cycles allow stratigrap hic sections to be calibrated in time, constraining the duration of th e microfloral turnover to an interval of 21 ky. The geologically brief palynofloral break is similar to Cretaceous/Tertiary boundary fern sp ikes. These data support a Triassic/Jurassic boundary impact-extinctio n scenario.