GP23A-1284
Absolute Geomagnetic Paleointensity from the ~1.1 Ga Baraga-Marquette Dike Swarm (Michigan, USA).
Tuesday, 15 December 2015
Poster Hall (Moscone South)
Marine Séverine Foucher1, Elisa J Piispa2 and Aleksey V Smirnov1, (1)Michigan Technological University, Geological and Mining Engineering and Sciences, Houghton, MI, United States, (2)Michigan Technological University, Houghton, MI, United States
Abstract:
Understanding the geomagnetic field intensity recorded by Precambrian rocks is essential to obtain insight into the nature and evolution of the Earth’s early geodynamo. However, our current knowledge of this period remains very limited. We analyzed 19 diabase dikes from the Baraga-Marquette swarm (Michigan, USA) which intruded during the formation of the ~1.1 Ga North American Mid-Continent Rift (MCR) system. Both normal and reversed polarity dikes contain stable primary magnetization carried predominantly by single to pseudo-single domain magnetite and/or low-Ti titanomagnetite. We will present new paleointensity determinations retrieved from the dikes using several paleointensity techniques (e.g. LTD- Thellier, LTD-Shaw) and discuss their implications for the geodynamo evolution at the time of the MCR formation.
