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Winter 2004-5, Vol. 14, No. 4
Johann von Lamont (1805-1879): A pioneer in geomagnetism
In 2005 we can commemorate the 200th Heinrich Soffel birthday of Johann von Lamont (Fig. 1), Prof. Emeritus a pioneer in geomagnetism in the middle University of of the 19th century. He belonged to the München group around Gauss, von Humboldt, Sabine, Angström and others (forming the Göttingen Magnetic Union) who established within a few years an international network of geomagnetic observatories around the word (Barraclough et al., 1992) upon which much of our present day knowledge about the geomagnetic field rests. Johann von Lamont was born as John Lamont on 15 December 1805 in Corriemulzie near Braemar in Central Fig. 1. Portrait of Johann von Lamont from 1856 showing him at the age of 50. of Johann von Lamont from Fig. 1. Portrait Scotland. His father, Robert Lamont, was a forester and administrator to James, the second Earl of Five. When Robert engineering which helped him later in the the Observatory in 1835 at the age of 29. Lamont died suddenly in 1816 from an construction and production of instru- More details about the Lamont family, accident with his horse the family had to ments for observatory and field work. the life and the scientific career of search for a sponsor who could take care Since 1827 he spent most of the time of Johann von Lamont can also be taken of the education of the bright 12 year old his vacations as a student in the Royal from Wienert (1966) and Beblo & Soffel boy John. In 1817, Father Gallus Astronomical Observatory which had (1991). Robertson, the dean of the Scottish been built in 1816-1817 in Bogenhausen, The early 1830’s were very Monastery St. James from Regensburg in at that time a small village close to important for geomagnetism due to the Bavaria visited Scotland in search of Munich. In 1828 he was appointed as an initiatives of Carl Friedrich Gauss and talented students for his monastery assistant in the observatory and in 1830 Alexander von Humboldt. During his school. John received a fellowship and he got a PhD at the University of expeditions, which led him to remote was taken to Regensburg for an educa- Munich. Due to the bad health of the parts of our globe, von Humboldt had tion in theology and sciences. However, director of the observatory, Georg von recognised that the origin of the spatial the main interests of the boy were not in Soldner, Lamont was soon in charge of and temporal variations of the geomag- theology but in mathematics and natural doing all the astronomical routine work. netic field could only be investigated by sciences. This was soon recognized by When von Soldner died in 1833 Lamont world-wide simultaneous and permanent Father Benedict Deasson, one of his was on his own and entirely responsible. observations in a global network of teachers, and John was trained in these He was finally appointed as director of Lamont disciplines including also mechanical 1 continued on p. 8... Visiting Fellows’ Reports
decreased sharply in passing through the reduce or partially remove the internal Magnetic Memory in MD strains and stresses produced by crystal Morin transition (TM). At TM, 97% of the Hematite original SIRM is demagnetized with the defects. A large single crystal of Özden Özdemir disappearance of spin-canting and the hematite (6 mm) was heated in zero field University of Toronto In previous years at the IRM, I onset of c-axis antiferromagnetism. in air at 600°C for 3 and 5 hours. I used ozdemir@physics.utoronto.ca a Schoenstedt thermal demagnetizer to studied low-temperature demagnetization Between TM and 20 K, there was no of TRM and SIRM of natural single further demagnetization. The residual 3% anneal the crystal in zero field. The crystals of hematite with grain sizes of the original remanence remained sequence of the annealing experiments between 1-6 mm. The zero-field cooling constant. In warming back though the was: (1) thermally demagnetize the and warming curves of SIRM for a 4 mm Morin transition, 43% of the original crystal at 705°C, anneal for 3 hours; (2) hematite crystal are shown in Figure 1. remanence was recovered. This value is produce 0.1 mT TRM and measure M ; (3) LTD by cooling the crystal to In cooling from 300 K, the remanence much higher than the SIRM memory TR ratios of 30-32% measured for SD 77 K in liquid N2 and measure the TRM hematites with grain sizes memory; (4) repeat (1) to (4) for 5-hour 1.0 between 0.12-0.23 µm. annealing experiments. The intensity of TRM decreased 7% At TM, as spins rotate from the (0001) plane to the c-axis, after 3-hours annealing. However, the 0.8 intensity of the TRM memory was α -Fe O the magnetocrystalline 23 anisotropy constant passes reduced much more. After 3-hours (300) Single crystal through zero and changes sign. annealing, the crystal had a 30% lower 0.6 In MD hematite, domain walls TRM memory. Five hours annealing HSIRM // (0001) blocked by magnetocrystalline had further effect on the memory: about controlled pinning become free 2/3 of the initial memory was retained. 0.4 to jump and lead to demagneti- It appears that annealing reduced the SIRM SIRM zation of a large fraction of the number of strain centers but did not M/M original SIRM. The remaining completely remove all of them. The 0.2 43% of the room-temperature memory must be due to strongly pinned SIRM was not destroyed by domain walls, probably pinned magneto- cycling through T . strictively by dislocations or other 0 M 0 50 100150 200 250 300 This year at the IRM, I crystal defects. investigated the effect of I would like to thank Mike, Peat, Temperature, T (K) annealing on the TRM Ramon and Thelma for their help and memory. Annealing could hospitality.
Normalized zero-field cooling and warming curves of SIRM for a 4 mm single crystal of hematite. Field is applied along (0001).
Guillaume Plenier However, complex fabrics (those that fraction of super paramagnetic (SP) grains. Cooling the sample below the IPGP and CNRS Origin of complex magnetic differ significantly from the normal case) SP-blocking temperature would lead to [email protected] appear to be more prevalent than is fabrics an increase in the fraction of single and generally accepted. Indeed, entire sites can yield a single well-defined complex domain grains that would, in turn, Jonathan Glen The aim of our visit was to determine fabric. As a result, independent flow change the sample’s AMS fabric U. S. Geological Survey what factors control complex fabrics in indicators (e.g., vesicle orientation or (driving it towards an inverse fabric) and [email protected] igneous rocks, and to assess whether petrofabric studies) are needed to allow one to infer the flow direction. magma flow directions could be confidently infer magma flow directions. To test this idea, we applied an recovered from them. Interestingly, some of the most existing high-field method (Ferré et al., commonly observed complex fabrics are 2000; Thill et al. 2000; Kelso et al. Introduction ones that mimic the normal case, in that 2002), for the first time, at low tempera- Until recently, studies of the the AMS axes are aligned with the flow tures. In addition we performed anisotropy of magnetic susceptibility coordinates but are flipped with respect to magnetic mineral identification, based (AMS) of dikes and lavas have largely each other (Figure 1). One of the most on low-temperature crystallographic assumed a simple relation between the compelling explanations for these transitions using an MPMS, and principal AMS directions and magma “permuted” fabrics involves mixtures of determination of magnetic grain size, flow. In the so-called “normal” magnetic single domain and multidomain grain with the use of hysteresis curves, FORC fabric case, the magnetic foliation sizes (Rochette et al., 1992; Ferré, 2002). distribution analyses, and low-tempera- mimics the flow plane (i.e., the AMS Assuming grain size mixtures are ture AC-susceptibility measurements, to minimum — Kmin, which is the normal responsible for these permuted fabrics, assess the actual factors responsible for to the foliation plane, lies perpendicular one might be able to recover the true flow the permuted fabrics. to a dike’s walls or to a lava’s bottom) direction by isolating the influence of the Two sets of samples yielding and the magnetic lineation (given by the different grain size fractions on the permuted fabrics were studied: mid- AMS maximum — Kmax) parallels the magnetic fabric. It might be particularly Miocene dikes from the Roberts magma flow direction. Mountains, NV (eastern Northern 2 appropriate for samples containing some Normal flow coordinates Kmax flow Kmin direction K1 K3 LTHFASR - small cube Kint K2 K1 Max Specimen 0110 N AMS paleomag specimen dike walls or flow top and bottom K2 Int (parallel to flow plane) K3 Min
Normal Flat Normal Fin MD 300a K2-K3 flip 200 175 np + ip: Rochette et al. , 1992 100 300b 25 AMS 200 300a AMS 300b 175 Intermediate Flat Intermediate Fin
K1-K2 flip 3-axis flip
100 25 100 200 25 Inverse Parallel Inverse Perpendicular 175 300a 300b 3-axis flip K1-K3 flip AMS
Figure 2: Comparison of the LTHFASR measurements (in color) at different temperatures no + ip: Rochette et al. , 1992 (in °K) with the low-field room-temperature AMS (black) fabric for the specimen 0110 from the Black Butte locality (Oregon). The plot is an equal area projection of the lower SD hemisphere in geographic coordinates. 300b is a repetition of 300a after cycling through the lower temperatures. Figure 1: The normal, and five permuted AMS fabrics as defined in the flow plane. The gray arrows (after Rochette et al., 1992) illustrate that these six fabrics can be obtained by mixtures of multidomain prolate (np) or oblate (no) with single domain prolate (ip) grains. We performed Low-Temperature direction). The switch of axes progresses steadily over a range of 200 to 25K, Nevada Rift), and andesite flows from High Field Anisotropy of Magnetic Susceptibility (LTHFAMS) and satura- indicating that the phenomena is not the Eastern Cascade Range, OR (Black likely the result of passing through Butte locality) for which the flow tion remanence (LTHFASR) in order to force fabric changes. isotropic or Verwey transitions. Instead, directions are known. We also estimated it might arise from competing anisotro- the influence of paramagnetic grains and Preliminary results: pies (shape, magnetocrystalline, stress), a single domain titanomagnetites on the change in anisotropy constants, or AMS signal using 1) High Field Our preliminary results indicate that, while the magnetic carriers span a range perhaps a different fabric held by large- Anisotropy of Magnetic Susceptibility and fine-grained fractions. (HFAMS), and 2) Anisotropy of of titanomagnetite compositions, the magnetic mineralogy does not seem to We are planning future measurements Anhysteretic Remanent Magnetization to: 1) resolve the origin of this (AARM) plus High Field Anisotropy of correlate with the AMS fabric. FORC distributions, AARM, and HFASR LTHFASR phenomena, 2) further assess Saturation Remanence (HFASR) the underlying cause for the fabrics measurements, respectively. results argue against mechanisms involving grain size mixtures being at the observed in our samples, and 3) determine if the LTHFAMS technique Experiments: origin of the complex fabrics in our samples. Other mechanisms such as will prove useful in recovering flow We performed MPMS measurements directions in samples with SP grains. on samples displaying different AMS magnetic grain interactions, competing magnetic fabrics, rolling of elongated fabrics in order to identify magnetic References: minerals based on low-temperature particles in strong velocity gradients, or crystallographic transitions. magneto-crystalline anisotropic effects Ferré, E. C., 2002. Geophys. Res. Lett., We applied First Order Reversal may be more likely causes for the 10.1029/2001GL014367. Curves (FORC) measurements (at room permuted fabrics observed at our Kelso, P. R., Tikoff, B., Jackson, M., and temperature and ~300ºC) to characterize localities. Sun, W.W., 2002. Geophys. J. magnetic grain sizes associated with each Additionally, we obtained an interest- Int.,151, 2, 345-359. fabric type. ing result from the LTHFASR data that Rochette, P., Jackson, M. and Aubourg, We made Anisotropy of Anhysteretic we believe warrants further investigation. C., 1992. Rev. of Geophys., 30-3, Remanent Magnetization (AARM) The low-temperature, high-field 209-226. measurements to check the influence of measurements led to the flipping of the Thill, J.W., Ferré, E.C., Rainey, E.S.G., Single Domain (SD) titanomagnetites on ASR axes upon cooling that, during and Teyssier, C., 2000. EOS, Trans. the AMS signal. warming reverts back to the original AGU, 81, 367. We performed High Field Anisotropy of fabric (Figure 2). The cooling/warming Magnetic Susceptibility (HFAMS) and process, therefore, is non-destructive to We thank the IRM crew for insights, saturation remanence (HFASR) measure- the natural fabric, unlike other magnetiz- discussions, and help in implementing ments to resolve paramagnetic and ing and demagnetizing methods (such as the LTHF measurements. ferromagnetic fabrics. IRM experiments that impress a fabric on the sample that simply mimics the field 3 Alteration & Remagnetization from the magnetosomes’ unique arrangement in chains. Moreau, M. G., Ader, M. and Enkin, R. J., 2005, The magnetization of clay-rich rocks in sedimentary basins: low-temperature Data Processing and Analysis experimental formation of magnetic carriers in natural samples: Earth & Planetary Science Muxworthy, A. R., King, J. G. and Heslop, D., Letters, v.230, no.1-2, p.193-210. 2005, Assessing the ability of first-order When we heated argillites to 150°C in argon reversal curve (FORC) diagrams to unravel with an applied magnetic field, a CRM was complex magnetic signals: Journal of acquired, and most of the newly formed Geophysical Research-Solid Earth, v.110, magnetic carriers were PSD magnetite. no.B1. Ferrimagnetic iron sulphide and hematite formed FORC distributions for mixtures containing in samples with less than 3% calcite, and new only hard magnetic minerals like hematite or magnetite is sometimes completely absent in goethite can be adequately described by a linear samples containing less than 0.5% calcite. SEM addition of the two end- members, because there studies indicate that the new magnetic carriers are virtually no magnetostatic interactions are associated with pre-existing pyrite. Thus between the phases. Mixtures dominated by magnetite can be produced in argillaceous softer minerals like magnetite and maghemite sediments at the normal temperatures and are more susceptible to interactions and exhibit pressures found in sedimentary basins, without nonlinear behavior. When a hard phase with low
any external supply from long-range fluid flow. MS like hematite is mixed with a softer phase
with high MS like magnetite, it can still be Zwing, A., Matzka, J., Bachtadse, V. and Soffel, identified using the FORC technique, whereas it H. C., 2005, Rock magnetic properties of is impossible to do so using standard magnetic remagnetized Palaeozoic clastic and hysteresis measurements. carbonate rocks from the NE Rhenish massif, Germany: Geophysical Journal International, Yu, Y. J. and Tauxe, L., 2005, On the use of v.160, no.2, p.477-486. magnetic transient hysteresis in paleomag-
biohermal carbonate rocks have high MRS / MS demagnetization. According to our simulations, and H / H ratios similar to those from TH increases as the grain size increases and as Travel theodolite, Johann von Lamont 1854 CR C remagnetized carbonate rocks from North the aspect ratio decreases. TH from the χ America, and magnetic viscosity and fd give simulation for samples with aspect ratio q = 1.5 strong evidence for SP magnetite. MD material agrees well with the experimental observations obscures the contributions of other material for annealed magnetites of smaller sizes. In completely in most siliciclastic rocks and partly general, small TH is a clear indication for the in platform carbonate rocks. absence of complex magnetized structures. Current Abstracts Biogeomagnetism Environmental Magnetism and Paleoclimate Proxies A list of current research articles Vali, H., et al., 2004, Formation of tabular dealing with various topics in the single-domain magnetite induced by Bidegain, J. C., Evans, M. E. and van Velzen, A. Geobacter metallireducens GS-15: Proceedings physics and chemistry of magnetism is J., 2005, A magnetoclimatological investiga- of the National Academy of Sciences of the tion of Pampean loess, Argentina: Geophysi- a regular feature of the IRM Quar- United States of America, v.101, no.46, p.16121- cal Journal International, v.160, no.1, p.55-62. terly. Articles published in familiar 16126. The magnetic susceptibility profile shows a geology and geophysics journals are The size and shape of extracellular magnetite clear sequence of maxima and minima that included; special emphasis is given to depend on the culture conditions and type of correspond to lithological variations, but bacteria. Under typical CO2-rich culture interpretation of these correlations is not current articles from physics, chemis- conditions, GS-15 is known to produce χ straightforward. Measured values of fd fall try, and materials-science journals. superparamagnetic magnetite (crystal diameters between those observed in Siberia and China. Most abstracts are culled from of approximately <30 nm). We were able to Thermomagnetic analysis of an embedded ash INSPEC (© Institution of Electrical produce a unique form of tabular, single-domain layer shows the ash to be magnetically magnetite under nontraditional (low-CO ) culture Engineers), Geophysical Abstracts in 2 indistinguishable from the El Cristo deposits. conditions. This magnetite has a distinct crystal However, its measured χ cannot explain the Press (© American Geophysical fd habit and magnetic properties. This magnetite intermediate values found there. The overall Union), and The Earth and Planetary could be used as a biosignature to recognize outcome is that neither of the existing Express (© Elsevier Science Publish- ancient biological activities in terrestrial and magnetoclimatological models can adequately ers, B.V.), after which they are extraterrestrial environments and also may be a account for the complexities of the Pampean subjected to Procrustean editing and major carrier of the magnetization in natural loess. sediments. condensation for this newsletter. An Geiss, C. E., Zanner, C. W., Banerjee, S. K. and extensive reference list of articles Weiss, B. P., et al., 2004, Ferromagnetic Joanna, M., 2004, Signature of magnetic (primarily about rock magnetism, the resonance and low-temperature magnetic enhancement in a loessic soil in Nebraska, physics and chemistry of magnetism, tests for biogenic magnetite: Earth and United States of America: Earth & Planetary and some paleomagnetism) is continu- Planetary Science Letters, v.224, p.1-2. Science Letters, v.228, no.3-4, p.355-367. We confirm that the Moskowitz test is a ally updated at the IRM. This list, The A horizons of the modern soil have higher distinctive indicator for magnetotactic bacteria values of concentration-dependent parameters, with more than 7500 references, is and provide the first direct experimental such as χ, IRM and ARM, combined with available free of charge. Your evidence that this is accomplished via sensitivity χ increases in fd and ARM/IRM ratios. The contributions both to the list and to to the magnetosome chain structure. We also magnetic properties of the soil profile are the Abstracts section of the IRM demonstrate that the FMR spectra of four dominated by ferrimagnetic magnetite or different strains of magnetotactic bacteria and a Quarterly are always welcome. maghemite. Analyses of “soft” HIRM (sIRM) magnetofossil-bearing carbonate have a form and “hard” IRM (hIRM), however, do show that distinct from all other samples measured in this approximately 80-90% of the remanence study. We suggest that this signature also results 4 carrying magnetic component exists in the form of hematite or goethite and that the magnetically of the Earth & Planetary Interiors, v.148, no.2-4, Geophysics Geosystems, v.5. enhanced horizons are enriched in both ferri- and p.149-156. ThellierTool4.0 (available at http://earthref.org/ antiferromagnetic minerals. A secondary magnetic field generated by crustal tools/) provides the possibility to analyze a wide remanent sources is capable of magnetizing range of different modifications of the absolute Liu, Q. S., et al., 2004, Mechanism of the deeper portions of crust that cools through its paleointensity experiment. Besides the Arai plot magnetic susceptibility enhancements of the blocking temperatures in an absence of dynamo. and orthogonal vector projections, additional Chinese loess: Journal of Geophysical Magnetite grains less than 0.01 µm in size, and plots regarding alteration and MD checks enable Research-Solid Earth, v.109, no.B12. hematite grains larger than 0.01 mm in size are the user to visualize the quality of individual Magnetic properties of magnetic separates and capable of magnetizing magnetic minerals determinations. Uniform selection criteria can be residues show that (1) with moderate degrees of contained in surrounding volume, triggering a applied, and a set of such criteria with emphasis pedogenesis (χ < 10 x 10-7 m3 kg-1), χ is self-magnetizing process that can continue in the on minimal bias due to alteration, MD enhanced more by increased concentration of absence of magnetic dynamo and continue remanence, and analysis/experimental SSD magnetic particles than by viscous SP strengthening and/or weakening magnetic inaccuracies is suggested. particles. For more mature paleosols with χ > anomalies on Mars. (10-12) x 10-7 m3 kg-1, contributions of Pan, Y., Hill, M. J., Zhu, R. and Shaw, J., 2004, pedogenically related PSD particles become Further evidence for low intensity of the significant; (2) pedogenic particles have a Instruments & Techniques geomagnetic field during the early Cretaceous narrow grain size distribution concentrated time: using the modified Shaw method and above the SP/SSD threshold; and (3) ARM is Le Goff, M. and Gallet, Y., 2004, A new three- microwave technique: Geophysical Journal carried dominantly by SD grains. Moreover, we axis vibrating sample magnetometer for International, v.157, no.2, p.553-64. propose that only the nonextractable fraction of continuous high-temperature magnetization Basalts from northeastern China (K/Ar age, 125- χ , MS and MRS show a strong relationship with measurements: applications to paleo- and 120 Ma) give an average virtual dipole moment the degree of pedogenesis. archeo-intensity determinations: Earth & of (3.1±1.0)*1022 A m2 using the modified Shaw Planetary Science Letters, v.229, no.1-2, p.31- method, and (2.9±0.9)*1022 A m2 using the Peck, J. A., et al., 2004, A magnetic mineral 43. microwave technique. These low estimates of record of Late Quaternary tropical climate Our new 3-axis VSM allows continuous high-T geomagnetic field strength are in agreement with variability from Lake Bosumtwi, Ghana: measurements of individual cylindrical ~0.75 previous results of the same time interval Palaeogeography Palaeoclimatology cm3 samples up to ~650°C and the acquisition of obtained by the Thellier method with pTRM Palaeoecology, v.215, no.1-2, p.37-57. TRM in any direction and field intensity up to checks. Five distinctive magnetic mineral zones (A-E) 200 µT. We propose a fast (less than 2.5 h) were identified in the 11-m-long sediment cores automated experimental procedure which allows Roberts, A. P. and Winklhofer, M., 2004, Why that span the last 26,000 calendar years. This one to take into account both the cooling rate are geomagnetic excursions not always work demonstrates that the magnetic properties dependence of TRM acquisition and anisotropy recorded in sediments? Constraints from of Lake Bosumtwi sediment are a sensitive of TRM. Several examples of analyses of ancient post-depositional remanent magnetization recorder of abrupt climate change of global magnetization demonstrate the quality and lock-in modelling: Earth & Planetary Science significance. reliability of the data. Letters, v.227, no.3-4, p.345-359. We used a cubic lock-in function to model “best- case” scenarios for the paleomagnetic record Extraterrestrial Magnetism Magnetic Field Records and when a high-frequency geomagnetic input signal Paleointensity Methods is convolved with the sediment lock-in function Chevrier, V., Rochette, P., Mathé, P. E. and for a wide range of sedimentation rates. Our results suggest that in order to consistently detect Grauby, O., 2004, Weathering of iron-rich Dunlop, D. J., Zhang, B. X. and Özdemir, Ö., phases in simulated Martian atmospheres: the presence of geomagnetic excursions, it is 2005, Linear and nonlinear Thellier ideal to work with sediments that maintain Geology, v.32, no.12, p.1033-1036. paleointensity behavior of natural minerals: Metallic iron α-Fe, magnetite, and pyrrhotite minimum sedimentation rates above 10 cm/kyr. Journal of Geophysical Research-Solid Earth, Failure to document excursions in many were aged in CO2 + H2O or CO2 + H2O2 v.110, no.B1. apparently high-resolution analyses probably atmospheres at room temperature for 1 yr. Only Susceptibility, hysteresis, and coercivity data the magnetite remained stable during experi- results from slower DRM lock-in, or to indicate that the plagioclase extracted from unrecognized intervals of slow sedimentation in ments. Goethite is the main crystalline iron- Matachewan diabase dikes contains mainly SD bearing end product, associated with ferrihydrite. environments with higher average sedimentation magnetite while the mafic minerals rates. If hematite is the dominant iron oxide that colors (clinopyroxene, biotite, and actinolite) contain the Red Planet, our results imply strong changes mainly MD magnetite. In simulated Thellier in water activities of the primary CO and H O Sagnotti, L., et al., 2005, Apparent magnetic 2 2 experiments the plagioclase behaved ideally, rich atmosphere, or long-term evolution, for polarity reversals due to remagnetization whereas the mafic minerals had strongly curved resulting from late diagenetic growth of goethite to further convert into hematite. Our Arai plots sagging below the ideal SD line. experiments suggest that iron weathering may greigite from siderite: Geophysical Journal Neither LTD nor AF cleaning to 15 mT before International, v.160, no.1, p.89-100. have been active until recent times and would each Thellier step gave reliable paleointensity not have required bodies of liquid water. A mixed-polarity zone, representing alternations values. No presently available pretreatment between remagnetized and non-remagnetized renders the paleointensity data of MD grains strata, has been documented within the lower Gattacceca, J. and Rochette, P., 2004, Toward a usable. robust normalized magnetic paleointensity few metres of the CRP-1 core (Ross Sea, method applied to meteorites: Earth & Antarctica). The normal polarity remagnetization Gratton, M. N., Shaw, J. and Herrero-Bervera, is carried by interacting SD greigite particles, Planetary Science Letters, v.227, no.3-4, p.377- E., 2005, An absolute palaeointensity record 393. while the reversed-polarity magnetization of non- from SOH1 lava core, Hawaii using the remagnetized strata is carried by magnetite with A new paleointensity method based on microwave technique: Physics of the Earth & normalization by the derivative dIRM/dAF a broad range of grain sizes and negligible Planetary Interiors, v.148, no.2-4, p.193-214. magnetostatic interactions. This study is part of a (REM’ method) provides an estimate of the Microwave palaeointensity results obtained from absolute paleointensity with an uncertainty of growing catalogue of remagnetizations involving 392 samples covering the last 45 ka show trends greigite, which suggests that occurrences of about a factor two. For L ordinary chondrites, an similar to those in other Hawaiian absolute upper limit of 1 µT is proposed for the greigite should be treated with caution in palaeointensity data. Direct comparison with palaeomagnetic and environmental magnetic paleofield. Tentative paleofield estimates in the previous Thellier data from the SOH1 core µ studies. 0.05-0.5 T range are proposed for LL ordinary shows some discrepancies between the two chondrites, which is much lower than previous methods, with the Thellier data yielding Thomas, D. N., Hill, M. J. and Garcia, A. S., results. Results from Martian meteorites are generally higher palaeointensity estimates than scattered between 1 and 24 µT and may 2004, Comparison of the Coe-Thellier- the microwave data. In view of these discrepan- Thellier and microwave palaeointensity represent the crustal magnetic field of the planet cies between the two methods, the introduction after dynamo shutdown. techniques using high-titanium of raw palaeointensity data into the public titanomagnetites: results from a Tertiary domain is suggested. Kletetschka, G., et al., 2005, Grain size basaltic intrusion from the Sydney Basin, New South Wales: Earth & Planetary Science dependent potential for self generation of Leonhardt, R., Heunemann, C. and Krása, D., magnetic anomalies on Mars via thermorema- Letters, v.229, no.1-2, p.15-29. 2004, Analyzing absolute paleointensity Thermomagnetic and low-temperature nent magnetic acquisition and magnetic determinations: Acceptance criteria and the interaction of hematite and magnetite: Physics susceptibility measurements suggest that the software ThellierTool4.0: Geochemistry dominant magnetic mineral is Ti-enriched 5 titanomagnetite (~TM65-TM50). No alteration is iron oxides (magnetite and hematite) and minor Walton, D., Boehnel, H. and Dunlop, D. J., observed in the dominant temperature range pyrite. If the localities studied are representative 2004, Response of magnetic nanoparticles to (~70-300°C) used for calculation of of seismogenic faulting, the calculated oxygen microwaves: Applied Physics Letters, v.85, palaeointensities. Statistically indistinguishable fugacities indicate that, in the system C-O-H-S, no.22, p.5367-5369. µ mean palaeointensities of 27.1±4.0 T (N=28) H2O and CO2 should be the dominant fluid Two important processes in ferromagnetic and 27.4±4.0 µT (N=28) were obtained from the species. resonance are the first-order absorption of a CTT and microwave techniques, respectively, photon and creation of a single magnon, and a suggesting that the dipole field was approxi- Ono, S., Funakoshi, K., Ohishi, Y. and Takahashi, second-order process in which the absorption of mately 59% of the present day value at ca. 49 E., 2005, In situ x-ray observation of the phase a photon results in the creation of two magnons
Ma. transformation of Fe2O3: Journal of Physics- of equal and opposite wave vector. We have Condensed Matter, v.17, no.2, p.269-276. found that under resonance conditions for the Thouveny, N., et al., 2004, Geomagnetic In situ observations of the phase transition in second-order process, samples containing
moment variation and paleomagnetic Fe2O3 were carried out in a multianvil and in a ~0.1% magnetite absorb energy from the excursions since 400 Kyr BP: a stacked record diamond anvil cell high-pressure apparatus using microwave field at the same rate as a solid from sedimentary sequences of the Portu- synchrotron radiation. The phase boundary magnetite sample. The resultant very high guese margin: Earth and Planetary Science between the haematite and high-pressure phase in energy density in the magnetic nanoparticles, Letters, v.219, p.3-4. the temperature range of 800-2500 K was coupled with a significant thermal energy In these clayey-carbonates we find a series of determined to be P (GPa) = 29.4(±0.4) + 0.0046 barrier with the matrix, leads to a large directional anomalies occurring during relative (±0.0015) x (T (K) - 1000). This result should temperature difference between the grains and paleointensity (RPI) lows. Three of these resolve a dispute regarding the transition pressure their surroundings that makes it possible to
correspond to the Laschamp excursion (42 kyr of haematite among previous studies on Fe2O3. magnetize and demagnetize the sample with a BP), the Blake event (115-122 kyr BP) and the relatively small increase in sample temperature. Icelandic basin excursion (190 kyr BP). A fourth directional and RPI anomaly recorded at 290 kyr Magnetization & Demagnetization BP defines the ‘Portuguese margin excursion’. Processes Mineral & Rock Magnetism Four non-excursional RPI lows are recorded at the ages of the Jamaica/Pringle Falls, Mamaku, Borradaile, G. J., Lucas, K. and Middleton, R. S., Dutta, P., et al., 2004, Magnetic properties of Calabrian Ridge 1, and Levantine excursions. 2004, Low-temperature demagnetization nearly defect-free maghemite nanocrystals: The RPI record is characterized by a periodicity isolates stable magnetic vector components in Physical Review B, v.7017, no.17, p.4428. of 100 kyr, paleointensity lows often coinciding magnetite-bearing diabase: Geophysical M(H,T) and the electron magnetic resonance with the end of interglacial stages. Journal International, v.157, no.2, p.526-36. (EMR) parameters of maghemite nanocrystals Multicomponent NRMs were simulated IRMs or are reported for the 4 K-300 K range. TEM of Wehland, F., Alt-Epping, U., Braun, S. and ARMs in different, nonoverlapping coercivity the nanocrystals shows them to be nearly Appel, E., 2005, Quality of pTRM acquisition ranges, along three orthogonal axes or along two spherical samples (aspect ratio a/b=1.15) with in pyrrhotite-bearing contact-metamorphic nonorthogonal directions. The known directions diameter D=7(1) nm, and XRD yields D=6.4 limestones: possibility of a continuous record of the experimentally applied vector components nm with negligible strain. M(H) data for T>TB of Earth magnetic field variations: Physics of were always more successfully verified by AF fits the modified Langevin function the Earth & Planetary Interiors, v.148, no.2-4, µ χ µ µ demagnetization if LTD was first applied. For the M=MSL( pH/kBT)+ aH with p=8000(500) B/ p.157-173. same specimens, LTD reduced the same artificial particle and MS=80 emu/g, identical to MS for Based on magnetic susceptibility, the pyrrhotite/ γ remanences by 50 per cent for the coercivity bulk -Fe2O3. The large value of MS, the small magnetite ratio and thermal modelling we define range 0-15 mT, by 25 per cent for the range 15-30 value of coercivity HC~20 Oe at 5 K, the lack of three metamorphic zonations: a contact zone of a mT, and negligibly for higher-coercivity fractions. exchange bias in a field-cooled sample, and mixed magnetic assemblage and low χ, a negligible strain point to nearly defect-free pyrrhotite-bearing transitional zone, where full Li, Y. X., Kodama, K. P. and Smith, D. P., 2004, nanocrystals. TRMs are acquired by heating to T> T the C.po, New paleomagnetic, rock magnetic, and Curie temperature of pyrrhotite, and a marginal petrographic results from the Valle Group, Lagroix, F., Banerjee, S. K. and Moskowitz, B. zone containing pyrrhotite and magnetite Baja California, Mexico: Exploring the causes M., 2004, Revisiting the mechanism of generated at T< T . The fact that TRMs can C.po of anomalously shallow paleomagnetic reversed thermoremanent magnetization consist of independent pTRMs is successfully inclinations: Journal of Geophysical Research- based on observations from synthetic ferrian tested by modified Thellier experiments. It is Solid Earth, v.109, no.B11. ilmenite (y=0.7): Journal of Geophysical shown that a metamorphic environment with low The inclination is 38.7° shallower than that Research-Solid Earth, v.109, no.B12. fluid circulation provides a scenario for the predicted by the reference paleopole for North Magnetic ordering temperatures of the cation recording of independent pTRMs. America. Laboratory experiments indicate that ordered domains, in all samples, are ~380 K. compaction could account for only 7.5° of the Cation disordered domains, resulting from inclination shallowing. Although primary quenching from high temperatures, have Magnetic Microscopy and anomalously shallow inclinations could indicate magnetic ordering temperatures of 418 K Spectroscopy significant southerly, then northerly, (Q1300), 410 K (Q1050), and 425 K (Q900). paleolatitudinal offset, a more likely scenario is a The data unambiguously support a less than Eisebitt, S., et al., 2004, Lensless imaging of late Cenozoic low-temperature remagnetization, perfect ferrimagnetic - antiferromagnetic magnetic nanostructures by X-ray spectro- which is suggested by alteration along the edges exchange interaction as the fundamental source holography: Nature, v.432, no.7019, p.885-888. of some detrital silicate grains and a bimodal of RTRM. The strength of the “effective’’ We demonstrate a versatile technique for magnetic grain size distribution. exchange anisotropies are estimated at ~ 2.7 mT imaging nanostructures, based on the use of (Q1300), ~ 12 mT (Q1050), and 0 mT (Q900). resonantly tuned soft X-rays for scattering Liu, Q. S. and Yu, Y. J., 2004, Multi-cycle low- However, favorable conditions for the contrast and the direct Fourier inversion of a temperature demagnetization (LTD) of acquisition of RTRM are dependent not only on the strength of the exchange anisotropy but also holographically formed interference pattern. As multidomain Fe3O4 (magnetite): Journal of an example, we have used the resonant X-ray Magnetism & Magnetic Materials, v.283, no.2-3, on the crucial role played by the size of the magnetic circular dichroism effect to image the p.150-156. cation ordered domains. magnetic domain structure in a Co/Pt multilayer MC-LTD was performed for four temperature film with a spatial resolution of 50 nm. intervals, 300-150 K, 150-125 K, (cycling Liu, Q. S., Torrent, J., Yu, Y. J. and Deng, C. L., 2004, Mechanism of the parasitic remanence through the isotropic point Tk), 125-95 K (cycling of aluminous goethite: Journal of Geophysical O’Hara, K. D. and Huggins, F. E., 2005, A through the Verwey transition TV ~ 120 K) and Mössbauer study of pseudotachylytes: redox 95-60 K. Results show that the remanence loss Research-Solid Earth, v.109, no.B12.
conditions during seismogenic faulting: during MC-LTD depends on the number of LTD We found that TB is systematically higher than T for a set of well-characterized aluminous Contributions to Mineralogy & Petrology, v.148, cycles. Above TV, demagnetization of remanence N no.5, p.602-614. after MC-LTD is caused by the reorganization of goethite samples. The difference between TB
This is the first detailed study of the redox state magnetic domains. For the 95-125 K interval, the and TN increases from ~8-9 K for a pure of pseudotachylytes. We examine frictional melts remanence loss results from the changes of easy goethite (that contains vacancies) to >20 K for
from five localities by analyzing host rocks and axes from the cubic [001] to the monoclinic c- Al-substituted goethites. This indicates that TB
corresponding pseudotachylytes using axis. These two processes approximately follow and TN change independently with the Mössbauer spectroscopy. The main iron-bearing the Boltzmann-analog relation, but the latter diamagnetic substitutions, suggesting a phases in the pseudotachylytes are involves more degree of freedom. fundamental difference of origin for parasitic phyllosilicates (biotite, muscovite and clays) and remanence and for antiferromagnetism. 6 Nonetheless, both parasitic remanence and AFM reducible oxides (Feox2), including goethite, redeposited melt-rich, clast-size sorted, fine-
could exist along the goethite c axis. hematite and akaganeite; (4) magnetite (Femag); grained suevites; melt-rich, no clast-size sorting,
(5) poorly reactive sheet silicate Fe (FePRS); (6) medium-grained suevites; coarse suevitic melt
Pilkington, M., Ames, D. E. and Hilderbrand, A. pyrite Fe (Fepy); and (7) unreactive silicate Fe agglomerates; coarse melt-rich heterogeneous
R., 2004, Magnetic mineralogy of the (FeU). As such, this is the first extraction scheme suevites; brecciated suevites; and coarse Yaxcopoil-1 core, Chicxulub: Meteoritics & specifically developed to allow the separate carbonate and silicate melt suevites. Low-field k Planetary Science, v.39, no.6, p.831-41. identification of magnetite, and the first to allow ranges from -0.3 to 4018 µSI, and the NRM Exceptional magnetic properties are found in a a complete evaluation of Fe carbonate phases intensity ranges from 0.02 to 37510 mA/m. In basement clast (metamorphosed quartz gabbro), such as siderite and ankerite. most cases, characteristic single component which has k >45000 µSI and an NRM of 77.5 A/ magnetizations are observed. Both the clasts and m. Magnetic mafic basement clasts are a Schwertmann, U., Stanjek, H. and Becher, H. H., matrix forming the breccia appear to have been common component in the Yax-1 impactite 2004, Long-term in vitro transformation of 2- subjected to a wide range of temperature/ sequence. The high k and NRM in the mafic line ferrihydrite to goethite/hematite at 4, 10, pressure conditions and show distinct rock basement clasts are caused by the replacement of 15 and 25° C: Clay Minerals, v.39, no.4, p.433- magnetic properties. An extended interval of amphiboles and pyroxenes by an assemblage 438. remanence acquisition and secondary partial or with fine <1 µm magnetite, ilmenite, K-feldspar, 2-line ferrihydrite stored in water at ambient total remagnetization may explain the and stilpnomelane, which occurred before temperatures from 4 to 25°C and at ten different paleomagnetic results. impact. Similar alteration mechanisms, if pH values between 2.5 and 12 for up to 10-12 y operative within the melt sheet, could explain the transformed to both goethite and hematite at all presence of the high amplitude magnetic temperatures and pH values except at pH 12 Paleomagnetism & Tectonics anomalies observed at Chicxulub. where only goethite was formed. The rate and degree of transformation (20-100%) increased Kent, D. V. and Tauxe, L., 2005, Corrected Late with increasing pH and temperature. The hmt/ Triassic latitudes for continents adjacent to Mineral Physics & Chemistry (hmt+gt) ratio varied between 0 and ~0.8, the North Atlantic: Science, v.307, no.5707, increased with increasing temperature and p.240-4. Burton, B. P., Chaka, A. and Singh, D. J., 2005, showed a strong maximum at pH 7-8. The We use a method based on a statistical Chemical, magnetic and charge ordering in maximum coincides with the zero point of geomagnetic field model to recognize and correct charge of ferrihydrite where its solubility and, the system hematite-ilmenite, Fe2O3-FeTiO3: for inclination error in sedimentary rocks from Phase Transitions, v.78, no.1-3, p.239-249. thus, its via-solution transformation rate to early Mesozoic rift basins in North America, Spin polarized electronic structure calculations goethite are minimal. Greenland, and Europe. The congruence of the of total energies for ordered supercells in the corrected sedimentary results and independent
system Fe2O3-FeTiO3 suggest that some layered data from igneous rocks on a regional scale ordered phases are more stable than an NRM Carriers and Origins indicates that a geocentric axial dipole field isocompositional mechanical mixture of hematite operated in the Late Triassic. The corrected and ilmenite. This result contradicts established Maher, B. A. and Hallam, D. F., 2005, Magnetic paleolatitudes indicate a faster poleward drift of ideas about hematite-ilmenite phase relations carriers and remanence mechanisms in 0.6° per million years for this part of Pangea and because it suggests that there is at least one magnetite-poor sediments of Pleistocene age, suggest that the equatorial humid belt in the Late stable ordered phase with a bulk composition southern North Sea margin: Journal of Triassic was about as wide as it is today. intermediate between hematite and ilmenite. The Quaternary Science, v.20, no.1, p.79-94. electronic structure of a 30-atom layered Within oxidised fluvial sediments, the magnetic Muttoni, G., Erba, E., Kent, D. V. and Bachtadse, supercell was studied by a variety of techniques, carriers appear to be relict magnetic minerals V., 2005, Mesozoic Alpine facies deposition as to investigate possible charge ordering on Fe (ferrian ilmenites, chromites, haematite and a result of past latitudinal plate motion: sites, that is a postulate of the ‘lamellar goethite), which sometimes carry a reliable Nature, v.434, no.7029, p.59-63. magnetism hypothesis’, but significant Fe2+-Fe3+ primary DRM but often have a VRM overprint. In the Alpine - Mediterranean region shallow- ordering is not predicted. Within some reduced marine and intertidal water sediments were replaced by mainly pelagic sediments, the iron sulphide, greigite, has been limestones in the Early Jurassic period, Poulton, S. W. and Canfield, D. E., 2005, found to carry a reliable, ‘syn’-depositional radiolarian cherts in the Middle - Late Jurassic Development of a sequential extraction CRM. In all the sediments, magnetic inclusions period, and again pelagic limestones in the Late procedure for iron: implications for iron within silicates are abundant, are significant for Jurassic - Cretaceous period. This sequence has partitioning in continentally derived the mineral magnetic signal but contribute little previously been interpreted in terms of vertical particulates: Chemical Geology, v.214, no.3-4, to any recoverable palaeomagnetic information. variations of the carbonate compensation depth p.209-221. (CCD) relative to the ocean floor. We propose an A sequential extraction procedure for iron in Urrutia-Fucugauchi, J., Soler-Arechalde, A. M., alternative explanation for the facies tripartition modern and ancient sediments recognizes seven Rebolledo-Vieyra, M. and Vera-Sanchez, P., based on palaeolatitudinal data: the Lombardian operationally derived iron pools: (1) carbonate 2004, Paleomagnetic and rock magnetic study basin drifted initially towards, and subsequently
associated Fe (Fecarb), including siderite and of the Yaxcopoil-1 impact breccia sequence, away from, a near-equatorial upwelling zone of
ankerite; (2) easily reducible oxides (Feox1), Chicxulub impact crater (Mexico): Meteoritics high biosiliceous productivity. Our tectonic including ferrihydrite and lepidocrocite; (3) & Planetary Science, v.39, no.6, p.843-56. model may explain the deposition of radiolarites The Yax-1 breccia sequence consists of throughout the Mediterranean and Middle Eastern region during the Jurassic period.
IRM Visiting Fellows John W. Geissman (University of New January-June 2005 Mexico) How are Red Beds Remagne- tized and, Oh, What a Fault! Phil McCausland (University of Dorothy Bauch (University of Roches- David Krása (University of Munich) Michigan) Investigation of fine-scale ter) Study of low-temperature magnetic Titanomaghemite inversion in oceanic remanence carriers within granitoid properties of Archean silicate crystals basalts rocks Reminder: Applications France Belley (Southern Illinois France Lagroix (Institut de Physique du Nuno Joao de Oliveira e Silva for Visiting Fellowships University) Low temperature magnetic Globe de Paris) The effects of citrate- (Universidade de Aveiro) Study of during the second half properties of natural and synthetic bicarbonate-dithionite on the magnetic magnetic moment, anisotropy and Fe of 2005 are due April olivine mineral population in loess and paleosol local environment distributions in 30! Laurent Carporzen (Institut de samples from central Alaska ferrihydrite nanoparticles dispersed in an hybrid matrix Physique du Globe de Paris) How to Melina Macouin (LMTG UMR 5563) explain the two distinct Verwey transi- Investigating the rock magnetic signature tions in the shocked rocks from the of the global aftermath of the Vredefort meteorite impact crater? Neoproterozoic glaciations 7 geomagnetic observatories. He suc- temporal resolution simultaneously in vertical intensity not only in an ceeded in convincing the Russian Göttingen (Gauss), Leipzig (Weber) and observatory environment but also at ...Lamont Academy of Sciences in St. Petersburg in Munich (Lamont) during a magnetic stations in the field. He produced 45 continued from p. 1 1829 and the Royal Society in London in storm. However, Lamont’s plans were to instruments of this sort in his own 1836 of the importance of his plans. A. build a complete geomagnetic observa- workshop, which he had set up in his Kupffer from St. Petersburg established tory for permanent measurements at the private living room at the observatory. four observatories in Russia while E. site of the Astronomical Observatory. In His training in mechanical engineering Sabine and H. Lloyd organised the those days Gauss and others were by the Scottish monks at the monastery foundation of geomagnetic observatories convinced, that it would take just a few school in Regensburg turned out to be a in the British Empire. The Royal Society (about 5) years of a world wide common great help for him. Later, the workshop in London invited also other European observation of the geomagnetic phenom- became part of the observatory and the countries to follow their example. On the ena to unravel the mysteries of technicians, which he had first paid from European continent C. F. Gauss and W. geomagnetism. It turned out that this view his own salary and from the profits he Weber from Göttingen also supported was far too optimistic. made from selling the instruments, these ideas by building a geomagnetic The money for the buildings and the became employees of the observatory. observatory in Göttingen and by instrumentation of the Geomagnetic Lamont’s instrument (Reisetheodolit, founding in 1836 the “Göttinger Observatory in Munich was provided on Fig. 2) was sold to observatories in all Magnetischer Verein” (Göttingen 17 January 1840 by King Ludwig I. of parts of the world and they served for Magnetic Union) which aimed at the Bavaria and his son, the later King many years in geomagnetic observato- installation of a global network of Maximilian II. from their private funds. ries and for survey work. geomagnetic observatories with In April 1840 the construction works for After six years, the first wooden standardised equipment for absolute a wooden subsurface observatory began. subsurface constructions broke down measurements and for the observation of It was completed in July 1840. The floor and had to be replaced by new likewise temporal variations of D, I and H. The of the observatory room was 3.80 m partly subsurface buildings. The foundation of the Geomagnetic below surface level to avoid the influence instruments for absolute measurements Observatory in Munich in 1840 is also a of the daily temperature variations. and the variometers were separated. Due result of these activities. Illumination came from windows in the to the use of small magnets instead of However, geomagnetic observations roof. Four 8.8 m long and 1.80 m wide the 11,7 kg magnets in the instruments in Munich started already in 1836 by the tunnels lead to approximately magnetic provided by Gauss the buildings could initiatives of Lamont with sporadic North, East, South and West. The place be made very much smaller. However, measurements of D, H and I. It was even was connected with the main observatory even these more robust wooden possible to measure D and H with a high building by a 35 meter long tunnel. The buildings were not to last for a long time tunnel leading to the West had an opening leading to other buildings made of stone through which a cross at the top of the St. in the following years. Details can be Anna church could be observed as a taken from Wienert (1966). reference mark with a theodolite. The In the late 1840’s and early 1850’s variations of the declination and the Lamont started to make regional horizontal intensity were measured with magnetic surveys at about 120 points in instruments built by Gauss and the Kingdom of Bavaria (Fig. 3), which Meyerstein in Göttingen consisting of he extended later to a number of 250 suspended magnets with a weight of 11,7 stations. He also made measurements in kg. On the 1st of August 1840, 6 o´clock other States in Southern Germany. His in the morning, the Munich Geomagnetic maps published in 1854 with isolines for Observatory started with the first D, H and I for Bavaria and Southern measurements. Regular observations with Germany as well as for Central Europe, the variometers were made with hourly all reduced to 1 January 1850, are part readings during the day and bihourly the classical literature of geomagnetism. readings at nighttime. Lamont performed A few years later he made similar personally three morning and one evening surveys also in neighbouring countries reading, three technicians made the and published charts for D, I and H for others. Once a month, at dates which France, Spain and Portugal (published where announced worldwide in advance in 1858), and Holland, Belgium, Prussia by the Göttingen Magnetic Union, and Denmark (published in 1859). Some readings were also taken at shorter time of Lamont’s measured points, all of intervals. In May 1841 Lamont replaced them well described and documented, the Gauss variometers by instruments of can still be used today. However, many his own design using much smaller have been destroyed or given up due to magnets for the observation of shorter the growth of cities and industrial noise. periods and the new (Lamont’s) position Soon after his appointment as for the deflecting magnets to observe the director of the Royal Astronomical variations of the horizontal intensity. This Observatory, Lamont became member of principle is still used today in some the Royal Bavarian Academy of observatories. Automatic recording of Sciences (1836) and he was later (1853) such observations had not yet been also appointed to the Chair in As- invented, so all readings were written tronomy at the University of Munich Figure 2. Lamont’s famous “Reisetheodolit” (nonmagnetic down by hand in books. A few years later when it had become vacant. He received theodolite for measuring D, H and I in field stations) developed Lamont developed his own magnetic a high medal from the bavarian king and built by Lamont. He produced 45 of them in the workshop theodolite with which he could measure Ludwig II including the privilege of 8 at the observatory. the declination, the horizontal and the naming himself “von” Lamont. On istribution of the measured points (top) and isolines for the istribution of the measured 2005 of almost 17°. 1 January 1850 were: D = 15° 53.9´ W, I = 64° 59.5´, H 19523 nT. D = 15° 53.9´ W, 1 January 1850 were: inclination I (bottom) and declination D (next page). Isolines show differences of 10 minutes for D and I. Values for Munich on of 10 minutes for D and I. Values inclination I (bottom) and declination D (next page). Isolines show differences is a change in declination Munich between 1850 and So there D = 1° 30´ E, I 64° 10´, H 20900 nT. day values are: Present Figure 3. Magnetic charts for Bavaria and southern Germany, reduced to 1. January 1850, published in 1854. The maps show the d reduced 3. Magnetic charts for Bavaria and southern Germany, Figure 9 etail shown below). The laboratory for paleo- and rock magnetism is etail shown below). The laboratory for paleo- and rock located in Niederlippach, near Landshut. 10 to 1. January 1850, published in 1854 (top; d reduced 3, continued. Declination chart for Bavaria and southern Germany, Figure their correlation with geomagnetic also a newly installed seismic observa- phenomena. From his data he estimated tory in 1905) were moved from the depth of the molasse basin below Lamont, Johann von Bogenhausen to a less disturbed place Munich to be 1.5 km, a value which b. Dec 15, 1805, Corriemulzie, Scotland near Fürstenfeldbruck, about 35 km to turned out to be correct by drilling in the d. Aug 5, 1879, München-Bogenhausen the west of Munich. It is part of the 20th century. So he can also be regarded worldwide network of geomagnetic Lamont is remembered for important contributions in as an early pioneer of a method which is observatories forming INTERMAGNET astronomy, geodesy, meteorology and geophysics. now known as magnetotellurics. Already as well as the network of seismic He determined the orbital periods of Uranus’ in 1853 he donated a large amount of broadband stations. I am happy to have satellites Ariel and Titan, and from those calculated money to the University of Munich to been one of the successors of Johann von the mass of Uranus. He determined the differences support poor students of natural sciences Lamont as director of the of longitude of Vienna, Munich, Geneva, and with fellowships. Fürstenfeldbruck Observatory from Strasburg, and completed the astronomical triangula- Lamont received many honours 1983-2002. tion of Bavaria. A skillful instrument designer, during his active career. He was member Lamont developed and refined a theodolite for in a large number of academies and Heinrich Soffel measuring magnetic field orientation and intensity, as scientific societies. It would lead too far Prof. Emeritus, University of Muenchen; well as various meteorological instruments. The to list them all. In 1934 the Lamont Clan January 2005 cirumdecadal periodicity in the geomagnetic field erected a monument in Invery, a small was first identified by Lamont and was subsequently village close to the place where Lamont References: correlated with sunspots and solar activity by Wolf in was born and lived during his first 12 Zürich. years. The inscription on the monument Barraclough D.R., Clark, T.D.G., facing north is: Cowley, S.W.H., Gubbins, D., THIS STONE COMMEMORATES JOHN LAMONT, Hibberd, F.H., Hide, R., Kerridge, D.J., Lowes, F.J., Malin, S.R.C., August 5th 1879 he died in his apartment 1805-1879, WHO WAS BORN AT Murthy, T., Rishbeth, H., Runcorn, in the Observatory where he had worked CORRIEMULZIE. HIS NAME IS WRITTEN IN THE S.K., Soffel, H.C., Stewart, D.N., for 51 years. He is buried close to the HISTORY OF SCIENCE AS JOHANN VON Stuart, W.F., Whaler, K.A., Winch, Astronomical Observatory in the LAMONT, ASTRONOMER ROYAL OF BAVARIA. D.E.: 150 years of magnetic churchyard of St. Georg in Munich- The inscription of the side facing south is observatories: recent researches on Bogenhausen. taken from Psalm 19: world data. Surveys in Geophys., 13, However, it should be mentioned that 47-88, 1992. Johann von Lamont was not only a good DAY UNTO DAY UTTERETH SPEECH AND NIGHT Beblo, M. and Soffel, H. (Eds),: 150 geomagnetist (his monographs like UNTO NIGHT SHEWETH KNOWLEDGE. years geomagnetic observatories “Handbuch des Erdmagnetismus”, München-Maisach-Fürstenfeldbruck. “Astronomie und Erdmagnetismus”, There are also inscriptions on the other Münchner Geophys. Mitteilungen, “Handbuch des Magnetismus” are two sides in German and Gaelic with the Münchner Univers. Schriften, ISSN classical textbooks on this subject in same text of Psalm 19. A crater on the 0931-2145, 5, 1991. German language), he was also a very near side of the Moon at 4.4°N, 23.3°E Wienert, K.,: 125 Jahre erdmagnetische active astronomer (he determined the with a diameter of 170 km and a crater Beobachtungen in München, positions of more than 80000 stars), on Mars at 58.3°S, 113.3°W with a Maisach und Fürstenfeldbruck. In: meteorologist and geodesist. He was also diameter of 72 km bear Lamont´s name. Zum 125-jährigen Bestehen der one of the first who studied the temporal More than 50 years after the death of Observatorien München-Maisach- variations of earth currents and showed Lamont the Munich geomagnetic (and Fürstenfeldbruck, München 1966.
RAC Rotates IRM Staff and Post-docs
The IRM’s Review and Advisory We are delighted to welcome Brian tal Influences on the Magnetic Properties Committee (RAC) is responsible for Carter-Stiglitz to the IRM’s professional of Lake Sediments”) joined the IRM evaluating Visiting Fellowship proposals, staff, following the (semi-)retirement of research staff in the fall, with funding and it provides strategic guidance on Jim Marvin last year. After completion from the MagIC (Magnetic Information instrumentation and community of his wide-ranging doctoral dissertation Consortium) database project involving infrastructure, to help maximize the (“Rock Magnetism: Studies in Theory, reasearchers from Scripps Institute of value of IRM as a shared international Data Manipulation, and Application”) Oceeanography, IRM, and other resource for rock-magnetic research. here in 2003, Brian carried out a post- institutions (http://earthref.org/MAGIC/). Members typically serve six-year terms, doctoral project on sedimentary Ramon is working on methods of data and turnover is staggered every two remanence with Jean-Pierre Valet at the analysis and processing, and on synthesis years. With the completion of their Institut de Physique du Globe de Paris and characterization of magnetic service we heartily thank Lisa Tauxe, (IPGP). As an IRM staff member, Brian reference materials. Jim Channell and Ron Merrill for their will participate in visitor support, In addition, we are currently in the insights and efforts. We also welcome instrument maintenance, database and process of hiring another post-doc to new members Özden Özdemir, John software development, and rock- complete a project on the low-tempera- Tarduno and Jeff Gee, who join Rob magnetic research. ture behavior of magnetite and the Coe (RAC Chair), Cor Langereis and Post-doctoral associate Ramon Egli Verwey transition, in collaboration with Pierre Rochette on the RAC. (PhD ETH-Zürich, 2003: “Environmen- Brian and Bruce. 11 The Institute for Rock Magnetism is press), or if you have any suggestions dedicated to providing state-of-the-art to improve the newsletter, please facilities and technical expertise free of notify the editor: charge to any interested researcher who Mike Jackson applies and is accepted as a Visiting Institute for Rock Magnetism Fellow. Short proposals are accepted University of Minnesota semi-annually in spring and fall for work 291 Shepherd Laboratories to be done in a 10-day period during the 100 Union Street S. E. following half year. Shorter, less formal Minneapolis, MN 55455-0128 visits are arranged on an individual basis phone: (612) 624-5274
through the Facilities Manager. fax: (612) 625-7502 LAMONT The IRM staff consists of Subir e-mail: [email protected] Banerjee, Professor/Director; Bruce www.irm.edu Moskowitz, Professor/Associate Director; Jim Marvin, Emeritus Scientist; Mike Jackson, Peat Sølheid, and Brian Carter-Stiglitz, Staff Scientists. I Funding for the IRM is provided by the National Science Foundation, the W. M. Keck Foundation, and the University of Minnesota. The IRM Quarterly is published four The U of M is committed to the policy times a year by the staff of the IRM. If that all people shall have equal access to you or someone you know would like to its programs, facilities, and employment be on our mailing list, if you have without regard to race, religion, color, something you would like to contribute sex, national origin, handicap, age, (e.g., titles plus abstracts of papers in veteran status, or sexual orientation. Collector’s Series #36
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