Age and Paleogeographic Implications of a Pre-Tertiary Flora in the Blue Mountains, Northeastern Oregon

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The principal investigator will collect and study the Jurassic flora which was recently discovered in one of the allochthonous pre-Tertiary terranes in the Blue Mountains of northeastern Oregon. A preliminary examination of several small collections of these fossils has shown that the flora consists of both well preserved leaf impressions and permineralized wood representing a variety of ferns, seed ferns, cycadophytes, ginkgos, and conifers. A detailed study of this flora will provide new data to test the hypothesis that the pre-Tertiary terranes in the Blue Mountains originated in a near-equatorial location and were subsequently displaced hundreds or even thousands of kilometers before colliding with the North American craton sometime during the Mesozoic. Also, the work will establish the age of the flora, information which should shed light on the timing of the movements of these terranes. The project will emphasize a comparison of the Blue Mountain flora to other Mesozoic floras to which it might possibly be related, especially the Jurassic and Lower Cretaceous floras that have been described from many localities around the rim of the Pacific Ocean basin. In addition, the general paleoclimatic requirements of the flora will be evaluated in order to learn something about the climatic regime in which it probably lived.