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The Origin And Evolution Of Impact Crater Lakes: A Case Study Of The Ries Impact Structure, Germany, Matthew J. O. Svensson
The Origin And Evolution Of Impact Crater Lakes: A Case Study Of The Ries Impact Structure, Germany, Matthew J. O. Svensson
Electronic Thesis and Dissertation Repository
Impact events are known to generate hydrothermal systems, which can subsequently vent into an overlying crater lake and potentially create ideal conditions for some microbial life-forms. Thus, early post-impact sedimentary deposits would be excellent targets for Mars sample return, and as such, the robust characterization of such deposits on Earth is critical. In this thesis, we establish an improved understanding of how the Ries crater lake formed, and how an active impact-generated hydrothermal system influenced its early evolution. The ~14.8 Ma Ries impact structure hosts the majority of its paleolake deposits within the structure's central basin with some deposits situated …
Subsurface Correlation Of Lower Silurian Medina Group, Southwestern Ontario, Rhys H. Paterson
Subsurface Correlation Of Lower Silurian Medina Group, Southwestern Ontario, Rhys H. Paterson
Electronic Thesis and Dissertation Repository
The Medina Group succession in southwestern Ontario includes, in ascending order: the Whirlpool, Manitoulin, Cabot Head, Power Glen, Devils Hole-Balls Falls, Grimsby, and Thorold formations. Subsurface mapping in central and eastern Lake Erie has resulted in the recognition of three stratigraphic packages within the Medina Group based upon the integration of sedimentologic, stratigraphic and geophysical borehole logs. The interplay between changing paleoenvironments, sediment provenance, and regional tectonics and associated sea level fluctuations has resulted in the accumulation of a complex mosaic of mixed siliciclastics and carbonates. Manitoulin Formation carbonates and Whirlpool Formation siliciclastics display consistent thicknesses across the study area. …