Time calibration of ~riassic/~urassic ~icro~ora~ turnover, eastern North America
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چکیده
Palynological data from the Newark basin of the Newark Supergroup reveal a spike in the spore/pollen ratio at the TriasGc/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 stratigraphic sections to be calibrated in time, constraining the duration of the microfloral turnover to an interval of 21 Icy, The geologically brief palynofloral break is similar to Cretaceous/Tertiary boundary fern spikes. These data <upport ;I Triassic/Jurassic boundary impact-extinction scenario.
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