The Effect of Measuring Magnetic Susceptibility of Water Samples by Starting with Isothermal Remanent Magnetization (IRM) before Anhysteretic Remanent Magnetization (ARM)

The present study focuses on two post-orogenic plutons, the Athos (Grigoriou) and Samothraki granites, as well as the Samothraki volcanics, located in the vicinity of the North Aegean Trough. A detailed palaeomagnetic study was carried out, with the aim of constraining the age and mechanism of tectonic rotations. In addition, anisotropy of low field magnetic susceptibility (AMS) was studied and isothermal remanent magnetization (IRM) and thermomagnetic analyses were performed. Finally, a radiometric age for the Athos granite was obtained (43.3 ± 1.0 Ma K/Ar biotite). The measured declinations indicate clockwise rotations of the Athos (16.6°) and Samothraki (36.3°) blocks. The age of rotation is constrained to be <18 Ma at Samothraki, whereas the much smaller rotation of the Athos block can only be dated as younger than Eocene. Comparing the new palaeomagnetic data to the published dataset for Northern Greece, we suggest that the palaeomagnetically determined rotations in the vicinity of the North Aegean Trough are dominantly of post-Early Miocene age, and are controlled by major strike-slip faults and distributed "small" or minor faults.

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Application of the pseudo-Thellier technique to a paleomagnetic record from lake El Trébol (Patagonia, Argentina)

Geofísica Internacional ◽

10.22201/igeof.00167169p.2008.47.4.2144 ◽

2008 ◽

Vol 47 (4) ◽

pp. 319-327

Author(s):

C. S. G. Gogorza ◽

S. Torcida ◽

A. M. Sinito ◽

M. A. E. Chaparro

Keyword(s):

Magnetic Susceptibility ◽

Error Estimates ◽

Sediment Core ◽

Standard Method ◽

Remanent Magnetization ◽

Reasonable Agreement ◽

Natural Remanent Magnetization ◽

Isothermal Remanent Magnetization ◽

Low Field ◽

Relative Paleointensity

The pseudo-Thellier technique was applied to obtain relative paleointensity determinations using a sediment core from Lake El Tre?bol (Patagonia, Argentina). Measurements of intensity of natural remanent magnetization left (NRMleft) after AF demagnetization versus intensity of anhysteric remanent magnetization gained (ARMgained) at the same peak were carried out on a set of samples. Two versions of a jackknife resampling scheme were used to get error estimates on the paleointensity. The pseudo-Thellier paleointensity records were compared with the authors previous results where the remanent magne- tization at 20mT (NRM20mT) has been normalized using the anhysteric remanent magnetization at 20mT (ARM20mT), the satu- ration of the isothermal remanent magnetization at 20mT (SIRM20mT) and the low field magnetic susceptibility (k) (Gogorza et al., 2006). The pseudo-Thellier record shows a reasonable agreement with the standard method of normalization (NRM20mT/ ARM20mT).

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Late Holocene Changes in Precipitation and Hydrography Recorded in Marine Sediments from the Northeastern Caribbean Sea

Quaternary Research ◽

10.1006/qres.2001.2249 ◽

2001 ◽

Vol 56 (1) ◽

pp. 87-102 ◽

Cited By ~ 33

Author(s):

Johan Nyberg ◽

Antoon Kuijpers ◽

Björn A. Malmgren ◽

Helmar Kunzendorf

Keyword(s):

Magnetic Susceptibility ◽

Puerto Rico ◽

North Atlantic ◽

Remanent Magnetization ◽

Caribbean Sea ◽

Isothermal Remanent Magnetization ◽

Low Latitude ◽

Saturation Isothermal Remanent Magnetization ◽

Magnetic Parameters ◽

Mineral Magnetic

AbstractWe present a record of climate variability spanning the last 2000 years obtained from sediment cores retrieved south and west of Puerto Rico in the northeastern Caribbean Sea. The records include lithological and mineral magnetic parameters as well as planktonic foraminifer data. For chronostratigraphic control, AMS 14C and 210Pb/137Cs measurements were made. Harmonic analysis of the values of the mineral magnetic parameters “saturation isothermal remanent magnetization” (SIRM), “anhysteric remanent magnetization divided by magnetic susceptibility” (ARM/χ), and “saturation isothermal remanent magnetization divided by magnetic susceptibility” (SIRM/χ) indicate the existence of a ∼200-year-long climate cycle in the northeastern Caribbean during the last 2000 years. The detected cycle may reflect changes in precipitation patterns over the low-latitude North Atlantic Ocean and surrounding continental areas. Higher organic carbon contents appear in the sediments both off southern and western Puerto Rico before and at the onset of the Little Ice Age around A.D. 1300 to 1500. This is indicative of increased run off and/or enhanced surface productivity possibly associated with more intense wind-induced upwelling. Major changes in the geochemical and mineral magnetic records around A.D. 850–1000 concur with changes in other records from the Caribbean and North African regions indicating a shift toward a more humid climate over the low-latitude North Atlantic.

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Anisotropy of out-of-phase magnetic susceptibility: an approach for magnetic subfabrics determination

10.5194/egusphere-egu21-2835 ◽

2021 ◽

Author(s):

Cláudia Cruz ◽

Helena Sant'Ovaia ◽

William McCarthy ◽

Fernando Noronha

Keyword(s):

Magnetic Susceptibility ◽

Remanent Magnetization ◽

Shape Parameter ◽

Direct Determination ◽

Anhysteretic Remanent Magnetization ◽

The Matrix ◽

Low K ◽

Permanent Magnetization ◽

Bulk Response

The Anisotropy of Magnetic Susceptibility (AMS) represents the contribution of all minerals in rock samples (paramagnetic, diamagnetic, and/or ferromagnetic minerals). An intermediate AMS tensor may be recorded in rocks where a composite fabric is present, due to the presence of both paramagnetic and ferromagnetic minerals, being possible to be resolved into two distinct subfabrics using techniques as out-of-phase AMS (opAMS). The magnetic susceptibility measured in alternating field can be resolved into in-phase and out-of-phase components. In-phase AMS (ipAMS) measures the bulk response of all minerals in a sample however, opAMS is only sensitive to selected ferromagnetic minerals such as hematite, titanomagnetite, and ultrafine magnetite. The opAMS can be harnessed as a tool for direct determination of magnetic subfabrics defined by ferromagnetic minerals. This work focuses on three Portuguese plutons: Lamas de Olo, Lavadores-Madalena, and Santa Eul&#225;lia. The preliminary results show that magnetic susceptibility is lower in opAMS, the degree of magnetic anisotropy is much higher in opAMS and the ellipsoid shape parameter has no significant differences in opAMS or ipAMS. The ipAMS and opAMS tensors are in general coaxial, pointing out that standard AMS fabric is parallel to the subfabric of minerals like hematite, titanomagnetite, and ultrafine magnetite. Two sites from Lamas de Olo Pluton with low in-phase magnetic susceptibility (ipKm) values were also measured, showing two different scenarios: (i) the coaxially is present in one site, pointing out the presence of minerals like hematite (after magnetite) but with the same orientation as the matrix; (ii) different orientation of K1 and K3 in ipAMS and opAMS suggesting the presence of a ferromagnetic oxide like hematite (after magnetite) but with a different orientation from the paramagnetic minerals. Nevertheless, it should be noted that in samples with low Km values, the presence of ferromagnetic minerals is scarce (or absent) and the opAMS has minor accuracy (the associated error is greater). The opAMS findings attain similar results to the anisotropy of anhysteretic remanent magnetization (AARM) studies, once both are related to the presence of ferromagnetic minerals, and their magnetic properties. However, the opAMS does not require the permanent magnetization of samples and is measured simultaneously with the ipAMS. With further works, a larger number of samples will be measured to accomplish more information, and AARM measurements will be performed on the same samples to compare the ipAMS, opAMS, and AARM tensors.Acknowledgements: This work was funded by the Funda&#231;&#227;o para a Ci&#234;ncia e a Tecnologia (FCT) under UIDB/04683/2020 project.

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Mineralogy and Magnetic Behavior of Yellow to Red Xuanhua-Type Agate and Its Indication to the Forming Condition

Minerals ◽

10.3390/min11080877 ◽

2021 ◽

Vol 11 (8) ◽

pp. 877

Author(s):

Danyi Zhou ◽

Guanghai Shi ◽

Suzhen Liu ◽

Bailing Wu

Keyword(s):

Raman Spectroscopy ◽

Magnetic Susceptibility ◽

Iron Oxides ◽

Fluid Inclusions ◽

Remanent Magnetization ◽

Magnetic Behavior ◽

Homogenization Temperature ◽

Isothermal Remanent Magnetization ◽

Magnetic Minerals ◽

Forming Condition

Iron oxides/hydroxides are important magnetic minerals to provide information about changes in the forming environment. However, the magnetic behavior in agate has been rarely investigated. In this study, the magnetic behavior of the Xuanhua-type agate with intense yellow to red colors from the Xuanhua District (China) was investigated by temperature dependence of magnetic susceptibility, hysteresis loop, isothermal remanent magnetization and the analysis of remanent coercivity components from the gradient acquisition plot. Yellow goethite and red hematite can be quantitatively identified by XRD and Raman spectroscopy due to their relatively higher content. Results showed that the red, yellow and orange Xuanhua-type agate had different magnetic behavior, and magnetite existed in the yellow and orange ones. Fluid inclusions in such agate had the homogenization temperature of ~168 °C to 264 °C. All results suggested that the dehydration of goethite to form hematite was the main reason for the high remnant coercivity (above 1000 mT) of hematite in the red agate. The co-existence of magnetite and goethite in the yellow and orange agate reflects the transformation from Fe2+ to Fe3+, indicating the change in the redox property of the environment. Unique patterns mainly formed by hematite and goethite make it a popular gem-material with high research value.

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Magnetic susceptibility and isothermal remanent magnetization in human tissues: a study case

BioMetals ◽

10.1007/s10534-015-9879-z ◽

2015 ◽

Vol 28 (6) ◽

pp. 951-958 ◽

Cited By ~ 8

Author(s):

H. Sant’Ovaia ◽

G. Marques ◽

A. Santos ◽

C. Gomes ◽

A. Rocha

Keyword(s):

Magnetic Susceptibility ◽

Remanent Magnetization ◽

Human Tissues ◽

Isothermal Remanent Magnetization ◽

Study Case

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Large field impressed anisotropy of magnetic susceptibility (AMS) in metamorphic volcanoclastic rocks from the western Central Pamir with ilmeno-hematite as the main magnetic carrier.

10.5194/egusphere-egu2020-2702 ◽

2020 ◽

Author(s):

Pierrick Roperch ◽

Jovid Aminov ◽

Guillaume Dupont-Nivet ◽

Stéphane Guillot ◽

France Lagroix

Keyword(s):

Magnetic Susceptibility ◽

Remanent Magnetization ◽

Strong Field ◽

Large Field ◽

Magnetic Characteristics ◽

Magnetic Carrier ◽

Isothermal Remanent Magnetization ◽

Clastic Rocks ◽

Magnetic Fabrics ◽

Degree Of Anisotropy

Field impressed AMS fabric, although it has been recognized for a very long time, has been the subject of very few publications in the paleomagnetic literature. This effect has been mainly described in samples with magnetite as a main magnetic carrier. This fabric is usually of low magnitude and observed mainly in nearly isotropic rock after application of static AF demagnetization or after acquisition of an isothermal remanent magnetization (IRM).&#160;Forty four paleomagnetic sites have been sampled in a >2 km thick sequence of Cretaceous volcano-clastic rocks from the western Central Pamir mountain (Tadjikistan).&#160;These rocks present a medium grade level of metamorphism characterized by fine grained recrystallisation of biotite.&#160;The magnetic properties are very homogeneous across the sequence. Bulk magnetic susceptibilities vary between 150-250 &#956; SI. The AMS magnetic fabrics correspond to triaxial tensors with a well defined foliation plane and a steeply dipping magnetic lineation. The degree of anisotropy varies between 1.03 and 1.2. This fabric was likely acquired during the deformation associated with the emplacement of Middle Miocene gneiss domes.&#160;SEM/EDS data indicate that the main iron oxide mineral is hematite with up to 15% of ilmenite in solid solutions. This is in agreement with unblocking temperatures of SIRM around 630 &#176;C, lower than the one of pure hematite.&#160;One of the most surprising magnetic characteristics of these rocks is the effect of strong-field remanent magnetizations upon the AMS. During the acquisition of an Isothermal Remanent Magnetization (IRM), the initial AMS is progressively obliterated by a new AMS fabric. The field-impressed AMS is characterized by a decrease of the magnetic susceptibility along the direction of the IRM and an increase in magnetic susceptibility in the orthogonal plane. The field-impressed AMS is thus mainly oblate with a degree of anisotropy usually between 1.2 and 1.4. As far as we know, such a strong effect has never been reported. In sandstone with detrital hematite as the main carrier, the degree of the induced AMS fabric is less than 1.02 suggesting that the ilmenite content in the metamorphic hematite is the main cause of the large observed field induced fabric in these rocks.&#160;

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Micromagnetic calculations of the effect of magnetostatic interactions on isothermal remanent magnetization curves: implications for magnetic mineral identification

Journal of Geophysical Research Solid Earth ◽

10.1029/2021jb022335 ◽

2021 ◽

Author(s):

Fan Bai ◽

Liao Chang ◽

Thomas A. Berndt ◽

Zhaowen Pei

Keyword(s):

Remanent Magnetization ◽

Magnetic Mineral ◽

Magnetization Curves ◽

Isothermal Remanent Magnetization ◽

Mineral Identification ◽

Magnetostatic Interactions

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anhysteretic remanent magnetization

Dictionary Geotechnical Engineering/Wörterbuch GeoTechnik ◽

10.1007/978-3-642-41714-6_11992 ◽

2014 ◽

pp. 51-51

Keyword(s):

Remanent Magnetization ◽

Anhysteretic Remanent Magnetization

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Linking cave sediments and soil magnetism in the Urșilor cave (Romania)

10.5194/egusphere-egu21-2973 ◽

2021 ◽

Author(s):

Cristian George Panaiotu ◽

Cristian Necula ◽

Relu D. Roban ◽

Alexandru Petculescu ◽

Ionut-Cornel Mirea ◽

...

Keyword(s):

Magnetic Susceptibility ◽

Frequency Dependence ◽

Remanent Magnetization ◽

Rock Magnetism ◽

Magnetic Mineral ◽

Magnetic Data ◽

Sediment Samples ◽

Superparamagnetic Particles ◽

Susceptibility Data ◽

Cave Sediments

Cyclical changes in the magnetic mineral assemblages have been observed in numerous sedimentary records confirming the relationship between rock magnetism and past global change. Several studies have shown that the magnetic susceptibility data of cave sediments reflect both long- and short-term climatic oscillations. These magnetic susceptibility variations are attributed to changes in climate-controlled pedogenesis which influence the production of low coercivity magnetic mineral phases, magnetite, and maghemite outside the cave. These soils with climate-dependent magnetic properties are then washed, blown, or tracked into the cave where they accumulate, creating the changes observed in rock magnetic data. We present a rockmagnetism study of the sediments from the Ur&#537;ilor cave and the soils above the cave. Our focus is the detailed characterization of the ferromagnetic mineralogy preserved in the cave sediments and its links with potential soil sources. In the cave, we sampled four sections (2-3 m high) consisting mainly of silts and clays, with some sand layers. The age of the sediments is older than 40 ka. At the surface, we sampled various types of soils from 9 sites. For all samples, we measured: variation of magnetic susceptibility with frequency (976 and 15616 Hz), the anisotropy of magnetic susceptibility, isothermal remanent magnetization, and anhysteretic remanent magnetization. Because soils are characterized by the presence of superparamagnetic magnetite produced by pedogenesis which can be detected by the frequency dependence of magnetic susceptibility, we also measured the frequency dependence of soils and selected cave sediment samples at 13 frequencies (between 128 and 512000 Hz). Multi-frequencies measurements of the magnetic susceptibility of recent soils show that all the sampled soils have a strong frequency dependence indicating the presence of superparamagnetic particles produced by pedogenesis. Most of the sediment samples have an important frequency dependence similar to the one observed in the recent soils. As a preliminary conclusion, we can state that most of the fine cave sediments contain superparamagnetic particles, which can be probably attributed to soils transported into the cave by erosion. These results suggest that during the deposition of high magnetic susceptibility sediments it was a climate favorable for intense pedogenesis. The interpretation of the intervals with lower values of magnetic susceptibility is still under investigation to decide if represents a climatic signal or a change in the dynamics of sediment transport. Acknowledgment: The research leading to these results has received funding from the EEA Grants 2014-2021, under Project contract no. EEA-RO-NO-2018-0126.

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