326 Jurassic Nassellariina (Radiolaria) from North American geologic terranes

Jurassic Nassellariina (Radiolaria) from North American geologic terranes - BAP #326 Much of the western part of the Cordilleran Region of North America is characterized by geologic terranes which originated at low latitudes and were displaced to higher latitudes during the Late Paleozoic and Mesozoic. Many of these terranes such as the Wrangellia terrane have been displaced hundreds or even thousands of kilometers from lower, near-equatorial latitudes to their present positions. The magnitude of the tectonic complexity of the western Cordilleran Region is immense. Obviously, paleontologists must consider the displaced terrane problem in their attempts to compile meaningful biostratigraphic zonations and zoogeographic reconstructions for the Mesozoic of this region and indeed, the entire Circum -Pacific margin. The potential utility of Radiolaria in Mesozoic biostratigraphic and paleo-oceanographic studies and in geology in general is enormous. Radiolarian zonal schemes now rival thos