1. Investigation of Subsurface Magma Feeders Taryn Serwatowski Dr. Sven Morgan Department of Geology CMU

2. Introduction  One type of magma intrusion is called a laccolith  The current model for how laccoliths form involves vertical magma “feeders” called dikes  In this model, magma pushes its way through a crack and then spreads horizontally between layers of rock and creates a dome shape  We think the TML was fed by a horizontal feeder

3. The Trachyte Mesa Laccolith Top of dome

4. Background: Evidence of horizontal magma flow  The TML lies along an axis that can be traced directly back to Mt. Hillers  Magma flow direction and minerals are also aligned along this same axis  Both igneous bodies are of the same age and have the same chemical composition

5. Mount Hillers Area of Research Trachyte Mesa

6. Traverses 900 ft

7. Why collect our data here?  The area is directly between Mt. Hillers and the TML  The area is flat lying  There are overlying layers of sedimentary rock

8. Methods: How we acquired our data  Seismic Reflection and Ground Penetrating Radar were used  Waves sent in the ground reflect back when they strike a subsurface contact  Denser materials will create a high seismic reflection  A seismograph at the surface recorded the image of each wave How seismic reflection works

9. Acquiring Seismic Data

10. Anomalies found on 2 nd traverse

11. Anomaly found on 3 rd traverse

12. Anomalies found on 4 th traverse

13. Map x x x x x X Mt. Hillers

14. Results  Presence of highly reflective interfaces detected  Calculated depth to reflectors correlates with hypothesized depth  Reflectors oriented in line between the laccolith and Mount Hillers  These anomalies also correspond with magnetic anomalies along the same traverses

15. Conclusions  Not all laccoliths may have formed from vertical feeders  Studying the Trachyte Mesa can provide clues to how magma travels through the subsurface  Strong evidence exists for a subsurface connection between the TML and Mt. Hillers  Seismic Reflection supports theory of horizontal magma feeders  GPR data proved to be unsuccessful  A future survey using a hammer blow at each geophone could result in more reliable data

16. Questions? Investigation of Subsurface Magma Feeders