T32 Showcase of Undergraduate Research Posters by 2YC and 4YCU Geoscience Students (Posters)

Sunday, 4 November 2018
9:00 AM - 5:30 PM
Halls J-K

RECONSTRUCTING LINKS BETWEEN CENOZOIC HYDROCLIMATE, AND ECOSYSTEM PARAMETERS IN THE JOHN DAY REGION, CENTRAL OREGON

Paper number: T32-35
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

Abstract

Through the long term cooling trend of the past 50 million years many terrestrial landscapes have grown more arid. An example is the western United States, where ancient, massive lakes have evaporated, and many ecosystems have transitioned from forest to grasslands and shrubs. Since rainfall in this region is largely delivered along storm trajectories, upstream (coastal) conditions strongly influence those downstream (inland). In this study we focus on John Day Fossil Beds National Monument, a near-coastal site through much of the Cenozoic with nearly-continuous sedimentation over the last 50 million years. Since the Eocene, this site has gradually shifted inland and experienced dramatic changes in aridity similar to those observed in many other places around the world. In addition, both hydroclimate and vegetation changes influenced weathering patterns in the John Day region. Combining isotope data, elemental analysis, and clay mineralogy with a vapor transport model we develop a spatially-resolved pattern of regional aridification. Specifically, our data support a transition from wet to arid conditions around the Eocene-Oligocene boundary. While this shift is likely observed on a regional scale, the eastern part of our study region may have become more arid than the west due to local topography intercepting westerly moisture. Together, these data and model results suggest that complex, localized topographic features influenced aridity and possibly vegetation evolution.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-322928

© Copyright 2018 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.