Institute for Rock Magnetism (IRM)
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The Institute for Rock Magnetism (IRM) was established in the fall of 1990 as a National Multi-User Facility whose core mission is to serve the greater geomagnetic community by providing free-of-charge access to state-of-the-art facilities and technical expertise, and by encouraging visiting researchers in their studies of important new topics in rock magnetism and related interdisciplinary fields. See the website at http://www.irm.umn.edu/IRM.
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Browsing Institute for Rock Magnetism (IRM) by Author "Brachfeld, Stefanie"
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Item IRM Quarterly, Volume 03, Number 2 (Summer 1993). Cover article: Performing Tasks at the IRM Takes Time(University of Minnesota. Institute for Rock Magnetism, 1993) Brachfeld, Stefanie; Foss, Sherry; Hunt, Chris; Kletetschka, Gin; Marvin, Jim; Moskowitz, Bruce; Rubin, Scott; Sahu, Sanghamitra; Solheid, PeatItem IRM Quarterly, Volume 03, Number 3 (Fall 1993). Cover article: Tasks at the IRM Still Take Time(University of Minnesota. Institute for Rock Magnetism, 1993) Brachfeld, Stefanie; Foss, Sherry; Hunt, Chris; Kletetschka, Gin; Marvin, Jim; Moskowitz, Bruce; Rubin, Scott; Sahu, Sanghamitra; Solheid, PeatItem IRM Quarterly, Volume 03, Number 4 (Winter 1993-1994). Cover article: Tasks at the IRM Take Time, Part III(University of Minnesota. Institute for Rock Magnetism, 1994) Brachfeld, Stefanie; Foss, Sherry; Hunt, Chris; Kletetschka, Gin; Marvin, Jim; Moskowitz, Bruce; Rubin, Scott; Sahu, Sanghamitra; Solheid, PeatItem IRM Quarterly, Volume 05, Number 3 (Fall 1995). Cover article: IRM Hosts Workshop on Sedimentary Biogeomagnetism(University of Minnesota. Institute for Rock Magnetism, 1995) Brachfeld, StefanieItem IRM Quarterly, Volume 09, Number 2 (Summer 1999). Cover article: Magnets on Ice: Holocene Paleoclimate Records from the Antarctic Peninsula(University of Minnesota. Institute for Rock Magnetism, 1999) Brachfeld, StefanieItem A new high-resolution geomagnetic paleointensity record for the North American Holocene: A comparison of sedimentary and absolute intensity data(Journal of Geophysical Research (American Geophysical Union), 2000) Brachfeld, Stefanie; Banerjee, SubirA new high-resolution paleointensity record for North America has been constructed using Holocene sediments from Lake Pepin, Minnesota. Lake Pepin sediments yield the same Holocene paleosecular variation curve as nearby Lake St. Croix and satisfy all of the criteria recommended for paleointensity studies. Absolute paleointensity data for North America recorded by Holocene volcanic and archeomagnetic samples provide an independent record of geomagnetic field paleointensity against which the relative intensity records from Lake Pepin and Lake St. Croix can be compared. Since the absolute field paleointensity is known a priori, the effects of the magnetic recording assemblage can be isolated. Anhysteretic remanent magnetization (ARM) is the best choice among normalization parameters for the Lake Pepin sediments as the natural remanent magnetization (NRM) normalized by ARM shows no coherence with magnetic grain size proxies and yields a record of relative paleointensity peaks and troughs whose amplitudes are very similar to those in the archeomagnetic (ARCMAG) and Lake St. Croix data sets. Features with a wavelength of 1000 years are correlative between the three paleointensity records. NRM normalized by saturation isothermal remanent magnetization (SIRM) and by susceptibility (χ) shows grain-size dependences that cause errors in the amplitudes of paleointensity features. NRM/SIRM and NRM/χ are not coherent with their normalizers but are both strongly coherent with independent grain size proxies such as the median destructive field of the NRM and HCR. We successfully removed the grain size dependences from NRM/SIRM by applying a correction function based on the linear relationship between normalized intensity and the median destructive field of the NRM.