|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
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.
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