Miocene Geomagnetic Field Behavior and Tectonic Evolution of Iceland: Absolute Paleointensity, Paleomagnetic, and Geochronological Study of the Vestfirdir Peninsula Lava Flows

This research project aims to explore the history and behavior of Earth's magnetic field over millions of years by investigating volcanic lava flows in Iceland. A key objective is to obtain precise ages from a representative set of these flows, including the oldest flows in Iceland. Understanding how Earth's magnetic field has changed over time is crucial for improving our knowledge of the Earth's inner workings and its geodynamo system, which generates the magnetic field.

By studying lava flows that span from 8.5 to 16 million years ago, the project will help fill significant gaps in the global database of Earth's magnetic field strength. The data gathered will significantly extend accurate models of Earth's magnetic field by several million years, offering new insights into geomagnetic field reversals and the geological processes that drive these changes.

Additionally, this research will shed light on the tectonic and volcanic activity in Iceland, enhancing our understanding of Earth's geological processes and their timescales. The research also includes an important educational component, engaging undergraduate students in hands-on research and offering outreach opportunities to local communities, including the Keweenaw Bay Indian Community.

These efforts will encourage broader public engagement with science, inspire and train the next generation of scientists, and help raise awareness of Earth's magnetic field and the global geological processes shaping our planet.

Nearly continuous volcanic activity in Iceland over the last ~16 Ma presents an excellent opportunity to study the behavior, geometry, strength, and variability of Earth’s magnetic field, crucial for understanding geodynamo mechanisms and the evolution of the Earth's deep interior. While the paleodirectional record from the Icelandic lava flows is relatively well established, there are still significant gaps in the absolute paleointensity database, especially for the Miocene epoch.

Additionally, the number of reliable age determinations for Icelandic lavas is limited. The project will conduct a comprehensive paleointensity, paleodirectional, and geochronological investigation of the Miocene lava flow sequences (~8.5 to 16 Ma) exposed in the Vestfirðir peninsula of northwestern Iceland. To do this, the team will use several paleointensity determination methods, including the IZZI version of the Thellier-Thellier method and the LTD-DHT-Shaw method, along with thorough rock magnetic analyses. 40Ar/39Ar incremental heating method will determine precise ages for a representative set of basalt samples, including some of the oldest lava flows found in Iceland.

Filling the existing gaps in Iceland’s paleointensity database and improving data quality will advance our understanding of the spatiotemporal trends of the time-averaged geomagnetic field over millions to tens of millions of years. The results will provide vital insights into geodynamo mechanisms and contribute to the development of robust geomagnetic field models for the last 16 Ma.

The results aim to refine the paleosecular variation estimates for Iceland and to probe the existence of long-term non-dipole features of the geomagnetic field. In addition, the new data will enhance understanding of the tectono-magmatic evolution of Iceland, including the duration of the magmatic hiatus associated with the transition from the Northwest Iceland rift zone to the Snæfellsnes-Húnaflói rift zone at ~15 Ma, and will improve the correlation of lava flow sequences across the Vestfirðir peninsula. The project will support a postdoctoral researcher and several undergraduate research assistants.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.