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Full-Text Articles in Physical Sciences and Mathematics
The Relationship Between Exsolution And Magnetic Properties In Hemo-Ilmenite: Insights From Mössbauer Spectroscopy With Implications For Planetary Magnetic Anomalies, Laurie Brown, M. D. Dyar, S. A. Mcenroe, E. Murad, H. Schiellerup
The Relationship Between Exsolution And Magnetic Properties In Hemo-Ilmenite: Insights From Mössbauer Spectroscopy With Implications For Planetary Magnetic Anomalies, Laurie Brown, M. D. Dyar, S. A. Mcenroe, E. Murad, H. Schiellerup
Laurie Brown
Remanence properties of ilmenites with exsolved hematite have recently been the object of much study, because their high natural remanent magnetization (NRM) is greater than predicted for these two minerals. X-ray diffraction (XRD) and Mössbauer spectroscopy in conjunction with electron microprobe and NRM measurements were used to explore the possibility that single domain (SD) hematite lamellae in the ilmenite host could explain the observed remanence, and to determine if magnetite is present. XRD results show the presence of ilmenite and hematite. Mössbauer data show that only species assigned to hematite, ilmenite, and a small amount of tetrahedral Fe3+ are present. …
Paleomagnetic Directions And 40ar/39ar Ages From The Tatara-San Pedro Volcanic Complex, Chilean Andes: Lava Record Of A Matuyama-Brunhes Precursor?, Laurie Brown, J. C. Pickens, B. S. Singer, B. R. Jicha
Paleomagnetic Directions And 40ar/39ar Ages From The Tatara-San Pedro Volcanic Complex, Chilean Andes: Lava Record Of A Matuyama-Brunhes Precursor?, Laurie Brown, J. C. Pickens, B. S. Singer, B. R. Jicha
Laurie Brown
Lava flows within Quebrada Turbia valley of the Tatara San Pedro volcanic complex, in central Chile (36°S, 289°E), preserve a detailed record of what was presumed to be the Matuyama-Brunhes geomagnetic reversal. A sampling traverse in the central west wall of the valley yields reverse and transitional polarity flows of the Quebrada Turbia sequence. Two kilometers to the north, another section yields 17 transitional flows from the same volcanic sequence overlain by flows with normal polarity. The 40Ar/39Ar incremental heating experiments on lavas within the two sections provide nine independent age determinations and yield a weighted mean of 791.7 ± …
Magnetic Anomalies, Layered Intrusions And Mars, Laurie Brown, S. A. Mcenroe, J. R. Skilbrei, P. Robinson, F. Heidelbach, F. Langenhorst
Magnetic Anomalies, Layered Intrusions And Mars, Laurie Brown, S. A. Mcenroe, J. R. Skilbrei, P. Robinson, F. Heidelbach, F. Langenhorst
Laurie Brown
Studies of remanence-controlled magnetic anomalies on Earth provide possibilities to interpret the nature of crustal rocks that cause the large remanent anomalies on Mars. What types of conditions on Earth can create large remanent magnetic anomalies? Such an anomaly, extending for 20 km centered over a norite layer in the Bjerkreim-Sokndal (BKS) Intrusion, shows a minimum −13000 nT below background in the helicopter survey. Modeling of the anomaly requires a natural remanent magnetization (NRM) value of 24 A/m, similar to values measured in norite samples and to values invoked to explain the anomalies on Mars. Preliminary magnetic assessment considers the …