The Efficacy of Stromatolites as Paleomagnetic Recorders
Mentor 1
Julie Bowles
Location
Union Wisconsin Room
Start Date
27-4-2018 1:00 PM
Description
The geosciences’ subdiscipline of paleomagnetism plays an important role in understanding the history of the Earth. Geologic records of paleomagnetic fields can become corrupted over time by the perpetual, dynamic processes taking place on Earth; thus, locating ancient Earth materials capable of accurately recording magnetic fields is essential to understand field behavior over geologic time. Stromatolites are laminated sedimentary rocks, the oldest of which are at least 3.5 billion years old. In principle, their magnetic records could therefore tell us something about Earth’s inner core formation. Stromatolites are thought to have formed in shallow waters via a bio-mediated process involving cyanobacteria. A microbial mat forms a sticky exterior film. In principle, as magnetic sediments fall through water they tend to preferentially align in the direction of the geomagnetic field; these sediments subsequently land on and are incorporated into the microbial mat, resulting in a continuous record of field behavior with a resolution of perhaps 5-20 years. This pilot study uses a stromatolite ~530 million years old, with an aim to determine the efficacy of stromatolites as paleomagnetic recorders. With the use of magnetic instruments housed in the UWM Paleomagnetism Laboratory, the magnetic directions recorded by the stromatolite were determined. I will assess the directional variability within the stromatolite and compare the directions to those determined from near-by rocks of the same age. If successful, this study will help uncover the paleomagnetic field direction from ~530 Ma as well as establish the reliability of stromatolites as paleomagnetic recorders.
The Efficacy of Stromatolites as Paleomagnetic Recorders
Union Wisconsin Room
The geosciences’ subdiscipline of paleomagnetism plays an important role in understanding the history of the Earth. Geologic records of paleomagnetic fields can become corrupted over time by the perpetual, dynamic processes taking place on Earth; thus, locating ancient Earth materials capable of accurately recording magnetic fields is essential to understand field behavior over geologic time. Stromatolites are laminated sedimentary rocks, the oldest of which are at least 3.5 billion years old. In principle, their magnetic records could therefore tell us something about Earth’s inner core formation. Stromatolites are thought to have formed in shallow waters via a bio-mediated process involving cyanobacteria. A microbial mat forms a sticky exterior film. In principle, as magnetic sediments fall through water they tend to preferentially align in the direction of the geomagnetic field; these sediments subsequently land on and are incorporated into the microbial mat, resulting in a continuous record of field behavior with a resolution of perhaps 5-20 years. This pilot study uses a stromatolite ~530 million years old, with an aim to determine the efficacy of stromatolites as paleomagnetic recorders. With the use of magnetic instruments housed in the UWM Paleomagnetism Laboratory, the magnetic directions recorded by the stromatolite were determined. I will assess the directional variability within the stromatolite and compare the directions to those determined from near-by rocks of the same age. If successful, this study will help uncover the paleomagnetic field direction from ~530 Ma as well as establish the reliability of stromatolites as paleomagnetic recorders.
