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

首席调查员将收集和研究最近在俄勒冈州东北部蓝山的一个异地前第三纪地体中发现的侏罗纪植物群。对这些化石的几个小收藏品的初步检查表明，植物群包括保存完好的叶印记和代表各种蕨类、种子蕨类、苏铁类、银杏和针叶树的过矿化木材。对这种植物群的详细研究将提供新的数据，以检验以下假设：蓝山地区的前第三纪地体起源于近赤道位置，随后在中生代某个时候与北美克拉通相撞之前，发生了数百甚至数千公里的位移。此外，这项工作还将确定植物群的年龄，这些信息应该有助于阐明这些地体的运动时间。该项目将侧重于将蓝山植物群与可能与之相关的其他中生代植物群进行比较，特别是在太平洋盆地边缘许多地方描述的侏罗纪和下白垩统植物群。此外，还将评估植物区系的一般古气候要求，以便了解它可能生活的气候状况。

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.