Olsen Paul E. author Columbia University. Earth and Environmental Sciences Kent Dennis V. author Columbia University. Lamont-Doherty Earth Observatory Et-Touhami Mohammed author Puffer John author Columbia University. Lamont-Doherty Earth Observatory originator text Articles 2003 English Early Mesozoic tholeiitic flood basalts of the Central Atlantic Magmatic Province (CAMP) are interbedded throughout much of their extent with cyclical lacustrine strata, allowing Milankovitch calibration of the duration of the extrusive episode. This cyclostratigraphy extends from the Newark basin of the northeastern US, where it was first worked out, to Nova Scotia and Morocco and constrains the outcropping extrusive event to less than 600 ky in duration, beginning roughly 20 ky after the Triassic-Jurassic boundary, and to within one pollen and spore zone and one vertebrate biochron. Based principally on the well-known Newark astronomically calibrated magnetic polarity time scale with new additions from the Hartford basin, the rather large scatter in recent radiometric dates from across CAMP (>10 m.y.), centering on about ~200 m.y., is not likely to be real. Rather, the existing paleomagnetic data from both intrusive and extrusive rocks suggest emplacement of nearly all the CAMP within less than 3 m.y. of nearly entirely normal polarity. The very few examples of reversed magnetizations suggest that some CAMP activity probably occurred just prior to the Triassic-Jurassic boundary. Published paleomagnetic and 40Ar / 39Ar data from the Clubhouse Crossroads Basalt are reviewed and with new paleomagnetic data suggest that alteration and possible core misorientation could be responsible for the apparent differences with the CAMP. The Clubhouse Crossroads Basalt at the base of the Coastal Plain of South Carolina and Georgia provides a link to the volumetrically massive volcanic wedge of seaward dipping reflectors present in the subsurface off the southeastern US that may be part of the same igneous event, suggesting that the CAMP marks the formation of the oldest Atlantic oceanic crust. Geology Paleontology Hames W. editor Renne P. editor McHone J. G. editor Ruppel C. editor Washington, D.C. American Geophysical Union 2003 7 32 http://dx.doi.org/10.1029/136GM02 136 http://hdl.handle.net/10022/AC:P:12318 NNC NNC 2012-02-03 12:21:44 -0500 2012-11-28 13:25:24 -0500 6457 eng