Implications of astronomical climate cycles to the chronology of the Triassic

A high resolution climate record from a thick, continuous sedimentary sequence in the Newark basin provides the basis for an astronomically calibrated time scale for the Late Triassic. The astronomical vernier, indexed to radiometric dates that indicate an age of 202 Ma for the Triassic/Jurassic boundary, suggests that the Late Triassic was about 31 m.y. long, or constituted about 2/3 of the entire Triassic. A detailed geomagnetic polarity time scale developed in conjunction with the cycle stratigraphy provides a mechanism to extend the astronomical chronology to other sections in the world