• Contribution of multidomain titanomagnetite to the intensity and stability of Mars crustal magnetic anomalies 

  Brachfeld, Stefanie A.; Cuomo, David; Tatsumi-Petrochilos, Lisa; Bowles, Julie A.; Shah, Deepa; Hammer, Julie E. (2014-11-26)

  Two basalts with compositions relevant to the crusts of Mars and Earth were synthesized at igneous temperatures and held at 650°C for 21 to 257 days under quartz-fayalite-magnetite ƒO2 buffer conditions. The run products ...

• Behavior of oceanic crustal magnetization at high temperatures: Viscous magnetization and the marine magnetic anomaly source layer 

  Bowles, Julie A.; Johnson, H. Paul (1999-08-01)

  Although the source layer for marine magnetic anomalies has been assumed to be the extrusive basalts of uppermost ocean crust, recent studies indicate that lower crustal rocks may also contribute. Because the temperature ...

• Source of tiny wiggles in Chron C5: A comparison of sedimentary relative intensity and marine magnetic anomalies 

  Bowles, Julie A.; Tauxe, Lisa; Gee, Jeffrey S.; McMillan, David; Cande, Steve (2003-06-14)

  In addition to the well-established pattern of polarity reversals, short-wavelength fluctuations are often present in both sea-surface data ("tiny wiggles") and near-bottom anomaly data. While a high degree of correlation ...

• Geomagnetic paleointensity in historical pyroclastic density currents: Testing the effects of emplacement temperature and postemplacement alteration 

  Bowles, Julie A.; Gee, Jeffrey S.; Jackson, Mike J.; Avery, Margaret S. (2015-10-26)

  Thellier-type paleointensity experiments were conducted on welded ash matrix or pumice from the 1912 Novarupta (NV) and 1980 Mt. St. Helens (MSH) pyroclastic density currents (PDCs) with the intention of evaluating their ...

• Multicomponent cubic oxide exsolution in synthetic basalts: Temperature dependence and implications for magnetic properties 

  Bowles, Julie A.; Tatsumi-Petrochilos, Lisa; Hammer, Julie E.; Brachfeld, Stefanie A. (2012-01-01)

  Although the compositional unmixing of cubic-structured iron oxides has profound effects on the magnetic properties of rocks that contain them, a basic understanding of the kinetics and thermodynamics of this process has ...

• Timing of magnetite formation in basaltic glass: Insights from synthetic analogs and relevance for geomagnetic paleointensity analyses 

  Bowles, Julie A.; Gee, Jeffrey S.; Burgess, Katherine; Cooper, Reid F. (2011-02-09)

  Absolute paleointensity estimates from submarine basaltic glass (SBG) typically are of high technical quality and accurately reflect the ambient field when known. SBG contains fine-grained, low-Ti magnetite, in contrast ...

• Magnetic and petrologic characterization of synthetic Martian basalts and implications for the surface magnetization of Mars 

  Bowles, Julie A.; Hammer, Julie E.; Brachfeld, Stefanie A. (2009-01-01)

  A suite of synthetic Martian basalts is generated with the objective of providing fundamental material properties data for use in modeling and interpretation of mission data. We systematically evaluate the effects of major ...

• Tracer-based Separation of Advection and Dispersion from Breakthrough Curves 

  Paradis, Charles; Sultana, Rakiba (2024-01-01)

• Spectral mapping of zeolite bearing paleolake deposits at Lake Tecopa, California and its implications for mapping zeolites on Mars 

  Kodikara, Gayantha R.L.; McHenry, Lindsay J.; van der Meer, Freek D. (2022-08-11)

  While non-analcime zeolites are plausible mineral constituents of the Martian surface, their lack of prominent spectral characteristics in the visible to shortwave infrared wavelength region makes them difficult to identify ...

• Data-Driven Fuzzy Weights-Of-Evidence Model for Identification of Potential Zeolite-Bearing Environments on Mars 

  Kodikara, Gayantha R.L.; McHenry, Lindsay J. (2023-09-28)

  The evolution of the climate and hydrochemistry of Mars is still a mystery but it must have been at least occasionally warm and wet to have formed the ancient fluvial and lacustrine landforms observed today. Terrestrial ...

• Absolute Paleointensity Study of Miocene Tiva Canyon Tuff, Yucca Mountain, Nevada: Role of Fine‐Particle Grain‐Size Variations 

  Abdulghafur, F.; Bowles, Julie A. (2019-12-04)

  Fine‐grained, Ti‐poor titanomagnetite in the ~12.7 Ma Tiva Canyon (TC) Tuff systematically increases in grain size from superparamagnetic (SP) at the flow base to single domain (SD) at a few meters height. This allows us ...

• Paleointensity Estimates From Ignimbrites: The Bishop Tuff Revisited 

  Avery, Margaret S.; Gee, Jeffrey S.; Bowles, Julie A. (2018-09-18)

  Volcanic ash flow tuffs (ignimbrites) may contain single domain‐sized (titano) magnetite that should be good for recording geomagnetic field intensity, but due to their complex thermal histories also contain other magnetic ...

• Curie Temperature Enhancement and Cation Ordering in Titanomagnetites: Evidence From Magnetic Properties, XMCD, and Mössbauer Spectroscopy 

  Bowles, Julie A.; Lappe, S.-C. L. L.; Jackson, Mike J.; Arenholz, E.; van der Laan, G. (2019-04-23)

  Previous work has documented time‐ and temperature‐dependent variations in the Curie temperature (Tc) of natural titanomagnetites, independent of any changes in sample composition. To better understand the atomic‐scale ...

• Magnetic Mineral Populations in Lower Oceanic Crustal Gabbros (Atlantis Bank, SW Indian Ridge): Implications for Marine Magnetic Anomalies 

  Bowles, Julie A.; Morris, A.; Tivey, M. A.; Lascu, Ioan (2020-02-28)

  To learn more about magnetic properties of the lower ocean crust and its contributions to marine magnetic anomalies, gabbro samples were collected from International Ocean Discovery Program Hole U1473A at Atlantis Bank on ...

• A Feasibility Study of Microbialites as Paleomagnetic Recorders 

  Jung, Ji-In; Bowles, Julie A. (2021-03-05)

  Microbialites–layered, organosedimentary deposits–exist in the geologic record and extend back in deep time, including all estimated times of inner core nucleation. Microbialites may preserve magnetic field variations at ...

• Assessing New and Old Methods in Paleomagnetic Paleothermometry: A Test Case at Mt. St. Helens, USA 

  Bowles, Julie A.; Gerzich, Devin; Jackson, Mike J. (2018-06-07)

  Paleomagnetic data can be used to estimate deposit temperatures (Tdep) of pyroclastic density currents (PDCs) by finding the laboratory temperature at which a PDC-associated thermal remanence is removed. Paleomagnetic ...

• Paleointensity applications to timing and extent of eruptive activity, 9°–10°N East Pacific Rise 

  Bowles, Julie A.; Gee, Jeffrey S.; Kent, Dennis V.; Perfit, Michael R.; Soule, S. Adam; Soule, S. Adam (2006-06-08)

  Placing accurate age constraints on near-axis lava flows has become increasingly important given the structural and volcanic complexity of the neovolcanic zone at fast spreading ridges. Geomagnetic paleointensity of submarine ...

• Geology of the Alarcon Rise, Southern Gulf of California 

  Clague, David A.; Caress, David W.; Dreyer, Brian M.; Lundsten, Lonny; Paduan, Jennifer B.; Portner, Ryan A.; Spelz-Madero, Ronald; Bowles, Julie A.; Castillo, Paterno R.; Guardado-France, Rigoberto; Le Saout, Morgane; Martin, Julie F.; Santa Rosa-del Río, Miguel A.; Zierenberg, Robert A. (2018-03-15)

  Abstract Meter-scale AUV bathymetric mapping and ROV sampling of the entire 47 km-long Alarcon Rise between the Pescadero and Tamayo transforms show that the shallowest inflated portion of the segment hosts all four active ...

• Malleable Curie Temperatures of Natural Titanomagnetites: Occurrences, Modes, and Mechanisms 

  Jackson, Mike J.; Bowles, Julie A. (2018-01-24)

  Abstract Intermediate-composition titanomagnetites have Curie temperatures (Tc) that depend not only on composition but also on thermal history, with increases of 100°C or more in Tc produced by moderate-temperature ...

• Effects of titanomagnetite reordering processes on thermal demagnetization and paleointensity experiments 

  Bowles, Julie A.; Jackson, Mike J. (2016-12-17)

  Titanomagnetite (Fe3-xTixO4, 0≤x≤1) is a common, naturally occurring magnetic mineral critical to many paleomagnetic studies. Underlying most interpretations is the assumption that, lacking chemical alteration, Curie ...

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