Did an Amazon-Styled River Flow Through Montana?

• Main Author: Kilcoyne, David
• Format: Text
• Language: unknown
• Published: ScholarWorks at University of Montana 2015
• Subjects: Labrador Sea
• Online Access: https://scholarworks.umt.edu/umcur/2015/poster_1/20

The Colorado River flows through the Grand Canyon, Arizona and has done so for tens of millions of years. Today it drains in the Gulf of Mexico, yet this route opened up 5.3 million years ago. Erosional data suggests that 20 million years ago the river was very different to today. My research will test the hypothesis that the Colorado River ran north though Montana, and drained to the Labrador Sea 30 million years ago. The proposed river would be on a similar scale to the Amazon River today. Should the hypothesis be proved, the path of this river could help locate potential water aquifers, which would be important to drought-ridden California and Utah, or gold and other metallic resources deposited by this paleo river. Also, the river banks could hold fossil evidence which may improve our knowledge of climate change, evolution, and improve biostraitigraphic accuracy. My research will focus on the Caliente-Enterprise Zone (CEZ), SW Nevada. Intensive volcanics from 36-13 Ma, along with crustal extension from 17-5 Ma create a complex geologic zone that resembles nothing of it paleoenvironment. I will also investigate if there is any relationship between the volcanics and the Renova formation, an ash deposit in Montana which holds important fossil evidence, whose origin is currently unknown. The volcanics and the Renova formation occur in tandem in geologic time. My research is sedimentology-based, examining ash deposits in the CEZ, sedimentary structures and other evidence of fluvial agents 25-6 Ma. The region has not been examined using this approach previously, and is currently mapped as purely volcanic in nature, which is may be incorrect. New field data taken from appropriate sedimentary outcrops of the CEZ will be presented.