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Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Earth Sciences

Portland State University

2023

Geology

Articles 1 - 2 of 2

Full-Text Articles in Physical Sciences and Mathematics

Rift-Induced Disruption Of Cratonic Keels Drives Kimberlite Volcanism, Thomas M. Gernon, Stephen M. Jones, Sascha Brune, Thea K. Hincks, Martin Palmer, John C. Schumacher, Rebecca M. Primiceri, Matthew Field, William L. Griffin, Suzanne Y. O'Reilly, Derek Keir, Christopher J. Spencer, Andrew S. Merdith, Anne Glerum Jul 2023

Rift-Induced Disruption Of Cratonic Keels Drives Kimberlite Volcanism, Thomas M. Gernon, Stephen M. Jones, Sascha Brune, Thea K. Hincks, Martin Palmer, John C. Schumacher, Rebecca M. Primiceri, Matthew Field, William L. Griffin, Suzanne Y. O'Reilly, Derek Keir, Christopher J. Spencer, Andrew S. Merdith, Anne Glerum

Geology Faculty Publications and Presentations

Kimberlites are volatile-rich, occasionally diamond-bearing magmas that have erupted explosively at Earth’s surface in the geologic past1,2,3. These enigmatic magmas, originating from depths exceeding 150 km in Earth’s mantle1, occur in stable cratons and in pulses broadly synchronous with supercontinent cyclicity4. Whether their mobilization is driven by mantle plumes5 or by mechanical weakening of cratonic lithosphere4,6 remains unclear. Here we show that most kimberlites spanning the past billion years erupted about 30 million years (Myr) after continental breakup, suggesting an association with rifting processes. Our dynamical …


Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen Jul 2023

Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen

Dissertations and Theses

Volcanic glass has been used extensively as a paleoclimate proxy. Deuterium (2H) concentrations in glass have been found to be stable over geologic timescales, making δD a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in ash. Here, I analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ashflow tuff, and create an isoscape to assess variations in δD across Oregon during that time. Additionally, I examine compositional data from glass shards to explore the relationship between δD and shard composition. The RST exhibits well defined …