580 ky duration of the Early Jurassic flood basalt event in eastern North America estimated using Milankovitch cyclostratigraphy

Abstract--Early Jurassic-age tholeiitic flood basalts of the Newark Supergroup of the eastern United States are interbedded with strata composed of a hierarchy of lake-level sedimentary cycles of Milankovitch climate cycle origin. Based principally on the Newark basin section, known from continuous core, these cycles constrain the duration of the extrusive and associated intrusive event in exposed basins to 580±100 ky at 201 Ma, immediately postdating the Triassic-Jurassic boundary. Subsurface basalts of the southeastern U.S. and basalts of the early Mesozoic basins of Morocco and Iberia also appear to have been extruded contemporaneously with those of the Newark Supergroup. In addition, most--if not all--early Mesozoic tholeiitic dikes and plutons in eastern North America, western Africa, and Iberia were intruded at about the same time.

Figure 1 [48 kb]: Pangea and the Newark Supergroup.
Figure 2 [48 kb]: Milankovitch cycles.
Figure 3 [52 kb]: Composite section of extrusive interval, Newark basin.
Figure 4 [36 kb]: Power spectra.
Figure 5 [44 kb]: Comparison of Newark basin depth ranks with climatic precession.
Figure 6 [40 kb]: Comparison of extrusive interval depth ranks and basalt geochemistry.

Go back to list of publications

duration.html-- Revised: 1 March 1999
Copyright © 1999 Rutgers University