Ice at the Equator: The Record and Implications of Alpine Glaciation Within the Ancestral Rocky Mountains of Western Pangea

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Ice at the Equator: The Record and Implications of Alpine Glaciation within the Ancestral Rocky Mountains of Western PangeaGerilyn Soreghan and Michael SoreghanEAR-0230332, University of OklahomaABSTRACTThe best-documented pre-Quaternary "icehouse" occurred during the Pangean supercontinent interval (300 My ago), when continental glaciers are known to have covered much of the southern polar region of Earth (Gondwanaland). Owing to key similarities with our modern icehouse, the Pangean interval has intrigued geoscientists interested in improving our understanding of Earth's climate system. Critical to improving both climatic and tectonic models, however, are key geologic constraints-in particular, on the possible existence and extent of mountains and mountain glaciers in low-latitude Pangea. To date, evidence for (late Paleozoic) glaciers beyond the limits of the southern polar region has never been reported, and tropical mountain elevations for this interval remain unknown. Documentation of low-latitude ice would contribute to our understanding of both equatorial climate conditions and mountain elevations for this time interval, thus impacting both climatic and tectonic issues.This project involves investigation of the hypothesis that the Ancestral Rocky Mountains of equatorial western Pangea (300 My ago) were glaciated. Preliminary evidence for this hypothesis occurs in the form of preserved sediments and landforms in the western U.S. (Colorado) that appear to have been shaped by (late Paleozoic) glacial processes. Research on the depositional attributes, composition, and distribution of the Permo-Pennsylvanian (ca. 310-280 My old) Cutler Formation and related rocks will be conducted to test the hypothesis that these sediments record a glacial influence. The research will also entail analysis of landforms and Quaternary sediments to assess the origin (fluvial or glacial) and age of buried topography preserved within highlands of the Ancestral Rocky Mountains. Confirmation of alpine glaciation within equatorial Pangea would imply more extensive icehouse conditions and significantly higher elevations than previously envisaged for this time and region, and would provide needed boundary conditions for constraining climatic and tectonic models. Accordingly, this research should provide benefits to geoscientists interested in earth history in general, as well as general society interested in and impacted by future climate change.