Depositional setting, fossil flora, and paleoenvironment of the Early Eocene Falkland site, Okanagan Highlands, British Columbia

摘要

The fossil flora and depositional setting of the Early Eocene Falkland site in the southern interior of British Columbia, Canada, is reported in detail for the first time, using a census sampling approach. The Falkland site is part of the series of Okanagan Highlands fossil localities in British Columbia and Washington State that represent relatively cool upland environments within the context of the greenhouse world of the Early Eocene, providing microthermal (mean annual temperature (MAT) <13 degrees C) climatic conditions for the establishment of cool-adapted plants geographically adjacent to subtropical elements from lowland floras. Plant community composition of the Falkland flora is most similar to the Republic (Washington) and McAbee (British Columbia) floras based on high Sorenson similarity coefficients, together forming a southern cluster of Okanagan Highlands sites. The site is a lacustrine deposit that formed in a volcanically active landscape. Paleoclimate reconstructions based on leaf physiognomy characterize the site as microthermal (MAT 8.9 +/- 2.0 degrees C by leaf margin analysis or 11.9 +/- 2.0 degrees C by climate leaf analysis multivariate program (CLAMP)), mesic (mean annual precipitation (MAP) 114 (+49)(-35) cm/year), and equable (cold month mean temperature (CMMT) 3.0 +/- 2.0 degrees C). Paleoelevation of the site is estimated to be similar to or slightly higher than modern levels (> 1.3 km) during the Early Eocene. The Falkland locality adds new data to the temporal, latitudinal, and altitudinal gradients of the Okanagan Highlands series, reflecting the regional landscape of northwestern North America during the warmest period of the Cenozoic.