Michigan Technological University Digital Commons @ Michigan Tech Dissertations, Master's Theses and Master's Reports 2019 PALEOMAGNETIC INVESTIGATION OF IGNEOUS ROCKS DEFORMED BY THE KEWEENAW FAULT IN THE NORTHWESTERN KEWEENAW PENINSULA. Daniel Trekas Michigan Technological University, [email protected] Copyright 2019 Daniel Trekas Recommended Citation Trekas, Daniel, "PALEOMAGNETIC INVESTIGATION OF IGNEOUS ROCKS DEFORMED BY THE KEWEENAW FAULT IN THE NORTHWESTERN KEWEENAW PENINSULA.", Open Access Master's Thesis, Michigan Technological University, 2019. https://doi.org/10.37099/mtu.dc.etdr/939 Follow this and additional works at: https://digitalcommons.mtu.edu/etdr Part of the Geology Commons, and the Geophysics and Seismology Commons PALEOMAGNETIC INVESTIGATION OF IGNEOUS ROCKS DEFORMED BY THE KEWEENAW FAULT IN THE NORTHWESTERN KEWEENAW PENINSULA. By Daniel B. Trekas A THESIS Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE In Geophysics MICHIGAN TECHNOLOGICAL UNIVERSITY 2019 © 2019 Daniel B. Trekas This thesis has been approved in partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE in Geophysics. Department of Geological and Mining Engineering and Sciences Thesis Advisor: Aleksey Smirnov Committee Member: Chad Deering Committee Member: James DeGraff Department Chair: John Gierke Table of Contents 1.0 Introduction ..................................................................................................................1 1.1 Midcontinent Rift System ...................................................................................................... 1 1.2. The Portage Lake Volcanics ................................................................................................. 6 1.3. Site Descriptions ................................................................................................................... 9 2.0 Methods .......................................................................................................................13 2.1 Sample Collection ................................................................................................................ 13 2.2 Thermal Demagnetization .................................................................................................... 15 2.3 Thermomagnetic Analyses ................................................................................................... 18 2.4 Magnetic Hysteresis Analyses ............................................................................................. 19 3.0 Results .........................................................................................................................22 3.1 Paleomagnetism ................................................................................................................... 22 3.2 Thermomagnetic Analyses ................................................................................................... 41 3.3 Magnetic Hysteresis Analyses ............................................................................................. 47 4.0 Discussion....................................................................................................................52 5.0 Conclusion ..................................................................................................................58 References .........................................................................................................................59 ii List of Figures Figure 1. Map of the Midcontinent Rift ..............................................................................1 Figure 2. Map of the Lake Superior Basin ..........................................................................3 Figure 3. Cross-section of the Lake Superior Basin ...........................................................5 Figure 4. Map of Sample Locations ..................................................................................10 Figure 5. PM01-08 and PM11 sample Outcrop Images ....................................................12 Figure 6. Pomeroy Orienting Fixture with Brunton Compass ..........................................14 Figure 7. 2G Enterprise 760-R SRM .................................................................................15 Figure 8. ASC TD-48SC Thermal Specimen Demagnetizer ............................................16 Figure 9. Example of Demagnetization Behavior .............................................................17 Figure 10. AGICO MFK1-FA Kappabridge .....................................................................19 Figure 11. MicroMag Model 2900 AGM .........................................................................20 Figure 12. Example of a Magnetic Hysteresis Loop .........................................................22 Figure 13. Equal Area and Vector Plot PM01 ..................................................................31 Figure 14. Equal Area and Vector Plot PM02 ..................................................................32 Figure 15. Equal Area and Vector Plot PM03 ..................................................................33 Figure 16. Equal Area and Vector Plot PM04 ..................................................................34 Figure 17. Equal Area and Vector Plot PM05 ..................................................................35 Figure 18. Equal Area and Vector Plot PM09 ..................................................................36 Figure 19. Equal Area and Vector Plot PM10 ..................................................................37 Figure 20. Equal Area and Vector Plot PM11 ..................................................................38 Figure 21. Equal Area and Vector Plot PM06 ..................................................................40 iii Figure 22. Equal Area and Vector Plot PM07 ..................................................................40 Figure 23. Equal Area and Vector Plot PM08 ..................................................................41 Figure 24. Thermal Demagnetization Curves PM01-PM04 .............................................45 Figure 25. Thermal Demagnetization Curves PM05 & PM09-PM11 ..............................46 Figure 26. Thermal Demagnetization Curves PM06 & PM07 .........................................47 Figure 27. Magnetic Hysteresis Loops PM01-PM04 ........................................................48 Figure 28. Magnetic Hysteresis Loops PM05-PM07 & PM11 .........................................49 Figure 29. Backfield Demagnetization Plots PM01-04 ....................................................50 Figure 30. Backfield Demagnetization Plots PM05-07 & PM11 .....................................51 Figure 31. Day Plot of Hysteresis Data PM01-PM07 & PM11 ........................................52 Figure 32. Equal-area Plot with a Summary of Paleomagnetic Results ...........................55 Figure 33. Site-mean Paleomagnetic Directions for Sites PM02 and PM09, Browning, and Beske-Diehl (1987), and from Kulakov (2014) ..........................................................56 iv List of Tables Table 1. Previous Paleomagnetic Data for the PLV............................................................8 Table 2. PM01-PM11 Site Coordinates and Summary .....................................................11 Table 3. Site PM01 Summary ...........................................................................................23 Table 4. Site PM02 Summary ...........................................................................................24 Table 5. Site PM03 Summary ...........................................................................................25 Table 6. Site PM04 Summary ...........................................................................................26 Table 7. Site PM05 Summary ...........................................................................................26 Table 8. Site PM06 Summary ...........................................................................................27 Table 9. Site PM07 Summary ...........................................................................................27 Table 10. Site PM08 Summary .........................................................................................28 Table 11. Site PM09 Summary. ........................................................................................28 Table 12. Site PM10 Summary .........................................................................................29 Table 13. Site PM11 Summary .........................................................................................29 Table 14. PM01-PM11 Result Summary ..........................................................................54 v Acknowledgments I would like to thank my advisor Aleksey Smirnov and committee members Chad Deering and James DeGraff for all there help and advice throughout my research. I would like to thank all those who helped me with my research. All those who have helped me with lab work: Katie Bristol, Marine Foucher, Sonia Jin, and Adren Rigdon All those who have helped me with sample collection: Graham Hubbell, Elisa Piispa, Leonid Surovitckii, and Colin Tyrrell Property owners of sample sites for allowing me to sample: Chuck Brumleve, Hal Baldauf, Gina Nicholas, Frank Nicholas, and The Keweenaw Community Forest Company Lastly, I would like to thank my friends and family for all the support during my education and research. vi Abstract